川西南井研地区栖霞组白云岩储层发育主控因素

Main controlling factors of dolomite reservoir development of Qixia Formation in Jingyan area, southwestern Sichuan Basin

李蓉 李素华 石国山 苏成鹏 贾霍甫 林辉

中国石化西南油气分公司勘探开发研究院，四川 成都 610041 中国石化西南油气分公司地质中心实验室，四川 成都 610081

Research Institute of Exploration and Development, Southwest Oil and Gas Company, SINOPEC, Chengdu 610041, China Geological Center Laboratory, Southwest Oil and Gas Company, SINOPEC, Chengdu 610081, China)

四川盆地栖霞组白云岩勘探潜力大，川西南地区勘探程度较低，储层发育主控因素尚未明确。近期，井研地区栖霞组白云岩获得油气突破，通过新钻井岩心、薄片和测试资料分析，开展了栖霞组储层特征研究，探讨了储层发育主控因素。研究表明：研究区栖霞组岩性主要为基质白云岩、斑马构造白云岩和岩溶改造白云岩；储层以发育细—中晶白云岩为特征，晶间（溶）孔和溶洞为主要储集空间，为一套Ⅲ类低孔低渗裂缝￣孔隙（洞）型储层，在平落坝—井研一带储层厚度最大。沿乐山—龙女寺古隆起坡折带、微古地貌高地发育的生屑滩为储层发育提供物质基础；准同生期大气淡水淋滤溶蚀提高储层孔渗性能，同时为白云岩化流体提供优势渗流通道；早期白云岩化作用有效保持储集空间不被破坏，最大限度保存了早期孔洞系统。

The dolomite of Qixia Formation in Sichuan Basin has great exploration potential. Due to the low degree of exploration, the main controlling factors of reservoir development in southwest Sichuan Basin are not clear yet. Oil and gas breakthrough of the Qixia Formation dolomite are acheived in Jingyan area. The reservoir characteristics and the main controlling factors of development of Qixia Formation were studied by analyzing the core, thin sections and test data of new drilling wells. The research shows that the lithology is mainly matrix dolomite, zebra structure dolomite and karst modified dolomite. The reservoir rocks are mainly composed of fine to mesocrystalline dolomite, the reservoir spaces type are mianly intercrystal (dissolution) pore and karst caves, it is the Ⅲ type of low porosity and low permeability fracture-pore （cave） reservoir. The thickest reservoir is mainly developed from Pingluoba to Jingyan area. The bioclastic beach developed along the slope break belt of Leshan￣Longnyusi paleo-uplift provides material basis for reservoir development. Penecontemporaneous atmospheric water leaching and dissolution can improve reservoir porosity and permeability and provide dominant seepage channel for dolomitization fluids. Early dolomitization effectively kept the reservoir space intact and preserved the early pore and cave system to the maximum extent.

10.6056/dkyqt202301011