超高压大气田(藏)成因机理——以库车坳陷为例

Genetic Mechanism of Overpressure Large Gas Field(Reservoir)——An example from Kuqa depression in Tarim basin

在前人研究的基础上,分析了超高压对烃源岩、储集层和盖层等成藏要素的影响,研究了超高压对天然气运聚成藏的作用。以库车坳陷为例,结合烃源岩生烃史、圈闭形成史和高压演化史等地质史,分析了库车坳陷超高压大气田形成机理。研究认为,超高压在库车坳陷大气田的形成过程中起了重要的作用,抑制了侏罗系烃源岩的演化,改善了白垩系储集层的储集性能,提高了古近系膏泥岩盖层的封闭能力,为油气的幕式排烃和二次运移提供了条件。

Based on the previous study results, the influence of overpressure on the reservoir-forming factors such as source rock, reservoir and cap rock was analyzed, and the control effect of overpressure on natural gas migration and accumulation was researched. Taking Kuqa depression in Tarim basin as an example, combining with histories of hydrocarbon generation, trap formation and overpressure evolution, the genetic mechanism of overpressure large gas field in Kuqa depression was analyzed. The results show that the overpressure plays a significant role in its formation process by inhibiting the evolution of the Jurassic source rock, improving the quality of the Cretaceous reservoir and enhancing the seal ability of the Paleocene gypsum mudstone cap rock, and provides potential power for the episodic hydrocarbon expulsion and secondary hydrocarbon migration in this area.