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天然气地球科学 2012
Natural Gas Generation from the Xujiahe Formation Coal Measures in Guang'an Area,Sichuan Basin
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Abstract:
Guang′an gas field,a gas field in the central Sichuan basin,has a considerable geological reserve of natural gas,but the Xujiahe Formation coal measures is limited.In this paper,the Xujiahe Formation coal in the Guang′an area was selected to carry out the closed system pyrolysis and kinetics modeling in order to elucidate the characteristics and process of natural gas generation in this area.The HC generation history of natural gas is reconstructed by hydrocarbon generation kinetic parameters.The results indicate that natural gas generation was mainly started in the late Jurassic (168 Ma).Since the late Yanshan movement,the hydrocarbon generation ended due to crustal uplifted,and paleogeothermal temperature dropped drastically between Jurassic and Cretaceous,and the duration of hydrocarbon generation is about 28Ma.Hydrocarbon conversion is more than 50%,with quick generation of natural gas within a short period.Good reservoir-cap combination and undeveloped fracture is key to as preservation in long term in the Guang′an area,Sichuan basin.