塔中—巴楚地区东河砂岩储层发育特征及其主控因素

东河砂岩是一套优质储集层和富油层,也是塔里木盆地重要勘探目的层系.以砂岩储层特征为基础,观察研究区岩心、镜下薄片,研究沉积相在空间分布规律.结果表明:研究区东河砂岩经历压实、石英次生加大、碳酸盐胶结和溶解等多种成岩作用,压实和胶结作用为导致孔隙度下降的主要因素;溶解作用对储层空间形成起建设性作用.塔中—巴楚地区东河砂岩储层特征差异明显,塔中地区储层物性较好,为中高孔中高渗储层,目前处于中成岩阶段AⅠ亚期;巴楚地区储层物性较差,为低孔低渗储层,目前处于中成岩阶段AⅡ亚期.研究区东河砂岩储层发育的主控因素为沉积环境和成岩作用,优质储层主要分布于颗粒成分较纯、泥质含量较低的前滨相及上临滨亚相地区.

Characteristics of the Donghe Sandstone reservoir in Tazhong-Bachu area and the main controlling factors

The Donghe sandstone is an excellent reservoir and a major target sequence for petroleum prospecting in Tarim basin.To start with a study on the character of reservoir,based on the observation of core and rock slice,and a detailed work on the study of spatial and vertical distribution of the sedimentary facies in the studied area,the paper shows that the Donghe sandstones in the study area mainly went through the compaction,the quartz overgrowth,the cementation of carbonate,the dissolution and the other diagenesis.The compaction and the cementation are the major factors making the porosity decline,while the dissolution plays a constructive role in the formation of the reservoir space.The sand reservoir characteristic of the Donghe Formation in Tazhong is different from the Bachu’s.The Donghe sandstones’ reservoir properties in Tazhong is preferable,and the reservoir is characterized by medium-high porosity and permeability,so now the Donghe sandstones are in the middle diagenesis AⅠ stage.The Donghe sandstones’ reservoir properties in Bachu is poor,and the reservoir is characterized by low porosity and permeability,so the Donghe sandstones are now in the middle diagenesis AⅡ stage.This paper argues that the controlling factors of the sand reservoir in the Donghe sandstones are sedimentary facies and the diagenesis through comparative analysis between the Tazhong and the Bachu areas,and the good reservoir is mainly distributed in the foreshore upper nearshore areas with pure lithological components,low clay.