天然气成藏过程的充注效率研究——以川东石炭系为例

RESEARCH ON HYDROCARBON-CHARGING EFFICIENCY IN THE COURSE OF GAS ACCUMULATION: THE CARBONIFEROUS GAS POOL IN EAST SICHUAN BASIN

采用化学动力学的方法定量描述了川东地区石炭系烃源岩生烃和天然气的逸散过程,进而得到天然气成藏过程中的充注效率。分析认为:①天然气成藏过程中充注效率的变化主要受烃源岩生烃强度和天然气逸散强度的共同影响,具有相应的阶段性;②天然气的充注效率能够更加准确地反映天然气的成藏过程;③在喜山期天然气仍保持较高的充注效率是川东石炭系天然气晚期成藏的关键因素之一。

The method of chemical dynamics is adopted to describe quantitively the process of both hydrocarbon generating and gas releasing in the Carboniferous source rocks in East Sichuan areas, thus to hold the hydrocarbon-charging efficiency in the course of gas accumulation. In this case study, it is considered firstly that any change in hydrocarbon-charging efficiency, which has episodic characteristics, is mainly affected by the degree of both hydrocarbon-generating and gas releasing; secondly that hydrocarbon-charging efficiency can reflect the whole process of gas accumulation well and truly; last but not least that holding up relatively high hydrocarbon-charging efficiency in Himalayan period is one of the key factors on which gas gathered and accumulated in the late period to form Carboniferous gas pool in East Sichuan Basin.