准噶尔盆地腹部超压控制烃、储演化与油气充注过程

准噶尔盆地中生界地层普遍发育异常高压,且与油气分布关系复杂.为了明确异常高压形成演化过程与烃源岩成烃演化、储层成岩演化的关系及其在成藏期油气充注过程中的作用,综合利用钻井、测井和录井资料,充分采用地球物理与地球化学测试成果,建立地层压力、生物标志物、储层物性分布之间的相关性,明确异常高压对成烃、储层成岩演化以及油气充注过程的影响.结果表明：在超压作用影响下,烃类演化保持较长的时限,对于盆地腹部有效烃源岩的长期演化具有积极的促进作用;同时,储层砂岩的孔渗条件也直接或间接地受控于异常高压演化,是现今深部储层砂岩保持较好的孔渗条件的重要成因之一;成藏关键期,油气充注过程在超压或强超压驱替作用下,油气的横向和垂向运移具幕式排放特征.

Control of abnormal overpressure on hydrocarbon-reservoir evolution and hydrocarbon filling process in central of Junggar Basin

Abnormal high pressure develops widely in Mesozoic strata in Junggar Basin. The relationship of hydrocarbon distribution is complex. The aim of this paper is to get clear the role of the evolutionary process of abnormal high pressure formation, the hydrocarbon generation evolution and the diagenetic evolution of reservoir, as well as the hydrocarbon filling process in pool-forming period. Combining with the data of drilling, logging and well log, and taking full of use the results of geophysics and geochemical tests, this paper built the correlations among the formation pressure, biomarker compounds and reservoir property distribution for understanding the effect of abnormal high pressure on hydrocarbon generation, reservoir diagenetic evolution and the hydrocarbon filling process. The results show that under the effect of abnormal high pressure, hydrocarbon generation can keep a long time and play a positive role in the long-term evolution of effective source rock in the central of basin. Meanwhile, the permeability of sandstone reservoir condition is also controlled by the abnormal high pressure evolution directly or indirectly, which is one of the most important reasons why the permeability of deep reservoir sandstones remains in good conditions. In the key period of poolforming, the hydrocarbon filling process is under the overpressure or highly overpressure displacement and the oil and gas lateral and vertical migration has the episodic hydrocarbon-expulsion characteristics.