The Impact of The Neotectonics on the Late-Accumulation Reservoirs in the West Sichuan Foreland Basin and the Kuqa Foreland Basin, Mid-West China
Based on the former study results, some research methods, such as geological statistics, structure analysis, reservoirs analysis, geochemical analysis and physical simulation have been applied to analyze the controlling of the neotectonic movement on the oil and gas accumulation, taking Kuqa foreland basin and Chuanxi forland basin as study areas.
The analyses of the typical reservoirs and accumulation factors showed that the oil and gas are trapped in the Kuqa foreland basin and the existed pools were adjusted to new shallow-reservoirs or destroyed in the Chuanxi foreland basin since the neotectonic movement. The neotectonic movement controlled the accumulating factors of reservoirs: (1) accelerates the maturation of hydrocarbon rocks to generate and expel oil and gas; (2) forms new reservoir beds and reconstructs old reservoir beds, (3) forms new cap rocks, (4) forms new traps and deforms old traps, (5) generates new faults and causes old faults reactive, (6) generates a high pressure in the hydrocarbon rocks, (7) matches the oil and gas accumulating factors in a relative short time.
The formation process of oil and gas reservoirs can be summarized as “timing match, fault-pressure control, buoyancy adjust, late accumulation”. “timing match” needs the time of traps formation matching the time of hydrocarbon expelling; “fault-pressure control” means the oil and gas generated by hydrocarbon rocks migrate through the faults with the power of high pressure, “buoyancy adjust, late accumulation” describes that oil and gas in the beds adjust slowly to form a pool by the power of buoyancy.
AAPG Search and Discovery Article #90083 © 2008 AAPG Foundation Grants in Aid