川西坳陷大邑构造须三段储层裂缝类型及控制因素

川西坳陷大邑构造须家河组三段储层岩性以中细粒碎屑石英砂岩为主,孔隙度、渗透率很低,为典型的低渗透砂岩储层,裂缝对储层的储集和渗透能力具有重要影响,因此,该区裂缝发育特征及其控制因素的研究在储层油气资源的开发和评价中起着重要作用。文中以岩心裂缝观测和岩石力学实验数据为主要依据,对该区须三段储层的裂缝类型及发育特征进行描述和分析,探讨了构造裂缝发育的控制因素。研究表明,该区须三段低渗透砂岩储层主要发育构造裂缝、成岩裂缝和异常高压裂缝3种类型,其中构造裂缝最发育,主要受构造应力场、构造位置和岩石力学性质等因素控制,对油气的形成与分布影响最大。

Types and controlling factors of fractures for the third Member of Xujiahe Formation in Dayi structure,west Sichuan Depression

Tile reservoir of the third Member of Xujiahe Formation in Dayi structure of west Sichuan Depression is mainly fine grain quartz sandstone with very low porosity and penneability. This member is low penneability sandstone reserwfir and fracture has an impollant impact on tire storage and permeable property of reservoir. Therefore, the researeh on the fracture charaeteristies and controlling faclnrs plays an important role in the oil and gas resource exploitation and assessment. Based on core observations and tire experimental data of rock mechanics, this paper described and analyzed the type anti developmental characteristics of structural fractures in tirethird Member of Xujiahe Formation in this area. On this basis, it diseussed the controlling factor of structural fractures. Sludy shows tbat the major type of fracture in the low pemreability sandstone reservoir are structural fraeture, diagenelic fraeture and abnormal high pressure fracture. In them, structural fraclures are main fractures, which greatly affect on nil and gas formalion and distribution. The development of structural fracture is controlled by tectonics stress fieht, tectonic position and mechanical properties of rocks.