辽河西部凹陷南部沙三段储层沉积特征

Raservolr Sedimentary CharacteristIcs In Es3 to the Southwest Depression in Llaohe Basin

辽河盆地西部凹陷南部在沙三段沉积时期断陷活动强烈 ,发育了巨厚的深水泥岩和多期次缓坡型湖底扇沉积 ,为油气聚集成藏提供了丰富的油气源条件和储集条件。沙三段沉积时期 ,该区发育有齐家杜家台和锦州欢喜岭两大湖底扇沉积体系。受物源和基底构造的控制 ,湖底扇平面上可划分为内扇、中扇和外扇 3个亚相带。齐家杜家台和锦州欢喜岭湖底扇在沙三段沉积早期规模较小 ,中期规模最大 ,晚期萎缩。该区沙三段储层物性普遍较差 ,以低孔特低孔、低渗特低渗储层为主 ,其中湖底扇中扇辫状沟道微相砂体储集性能最好 。

During sedimentation stage of No. 3 member of Sahejie formation (Es 3), rift action is serious in the west depression of Liaohe Basin, thick deep-water mudstone and multistage flat slope lake floor fan deposit are developed, by which conditions of rich oil and gas resources and reserves are supplied. Two lake floor fan sedimentary systems of Qinjiatai-Dujiatai and Jinzhou-Huanxiling are developed in the area. Controlled by provenience and basement structure , three subfacies of inner fan ,middle fan and outer fan could be classified on the plane of lake floor fan. The scale of these 2 lake floor fans are small at the early Es 3 stage, large at middle stage and shrinking at late stage . In the area, reservoir physical property is generally poor with low and extremely low porosity-permeability,sandbodies of braid culvert microfacies are the best reservoirs of lake floor fan. On the plane, the reservoir physical properties are getting poorer from middle fanbraid culvert to middle fan front and then to outer fan subfacies.