塔里木盆地下奥陶统蓬莱坝组白云岩储层特征

Dolomite Reservoir Characteristics of Lower Ordovician Penglaiba Formation,Tarim Basin

通过钻井岩心观察、岩石薄片鉴定、物性测试及地球化学分析等手段,对塔里木盆地下奥陶统蓬莱坝组白云岩层岩石学特征、储集空间特征、储层物性特征进行了研究,并分析了控制储层发育的因素。认为分布于塔里木盆地巴麦、塔北、塔中大部分地区的蓬莱坝组主要为一套岩性纯、厚度大的白云岩层,其岩石类型以粉晶、细晶白云岩为主,同时也发育有泥晶白云岩、中—粗晶白云岩;储集空间类型以晶间孔、晶间溶孔、构造裂缝及溶蚀孔洞等为主;储层物性非均质性很强,不同地区的蓬莱坝组白云岩层的孔隙度和渗透率具有较大的差异;影响该组白云岩储层物性的因素主要有压实及压溶作用、胶结作用、重结晶作用、埋藏溶蚀作用、白云石化作用、构造作用及风化壳溶蚀作用等。

For dolomite reservoir of lower Ordovician Penglaiba Formation in Tarim Basin,the petrological,reservoir space and petrophysical-property characteristics and the factors controlling reservoir growth are studied in this paper based on core-drilled observation,thin-section identification,petrophysical-property test and geochemical analysis.It is considered that:(1) Penglaiba Formation in Bamai area,north and central Tarim Basin is almost composed of dolomite with large thickness,which mainly including silty to fine-grained dolomite and some micritic,middle-to coarse-grained dolomite;(2) the reservoir space includes intercrystalline pore,intercrystalline solution pore,solution pore and structural fracture;(3) it is characterized by strong heterogeneity and its permeability and porosity arevery different for Penglaiba reservoirs in different areas;and(4) the factors controlling petrophysical property are mainly compaction,pressure solution,cementation,recrystallization,burial dissolution,dolomitization,tectonism and weathering-crust dis solution.