元坝气藏须家河组三段储层特征与主控因素

Reservoir Characteristics and Main Controlling Factor of the Third Member of Xujiahe Formation in Yuanba Gas Reservoir

针对元坝气藏须家河组三段致密砂岩储层,开展了岩性、物性、储集空间类型及主控因素的研究,对物性实验数据的分析及薄片观察结果表明,元坝地区须三段的储层岩性以粗—中粒钙屑砂岩为主,含部分中—细粒的岩屑石英砂岩;钙屑砂岩的储集空间以次生溶孔为主,且以粒内溶孔为主,同时有部分微裂缝。该段储层物性表现为孔隙度较高,渗透率较低,为裂缝-孔隙型储层。元坝地区须三段钙屑砂岩储层发育程度受控于沉积作用,水下分流河道是该套砂岩储层发育的主要微相,溶蚀作用及构造破裂作用是控制该套储层形成的主要地质因素。研究成果对元坝地区须三段的勘探开发具有一定的指导意义。

Researches have been done on the lithologie character, physical property, reservoir space, and main controlling factor of the tight sand reservoir of the third member of Xujiahe Formation in Yuanba gas reservoir. The analysis of physical data and observation of thin section reveals that the lithology of sandstone reservoir is mainly coarse to medium calcarenaceous sand-stone with some medium to fine detritus quartz sandstone; calcarenaceous sandstone reservoir space is mainly secondary dissolved pore, with intergranular dissolved pores and crevices. Reservoir property is characteristic of low porosity and high permeability. Reservoir model is crevice and porosity reservoir. Sedimentary process controls the calcarenaceous sandstone reservoir development of the third Member of Xujiahe Formation in Yuanba gas reservoir. Underwater distributary channel deposit is the major microfacies in the calcarenaceous sandstone reservoir. Denudation and tectonic disruption are the major geologic factors. The research results are of significance in the exploration and development of the third Member of Xujiahe Formation in Yuanba gas reservoir.