Based on the analyses of generation, migration and accumulation of oil and gas in the structures of Kela 1, Kela 2 and Kela 3 in Kasangtuokai anticlinal belt using a series of geological and geochemical evidence, this...Based on the analyses of generation, migration and accumulation of oil and gas in the structures of Kela 1, Kela 2 and Kela 3 in Kasangtuokai anticlinal belt using a series of geological and geochemical evidence, this paper proposes that the rapid rate of hydrocarbon generation, main drain path for over-pressured fluid flow and converging conduit system are indispensable conditions for the rapid, late-stage gas accumulation in the Kelasu thrust belt in the Kuqa depression. Due to structural over-lapping and the resultant rapid burial, the maturity of the source rocks had been increased rapidly from 1.3 to 2.5% Ro within 2.3 Ma, with an average rate of Ro increase up to 0.539% Ro/Ma. The rapid matura-tion of the source rocks had provided sufficient gases for late-stage gas accumulation. The kelasu structural belt has a variety of faults, but only the fault that related with fault propagation fold and cut through the gypsiferous mudstone cap could act as the main path for overpressured fluid release and then for fast gas accumulation in low fluid potential area. All the evidence from surface structure map, seismic profile explanation, authigenic kaolinite and reservoir property demonstrates that the main drain path related with faults for overpressured fluid and the converging conduit system are the key point for the formation of the giant Kela 2 gas field. By contrast, the Kela 1 and Kela 3 structures lo-cated on both sides of Kela 2 structure, are not favourable for gas accumulation due to lacking con-verging conduit system.展开更多
文摘涪陵页岩气田开发的巨大成功(JY6-2HF井累产超过3×10^8 m^3)为五峰组-龙马溪组页岩气勘探开发提供了新的启示,这一成功的关键在于①焦石坝地区位于鄂西-渝东五峰组-龙马溪组深水沉积区,WF2-LM4笔石带页岩厚度较大,具有较好的页岩气富集的物质基础;②JY6-2HF井主要穿行在WF2-LM4笔石带页岩层位中,该套优质页岩与中东-北非的"Lower Hot Shale"具有全球可对比性。涪陵、威远和长宁等页岩气田开发井的主要水平段也都在这段笔石带之中,该笔石带页岩具有有机碳含量高(TOC>3%)、有机质孔最发育(有机质孔隙度>4%)和含气量高(6.87^9.02 m^3/t)等特点。综合分析认为,在类似的地质和工程条件下,页岩气井水平轨迹在WF2-LM4笔石带页岩中穿行比例决定了页岩气单井产量和最终可采储量(EUR)。研究成果将为四川盆地及其周缘五峰组-龙马溪组页岩气和世界其他地区志留系页岩气勘探开发提供参考。
基金the 973 Project (Grant No. 2001CB209103)the National Natural Science Foundation of China (Grant No. 42038059)the Key Science Research Project of Chinese Ministry of Education (Grant No. 10419)
文摘Based on the analyses of generation, migration and accumulation of oil and gas in the structures of Kela 1, Kela 2 and Kela 3 in Kasangtuokai anticlinal belt using a series of geological and geochemical evidence, this paper proposes that the rapid rate of hydrocarbon generation, main drain path for over-pressured fluid flow and converging conduit system are indispensable conditions for the rapid, late-stage gas accumulation in the Kelasu thrust belt in the Kuqa depression. Due to structural over-lapping and the resultant rapid burial, the maturity of the source rocks had been increased rapidly from 1.3 to 2.5% Ro within 2.3 Ma, with an average rate of Ro increase up to 0.539% Ro/Ma. The rapid matura-tion of the source rocks had provided sufficient gases for late-stage gas accumulation. The kelasu structural belt has a variety of faults, but only the fault that related with fault propagation fold and cut through the gypsiferous mudstone cap could act as the main path for overpressured fluid release and then for fast gas accumulation in low fluid potential area. All the evidence from surface structure map, seismic profile explanation, authigenic kaolinite and reservoir property demonstrates that the main drain path related with faults for overpressured fluid and the converging conduit system are the key point for the formation of the giant Kela 2 gas field. By contrast, the Kela 1 and Kela 3 structures lo-cated on both sides of Kela 2 structure, are not favourable for gas accumulation due to lacking con-verging conduit system.
