沧东凹陷孔二段斜坡演化及控砂控藏机制

Sand-Gathering and Reservoir-Controlling Mechanisms of Ek2 Slope in Cangdong Sag

沧东凹陷为一以构造及沉积特征为背景的叠加改造型湖盆,源储匹配关系复杂。受边界断裂活动及差异演化控制,形成了"两类三坡一带"的构造格局,即南部宽缓的大型继承性斜坡,北部对倾掀斜形成的两翼反转型斜坡及中央背斜带。受凹陷周缘四大盆外物源体系供给影响,发育10个规模不等的三角洲朵叶体,朵叶体沿湖盆边缘环带状分布。以岩性地层油气藏勘探思路为指导,针对孔二段斜坡演化特征及控砂控藏机制进行细致研究。根据研究成果共部署实施探井36口,工业油流井29口,探井成功率80。在三个斜坡区岩性油气藏及湖盆区致密油勘探取得突破,形成了斜坡区岩性油气藏控砂控藏地质认识,完善了断陷湖盆油气成藏理论,对富油气凹陷勘探工作具有参考意义。

The Cangdong sag is a superimposed basin. With the structural and sedimentary characteristics as the background, it has complex source reservoir matching relationship. Controlled by boundary faults and tectonic evolution of the difference in Cangdong sag, it formed the main geological features of“two types, three slopes and one tectonic belt”such as the large inherited slope in the south, central fold belt and two sides of the inversion of the slope in the north. Supplied by the four directions of provenance around the Cangdong sag, the distribution of ten different scale delta lobes are just around the lake. It is difficult to further deepen exploration. Guided by the idea of lithologic stratigraphic reservoir exploration, detailed study has been performed based on the evolution characteristics of Ek2 slope and the mechanism of sand control and reservoir control. According to the research results,36 exploration wells were deployed and 29 wells were obtained. The success rate of exploratory wells was 80%. Based on this geological understanding, great breakthroughs have been made in the exploration of lithologic oil reservoirs and tight oil deposits in the three slopes. On this basis, sand-control and reservoir-control theory of lithologic reservoir was established, and petroleum accumulation theory of fault basin was perfected. This study has an important guiding significance for oil exploration of the sags rich in oil and gas.