CHEN Shi jia, FU Xiao wen, SHEN Zhao guo, ZHAO Meng jun, HUANG Di fan. Molecular Nitrogen Genesis in Natural Gases and Relationship with Gas Accumulation History in Tarim Basin[J]. Acta Sedimentologica Sinica, 2000, 18(4): 615-618,623.
| Citation:
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CHEN Shi jia, FU Xiao wen, SHEN Zhao guo, ZHAO Meng jun, HUANG Di fan. Molecular Nitrogen Genesis in Natural Gases and Relationship with Gas Accumulation History in Tarim Basin[J]. Acta Sedimentologica Sinica, 2000, 18(4): 615-618,623.
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Molecular Nitrogen Genesis in Natural Gases and Relationship with Gas Accumulation History in Tarim Basin
- 1.
South west Petroleum Institute,Nanchong Sichuan 637001;
- 2.
Petroleum Exploration and Development Institute,CNPC,Beijing 100083
- Received Date: 1999-08-03
- Rev Recd Date:
1999-12-14
- Publish Date:
2000-08-10
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Abstract
Molecular nitrogen (N2 )content of marine saporpelic ytpe gases derived from Lower Paleozoic source rock is high, ranging from 1.61～36.2 percent of molecular nitrogen. N 2 content of wet gases ranges from 10.1% to 36.2%, while dry gases less than 10%, it is to say that N 2 content of wet gases is higher than that of dry gases.Why is there large difference of N 2 content between wet gases and dry gases derived from the same type source rock? What relationship it has with gas migration and accumulation ? Based on the composition and isotope geochemical characteristics of associated gases and non hydrocarbon gases,as well as rare gas in nature gas,N 2 genesis and origin are ascertained in this paper. The study shows that natural gases of middle high N 2 content belong to organic genesis,which is originated from lower Paleozoic marine carbonate source rock. It is indicates that N 2 content difference between wet and dry gas has close relationship to source rock, maturity and natural gas accumulation history.For the same type source rock, N 2 content in gas is controlled by source rock maturity and entrapment conditions.Because of the difference of nitrogen existence form in organic matter of carbonate and mudstone or shale source rock,nitrogen is mainly combined in kerogen by chemical bond for carbonate source rock,but for mudstone or shale source rock,besides chemical bond,nitrogen is bonded in clay mineral by ion substitution form during organic matter maturation.Thermal simulation shows that nitrogen release mechanism is different for the different source rock.N 2 release capacity reachs peak at the generation peak for carbonate source rock, N 2 content of gases decreasing at the high super maturity stage.While for mudstone or shale source rock, N 2 release capacity reachs peak at the high super stage.Therefore,N 2 content of natural gas entrapped at different maturity stage of source different, N 2 content variation in natural gases can be used to reveal natural gas accumulation history, and also to evaluate trap effectiveness. Lower N 2 content of dry gas in Tabei area demonstrates that oil and gas containing higher N 2 content at the generation peak have been lost,and that natural gas captured in the present traps is mainly originated from high super maturity source rock,The above conclusion is supported by heavy methane carbon isotope and large dryness of the gas,and also supported by geologic conditions of Tabei area. Higher N 2 content and lighter methane carbon isotope of wet gas in Tazhong area shows that gas maturity is lower than that of dry gas in most part of Tabei area,natural gas with high N 2 content formed by source rock at the generation peak is captured by trap.
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References
|
[1]
|
黄第藩.塔里木盆地东部天然气的成因类型及成熟度判识[J].中国科学(D辑),1996,26(4)：365～372 |
|
[2]
|
Littke R, Kroos B. Molecular nitrogen in natural gas accumulations:generation from sedimentary orgaric matter at high temperatures [J]. AAPG 1995,79(3):410～430 |
|
[3]
|
Littke R,Kroog B. Generation of nitrogen and methane from sedimen |
|
[4]
|
tary organic matter: implication on the dynamics of natural gas accumulation Chem[J]. Geol. 1995,126:291～318 |
|
[5]
|
3apЪκинлм, CтapoЪинeцИ C, Cтaднк B B. тeoхимияпpиpoдньLх raзoвнеφгeгазoнocньLx ЬaoceИHoB, 1984 |
|
[6]
|
Williams et al. Nitrogen isotope geochemistry of organic matter and minerals during diagenesis and hydrocarbon migration[J]. Geochnica et Comochmica Acta 1997,59(4):765～779 |
|
[7]
|
张子枢.气藏中N2的地质地球化学[J].地质地球化学,1988,2:51～56 |
|
[8]
|
杜建国,刘文汇,邵波,Faber E.天然气中氮气的地球化学特征成[J].沉积学报,1995,14(1):143～147 |
|
[9]
|
刘文汇,徐永昌.天然气氦氩同位素特征[J].科学通报,1993,38(9)：818～822 |
|
[10]
|
戴金星等.天然气地质研究新进展[M].北京：石油工业出版社,1997 |
|
[11]
|
Gold T, Held M. Helium-nitrngen-methane systematics in natural gases of Texas and Kansas[J]. Joural of Petroleum Geology, 1987,10(4): 415～424 |
|
[12]
|
Jenden P D et al. Origin of nitrogen-rich natural gases in California Great Vally: Evidence from helium, carbon and nitrogen isotope ratios [J]. Geochmica et Cosmochmica Acta 1988,52:851～861 |
|
[13]
|
Stevenson. Chemical state of the nitrogen in rocks Geochem[J]. Cosmochim. Acta 1962,26:797～811 |
|
[14]
|
Cooper J E Abedin K E. The relationship between fixed ammoniumnitrogen and potassium in clays from a deep on the Texas Gulf Coast [J]. TexasJ. Sci. 1981,33:103～111 |
|
[15]
|
Williams, Ferrll L B. Fixed-ammonium in clays associated with crudeoils[J]. Appl. Geochem, 1989,4:605～616 |
|
[16]
|
Williams et al. Ammonium substitution in ilite during maturation of organic matter[J]. Clays and clay minerals 1991,39 (4):400～408 |
|
[17]
|
Williams et al. Minerlition of organogenic ammonium in the Monterey Formation, Santa Maria and San Joaquin basins, Califoornian, USA [J]. Geochmica et Cosmochmica Acta 1992,56:1979～1991 |
|
[18]
|
Charlesworth M. Interaction of clay minerals with organic nitrogen compounds released by kerogen pyrolysis [J]. Geochmica et Cosmochmica Acta 1986,50:1431 ～1435 |
|
[19]
|
Keeney D R,Nelson D W. Nitrogen-inorganic froms[A]. In: Keeney A L, ed. methods of Analysis Part 2 [C]. Agron., Soil Sci. Soc. Amer., 1982. 643～698 |
|
[20]
|
Baxby M, Patience R L et al. The origin and diagenesis of sedimentary orgaric nitrogen[J]. Joural of Petroleum Geology, 1994,17(2):211 ～230 |
|
[21]
|
Maksimov S N F. Origin of high-nitrogen gas pools[J]. Internationl Geological Review. 1975,18(5):51 ～556 |
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