Different Hydrocarbon Accumulation Histories in the Kelasu‐Yiqikelike Structural Belt of the Kuqa Foreland Basin

The Kuqa foreland basin is an important petroliferous basin where gas predominates. The Kela‐2 large natural gas reservoir and the Yinan‐2, Dabei‐1, Tuzi and Dina‐11 gas reservoirs have been discovered in the basin up to the present. Natural gases in the Kelasu district and the Yinan district are generated from different source rocks indicated by methane and ethane carbon isotopes. The former is derived from both Jurassic and Triassic source rocks, while the latter is mainly from the Jurassic. Based on its multistage evolution and superposition and the intense tectonic transformation in the basin, the hydrocarbon charging history can be divided into the early and middle Himalayan hydrocarbon accumulation and the late Himalayan redistribution and re‐enrichment. The heavier carbon isotope composition and the high natural gas ratio of C1/C1–4 indicate that the accumulated natural gas in the early Himalayan stage is destroyed and the present trapped natural gas was charged mainly in the middle and late Himalayan stages. Comparison and contrast of the oils produced in the Kelasu and Yinan regions indicate the hydrocarbon charging histories in the above two regions are complex and should be characterized by multistage hydrocarbon migration and accumulation.

[1]  Minggang Li,et al.  Contractional Structure Model of the Transition Belt between Kuche Depression and South Tianshan Uplift , 2009 .

[2]  Yang Wenjing,et al.  Thick‐skinned Contractional Salt Structures in the Kuqa Depression, the Northern Tarim Basin: Constraints from Physical Experiments , 2008 .

[3]  Li Yan,et al.  Petroleum Migration Direction of the Silurian Paleo‐pools in the Tarim Basin, Northwest China , 2008 .

[4]  S. Inan.  Gaseous hydrocarbons generated during pyrolysis of petroleum source rocks using unconventional grain-size: implications for natural gas composition , 2000 .

[5]  F. Mango.  The light hydrocarbons in petroleum: a critical review , 1997 .

[6]  P. L. Thiez,et al.  Effect of waterwashing on light ends compositional heterogeneity , 1996 .

[7]  Bernhard M. Krooss,et al.  Generation of nitrogen and methane from sedimentary organic matter: implications on the dynamics of natural gas accumulations , 1995 .

[8]  A. Huc,et al.  Genetic and post-genetic molecular and isotopic fractionations in natural gases , 1995 .

[9]  J. Moldowan,et al.  Oil composition variation and reservoir continuity: Unity field, Sudan , 1994 .

[10]  Ė. Galimov.  Sources and mechanisms of formation of gaseous hydrocarbons in sedimentary rocks , 1988 .

[11]  W. A. England,et al.  The movement and entrapment of petroleum fluids in the subsurface , 1987, Journal of the Geological Society.

[12]  K. Thompson.  Classification and thermal history of petroleum based on light hydrocarbons , 1983 .

[13]  Martin Schoell,et al.  The hydrogen and carbon isotopic composition of methane from natural gases of various origins , 1980 .

[14]  K. Thompson.  Light hydrocarbons in subsurface sediments , 1979 .

[15]  W. Stahl.  Carbon and nitrogen isotopes in hydrocarbon research and exploration , 1977 .

[16]  G. Philippi.  The deep subsurface temperature controlled origin of the gaseous and gasoline-range hydrocarbons of petroleum , 1975 .