关键词: 沉积盆地, 超压, 断-压双控作用, 幕式流体流动, 油气成藏, 有机质, 热演化

Abstract: The development of overpressure in sedimentary basin has the important material and energy effects on oil and gas accumulation.Overpressure retardation of organic matter maturation can keep the deeply buried source rocks and the relatively old source rocks in the favorite hydrocarbon-generation and hydrocarbon-expulsion stage simultaneously with the young source rocks.The resultant delay in fluid release would lead to the centralized expulsion of hydrocarbon generated at different temperature and maturity,which increased the interval and volume of effective source rocks and further increased the accumulative hydrocarbon-expulsion rates.Such a process is favorable for late-stage rapid accumulation of hydrocarbon.Overpressure can cause natural hydraulic fracturing of strata,which is an important way for the primary expulsion of overpressure fluid flow.The secondary expulsion of overpressure fluid was controlled by overpressure development and the nature of faults.This kind of fluid flow may be called as overpressure-fault controlled fluid flow.The combination of the material and energy effects of overpressure determined the rapid hydrocarbon accumulation controlled by neotectonic movement or late-stage tectonic activities.The hydrocarbon accumulation was accomplished by episodic fluid injections.Each episode included steady converging and transient injection periods.The episodic accumulation rate was very high,and the large oil-gas fields could be formed within 0.1 million years.The tectonic activities had the constructive role for hydrocarbon accumulation.The neotectonic movement or late-stage tectonics controlled hydrocarbon distribution.

Key words: sedimentary basin, overpressure, overpressure-fault control, episodic fluid flow, hydrocarbon accumulation, organic matter, thermal evolution