玉北地区下奥陶统蓬莱坝组储层成岩作用与孔隙演化

Diagenesis and Pore Evolution of Lower Ordovician Penglaiba Formation Reservoir in Yubei Area

为明晰塔里木盆地玉北地区下奥陶统蓬莱坝组储层的成岩作用特征,基于岩心、薄片、扫描电镜、阴极发光、地球化学等资料,对储集空间特征、成岩作用类型和孔隙演化规律进行了深入探讨。结果表明:研究区建设性的成岩作用有溶蚀、白云石化、泥晶化、破裂、热液作用等,其中与T78界面相关的准同生溶蚀作用是优质储层形成的关键因素,埋藏溶蚀和热液作用在后期改善了储层物性。各种成岩作用控制了孔隙演化的历程,形成现今以溶蚀孔洞、晶间孔、晶间溶孔为主的储集空间。

In order to clarify the diagenesis characteristics of the lower Ordovician Penglaiba Formation of Yubei area in Tarim Basin,based on the core,microscopy,scanning electron microscope,cathodoluminescence and geochemical characteristics,the reservoir space characteristics and pore evolution are deeply discussed.It is concluded that the dissolution,dolomitization,mud crystallization,fracturing and hydrothermal process are constructive diagenesis,and the penecontemporaneous karst associated with the T78 interface is the key to form the high-quality reservoir;burial dissolution and hydrothermal process improve reservoir properties in the later stage.Various diagenesis control the course of pore evolution,finally form today’s reservoir space,which are mainly composed of dissolution pores,intercrystal solution openings and intergranular pores.