Advances in Earth Science ›› 2008, Vol. 23 ›› Issue (4): 390-400. doi: 10.11867/j.issn.1001-8166.2008.04.0390

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The Generation Synchroneity of H 2S and C 2+ Gaseous Alkane—Implications of Some Simulation Experiments

Zhang Jianyong 1,2,Liu Wenhui 1,3,Tenger 4,Wang Xiaofeng 1,Qing Ying 5, Ma Fengliang 6   

  1. 1.Lanzhou Oil-Gas Resource Centre , Institute of Geology and Geophysics, CAS,Lanzhou 730000,China; 2.Graduate University, CAS, Beijing 100039,China;3. Exploration & Production Research Institute, SINOPEC, Beijing 100083,China;4. Wuxi Reseurch Institute of Petroleum Geology, SINOPEC, Wuxi 214151,China;5. Research Institute of Exploration and Development, Jidong Oilfield, Tangshan 063004,China;6. PetroChina Exploration & Development Research Institute (Northwest), Lanzhou 730020,China
  • Received:2007-12-10 Revised:2008-02-20 Online:2008-04-10 Published:2008-04-10

Zhang Jianyong,Liu Wenhui,Tenger,Wang Xiaofeng,Qing Ying, Ma Fengliang. The Generation Synchroneity of H 2S and C 2+ Gaseous Alkane—Implications of Some Simulation Experiments[J]. Advances in Earth Science, 2008, 23(4): 390-400.

The thermochemical sulphate reduction (TSR) is believed to be the determinative factor for gas reservoirs to generate high content of H2S (the volume percent of H2S above 5%), but the main hydrocarbon compounds react with sulphate are still not distinctly made sure. In this paper, based on the contrast analysis of TSR reaction systems ( wet gas and magnesium sulfate, methane and calcium sulphate, heavy hydrocarbon and magnesium sulfate), through the analysis of TSR chemical equations and study of chemical kinetics and chemical thermodynamics, combined with geologic information, it is concluded that methane is believed to be the product of the TSR reaction between heavy hydrocarbon and sulphate, and not main reactant; there is synchroneity between the TSR reaction and the increasing of C2+  gaseous Alkane, the TSR reaction rate increase as C2+ Gaseous Alkane increase and the volume of H2S almost not increase till the wet gas cracked to be dry gas and then dry gas with H2S is generated. According to the analysis of oil and gas evolution stage, it is believed that TSR mainly at the stage of condensate gas generation by thermal cracking. When crude oil being cracked to be natural gas with H2S, the pressure system is changed and gas with H2S will be newly accumulated and the natural gas with H2S will be accumulated again in new traps if the structural environment changes. So, the volume of H2S in natural gas reservoirs is not only controlled by generation conditions but by other factors, such as migration pathway conditions, reservoirs conditions and preservation conditions.

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