摘要：

西部凹陷南部为辽河油田的重点探区之一，具有十分优越的石油地质条件。本区在沙三期断陷活动强烈，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，在西部凹陷南部发育有齐家—杜家台和锦州—欢喜岭两大湖底扇沉积体系。受物源区的距离、基底构造和主干断层活动的控制，湖底扇平面上具有分带性，可划分为内扇、中扇和外扇三个亚相带。齐杜和锦欢湖底扇在沙三早期规模较小，中期规模最大，晚期萎缩。本区沙三段储层物性普遍较差，以低孔—低渗、特低孔—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，平面上依中扇辫状沟道→中扇前缘→外扇亚相储层物性由好变差。储集性能的优劣主要受母岩区岩性、沉积作用、成岩作用等多种因素控制。沙三段湖底扇砂体在区内分布广泛，处于成熟生油岩的包围之中，位于油气运移的有利指向上，成藏条件优越，勘探前景广阔。

Abstract:

The southern West Depression of the Liaohe Basin has been developed with favorable geological conditions for oil and gas accumulation and thus is an important exploration area of the Liaohe Oil Company. In Shasan (third membre of the Shahejie Formation) period, huge deep water mudstone and multiple low-angle sloped lake floor fan sediments were deposited as a result of active faulting and subsiding. These deposits have provided abundant hydrocarben source rock and reservoir for the formation of oil and gas pools. During this period, the Qijia-Dujiatai and Jinzhou-Huanxiling lake floor fan depositional systems were developed in the southern West Depression. Controlled by the distance to the terrigenous province, basement structure and main faults, these lake floor fans can be sub-divided into three subfacies, inner fan, middle fan and outer fan. Both of these lake floor fans have smaller scale in the early Shasan period, largest scale in the middle Shasan period and decreased scale in the late Shasan period. The properties of the Shasan reservoirs are very poor in the study area, which are characterized by low porosity-permeability, extremely low porosity-permeability. The best reservoir of lake floor fan is the sandbodies of the middle-fan braided channel microfacies, and reservoir properties decrease from the middle-fan braided channel deposits through the middle fan front to the outer fan deposits. Reservoir characteristics are mainly controlled by lithology of parent rocks, deposition and diagenesis. The Shasan lake floor fan sandbodies distributed widely in the study area are surrounded by mature hydrocarbon source rocks and are located at the beneficial direction of oil and gas migration, hence having a promising exploration potential.