伊宁凹陷二叠系含油气系统评价

EVALUATION ON PERMIAN OIL AND GAS BEARING SYSTEM IN YINING DEPRESSION

伊宁凹陷以上二叠统铁木里克组为主要烃源岩 ,形成了P2 t-P2 t自生自储和P2 t-T2 -3 下生上储两套含油气系统。前一系统已被钻探所证实 ,为已知系统 ;后一系统为推测系统。盆地热模拟结果及与准噶尔盆地对比分析表明 :该凹陷的二叠系含油气系统在三叠纪早期进入生烃门限 ,早中侏罗世达生烃高峰 ,侏罗纪末结束生油进入生气阶段 ;油气大规模生成运移在T3 ～J1-2 时期 ;印支末幕构造运动 (距今 2 0 8Ma)为该系统的关键时刻。根据油气充注程度、运移方向及圈闭条件综合分析 ,凹陷内的南斜坡为该系统的有利勘探地区。

Tiemulike Formation in the Permian above Yining depression is mainly composed of hydrocarbon source rocks which has formed two complete oil-bearing systems of P 2t-P 2t self-generation & self-reserving and P 2t-T 2-3 lower intervals generation and upper interval reserving. The former system is a known system proved by drilling; the latter system is a system by deducing. The basin thermo-modeling results and comparatively analysis with Junggar basin indicate that the Permian oil and gas-bearing system in the depression had entered into hydrocarbon generation threshold by the earlier Triassic and had reached the peak of hydrocarbon generation by the earlier of the middle Jurassic and had ended oil generation and then gone into gas generation by the end Jurassic. Large scale of oil and gas generation and migration occurred in J 3-J 1-2 ,the last Indo-China episodic tectonic movement(208Ma up to now ) is a key movement of the system. The southern slope in the depression is believed to be a favorable region for the exploration of oil and gas on the basis of multi-analyses of the degree of oil and gas-filling, migration direction and trapping conditions etc.