Bransjeordliste Absorbsjonsabsorpsjon er evnen til væsker og faste stoffer til å suge opp vann eller andre væsker, inkludert uønskede gasser, i naturgassbehandling. Access Access er et system hvor markedsaktører har lov til å bruke kapasitet i rørledning, nettverk, gassbutikk eller annet gassanlegg. Tilgang er sentral for gjennomføringen av liberaliseringen av gassmarkedet og kontraster, derfor med den tradisjonelle modellen der eiers av transportsystemer, butikker osv. Eier all gass som strømmer gjennom utstyret og fungerer som eksklusive kjøpmenn for det. Se også Common Carriage. Begrenset tilgang . Forhandlet tilgang. Tredjeparts tilgang. Acid Gas Acid Gas er naturgass som inneholder en andel av gasser som karbondioksid eller brensulfid, som i kombinasjon med fuktighet danner sure forbindelser. Årlig Kontrakt Antall Årlig Kontrakt Antall (ACQ) er volumet av gass som Selger må levere og Kjøper må ta i et gitt kontraktsår. Det kan uttrykkes som et diskret nummer eller som et flertall av den daglige kontrakten. I praksis er mange kontrakter skrevet i skjemaer som gjør at Kjøperen kan ta betydelig under den angitte ACQ. Se også Nedadgående Mengde Toleranse. Årlig leveringsprogram Det årlige leveringsprogrammet (ADP) er en tidsplan for gassvolumer som skal leveres på bestemte datoer eller innenfor bestemte perioder i et kommende kontraktsår i en langsiktig kontrakt. I praksis vil dette ofte ha formen av en detaljert tidsplan som dekker de første månedene, med færre tall for resten av året, som deretter styrkes til tider fastsatt i kontrakten. Aquifer En Aquifer er en kropp av porøs stein mettet med vann. Gassfelt er vanligvis underlag av en akvifer som ofte gir trykk kjent som Water Drive for å hjelpe gassproduksjon. Underjordisk lagring av gass kan oppnås ved å pumpe gass ned i vannkilder under ugjennomtrengelige kappstein, og dermed effektivt lage et gassreservoar. Se også Reservoar. Underjordisk lagring. Arbitrage Arbitrage kjøper og selger det samme produktet på to forskjellige steder eller markeder for å utnytte forskjeller i pris. Associated Gas Associated Gas er gass som sameksisterer med olje i et overveiende oljefelt. Det kan være Cap Gas eller Solution Gas. Atferd og behandling av disse er forskjellige. Tilknyttet gass vil normalt bli solgt som selgerens nominasjonsgass, dvs. selgeren nominerer volumene gass tilgjengelig. På tradisjonelle gassmarkeder vil en slik gass gi en lavere pris enn ikke-tilknyttet gass. Autogenerasjon Autogenerasjon er generering av elektrisitet ved industrielt bekymring, hovedsakelig for å møte behovene til egen virksomhet. Se også Kombinert varme og kraft. Backhauling Backhauling er transport av gass tilsynelatende i motsatt retning til hovedstrømmen av rørledningen. Dette oppnås vanligvis ved bytteordninger i stedet for fysiske bevegelser. Også kjent som Reverse Flow. Balanserende avtaleavtaler for avtaler brukes til å definere prosedyrer for kapasitetsutnyttelse i rørledninger eller produksjon fra et gassfelt: 1) Rørledninger: En avtale for en rørledning er en avtale mellom en rørledningseier og andre brukere av rørledningen om prosedyrene for å vedtas for å sikre at gassvolumer som kommer inn til og fjernes fra rørledningen, er like over en gitt tidsperiode. Rørledninger krever vanligvis daglig balansering, men noen krever balansering i kortere perioder, ned til en time, spesielt der det er en kraftig kraftproduksjonsbelastning på rørledningen. Andre kan tillate lengre perioder, f. eks. 3 dager opp til månedlig. Månedlig balansering er bare hensiktsmessig der tredjepartsbelastninger er svært små (noen få prosent) i forhold til de viktigste brukerne. 2) Reserver: En avtale for reserver er en avtale mellom eierne av et gassfelt som markedsfører sine aksjer av gassen uavhengig av hverandre. Siden hver kjøper har et annet etterspørselsmønster, er eierne enige om at de ikke vil trekke reserver med en hastighet som vil føre til ubalanse i eierskapet til de gjenværende reserver, overstiger visse avtalt toleranser. Avtalen definerer også de rettsmidler som skal tas hvis disse toleransene overskrides. Hensikten er å sikre at eierandelen av de resterende reserver forblir konstant for alle praktiske formål. Base Load Base Load er leveringshastigheten (eller etterspørselen) under hvilken sendout (eller etterspørsel) ikke forventes å falle i en gitt periode. Strandpris Strandpris er et begrep som hovedsakelig brukes i Storbritannia, for å definere prisen som offshore gass overføres av produsenten ved utgangen fra landbasert behandlingsanlegg, hvoretter eierskap overføres før videre overføring eller bruk. Blastovn Gass produsert som et biprodukt fra bruk av cola i tradisjonelle høyovner. Denne gassen hadde lav kaloriværdi (omtrent en fjerdedel til en tredjedel av naturgass), men ble blandet med produsert gass i dagene før naturgass. Blokk A-blokk er et geografisk område som er definert i en konsesjonsavtale, ofte prefixed av Exploration, Development eller Production. Ofte definert med hensyn til breddegrad og lengdegrad, men kan også defineres ved henvisning til et lokalt rutenett, for eksempel i Mexicogolfen. Blåsing En metode for å produsere et gassondensatreservoar ved å la reservoartrykket falle som gass, produseres over tid uten å injisere noen gass igjen. Med denne produksjonsmetoden kan noe kondensat kondensere i reservoaret, hvor gjenvinningen ikke lenger er et praktisk forslag. Koker av gass (BOG) Koking off er et begrep som brukes i LNG-prosjekter. Men godt isolerte LNG lagertanker kan være, LNG er alltid på sitt kokpunkt, og små mengder vil fortsette å koke av. I flytende anlegg er det nødvendig med et lite volum av koker av gass for å sikre at anleggets flare er i drift. Koking av ikke nødvendig for dette formålet vil normalt bli brukt i anleggets eget lavtrykksbrennstoffsystem. På LNG-tankskip drevet av dampturbiner blir gassen vanligvis brukt som drivstoff for å kjøre skipene. Grensepris Prisen for hvilken gass selges ved grensen mellom to land. Vanligvis basert på toll eller andre offisielle importexportdata. Ofte brukt, spesielt i Europa, som et referansepunkt i gass kontrakter. Bensin Gas LPG. Vanligvis Butan eller Propan lagres i flytende tilstand ved moderat trykk i stålbeholdere til bruk i små boliger og kommersielle applikasjoner. Bundet Levering av ulike tjenester, for eksempel transport, lagring etc. i en obligatorisk pakke som kjøperen må godta totalt, uten å kunne velge hvilke elementer det krever. Se også Unbundling. Butan Et medlem av alkan-gruppen av hydrokarboner med fire karbonatomer i molekylet (C4H10, ofte forkortet til C4 i ikke-teknisk bruk). Butan er en fargeløs, brennbar gass ved normal temperatur og trykk, men er lett flytende ved trykk for lagring og transport. Det er to isomere former, normal og isobutan. Ved atmosfærisk trykk fortynnes isobutan ved 1200 ° C og normalt butan ved -100 ° C. Kvalitetsverdi (CV) Kalkværdi er mengden varme som produseres ved fullstendig forbrenning av drivstoff. Dette kan måles tørt eller mettet med vanndamp og netto eller brutto. Se også Bruttokalorverdi. Netto kalorierverdi. Cap 1. En klausul i en leveranseavtale hvor kjøperen er trygg på at han ikke må betale mer enn en gitt maksimumspris. Denne typen kontrakt er analog med et anropsalternativ. 2. I en Leverandekontrakt hvor kjøperen har fleksibilitet i det volumet det kan kreve, det maksimale som det har rett til enten over en periode (for eksempel et år) eller i løpet av kontraktens løpetid. Cap Gas Gass funnet i en Gaskett i forbindelse med olje, men ikke i forbindelse med det. Kapasitetsavgift En kapasitetsavgift er betalingen som er gjort for å reservere kapasitet i en rørledning, en gassbutikk eller annen infrastruktur. Ofte brukt sammen med etterspørselsavgift. Kapasitetshandel Kjøp og salg av oppkjøpte rettigheter til å flytte gass gjennom rørledninger til en Transporter. Kullsekvestrasjon og lagring Fangst av karbonutslipp til atmosfæren og lagring i karbonvask, hvilket kamera er naturlig, eller kan være utarmede hydrokarbonerfelt. Carbon Trading En systematisk prosedyre for utveksling av tillatelser for å produsere karbonutslipp. Se EU ETS. Videresende En avsetning innenfor en langsiktig Take or Pay-kontrakt hvor en kjøper som tar mer enn sin årlige kontraktskvantitet i et hvilket som helst år, er tillatt, under betingelser som er definert i kontrakten, å kompensere dette mot å påta seg i senere år som ellers ville ha pådratt seg noen form for sanksjon, for eksempel Take or Pay. Noen ganger kjent som Advance Make Good. Casing Head Petroleum Spirit (CHPS) Et alternativt navn for kondensater og spesielt for de som slipper ut ved eller nær brønnhodet. Hovedsakelig brukt i Nord-Amerika. Churning Churning er et begrep som brukes i gasshandel for å indikere antall ganger i gjennomsnitt at gass handles mellom innledende salg og sluttbruk. City Gas City gass er et begrep som brukes i enkelte deler av verden, for eksempel Egypt, India, Japan, Korea, for å referere til gass distribuert til kunder gjennom et lokalt distribusjonsanlegg, nedstrøms City Gate. Slike kunder vil være en blanding av boliger, kommersielle og industrielle avhengig av spesielle lokale forhold, men vil typisk utelukke kraftgeneratorer. I den siste byen kan gass ha vært gass produsert av kull og olje, men er nå overveiende naturgass. Se også bygass. City Gate Det punktet som et lokalt distribusjonssystem, som ofte er basert på en by eller by, aksepterer gass fra et overføringsfirma eller - system. En overføringspris på dette punktet kalles en City Gate-pris. Kullsengmetan (CBM) Kullsengmetan er metan som er eller kan gjenvinnes fra kullsømmer. Også kjent som Coal Seam Gas. CBM gjenvinnes ved å bore brønner i egnede kullsømmer og deretter redusere trykk i fjellet, vanligvis ved å pumpe ut vann, som kan være saltvann og presentere miljøproblemer, inntil metanet kan desorberes fra kullet. CBM, i motsetning til konvensjonell naturgass, er ikke fanget under en sel, men adsorberes i kullet. Det kan derfor forekomme i kullavsetninger som er sidelengs svært omfattende. Produksjonshastigheten er vanligvis mye mindre enn for konvensjonell gass. Utløpsrater er vanligvis ganske sakte og brønner kan produsere i mange år. CBM kan også produseres som et sikkerhetstiltak før kull blir utvunnet for å redusere forekomsten av eksplosive gassblandinger under gruvedriften. Se Kullminne Metan. Kullgasskull Gass er gass produsert av destruktive destillasjon av bituminøst kull. Hovedkomponentene er hydrogen (mer enn 50), metan (10 til 30) karbonmonoksid og høyere hydrokarboner. Vanndampen i kullgass holdt gamle rørleddene tette og reduserte dermed tap av gass. Hvis naturgass blir introdusert i samme rør uten korrigerende tiltak, kan det forekomme betydelige tap. Karbonmonoksidet er selvsagt giftig. Inhalering av kull gass var en favorisert måte å begå selvmord i byer med kullgassdistribusjon. Kullminnemetan (CMM) Metan gjenvunnet fra kullgruver, enten under aktiv eller etter forlattelse, som kan brukes i lokal kraftproduksjon eller varmeproduksjon. Det er sjelden tilgjengelig i tilstrekkelig mengde for å rettferdiggjøre behandling til rørledningskvalitet for levering til et rørledningssystem. Se: Coal Bed Metan. Coke Oven Gasskoksovnsgass er produsert som et biprodukt av koking av kull og var samtidig en hovedbestanddel av produsert gass. Kombinert syklusgassturbin En kombinert syklusgassturbin (CCGT) er en type kraftproduksjonsanlegg hvor varmen som genereres ved forbrenning av gassene, blir brukt to ganger. For det første blir gassen brent for å drive en Gassturbin. Deretter passerer de varme eksosgassene gjennom en varmeveksler for å heve damp til en sekundær dampturbineenhet. Kombinert syklusanlegg har en termisk effektivitet ca 50 større enn en vanlig enkel eller åpen turbin. Kombinert varme og kraft (CHP) Kombinert varme og kraft (CHP) er bruken av et enkelt enhetlig system for å levere både varme - og kraftkravene til et prosjekt, og minimere spild av varme. Kraften er produsert gjennom Gass Turbines eller en annen føreren. Avgassvarmen benyttes til andre krav enn strømgenerering. Også kjent som kraftvarme og total energi. Varekostnad Tidsavgift for en avgift for hver enhet av gass som faktisk er tatt eller transportert. Kan være i volumetriske eller varmeenheter. Skille mellom stående kostnader og etterspørselsavgift. Common Carriage Common Carriage er et begrep som ofte brukes om hverandre med Open Access og Third Party Access, men som faktisk er mer spesifikk. I et felles transportsystem får alle søkere om kapasitet (for eksempel i rørledning eller butikk) tilgang på like vilkår. Hvis totalvolumet som er forespurt, overskrider tilgjengelig kapasitet, reduseres bruken av alle parter pro rata: kapasiteten er rantet blant brukerne. Under åpen tilgang, hvis søkere søker mer kapasitet enn det er tilgjengelig, fordeles kapasiteten på først til mølle basis eller et betal-til-bok-system som tillater kapasitet å bli kontrahert for og handlet akkurat som å leie og subletting plass i en bygning . En rørledning eller butikkeier som også ønsker å bruke litt kapasitet for seg selv, må, i henhold til Open Access, gjøre det gjennom en armlengdes tilknyttet, hvis kommersielle forhold til kapasitetsleverandøren er transparent identisk med andre brukeres. Åpen tilgang er nødvendig på amerikanske rørledninger, der det er kjent som kontraktstransport. I Europa er begrepet Open Access noen ganger brukt likt som synonymt med Tredjeparts tilgang, for å definere tredjepartes rett til å bruke rørledningen eller utstyret til et annet selskap. I sin generelle form omfatter den Open Access, Common Carriage, Negotiated Access og Regulated Access. Et aspekt ved tilgang fra tredjepart er at det ikke i seg selv innebærer noen løsning på diskrimineringsspørsmålet mellom partene ved hjelp av fasilitetene. Se også Begrenset tilgang. Komprimert naturgass (CNG) CNG er naturgass komprimert i gassflasker, hovedsakelig brukt som et alternativ til flytende brensel i kjøretøyer. CNG forblir en gass uavhengig av mengden press. Ikke forveksles med flytende petroleumsgass. Kompressorstasjon Gass taper trykk da det reiser lange avstander gjennom rørledninger. For å sikre en jevn strømning og et tilstrekkelig trykk på uttakspunktet, må det komprimeres på kompressorstasjoner, typisk plassert hver 60 km til 100 km langs landtransportrørledninger. Offshore og i avsidesliggende områder kan det være praktisk og foretrukket å opprettholde høyere trykk og tillate større avstander mellom kompressorstasjoner. På store rørledninger drives kompressorer normalt av gasturbiner. Mindre rørledninger kan bruke dieselmotorer. Konsesjon En lisens tildelt enten av et statlig eller statlig oljeselskap. Det definerer et område, ofte referert til som en blokk. gitt til et selskap eller en gruppe av selskaper for leting, produksjon eller transport av olje og gass under bestemte vilkår og betingelser og for en fast periode. Konsesjonsområder blir ofte tildelt for leting. Hvis dette lykkes, defineres et mindre område, innenfor leteblokken, for å være en produksjonsblokk. Kan også brukes på tillatelser til å bygge rørledninger, kraftverk etc. Kondensatkondensat er en naturgassvæske med lavt damptrykk, produsert fra et reservoar med høyt trykk og temperatur. Kondensat vil skille seg naturlig fra en rørledning eller et separasjonsanlegg gjennom den normale kondensasjonsprosessen. Kan referere til en blanding av relativt lette karbonhydrater som forblir flytende ved normal temperatur og trykk. Det vil bli noe propan og butan oppløst i det. I motsetning til råolje. den inneholder lite eller ingen av de tunge hydrokarbonene som utgjør tung fyringsolje. Det er tre hovedkilder til kondensat: a) Flytende hydrokarboner som produseres fra et gassondensatreservoar. Disse kan bare være litt skillebare fra en lysstabilisert råolje. b) Flytende hydrokarboner som gjenvinnes ved overflaten fra ikke-assosiert gass. c) Flytende hydrokarboner som skilles ut når rå gass behandles. Dette kondensatet består vanligvis av C5 til C8. Kondenserende kjele En kondenserende kjele er en vannvarmer som er konstruert for økt effektivitet ved å bruke røykgasser ellers ventilert til atmosfæren for å forvarme vannet i kjelen. Tilkoblingsavgift Noen ganger brukes det som et synonym for Standing Charge, men mer riktig definert som et beløp som skal betales av kunden i en engangsbeløp eller avdrag for en forbindelse til leverandørsystemet. Entreprenør Et begrep som har en bestemt betydning i en produksjonsdelingsavtale. Entreprenøren er selskapet (vanligvis et produserende selskap) som forplikter seg til å utforske andor produsere for vertsregeringen i retur for definerte mengder av produsert gass eller olje. Konvergens En løst definert term som refererer til den økende bruken av naturgass i generering av elektrisitet. Når generasjonen blir helt eller i stor grad avhengig av naturgass, konvergerer gassleverandørens og kraftgeneratorens interesser, og det oppstår mulighet for å bytte gass mellom generasjon og direkte forsyning, avhengig av prisen tilgjengelig for hvert uttak. Prisene konvergerer når det ikke er noen fordel i bytte. Cost Gas Cost gass er gassen som en entreprenør anskaffer under en produksjonsdelingsavtale for å dekke kostnadene ved sin virksomhet i henhold til kontrakten. Kontraktøren driver normalt på egen risiko, og hvis det ikke oppdages noen hydrokarboner, er kostnadene helt for sin konto. Se også Profittgass. Kritisk trykk Minimumspresset som må påføres en gass før det kan flytes. Kritisk temperatur Temperaturen over hvilken en gass ikke vil væske, uavhengig av det påtrykte trykket. Råolje En blanding av hydrokarboner som eksisterer som væske i naturlige underjordiske reservoarer og forblir flytende ved atmosfæretrykk etter å ha passert gjennom overflatesepareringsanlegg. Råmateriale er råmaterialet som raffineres til bensin, oppvarmingsolje, jetbrensel, propan, petrokjemikalier og andre produkter. Kryogenikk Prosessen med å produsere, vedlikeholde og benytte svært lave temperaturer (under -46C - 50F). Relevant i LNG-virksomheten. Pute Gasspute Gass er igjen i en gassbutikk for å gi trykket som trengs for å produsere lagret gass, men som i seg selv forblir ufremstilt. Det er vanligvis av størrelsesorden 50 av det totale lagrede volumet for et akvatisk og utarmet felt, men mindre for andre lagringsformer. Når butikken er opprinnelig etablert Pute Gas, med mindre det er uproducerte reserver som er igjen i et delvis uttømt felt, kan det være en stor del av kapitalkostnaden. Pute Gass kan til slutt brukes når butikken er nedlagt. Også kjent som Base Gas. Daglig gjennomsnittlig send-out Total volum av gass levert over en periode, dividert med det totale antall dager i perioden. Daglig kontraktsmengde (DCQ) Mengden gass som en Kjøper nominelt forplikter seg til å kjøpe, og en Selger forplikter seg til å levere i en definert 24-timers periode. Selv om det finnes mange kontrakter, har dette uttrykket i seg selv lite betydning. Det kan tjene som et middel til å uttrykke årlig kontraktskvantitet dersom sistnevnte uttrykkes som et antall dager multiplisert med DCQ. Det kan også definere hastigheten som selgeren må kunne levere gass til. Se også: Daglig leveringsfrekvens. Daglig leveringsfrekvens Den daglige leveringsfrekvensen (DDR) er den hastigheten der selgerne skal kunne levere gass, uttrykt som et volum gass per dag, eller som et flertall av det daglige kontraktsmengden. Også kjent som Maksimal daglig mengde. Daily Peak Daily Peak er det maksimale gassvolumet som kan eller må leveres på en hvilken som helst dag i en gitt periode (vanligvis ett år). Dedikasjonskontrakt En Dedikasjonskontrakt er den rette termen for en utløpsavtale. under hvilken hele produksjonen fra et gassfelt er kjøpt og solgt. Grad Dag En grader dag er et mål på gjennomsnittstemperatur over en dag, og er vanligvis relatert til en temperaturgrense. For eksempel er en faktisk gjennomsnittstemperatur på 5C på en dag 2 grader dager varmere enn en forventet gjennomsnittstemperatur på 3C. Kan også brukes til å måle kumulativt kaldt vær over en periode. Dermed hvis sesongmessig normal temperatur i en måned er 18C og gjennomsnittlig faktisk temperatur gjennom måneden forventes å være 8C, vil måneden være 10 x 30 300 grader dager kaldere enn normalt. Leveres Et begrep som hovedsakelig brukes i LNG-fraktkontrakter for et arrangement hvor selgeren er ansvarlig for å arrangere og betale for frakt av gassen, og tittel passerer i leveringshavnen. Vanligvis er selgerens risiko større i en levert transaksjon fordi kjøperen bare betaler for den landede kvalitetskvantiteten, og Boil Off Gas er selgeransvaret. Selger er ansvarlig for oppklaringen gjennom toll og betaling av alle plikter, med mindre kontrakten fastsetter noe annet. Et alternativt navn på en Levert kontrakt er Ex Ship. Svært lik levering er kostnaden, forsikring og frakt (CIF). Dette er et arrangement hvor selger ordner og betaler for frakt og forsikring, som for en Leveret kontrakt, men risiko og tittel overføres fra selger til kjøper på en måte som er definert i avtalen (f. eks. Ved forsendelse eller ved levering av konnossement til kjøperen). CIF og Delivered blir ofte, men feilaktig, behandlet som om de var identiske fordi kostnadene til selgeren er de samme. Under en CIF-kontrakt, kan selgeren imidlertid unngå å være i besittelse av lasten innenfor jurisdiksjonen til kjøperlandsstaten. Dette kan være viktig for finanspolitiske eller juridiske grunner. Det tredje arrangementet som ofte møtes i frakt av LNG, er Free on Board (FOB), som brukes til å betegne leveranser hvor kjøperen ordner seg for frakt, og det er levering og endring av tittel på det tidspunktet lasten lastes inn i send på lasteporten. Etterspørselsavgift En månedlig eller årlig avgift betalt av en Kjøper for en nominert, reservert topp eller for det faktiske toppvolumet av gass tatt i en time eller dag i en gitt periode. Dermed kan et typisk uttrykk være dollar per tusen kubikkmeter topp timekapasitet per måned. Ofte brukt utveksling med kapasitetsavgift, selv om det kan argumenteres for at i strengt logikk, bør kravet om betaling på gassavgift og kapasitetsavgift til en transportavtale gis. Avhendingskontrakt En uttømmelseskontrakt er en produksjonssalgskontrakt der salgsvolumene i hovedsak styres av ytelsesegenskapene til det aktuelle gassfeltet. Et oppbyggingsmønster, et forventet platå og en metode for å bestemme nedgangsmengder vil bli definert i utgangspunktet, men kan endres ettersom produksjonsegenskapene til feltet bedre forstås gjennom driftserfaring. Kjøperen påtar seg således en stor andel av produksjonsrisikoen. Se også Dedikasjonskontrakt og Leverandekontrakt. Utløpsdriftsreservoar Et gassreservoar hvorfra gass gjenvinnes ved ekspansjon når gasstrykket faller med produksjon av gass opprinnelig på plass. Reservoaret kan derfor behandles som om det var en lukket tank. Gjenvinningsfaktorer på opptil 90 av gassen på plass kan oppnås. I slike reservoarer er det ingen vannkjøring. Deregulering Deregulering er reduksjonen i rollen som tilsynsorganer som vanligvis er forbundet med økt åpen konkurranse, og oppnås ved forenkling av regelverket. Deregulering bør ikke forveksles med liberalisering, noe som kan kreve innføring av transparente reguleringsprosesser. Derivater Derivater er finansielle instrumenter i utgangspunktet basert på handel med en fysisk vare, inkludert gass og andre former for energi. Se også Futures. Bytteavtaler. Duggpunkt Temperaturene under hvilke enten hydrokarboner (hydrokarbon duggpunkt) eller vann (duggpunkt) vil begynne å kondensere ut av en gitt gassstrøm. Kondensering reduserer nøyaktigheten av måling og skaper ulempen av væske sluger i rørledninger, som må slettes regelmessig ved å lede en gris om rørledningen. I tillegg kan vann reagere med karbondioksid eller hydrogensulfid i gassstrømmen for å danne syrer og med metan selv under passende betingelser for å danne hydrater. Derfor, i behandlingsstadiet, blir vannet normalt fjernet fra gasstrømmen for å redusere duggpunktet til et sted rundt -10 ° C ved standard rørledningstrykk. Distribusjon Den endelige fasen i transport av gass (og elektrisitet) og salg til sluttbrukere gjennom mellomstore rørledninger og lavt trykk med lav diameter. Retikulasjonsnettet. Diurnal Storage Bokstavelig talt, daglig lagring. Kortsiktig eller topplagring av gass i rørledninger eller gassholdere, for å møte lokale, daglige svingninger i etterspørselen, i motsetning til sesongbasert lagring. Mangfoldsfaktor Forholdet mellom summen av de individuelle maksimale kravene til flere forbrukere eller belastninger, til deres samtidige maksimale etterspørsel. Vanligvis mindre enn 1 for å gjenspeile at ikke alle kunder forventes å ta sitt høyeste krav samtidig. Se også Lastfaktor. Nedstrøms Disse aktivitetene i gasskjeden nærmest sluttkunder. Se oppstrøms. Nedadgående Mengde Toleranse (DQT) Nedre Mengde Toleranse (DQT) er det beløpet som en kjøper kan falle fra sin fulle årlige kontraktsmengde i en Take or Pay gass salgskontrakt uten å pådra seg sanksjoner. Hvis det ikke er noen bestemmelse som krever at kjøperen skal ta tilleggsmengder i påfølgende år for å klare seg for mangelen, blir årlig kontraktskvantum i kraft ACQ minus DQT. Se også Gjøre godt og sminke opp. Tørr gass Et alternativt navn for Lean Gas. Det betyr ikke fri for vann, men i noen tilfeller kan det være. Tørrgassfelt Et reservoar som vil gi tørrgass og meget små mengder kondensat, vanligvis mindre enn 10 fat per million kubikkfot. Dette tilsvarer 350 barrelsMMcm eller 60 kubikkmeter oljeMMcm gass antatt 0,159 barrelscubic meter. Tørrhull. Et borehull som ikke kan produsere kommersielle mengder olje eller gass. Konvensjonelt er begrepet brønn begrenset til et borehull som kan produsere olje eller gass. EFET European Federation of Energy Traders. En pressegruppe av europeiske energiselskapsfirmaer dedikert til å stimulere og fremme energihandel. Effektivitetseffektivitet, eller varmeeffektivitet, er forholdet mellom energiproduksjon og energiinngang i en prosess. En av de hyppigst oppdagede bruken av dette forholdet i gassindustrien er bruk av gass for kraftproduksjon, hvor strømforsyningen er uttrykt som en prosentandel av gassen som forbrukes, målt på grunnlag av en felles enhet, f. eks. kWh. Det må tas vare på å skille mellom netto og brutto effektivitet. Se også Bruttokalorverdi. Netto kalorierverdi. Sluttbruker Forbruker av gass, i bolig, næringsliv eller industri. Den endelige aktøren i gasskjeden. Entry-Exit En inngangs-avgangssystem er en der en gassleverandør belastes en inngangspris for å sette gass inn i et overførings - eller distribusjonsnett på et definert inngangspunkt og en utgangspris for fjerning av gassen ved et bestemt utgangssted. Prisene kan reflektere overbelastning ved inngangs - og utgangspunkter, men er de samme for alle brukere. Systemet kan være i motsetning med punkt-til-punkt-systemer, hvor transportkostnader avhenger av den faktiske eller teoretiske avstanden som tilbys av hver forsendelse av gass. Entry-Exit er sterkt favorisert av EU som et middel til å fremme gassliberalisering. ERGEG Den europeiske tilsynsmyndighetens gruppe for elektrisitet og gass. ERGEG er Europakommisjonens formelle rådgivende gruppe energiregulatorer. ERGEG ble etablert av Europakommisjonen i november 2003 for å bistå Kommisjonen med å skape et EU-marked for elektrisitet og gass. ERGEGs medlemmer er lederne av nasjonale energiregulerende myndigheter i EUs medlemsstater. Etanetan (C2H6, ofte forkortet til C2 i ikke-teknisk bruk) er en av de viktigste bestanddelene av naturgass sammen med metan. Koker ved -84.4C. Ved normale temperaturer er det en tørr, fargeløs og luktfri gass. Et råmateriale for etylenproduksjon. Etylen Også kjent som eten. En fargeløs gass (C2H4) produsert ved å knekke Hydrocarboner som etan eller nafta og brukes som råmateriale for petrokjemikalier, som for eksempel fibre og mange plastmaterialer. Koker ved -103.7C. EU ETS European Union Emissions Trading System. Den største multi-nasjonale, utslippshandelsordningen i verden, og en stor søyle i EUs klimapolitikk. Overflødig Gass Overflødig Gass er enten: a) Gass tatt til en pris som overstiger Daglig Leveringsfrekvens til en premiepris eller b) Gass tatt over årlig kontraktskvantitet. Avhengig av vilkårene i kontrakten og leveringsstatusen, kan slik gass kvalifisere som Carry Forward. Gjøre god eller sminke gass. Federal Energy Regulatory Commission (FERC) En amerikansk føderal myndighet som har ansvar for å regulere interstate gassindustrien. Har ingen jurisdiksjon over gassrørledning og forsyning der handelen er helt innenfor enkelte stater. Kullsyre som brukes som råmateriale i en industriell prosess, ikke som drivstoff. De viktigste bruk av naturgass som råmateriale er i produksjonen av ammoniakk og ammoniakkbaserte gjødsel og metanol. Et potensielt stort marked er bruk av gass for å lage syntetiske oljeprodukter som motorbensin og middeldestillater (se gass til væske). Kan også brukes til å betegne råmaterialet som brukes til å produsere elektrisitet, men statistiske oppsummeringer av gassforbruk skiller normalt denne bruken fra kjemiske råmaterialer. Se også Middle Distillate Synthesis. Feltvurdering Prosessen med å kvantifisere reservenivåer og produksjonspotensial for et nyoppdaget petroleums - (olje og gass) reservoar, vanligvis ved å bore en eller flere avgrensnings - eller vurderingsbrønner. Fast gassgass som en leverandør forplikter seg til å levere til en kjøper på vilkår som er angitt i kontrakten, uten avbrudd. Se også: Avbrytbar gass. Fischer-Tropsch-prosess En kjemisk prosess for å omdanne syntetgass til paraffiner ved polymerisering. Opprinnelig utviklet i begynnelsen av det 20. århundre for å lage bensin fra kull. Nylig forskning har identifisert katalysatorer som i stor grad øker effektiviteten av prosessen ved å lage svært lange voksholdige produkter, som deretter kan omdannes til meget høye kvalitet flytende brensel ved konvensjonell sprekkdannelse. Se midnatestillatsyntese. Brennbarhetsgrenser Minimums - og maksimumsandelene av gass i luften der gassen vil antennes. For naturgass ligger disse grensene omtrent mellom 5 og 15. Flaring Prosessen med å brenne uønsket naturgass eller olje. In the case of gas, usually occurs when it is associated with oil and cannot be economically exploited or re-injected. Now less prevalent, as governments seek to profit from the increased value of gas and reduce the advert environmental impact of burning hudrocarbons. Floating LNG Floating LNG (FLNG) is the use of purpose built or converted ships to enable regasification of LNG (and liquefaction) to be carried out offshore. FLNG has the advantage that LNG production and importation can start more quickly than could happen onshore, where lead times are often lengthened by the local approval process. It also enables the processes to move location to satisfy short term demand. Force Majeure A contractual term used to define circumstances in which a party to a contract is not obliged to carry out its obligations because of major events outside its control. Force Majeure can mean very different things, depending upon the law under which the contract is written and the provisions of the clause, which can vary widely. Examples of force majeure could be war, extreme weather, industrial action. Forward Trading Buying and selling gas (and other commodities) to be delivered at a later date, not under a long term contract. See Futures . Fuel Cell Equipment used to generate electric energy directly from the reaction of hydrogen and oxygen in the presence of a catalyst, without combustion. Natural gas can be used as a feedstock from which to obtain the hydrogen. Carbon dioxide will then be produced in the reformation process. Fuel Gas Gaseous fuels, in particular low pressure natural gas used to fuel production or treatment facilities. Futures A future is a contract to buy or sell a specified quantity of gas (or any other commodity) for a specified price on a pre-arranged date. The contract is usually of standard form and can itself be traded at an exchange such as NYMEX or the IPE . Gas:Oil Ratio . The gas:oil ratio is the relationship between the volume of gas produced at atmospheric pressure and the volume of oil produced in a given field. This volume will normally vary considerably over the life of the field. May be expressed as a simple volumetric ratio e. g. 500:1 or as cu ftBarrel. See also Solution Gas. Gas and Electricity Markets Authority (GEMA) The body which determines strategy and takes major policy decisions for Great Britains gas and electricity regulation. Day to day management of policy, resources and operational issues is carried out by the Office of Gas and Electricity Markets ( OFGEM ). Gas Cap In a field where oil is saturated with gas, so that it can dissolve no more, some gas will collect at the top of the reservoir, where it is known as cap gas, and forms a gas cap. Cap Gas overlies the oil and thus provides additional pressure for oil production, but will therefore often be produced only after all the oil has been produced and will then be treated as Non Associated Gas . Unlike Solution Gas . it is not commingled with the oil. Gas Condensate Field A field consisting of one or more reservoirs containing a mixture of gases at reservoir temperature and pressure, but which at normal temperature and pressure separates out into natural gas and Condensates . A gas condensate field is richer in liquids than a Dry Gas field but there is no precise point at which one becomes the other. Sometimes a reservoir will be produced primarily to obtain the condensate the gas may be re-injected, used as a secondary product, e. g. for LNG production or, particularly in areas remote from the market, flared. The liquid in a gas condensate field is often more valuable than the gas. See also Gas Cycling . Gas Condensate Ratio The ratio of gas to condensate in a gascondensate reservoir, usually expressed in practice as the ratio of Condensate to gas. Typical units are barrels of condensate per million cubic feet of gas. Gas Cycling or Re-Cycling A process in which produced gas is re-injected into the reservoir after removal of the condensate. This is to maintain the reservoir pressure and prevent Condensate from condensing in the reservoir and then becoming difficult to recover. This contrasts with Blowing Down the gas condensate field. Gas Day A period of 24 hours starting and ending at a stated time (often 0600 hours). Gas Detector An instrument used to detect the presence of various gases, often as a safety precaution to guard against leakage of flammable or toxic gases. Gas Gathering System A gas gathering system is a network of pipelines from a number of fields, collecting gas and bringing it to a central point, often a processing system or the inlet to a major transportation pipeline. Sometimes built where individual fields are not big enough to justify investment in separate pipelines and processing plant. Gas Grid A gas grid or network is a connected set of pipelines for the transmission and distribution of gas in a region or country to industrial, commercial and domestic users. See Reticulation. Gas Holder Over ground structure used to hold gas for within-day Peak Shaving purposes in urban areas. Gas holders are relics of the manufactured gas era and are steadily disappearing, their function being largely usurped by Line Pack. Gas Lift Injection of gas into an oil reservoir in order to mix gas with oil, reduce the fluid density and so assist oil flow. Gas Marketer A company that supplies gas to end users. See also Shippers . and Local Distribution Companies . Marketers are also major users of transportation capacity. Gas Processing The separation of oil and gas, and the removal of impurities and natural gas liquids from natural gas to meet the delivery Specification of a gas transportation pipeline. Gas Supplier A company that sells gas to the end consumer (UK). Gas to Liquid Gas to Liquid GTL processes convert natural gas into Synthetic Gasoline or Middle Distillates . using the Fischer Tropsch synthesis method. Increasingly relevant where gas is found in fields remote from markets such that delivery by pipeline is likely to be uneconomic. Gas Turbine A turbine propelled by the expansion of compressed air, heated by the combustion of a fuel such as natural gas or gas oil. Widely used for power generation. See Combined Cycle Gas Turbine. Gas Well A borehole sunk into the ground with the objective of bringing natural gas to the surface. GNL The French language acronym for LNG . stands for Gaz Natural Liquifi. Greenfield Often used to refer to a planned development which must be built from scratch on a new site, hence green field, without existing infrastructure. Gross Calorific Value (GCV) The heat generated by the complete combustion of a unit volume of gas in oxygen, including the heat which would be recovered by condensing the water vapour formed. The preferred value for expressing gas calorific quality in gas contracts. Also known as Gross Heating Value, Higher Calorific Value (HCV) or Higher Heating Value (HHV). See also Net Calorific Value. Heads of Agreement A non-binding statement of the main elements of a proposed agreement. See Memorandum of Intent (MOI). Heel LNG LNG left in ship and shore storage tanks to maintain their cryogenic temperatures. Henry Hub Henry Hub is the largest centralized point for natural gas spot and futures trading in the United States. The New York Mercantile Exchange (NYMEX) uses Henry Hub as the notional point of delivery for its natural gas futures contract. NYMEX deliveries at Henry Hub are treated in the same way as cash-market transactions. Many natural gas marketers also use Henry Hub as their physical contract delivery point or their price benchmark for spot trades of natural gas. Henry Hub is owned and operated by Sabine Pipe Line, LLC, which is a wholly owned subsidiary of ChevronTexaco. Henry Hub is based on the physical interconnection of nine interstate and four intrastate pipelines in Louisiana. Hexane A colourless gas (C9H14) naturally occurring in gas fields and normally left as part of the Condensate stream after separation. Boils at -69C. High Sulphur Fuel Oil (HSFO) The bottom of the oil barrel. The lowest priced oil product now, for environmental reasons, often banned or only allowed to be used where rigorous control of emissions is practiced. In some countries with developing gas-to-oil competition it may represent the marker for power station fuel. Hourly Peak The maximum volume of gas delivered or demanded in any one hour during a given period (usually 24 hours). Hub A term, met most frequently in the U. S. but also now used in Europe, for a geographical point at which several pipelines meet, storage is often available, and opportunities for gas trading can be exploited. There are many hubs in the U. S. of which the most important is Henry Hub . In Europe the largest hub is the National Balancing Point in the UK. Hydrates Ice-like solids in which methane molecules are held within the molecular spaces of the water molecule. Can form in pipelines and wells under certain conditions of near freezing temperatures and high pressures. Their formation is averted by ensuring that water vapour levels in the gas are kept below specified levels. See also Treatment . Dew Point . Hydrates are found naturally beneath the ocean at depths greater than 300m in many areas, where they are estimated to have locked up many trillions of cubic metres of methane. There is speculation that these hydrates may provide a commercial resource in the future. Hydrates have also been proposed as a means of transporting natural gas by sea, possibly competing with LNG. Hydrocarbon An organic compound containing only the elements hydrogen and carbon. Hydrocarbons exist as solids, liquids and gases. Impurities At the wellhead, natural gas will probably contain methane and various heavier fractions. It may also contain a number of non-hydrocarbons, some or all of which will need to be removed. There may also be substances introduced into the well as a result of drilling operations, such as inhibitors, mud etc. The principal harmful impurities in the gas itself are likely to be carbon dioxide and sulphur compounds, notably hydrogen sulphide, which can create corrosion in the pipelines in the presence of water and can seriously damage chemical plant units built of aluminium. Hydrogen Sulphide is also extremely toxic. Excessive water vapour can lead to the formation of acids and Hydrates . Some impurities, such as sulphur or helium, can be recovered economically as by-products if in sufficient concentration in the gas. Other impurities, such as inert gases and nitrogen cause no directly harmful effects but dilute the Calorific Value of the gas and mean that pipeline capacity is being wasted. Whether or not they should be removed is simply a question of economics. See also Treatment . Natural Gas Liquids . Condensates. Independent Power Plant (IPP) An IPP is an electric power generation plant owned and operated independently of the major national or regional entity, producing electricity for an industrial complex andor for sale to the electricity grid. Inert Gas: A chemically inert gas, resistant to chemical reactions with other substances. Integrated Gasification Combined Cycle (IGCC) A means of generating electricity from coal and other low grade hydrocarbons by gasifying them at the electricity generation site thereby gaining some of the efficiency of Combined Cycle Gas Turbine generation. While the chemical amp engineering principles are well understood it has yet to be demonstrated as a commercial proposition. International Energy Agency A Paris-based organisation which co-ordinates the energy policies of its member countries. The IEA also compiles detailed energy statistics and country reports, including countries outside the organisation itself. An autonomous wing of the Organisation for Economic Co-operation and Development (OECD). International Gas Union The International Gas Union (IGU) was founded in 1931. A worldwide non-profit organisation of national gas industry associations whose objective is to promote the technical and economic progress of the gas industry. Organises the triennial World Gas Conference. International Petroleum Exchange The IPEis an energy futures and options exchange based in London. Gasoil futures have been traded since 1981, Brent crude futures from 1988, and natural gas futures since 1997. Absorbed into ICE, the InterContinental Exchange in 2005. See also New York Mercantile Exchange. Interruptible Gas Gas made available under agreements permitting the supplier to terminate, or interrupt deliveries, usually for a limited number of days in a specific period. Usually sold at a reduced price and used to boost salestransportation in slack seasons (normally the summer). Important in load balancing because (by reducing gas demand) it is an alternative to using stored gas. The converse of Interruptible Gas is Firm Gas. Into Plant Price (IPP) The price charged for gas at its entry to the plant. Joint And Several A contract term relating to responsibilities under a contract, usually for payment, often misunderstood. Where, for example, there are several buyers in one contract, a joint responsibility does not mean an equal or pro rata responsibility. It means that if one buyer defaults on its liabilities the other buyers will be liable to make good that default. Where responsibilities are several, each party is responsible only for its own default. Kyoto Japanese city which was the location for an international agreement on the need to reduce the level of emissions of greenhouse gases into the Earths atmosphere. Lean Gas Lean gas is gas high in methane content (typically 95 or more) and with few higher fractions. Hence of relatively low Calorific Value . Also known as Dry gas. The converse of Rich Gas. Liberalisation A term often confused with Deregulation but often meaning quite the reverse. Liberalisation is the process of freeing a market from what are perceived as undue monopolistic forces, to achieve which a high degree of regulation may be required, at least in early years. Limited Access Limited Access refers to a gas distribution system in which the host pipeline owner moves its own merchant gas under different rules to those applying to outsiders contracting for spare capacity. The system applies to local distribution companies and intrastate pipelines in the US and is analogous to but not identical with Negotiated Access . See also Common Carriage. Limited Liability A provision in very large gas contracts under which limits are set to the amounts payable by a defaulting party in a contract. Line Pack Line pack is a procedure for allowing more gas to enter a pipeline than is being withdrawn, thus increasing the pressure, packing more gas into the system, and effectively creating storage. The packed gas can subsequently be withdrawn when needed. A useful method of meeting short term (hourly or diurnal) peak demand requirements. In some areas, where there is a particularly high peak demand, a series of additional pipeline loops may be laid near the entry to a network to provide additional line pack. Such systems are effectively a modern version of the traditional Gas Holder. Liquid Market A trading market characterised by the ability to buy and sell with relative ease, usually because there are many buyers and sellers. Liquefied Petroleum Gas Liquefied Petroleum Gas (LPG) is Propane . Butane . or propane-butane mixtures which have been liquefied through pressure, mild refrigeration, or a combination of both. Usually a derivative of refinery operations but often stripped out of natural gas streams, if rich enough. Conventionally sold in steel containers as Bottle Gas . Not to be confused with LNG. LNG (Liquefied Natural Gas) LNG is Natural Gas which has been cooled to a temperature, around the boiling point of methane (-162C), at which it liquefies, thus reducing its volume by a factor of around 600. The exact boiling of any gas mixture and the reduction in volume will depend on its composition. The process of Liquefaction is carried out in a liquefaction plant. Mostly these are very large scale plants built for projects transporting gas by sea, but in many countries small LNG plants have been built to liquefy gas during the seasons of low demand to provide Peak Shaving when required. LNG Plants consist of one or more LNG Trains, each of which is an independent gas liquefaction unit. It is more cost effective to add a train to an existing LNG plant, than to build a new LNG plant, because infrastructure built for early trains, such as ship terminals and other utilities, may be capable of being used or expanded for new LNG trains. The term Train is sometimes extended loosely to embrace the relevant shipping, storage and other facilities required to bring the resultant LNG to market. Liquefied gas is transported and stored as a boiling liquid under slight positive pressure until required for use, when it is warmed and allowed to re-gasify. In the case of Peak Shaving, the gas will normally be regasified at the plant itself or possibly transported for short distances by road, but large scale transportation is by sea, in specially designed insulated LNG vessels and delivered to LNG terminals, which have the requisite facilities for storage and regasification - the process by which LNG is warmed, usually through a heat exchanger, in order to become once more gaseous before emission into the Gas Grid. Load Duration Curve A visual and statistical expression of a number of (daily) demands over a long period, most often a year. Demands are normally ordered with the highest to the left and the lowest to the right, so that the horizontal scale bears no relation to calendar timing. Can be used, among other things, to measure volumes of demand (or supply) above a given threshold. The area beneath the curve and between horizontal thresholds represents the volume required to supply a particular market segment. The approach is used in both electricity and gas industries. Load Factor A measure of utilization for plant, or of the relationship between average and peak demand or supply, as determined by the formula: Average x 100 Peak. For supply and demand calculations average and peak most often refer to daily demand within a year, but any other periods are possible. The resulting figure is usually expressed as a percentage but, where the period covered is a year, the percentage is sometimes multiplied by 8760, so that the load factor is expressed as a number of hours. Thus a 50 Load Factor can also be expressed as 4380 hours. See also Swing. Local Distribution Company (LDC) A company that distributes natural gas primarily to small, residential and industrial end-users. Looping Increasing the capacity of a pipeline system, by adding parallel piping along part or whole of the route. Does not apply to the addition of compression facilities. Low Sulphur Fuel Oil (LSFO) Fuel oil with a low sulphur content. Usually less dense than High Sulphur Fuel Oil . In new markets with gas-to-oil competition this often represents the marker fuel for large segments of the industrial market. Madrid Forum The Madrid Fotum, otherwise known as the European Gas Regulatory Forum, set up to discuss issues regarding the creation of a true internal European gas market. The participants include national regulatory authorities, Member State governments, the European Commission, transmission system operators, gas suppliers and traders, consumers, network users, and gas exchanges. Make Good Make Good Gas is gas which a buyer must take in a later year because it has failed to take its full Annual Contract Quantity obligation in an earlier year, but has not used its full Downward Quantity Tolerance . It must nevertheless take excess gas in subsequent years to make good its deficiency, before it is entitled to claim any Make Up Gas to which it is entitled through shortfalls greater than the Downward Quantity Tolerance. Make Up Make Up Gas is gas for which a buyer has paid under Take or Pay obligations but not taken, and may have rights to receive in subsequent years for no further charge or at reduced prices after it has taken gas in excess of an agreed threshold volume. This is commonly the Annual Contract Quantity but may, for example, be ACQ minus Downward Quantity Tolerance . Make up gas should not be confused with Make Good Gas. Memorandum of Intent (MOI) Also known as Confirmation of Intent and Letter of Intent. A half way house to the signing of a full contract. Its legal status is rather unclear and its value lies largely in how it is viewed by the parties concerned. It will normally be a fairly brief document setting out the principal framework of the contract and specifying a date by which it is expected that a full contract will be completed. An MOI will often have a relatively brief validity, but in some cases they have served to govern active operations over a period of years. Also known as a Memorandum of Understanding (MoU) and Heads of Agreement (HoA). Merchant Pipeline A pipeline system which itself buys and sells part or all of the gas it transports, in contrast to a pipeline which simply carries gas on behalf of others. See also Open Access . Negotiated Access . Common Carriage. Meter Measuring devise, usually located at a point where ownership is transferred, for example at the entry to a customers premises, city gate, national border or gas processing plant. Note that to determine the energy content of the gas it will be necessary to monitor the composition amp hence calorific value of the gas. This is done at high pressure meter stations but not normally downstream of a city gate. Depending on the size of flow, meters may be: Flow meters, measuring gas throughput using a rotor which is made to revolve by the gas flowing through them Ultrasound meters, more sophisticated, based on the principle that sound waves travel faster with than against the flow. By measuring the difference in travelling time between the two sets of measurements the gas flow rate can be measured to an accuracy of more than 0.5 Orifice plate meters, older, and less accurate than other meters. Calculate flow rates by measuring the drop in pressure over a pierced obstructing plate placed in the pipeline. See also Telemetry. Methane A colourless, odourless flammable gas, lighter than air under normal conditions (CH4, often abbreviated to C1 in non technical usage). Methane is the first member in the alkane (paraffin) series and is the chief constituent of Natural Gas . At atmospheric pressure, it liquefies at -162C. Methanol Methyl alcohol, produced from natural gas via Synthesis Gas . Used as a chemical in the resin and paint industry and in the manufacture of Methyl Tertiary Butyl Ether, (MTBE) and acetic acid, but also of interest as a possible total or partial substitute for motor gasoline in cars. Very toxic. Middle Distillate Synthesis (MDS) A chemical process using the Fischer-Tropsch synthesis method for making synthetic middle distillates (principally naphtha, kerosene and gas oil) from natural gas. Midstream Those activities in the gas chain concerned with moving gas between the source and local distribution. See Upstream. National Balancing Point (NBP) The NBP is an imaginary (notional, or virtual) point at which all gas that has paid the entry charge to enter the UK National Transmission System is deemed to be located. The point at which most UK gas trading takes place, and the largest gas hub in Europe. See Entry Exit. Natural Gas Natural gas (NG) is a mixture of generally gaseous hydrocarbons occurring naturally in underground structures. Natural gas consists mainly of Methane and variable proportions of Ethane . Propane and Butane . There will usually be some condensate andor oil associated with the gas. More specifically, the term is also used to mean treated natural gas which is supplied to industrial, commercial and domestic users and meeting a specified quality. Natural Gas Act (NGA) Seminal example of deregulation liberalisation in the USA. Natural Gas Liquids (NGLs) Heavier hydrocarbons found in natural gas production streams and extracted for disposal separately. Within defined limits ethane, propane and butane may be left in the gas to enrich the Calorific Value . Whether to extract them or not is largely a commercial decision. Heavier fractions which are liquids at normal temperatures and pressures will be removed. The terms Natural Gas Liquids and Condensates are in practice used virtually interchangeably. Rather confusingly, there is no agreement on whether the term NGLs includes or excludes LPGs and both usages are current. Natural Gasoline Butanes and heavier fractions extracted from rich natural gas which, after stabilisation (removal of the lighter fractions) may be blended into motor gasoline. Negotiated Access Negotiated Access is a restricted form of Third Party Access, which excludes the requirement for the access terms to be transparent or applied equally to all applicants. It has been proposed in the European Union as a compromise by opponents of Open Access. Sometimes abbreviated to nTPA. Broadly defines access by one party to another partys facilities through negotiation, the result of which is, by implication, confidential, and not necessarily consistent with negotiations between the facility owner and other parties. See also Access . and Limited Access. Net Calorific Value, (NCV) The heat generated by the complete combustion of a unit volume of gas in oxygen, excluding the heat which would be recovered by condensing the water vapour formed. Net Calorific Value is usually seen as a measure of the effective heat produced rather than the total heat in the gas. Also known as Lower Calorific Value or Lower Heating Value. For natural gas, typically 10 lower than the GHV or HHV. See also Gross Calorific Value. Netback The price or value of a gas, at e. g. the border or the wellhead, calculated by deducting the costs associated with getting it from that point to the eventual point of sale from its competitive value at that point of sale. Used to estimate the comparative value of selling gas to various markets, and the worth of producing gas at all. Network Code A detailed contractual regime governing access to a gas grid. Network Codes exist or are being developed in several countries, especially in Europe. In North America the rules of the system are referred to as The Tariff. In particular, the contractual regime for the gas grid in Great Britain operated by National Grid. It is continually amended through rules approved by the GB energy regulator, ( Ofgem ). See also Tariff and Rates. New York Mercantile Exchange (Nymex) The worlds largest physical commodity futures exchange. Has existed for 130 years and pioneered the development of energy futures and options contracts in the 1970s. Nitrogen Oxides Oxides of Nitrogen (NOx) resulting from the combustion of fuels, causing atmospheric pollution in the form of smog. Non Associated Gas Non-Associated is gas found in a reservoir which contains no crude oil, and can therefore be produced in patterns best suited to its own operational and market requirements. See also Associated Gas. Odorants Strong smelling chemicals injected into natural gas, which otherwise is odourless, in order to make its presence more easily detectable. See Mercaptans. Odorisation The process of giving odourless natural gas a smell for safety reasons by injecting small quantities of organic sulphur compounds, such as Mercaptans . typically at the rate of 30 ppm. Usually carried out at the city gate or at the exit from the high pressure transmission system. OFGEM Office of Gas and Electricity Markets, (OFGEM) The regulator for the gas and electricity industries in Great Britain. Governed by the Gas and Electricity Markets Authority . Its powers are provided by the Gas Act 1986, the Electricity Act 1989 and the Utilities Act 2000. Successor organisation to OFGAS and OFFER, the former separate Gas and Electricity Regulators. Offtake Point The point in a gas system where gas is taken by supply pipe to a consumer. Oil Gasification The conversion of oil or naphtha into gas to be used as a fuel. See also Manufactured Gas. On the day Commodity Market (OCM) System of within-day gas trading introduced into Great Britain in 1999. A screen-based system designed to allow shippers, traders and the system operator (then Transco, now National Grid) to resolve within-day demand and supply imbalances in an orderly fashion. Open Access A system offering all applicants access to specified infrastructure. See Common Carriage. Open Cycle Gas Turbine (OCGT) A gas turbine, often derived from aero-engines, used for peak generation of electricity. Also used in conjunction with a steam turbine in a combined cycle power plant. When only the gas turbine is used it may be termed single cycle. Open Season A procedure for demonstrating to a regulator that capacity is offered on a transparent basis. It is used principally where pipelines are required by regulation to offer only transportation services, for example in North America and the Southern Cone of South America. It is also being used elsewhere as a means of gathering information about potential interest in a pipeline. LNG, storage etc project to help the sponsors decide how and when to size the project. Off-Peak The period during a day, week, month or year when the load being delivered by a gas system is not at its maximum volume. Over the Counter Trading (OTC) Trading that takes place outside a formal Exchange. Peak Day The day in the year on which the demand for gas is highest. In temperate areas this is normally a cold day in mid winter. In warmer areas it may occur midsummer, when there is a high air conditioning load met either directly by gas or by gas-fired power. A crucial indicator in planning and sizing gas infrastructure. Peak Hour The hour in the day in which demand for gas is highest. Chiefly relevant to distribution systems. Is normally around the midday or evening meal time Peak Load The maximum load produced or consumed by a unit in a stated period of time. In some tariff systems it is an important component of the tariff design, since it defines the capacity that is booked in the gas delivery system and must be paid whether or not used. Peak Shaving Peak shaving is a means of reducing the Peak Load on the gas transportation and supply system by supplying some gas from sources at or close to the point of ultimate consumption, thus improving the average Load Factor . Peak shaving may be daily or seasonal and will be handled in a variety of ways: - Underground storage . peak shaving LNG plants, Line Pack . Gas Holders . propane-air plant and, occasionally, special peak shaving supply contracts. A non-storage alternative to peak shaving is to interrupt I nterruptible Gas supplies. Permeability A measure of the ease with which liquids or gas flow through a reservoir rock. Compare this with Porosity . Gas will flow more easily than oil, and so can be recovered from rocks with lower permeability. Permeability is measured in Darcies. Gas reservoirs may have permeabilities of only a few millidarcies. Petrochemical An intermediate chemical derived from petroleum, hydrocarbon liquids, or natural gas, such as ethylene, propylene, benzene, toluene, and xylene. Pig Equipment used to clean or flush out liquids and other accumulated and unwanted items from the inside of an oil or gas pipeline. It is inserted into the pipeline and carried along by the flow of oil or gas. An intelligent pig includes measuring and sensing equipment which can be used to inspect a pipeline internally, which is useful after it has been buried underground Pipeline A tube for the transportation of crude oil or natural gas between two points, either offshore or onshore. Pipeline Capacity The amount of oil or gas that can be passed through a pipeline over a given period of time. Plateau In long term gas contracts the period of years for which the Annual Contract Quantity remains flat. The Plateau will normally be preceded by a build up period, during which the volumes increase and, in the case of a Depletion Contract will be followed by a period of decline until further production is no longer economic. Porosity The proportion of a rock volume (expressed as a percentage) that is occupied by the voids between mineral grains. Used to help estimate the volume of hydrocarbons in a field. Compare this with P ermeability . Power Purchase Agreement (PPA) A contract between a power station and the electricity purchasing organisation for the sale of electricity. Primary Energy The gross amount of energy used, measured in the quantities of the original fuel produced (e. g. crude oil) before conversion to other forms (e. g. refined petroleum products or electricity). Thus hydroelectric power and nuclear power are Primary, but power from generating stations consuming fossil fuels is not. Production Sharing Agreement (PSA) An agreement between an international producing company and a host government or state oil company under which the international company acts as risk-taking contractor investing in exploration andor production facilities in return for the right to export or sell a quantity of gas or oil that may be produced from the Concession or Block . Sometimes known as a Production Sharing Contract. The terms are interchangeable and the use of one or the other depends on the country. Profit Gas Frequently used to signify the gas received by a Contractor in a Production Sharing Agreement to provide the profit in the operation. Normally the Contractor will receive Cost Gas to cover its costs and, after other minor provisions, the remaining gas will be split with the host government in agreed proportions. In some countries profit gas is also subject to income tax, in other jurisdictions the State Oil Company is assumed to pay the income tax liability of the contractor. The proportion of profit gas is adjusted depending on local practice. May be used to signify the totality of gas remaining after Cost Gas, Royalty and similar items, including therefore both the Governments and the Contractors shares. Project Financing A method of financing in which the lender makes loans directly to a project and may claim repayment only out of that project. In theory, the lender has no recourse to the project sponsors other assets (non-recourse financing) but in practice this is rare. More commonly the extent of the sponsors liability is strictly defined (limited recourse financing). Propane A member of the alkane (paraffin) group of hydrocarbons with three carbon atoms in its molecule ( C3H8, often abbreviated to C3 in non technical usage). A frequent component of natural gas, also sold as a form of Bottled Gas . Liquefies at -42C. Proven Reserves Those quantities of petroleum which, by analysis of geological and engineering data, can be estimated with reasonable certainty to be commercially recoverable, from a given date forward, from known reservoirs and under current economic conditions, operating methods, and government regulations. Proven (proved) reserves can be categorised as developed or undeveloped. Where probabilistic methods have been used to estimate reserves, proven reserves are those with a better than 90 chance of being economically recoverable. Sometimes abbreviated as P90. Reserves with a greater than 50 chance but less than 90 chance are defined as Probable, or P50. Reserves with a greater than 10 chance but less than 50 chance are Possible or P10. Reserves may be classified as proved, if facilities to process and transport them to market are operational at the time of the estimate or there is a reasonable expectation that such facilities will be installed. Reasonable expectation is usually taken to mean that a developer has taken the decision to build the necessary facilities and the development plan has been approved by the relevant authorities. Thus large resources, such as those known to exist in North Alaska, are not classified as proven because there is no route to market. Different countries have adopted many different definitions of reserves, but gas contracts often refer to the Society of Petroleum Engineers (SPE) definitions. These and similar definitions from the World Petroleum Council were harmonised in 1997. Public Service Obligation A Public Service Obligation (PSO) is a requirement imposed by government on a company or companies to provide services which might not otherwise be profitable but are judged to be in the public interest. These could, for instance, include supplying gas to small or poor consumers, ensuring that appliances and other infrastructure is operating efficiently and safely, and ensuring that there are sufficient back-up gas supplies to cover emergency interruptions in supply. Public Utility Commission (PUC) State commissions in the USA responsible for regulating gas, and other utilities that operate within the boundaries of the state. See Regulation. Ramping Rate The rate at which the level of production can be increased after a partial or complete interruption. Rates North American term for the charges for the use of pipeline and storage capacity, referred to in other parts of the English-speaking world as Tariff. The North American definition of Tariff is more nearly equivalent to Network Code. Raw Natural Gas Natural gas still containing impurities and unwanted substances, such as water, nitrogen, carbon dioxide, hydrogen sulphide gas and helium. See also Impurities . Behandling. Recovery Factor The percentage of gas or oil in place in the reservoir which can be economically recovered. Gas Recovery factors may be around 60-70 in reservoirs with water drive from an Aquifer and up to 90 in Depletion Drive Reservoirs. Regasification The reconversion of LNG into gas suitable for pipeline transportation. See LNG. Regulated Access Access to infrastructure under terms and conditions set by or agreed with a Regulator . Such access will usually be open to all qualifying customers. See Common Carriage. Regulator (1) A mechanical device for controlling the pressure of gas within acceptable limits. Typically installed when has enters a low pressure distribution system for final use by small customers. (2) The person or body appointed to oversee the operation of the regulated parts of a gas industry. See Regulation. Regulation Regulation is a substitute for free market operation typically, in the gas industry, where all or part of the operations are carried out by institutional or natural monopolies. Provides a temporary or permanent counterweight to the economic power of the monopoly. Often exercised politically by government departments, but in many countries independent regulation is thought preferable. In any case the rules governing regulation will normally have been laid down explicitly by government legislation. Regulation can be economic restricting the revenue and profits of operators - or legal policing legislation. Regulators are normally closely involved in the setting up of liberalised market systems, when they may use their central position to interpret and rule on the applicability of legislation either ex-ante or ex-post. See Common Carriage. Renewable Energy An energy form, the supply of which is partly or wholly regenerated in the course of the annual solar cycle. Thus solar and wind energy, hydropower and fuels of vegetable origin are regarded as renewable mineral fuels and nuclear power are not. Reservoir A reservoir is an accumulation of oil andor gas in a permeable and porous rock such as sandstone. A petroleum reservoir normally contains three fluids (oil, gas and water), which separate into distinct sections, owing to their varying specific gravities. Gas occupies the upper part of the reservoir as it is the lightest, oil the middle section, while water occupies the lower section. See also Permeability . Porosity . Gas Cap . Aquifer . Solution Gas . Proven Reserves. Reticulation A reticulation network is a small diameter, low pressure gas system serving residential and commercial customers. (From the Latin word reta, meaning net). See also Distribution. Retrograde Condensate A gas condensate which, in the reservoir, is close to the Dew Point of the fluid. A small reduction in pressure, by production of the field, leads to the condensation of higher hydrocarbons in the reservoir, causing a lower Recovery Factor . Royalty A tax on production volumes, often paid in kind, which is levied as a percentage of production. It is therefore not related to the profitability of the production project, merely to the volume of gas (or oil) produced. R:P Ratio The Reserves: Production Ratio is the number of years that current reserves would last at current production levels. Thus reserves of 100 divided by consumption of 20year gives an R:P ratio of 5, and implies a life of 5 years for the reserve. RPI-X A regulatory formula by which a regulated monopoly is allowed to increase its prices each year by the retail price index (RPI) minus a defined amount or percentage x (x is a variable). Gives consumers falling real prices and forces the utility to reduce costs if it is to maintain its level of profitability. Sales Gas Raw gas, after processing to remove LPG, condensate and carbon dioxide. Sales gas usually consists mainly of methane and ethane and is odorised. See Odorisation. Salt Cavity Storage The storage of gas in caverns leached out in gas-tight salt strata. Such caverns may be generated during the recovery of salt for commercial purposes, or may be purpose-built for gas storage. Scrubbing The process of purifying a gas or liquid by washing it with suitable chemicals in a contact vessel. Seal The layer of rock overlying a gas field which prevents the gas escaping from the reservoir. It is therefore of low Permeability . Salt and fine clays can provide good seal. Seasonal Normal The average (or normal) result for the time of year. Thus Seasonal Normal Temperature (SNT) is the average temperature on a calendar day, where the average has been measured over a suitably long period. Likewise Seasonal Normal Demand, Seasonal Normal Weather. SNT is an important factor in developing forecasts of gas usage. See Weather Correction. Seasonal storage Storage designed to be filled at times of low (season) demand and emptied at times of high demand, over months rather than days. Security of Supply Security of supply is a term with several meanings including: the provision of adequate infrastructure to cope with annual and peak demand the provision of sufficient gas to meet annual and peak demand ensuring that a country or area does not rely exclusively on one, or very few sources of supply. Seismic Survey A technique for establishing the presence of underground geological strata using sound waves. There are two main techniques - reflection or refraction. In the oil and gas industry by far the most common is reflection. In a reflection survey sound waves are sent into the ground and the echoes from boundaries between rock with different properties of density and sound velocity are recorded. The sound waves recorded at the surface can then be used to create maps of the rock layers in the subsurface to reduce the risk of drilling dry holes. A reflection seismic survey may be either 2D, in which the reflections are recorded along a line or 3D, in which the lines are very closely spaced to deliver a three dimensional view of the subsurface. A refraction seismic survey is a different technology in which the sound waves are refracted along rock boundaries rather than reflected from them. Send-Out The quantity of gas delivered by a plant or system during a specified period of time. Shipper A party negotiating for the transport of gas on its own behalf or as an agent for another. In liberalised markets shippers may not be allowed to operate transportation systems. Slug Catcher Plant installed in a gas pipeline system or gas processing plant to catch slugs of liquid. Usually this takes the form of a long section of pipe, inside which the pressure is allowed to drop by a controlled amount. See also Pig. Solution Gas Solution Gas, unlike Cap Gas is Associated Gas dissolved in oil. Produced inevitably with the oil and separated from it at the well-head. Solution Gas production is thus a function of oil production and of the GasOil Ratio . which changes over the life of the field. It is therefore an unreliable gas supply and difficult to market, unless the buyer or seller have large alternative sources. Has in the past largely been flared or vented but this is becoming less acceptable, largely for environmental reasons, although is still not uncommon in remoter areas. Separation is often carried out in two or three stages to maintain the gas pressure for pipelining as far as possible. Gas from the final stage separator is at low pressure and is normally used in the field or on the platform during production. The gas may be re-injected into the reservoir if it will not break through into the oil wells. Sour Gas Gas containing a high level of Carbon Dioxide or Hydrogen Sulphide, which are corrosive in the presence of water. They may therefore require drying or removal to preserve the pipeline. The converse of Sweet Gas. Spark Spread The spark spread represents the difference between the cost of fuel and the price of electric power produced. A positive spread indicates that the price of the power is higher than that of the fuel, and the spread is profitable. The spread can be calculated for any input fuel, such as natural gas, coal, or heating oil. Specification The technical description of the allowable limits of the chemical composition of gas which may be admitted into a pipeline or process. Specific Gravity The ratio of the density of gas to that of air, or the ratio of the density of a liquid to that of water, in both cases at the same temperature and pressure. Spot Trading A loose term covering the buying and selling of gas other than under a long term contract. Generally in trading parlance spot delivery means immediate delivery. Standing Charge Tariff term for a fixed charge, typically per quarter or per year, irrespective of the amount of gas actually taken. Synonymous with Connection Charge but to be distinguished from Demand Charge. Storage For natural gas storage facilities fall into several categories. Seasonal storage comprises depleted gas fields Aquifers S alt Cavity Storage mined caverns and disused mines. Peak storage includes Gas Holders . Line Pack . lengths of pipeline buried specifically for storage use, and LNG storage used either for base-load or peak-shaving duties, depending on the market. Increasingly used in liberalised markets to enable gas to be trade at any time of the year for reasons not related to peak demand. See also Peak Shaving . Straddle Plant A gas processing plant that straddles a gas transportation pipeline to remove NGLs from the gas stream. Because it is often more economic to transport Rich Gas a straddle plant is required to process the plant to final sales specification. The alternative location of a gas processing plant is close to the producing field. NGLs are then transported as liquids away from the field area either by separate pipeline or other means. Supply Contract A contract under which the seller undertakes to supply gas in guaranteed volumes over a fixed period of time. A Supply Contract is therefore in sharp contrast to a Depletion Contract as the seller assumes the volume risks. Whilst certain fields may be envisaged in the contract, the seller will normally have the right to substitute other suitable gas if necessary. Swaps (1) Arrangements under which gas destined for a market is delivered elsewhere, and substitute gas is supplied to the final market. For instance, Nigerian LNG contracted to Italy is delivered to France, and other gas contracted to France is delivered to Italy. (2) In trading, the exchange of a fixed price for a floating price for a future delivery. Sweet Gas Gas containing little or no Carbon Dioxide or Hydrogen Sulphide. Converse of Sour Gas. Swing The inverse of Load Factor . defined as: Peak volume transported (sold) Average volume transported (sold) Expressed as a percentage. Thus a load factor of 60 is a swing of 167. Often used to describe the flexibility of supplies over a year. Synthesis Gas Also known as Syngas, Synthesis Gas is a mixture of carbon monoxide and hydrogen produced from methane or other hydrocarbons and steam and used to produce various chemicals, notably methanol. It is also the basis for the Fischer Tropsch process. See also: Middle Distillate Synthesis. Synthetic Gasoline Motor gasoline produced from coal (by the Fischer Tropsch process) or from natural gas (by the Fischer Tropsch process or via methanol). See also Middle Distillate Synthesis. Take or Pay Take or Pay (TOP) is a common provision in gas contracts under which, if the Buyers annual purchased volume is less than the Annual Contract Quantity minus any shortfall in the Sellers deliveries, minus any Downward Quantity Tolerance . the Buyer pays for such a shortfall as if the gas had been received. The Buyer may have the right in subsequent years to take the gas paid for but not received, either free or for an amount to reflect changes in indexed prices. See also Make Up Gas. Tariff A schedule of rates or charges offered by a common carrier or utility. Tariffs are commonly available for all parts of the gas industry where third party access is enforced or offered, for example for gas transmission in pipelines, for the use of gas stores, for gas sales to residential customers. Telemetry A technique used in the gas industry for recording information at a distance from the Meter or other recording device, typically by radio transmission of the data. Temperature Demand Analysis The statistical analysis of the causal relationships between weather (and other) factors and the demand for gas. An essential prelude to forecasting demand. See Seasonal Normal and Weather Correction. Temperature Correction The process of adjusting actual gas usage to what it would have been at Seasonal Normal Temperatures, to allow comparisons to be made between results for different time periods, typically years. See weather correction. Title Transfer Title transfer is the transfer of which ownership of gas from the seller to the buyer. Typically this may occur somewhere between the well head and entry into the transmission system, at national border crossings, at the City Gate etc. In the world of traded gas, possible points of transfer become more numerous. A special case is the transfer of LNG at some specified point on the high seas. See Delivered. Trading Volume The number of contracts that change hands during a specified period of time. See also Churning. Transit The transportation of gas through a country or gas system en route to the final customer. For example, Russian gas may transit through Ukraine en route to customers in western Europe. Transmission The transportation of large quantities of gas at high pressures, often through national or regional transmission systems. The gas is then transferred into local distribution systems for supply to customers at lower pressures. Transmission Company The company responsible for operating a transportation system. In liberalised markets there is increasing pressure for such companies to be restricted to offering capacity in pipelines for sale, and to be barred from selling gas itself. The companies are also commonly known as Transmission System Operators (TSOs) a title which reinforces their restricted role. See Unbundling. Transmission Pipeline A network of pipelines moving natural gas from a gas processing plant via compressor stations, to storage centres or distribution points. Transparency A general term meaning open publication of information. In the gas industry it is generally used in relation to costs, prices and capacity, where information has traditionally been considered commercially confidential. Costs and prices generally reflect a number of elements, such as production, transportation, storage, service. Transparency generally involves separating out or U nbundling these elements, usually as a result of regulatory requirements. A further step towards transparency involves the publication of the methodology used to calculate the different elements of costs and prices. Transporter A gas pipeline company transporting gas belonging to other companies. Also the operator of LNG vessels. See Transmission Company. Trap A configuration of reservoir and seal rocks that can confine gas (or oil) which are lighter than water normally contained in the reservoir rock. Structural traps are formed by a closed structure of R eservoir rock overlain by a sealing formation (the Seal ). May also be formed by stratigraphic changes within a reservoir rock in which case it is known as a stratigraphic trap. Treatment Any gas purification process, but most generally applied to the treatment of gas immediately after production, to bring it to acceptable standard for the market in question andor to extract valuable components for separate sale. This may involve the removal of LPGs and will certainly involve stripping out Condensates . Carbon Dioxide and Hydrogen Sulphide and other sulphur compounds (see also Acid Gas ) mercury and excessive water which may be in the raw gas. Other impurities are occasionally encountered. Whether other inert gases such as nitrogen, helium etc are extracted will be a matter for economic evaluation. UKCS United Kingdom Continental Shelf. Unbundling Unbundling is a term with several meanings for the gas industry but more accurately, and originally, it was used to denote the separation of different services and the charges associated with them. Originally used in the US in restructuring the telephone industry. it was adopted in the gas industry to denote the separation of gas sales from transportation and storage services. This is still the most usual meaning of the term, particularly in North America, where large customers are now free to purchase gas and services separately. However the European Commission uses the term Unbundling to mean the financial disaggregation of different functions within integrated companies, such as transmission and marketing. Where companies perform multiple functions, the Commission has sought to require separate accounting for the functions. Its aim is therefore much more related towards Transparency and eliminating the potential for anti-competitive cross subsidisation activities. Underground Storage The storage of gas, for strategic or peak shaving reasons, in underground reservoirs. Depleted gas fields are often suitable. Other possibilities include depleted oil fields, Aquifers and Salt Cavity Storage . In the context of LNG, underground storage refers to normal LNG storage tanks which are, however, buried to provide greater safety in the event of leakages. Unitisation Agreement When a gas field extends over two or more production licences or leases with different ownership, most countries require that the field owners unitise their holdings i. e. decide how the reserves and production of the total field will be shared between the licensees, thus enabling the efficient depletion of the reserves. The Unitisation Agreement normally provides for the appointment of a field operator, a method of determining the reserves underlying each licence or lease and the frequency of reserve re-determination. Upstream Upstream, Midstream and Downstream are imprecisely defined terms used to separate activities along the gas and oil chain into homogenous groups. Upstream typically refers to exploration, development amp production of oil amp gas. Sometimes also defined to embrace Midstream, which typically covers transmission (as opposed to distribution) LNG shipping etc. Downstream typically refers to activities associated with delivery to final consumers, such as distribution systems and connections to customer premises. Water Drive In a porous rock, as gas is withdrawn from the reservoir, water expands into the region formerly occupied by the gas as pressure is released. This often has the result of trapping volumes of gas so that they cannot be produced, thus reducing the recovery of gas. Not a problem with a D epletion Drive Reservoir . See Aquifer. Water Gauge A measure often used to express the pressure of gas in distribution systems, using water instead of mercury. The gauge records how far up a gradated tube gas will lift a column of water. Distribution systems normally operate at about 300mm (12 inches) water gauge (i. e. 300mm above atmospheric pressure). For comparison, atmospheric pressure is a little above 10 metres of water. Wayleave The strip of land around a gas pipeline or other utility to which the utility has legal right of access for building and maintenance. Weather correction A procedure for estimating what customer demand would have been in S easonal Normal weather conditions. Thus in a cold year seasonal normal demand will be lower than actual demand and vice versa. Well A hole drilled into the ground, mostly by rotary rigs, in which a drill bit, which actually cuts the rock, is turned on the end of a drill string, made up of lengths of hollow steel pipe which are added to the string as the bit drills deeper into the ground. Wells have various descriptions depending on the stage of the production process at which they are drilled. Exploration wells are drilled to discover if gas (or oil) can be found Evaluation or appraisal wells are drilled to obtain more information about a previous discovery Development wells are drilled to produce gas from a field which is being developed, and are called Producing wells when the field enters commercial production. Wheeling Physically redirecting gas from one pipeline system to another at a Hub as opposed to changing the title by swap arrangements. Wobbe Index Occasionally referred to as the Wobbe number. A measure of the rate at which gas will deliver heat on combustion and hence of the compatibility of a gas with gas burning equipment. Working Gas In a gas store, the total volume of gas present less C ushion Gas . In other words the gas available for normal working. Hence working gas capacity - the total capacity of a storage facility minus cushion gas. GLOSSARY OF UNITS Absolute Pressure The sum of Atmospheric Pressure and Gauge Pressure i. e. pressure by reference to a vacuum Atmosphere: A measure of pressure, now largely superseded by the Bar to which it is nearly identical. Originally equal to 760 mmHg it has now been redefined as 101,325 pascals and consequently 1 atmosphere 1.01325 bars. Atmospheric Pressure The pressure of the weight of air and water vapour on the surface of the earth. Bar The most used unit for expressing gas pressure. It is equal to 100,000 pascals (Nm2), which is the official SI unit. 1 Bar is approximately atmospheric pressure. bbl A US barrel, 1 barrel 0.159 cubic metres 42 U. S. gallons (approx35 imperial gallons). The abbreviation is also sometimes written as B or b. bblday Barrels per day. Usually used to quantify a refiners output capacity or an oilfields rate of flow. Bcm Billion cubic metres (i. e milliard or 109 cubic metres). Billion In the US 109. Although elsewhere billion often signifies 1012, the Natural Gas industry has generally adopted the US usag e. Boe Barrels of oil equivalent - a frequently used number to quantify general energy requirements for practical purposes. One boe is usually taken as representing 5.8 MMBtu gross. British thermal unit A unit of heat still widely used in the gas industry, notably in North America and in LNG. Originally defined as the amount of heat required to raise the temperature of one lb of water from 60 to 61 Fahrenheit, it is now defined in relationship to a fixed number of Joules (1055.056 to three decimal points). The most common multiple is one million Btu, normally abbreviated to MMBtu and U. S. dollarsMMBtu is perhaps the most frequently used unit for comparing gas prices on a common basis. See also Therm. Cal Calorie. Formerly the SI unit of energy, now no longer part of the system but still extensively used in Europe. The calorie was nominally the amount of heat required to raise 1 gram of water by 1C at 1 standard atmosphere and starting from 14.5C, but is now defined arbitrarily as: 4.1868 J. The most common multiple used is the Megacalorie (Mcal). Cf Cubic feet. Measure of gas volume, referring to the amount of gas needed to fill a volume of one cubic foot at 14.73 pounds per square inch absolute pressure and 600F. cm Cubic metres. Note however that cm is also the official abbreviation for centimetre. Deca Therm Also deka therm. A term sometimes used in the U. S. in lieu of one million Btu. Gauge Pressure The amount of pressure shown by a gauge, i. e. the amount by which the pressure exceeds atmospheric pressure. See also Absolute Pressure. GJ GigaJoule. One GigaJoule is approximately equal to 9.478 MMBtu. One million Btu equals 1.055 GJ. GWh GigaWatts per hour. J Joule - The unit of energy in the SI system and the unit approved by the International Gas Union for the expression of heat in the gas industry. Its definition is one Newton metre. In practice the industry has been reluctant to embrace the Joule for commercial purposes and it is only current in Australia and New Zealand. For practical purposes the multiples most in use are the MegaJoule (MJ) and the GigaJoule (GJ), although Petajoule ( PJ ) is also seen. For quick calculations 1 GigaJoule is very close in value to 1 MMBtu. Kelvin Measurement of temperature equivalent to 1273.16 of the interval between absolute zero and the triple point of water. The official unit of the SI system. The Kelvin is identical to 1 degree Celsius, which is the term most often used in practice, but the scale is different (0C273.16 K). Note incidentally that the Kelvin is itself the unit of measurement and references to 1 degree Kelvin are incorrect. kW KiloWatt One thousand Watts. kWh KiloWatt hour - Together with its multiples, rapidly becoming the most used unit for energy in gas, although its use is not strictly in accordance with the SI system or with IGU preferences. Since 1 Joule 1 Watt per second, the conversion factor 1 kWh 3.6 MJ is exact. Long ton 2240 lb. The most usual form of non-metric ton. Mcf Thousand cubic feet. Mcm Thousand cubic metres. Milliard Synonymous with US billion - 109. MM Widely used in the gas industry to mean a million (106), although this usage is incorrect, according to the SI convention. Similarly M is often used to represent a thousand (103). When the lower case letters m and mm are used, these usually denote a thousand and a million respectively. In everything else M is correctly used to mean Million as in MWh. MMbbl Million barrels. MMcf Million cubic feet. MMcm Million cubic metres. MMscm Million standard cubic metres. Mtoe Million tonnes of oil equivalent. Mtpa Million tonnes per annum, a widely used unit of volume in the LNG industry. MW MegaWatt - one million Watts. ncm Normal Cubic Metre - A cubic metre measured at 0 C and 1013 mbar dry. The most used metric unit for measuring the volume of gas. It differs from the Standard cubic metre ( scm ) in the temperature at which the measurement is made. The Normal cubic metre thus contains about 5 more heat content than the Standard cubic metre. PJ PetaJoule - Standard unit in the Australian gas industry, equivalent to 1 million (106) GJ and therefore roughly equal to 1 million MMBtu . It is therefore close to 1 Bcf or some 30 million cubic metres. ppm Parts per million. Pressure The force exerted by one body on another, measured as force over area e. g. newtons per square metre. Psi Pounds per Square Inch common USEnglish unit of pressure, 14.5psi 1 bar. scf Standard cubic foot - The conditions for measuring the scf are in fact very close to, but not identical with, those for the standard cubic metre ( scm ). Despite its name, there is no single accepted standard for the standard cubic foot but the one most used is 60F and 30 in Hg, dry. scm Standard Cubic Metre - A cubic metre measured at 15C and 1013.25 mbar, dry. The unit of volume recommended by the IGU but not in normal use. See also ncm. Short ton 2000 lb. Used in the US. SI Multiples The SI system uses the following prefixes for multiples of the base units: 103 kilo (k), 106 mega (M), 109 giga (G), 1012 tera (T), 1015 peta (P), 1018exa (E). tce Ton of coal equivalent - Like the barrel of oil equivalent ( boe ) a measure of general energy requirement but now largely supplanted by the boe. Generally taken to have a value of approximately 27 MMBtu. Tcf Trillion (1012) cubic feet. Tcm Trillion (1012) cubic metres. Therm 100,000 British Thermal Units is still occasionally used as a unit for pricing gas, particularly in the UK. Thermie A term virtually identical to 1 Megacalorie but having 15C as its base, used primarily in Spain. toe Tonnes of oil equivalent - A metric measure used to quantify general energy requirements for practical purposes, an alternative to the barrel of oil equivalent. usually taken as representing 10,000 kilocalories net. Ton (t) A term covering a variety of measures: The metric tonne (1000 kg) The long ton (2240 lbs) The short ton (2000 lbs). The metric tonne is the one increasingly used. W Watt - The basic unit of electrical power, defined as one joule per second. Water Drive In a porous rock, as gas is withdrawn from the reservoir, water expands into the region formerly occupied by the gas as pressure is released. This often has the result of trapping gas so that it cannot be produced, thus reducing recovery from the reservoir. Water drive is not a problem with a D epletion Drive Reservoir . See also Reservoir. Water Gauge A measure often used to express the pressure of gas in distribution systems, using water instead of mercury. Distribution systems normally operate at about 300mm (12 inches) water gauge (i. e. 300mm above atmospheric pressure). For comparison, atmospheric pressure is a little above 10metres of water. See also Gauge Pressure. U.S. Energy Information Administration - EIA - Independent Statistics and Analysis NAAQS: National Ambient Air Quality Standards NAICS ( North American Industry Classification System ): A coding system developed jointly by the United States, Canada, and Mexico to classify businesses and industries according to the type of economic activity in which they are engaged. NAICS replaces the Standard Industrial Classification (SIC) codes. Name plate: A metal tag attached to a machine or appliance that contains information such as brand name, serial number, voltage, power ratings under specified conditions, and other manufacturer supplied data. Naphtha: A generic term applied to a refined or partially refined petroleum fraction with an approximate boiling range between 122 degrees and 400 degrees Fahrenheit. Naphtha-type jet fuel: A fuel in the heavy naphtha boiling range having an average gravity of 52.8 degrees API, 20 to 90 distillation temperatures of 290 degrees to 470 degrees Fahrenheit, and meeting Military Specification MIL-T-5624L (Grade JP-4).It is used primarily for military turbojet and turboprop aircraft engines because it has a lower freeze point than other aviation fuels and meets engine requirements at high altitudes and speeds. Note: Beginning with January 2004 data, naphtha-type jet fuel is included in Miscellaneous Products . Naphthas: Refined or partly refined light distillates with an approximate boiling point range between 122 and 400 degrees Fahrenheit. Blended further or mixed with other materials, they make high-grade motor gasoline or jet fuel. Also, used as solvents, petrochemical feedstocks. or as raw materials for the production of town gas. National Association of Regulatory Utility Commissioners (NARUC): An affiliation of the public service commissioners to promote the uniform treatment of members of the railroad, public utilities, and public service commissions of the 50 states, the District of Columbia, the Commonwealth of Puerto Rico, and the territory of the Virgin Islands. National Defense Authorization Act: The federal law, enacted in 1994 and amended in 1995, that required the Secretary of Energy to prepare the Baseline Report. National priorities list: The Environmental Protection Agencys list of the most serious uncontrolled or abandoned hazardous waste sites identified for possible long-term remedial action under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). The list is based primarily on the score a site receives from the Environmental Protection Agency Hazard Ranking System. The Environmental Protection Agency is required to update the National Priorities List at least once a year. National Rural Electric Cooperative Association (NRECA): A national organization dedicated to representing the interests of cooperative electric utilities and the consumers they serve. Members come from the 46 states that have an electric distribution cooperative. National Uranium Resource Evaluation (NURE): A program begun by the U. S. Atomic Energy Commission (AEC) in 1974 to make a comprehensive evaluation of U. S. uranium resources and continued through1983 by the AECs successor agencies, the Energy Research and Development Administration (ERDA), and the Department of Energy (DOE).The NURE program included aerial radiometric and magnetic surveys, hydrogeochemical and stream sediment surveys, geologic drilling in selected areas, geophysical logging of selected bore holes, and geologic studies to identify and evaluate geologic environments favorable for uranium. Native gas: Gas in place at the time that a reservoir was converted to use as an underground storage reservoir in contrast to injected gas volumes. Native load (electric): The end-use customers that the Load-Serving Entity is obligated to serve. NERC definition Natural gas: A gaseous mixture of hydrocarbon compounds, the primary one being methane . Natural gas field facility: A field facility designed to process natural gas produced from more than one lease for the purpose of recovering condensate from a stream of natural gas however, some field facilities are designed to recover propane, normal butane, pentanes plus, etc. and to control the quality of natural gas to be marketed. Natural gas gross withdrawals: Full well-stream volume of produced natural gas, excluding condensate separated at the lease. Natural gas hydrates: Solid, crystalline, wax-like substances composed of water, methane, and usually a small amount of other gases, with the gases being trapped in the interstices of a water-ice lattice. They form beneath permafrost and on the ocean floor under conditions of moderately high pressure and at temperatures near the freezing point of water. Natural gas lease production: Gross withdrawals of natural gas minus gas production injected on the lease into producing reservoirs, vented, flared, used as fuel on the lease, and nonhydrocarbon gases removed in treating or processing operations on the lease. Natural gas liquids production: The volume of natural gas liquids removed from natural gas in lease separators, field facilities, gas processing plants, or cycling plants during the report year. Natural gas marketed production: Gross withdrawals of natural gas from production reservoirs, less gas used for reservoir repressuring, nonhydrocarbon gases removed in treating and processing operations, and quantities vented and flared. Natural gas marketer: A company that arranges purchases and sales of natural gas. Unlike pipeline companies or local distribution companies, a marketer does not own physical assets commonly used in the supply of natural gas, such as pipelines or storage fields. A marketer may be an affiliate of another company, such as a local distribution company, natural gas pipeline, or producer, but it operates independently of other segments of the company. In States with residential choice programs, marketers serve as alternative suppliers to residential users of natural gas, which is delivered by a local distribution company. Natural gas plant liquids (NGPL): Those hydrocarbons in natural gas that are separated as liquids at natural gas processing, fractionating, and cycling plants. Products obtained include ethane. liquefied petroleum gases (propane. normal butane. and isobutane ), and natural gasoline. Component products may be fractionated or mixed. Lease condensate and plant condensate are excluded. Note: Some EIA publications categorize NGPL production as field production, in accordance with definitions used prior to January 2014. Natural gas plant liquids (NGPL) production: The extraction of gas plant liquids constituents such as ethane. propane. normal butane. isobutane. and natural gasoline. sometimes referred to as extraction loss. Usually reported in barrels or gallons, but may be reported in cubic feet for purposes of comparison with dry natural gas volumes. Natural Gas Policy Act of 1978 (NGPA): Signed into law on November 9, 1978, the NGPA is a framework for the regulation of most facets of the natural gas industry. Natural gas processing plant: Facilities designed to recover natural gas liquids from a stream of natural gas that may or may not have passed through lease separators andor field separation facilities. These facilities control the quality of the natural gas to be marketed. Cycling plants are classified as gas processing plants. Natural Gas Used for Injection: Natural gas used to pressurize crude oil reservoirs in an attempt to increase oil recovery or in instances where there is no market for the natural gas. Natural gas used for injection is sometimes referred to as repressuring. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Hvis du fortsetter å surfe på nettstedet, godtar du bruken av informasjonskapsler på denne nettsiden. Se vår brukeravtale og personvernregler. Slideshare bruker informasjonskapsler for å forbedre funksjonalitet og ytelse, og for å gi deg relevant annonsering. Hvis du fortsetter å surfe på nettstedet, godtar du bruken av informasjonskapsler på denne nettsiden. Se vår personvernerklæring og brukeravtale for detaljer. Explore all your favorite topics in the SlideShare app Get the SlideShare app to Save for Later even offline Continue to the mobile site Upload Login Signup Double tap to zoom out NATURAL GAS DEHYDRATION Share this SlideShare LinkedIn Corporation copy 2017
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