大牛地奥陶系马五段岩溶白云岩储层主控因素

针对鄂尔多斯盆地大牛地气田马五段储层成因的多样性，开展对岩溶白云岩储层主控因素的研究。通过岩芯、薄片观察及物性分析，明确了白云岩储层岩石学、储集空间及物性特征，并在此基础上利用测井，建立储层的识别标准。通过测井解释，运用风化壳残余厚度图和连井剖面，解释白云岩储层的主控因素，最后认为：（1）岩溶微古地貌沟槽溶蚀作用极为强烈，多发育溶蚀垮塌角砾岩，储层发育极差；岩溶高地储层相对较好；（2）岩性的差异导致白云岩储层溶蚀程度的强弱，膏质白云岩边溶蚀边垮塌，横向上延伸范围较广，垂向上可形成较深的垮塌，加剧了岩溶发育程度，含极少膏质白云岩容易发育溶孔及裂缝，有利储层发育；（3）不同白云石化作用造成储层的非均质性，准同生期发育的泥晶白云岩较为致密，粉细晶白云岩孔隙较为发育，且两者互层分布使得储层纵向上变化较大，但横向上较为连续。

Main Controlling Factors of the Karst Dolomite Reservoir of Ma 5 Member in Daniudi Area

We discuss the main controlling factors of the karst dolomite reservoir of the Ma 5 Member in the Daniudi area, with the aim of understanding its complexity and diversity. Through core and thin section observation, and analysis of porosity and permeability properties, we studied the petrology, reservoir space, and physical properties of the dolomite reservoir. Based on this analysis, we constructed a reservoir identification standard using well logging data, and inferred the main controlling factors of the dolomite reservoir through logging interpretation, the residual thickness of crust, and the profile of connected wells. We concluded that:(1) the hollows in the karst topography were intensively corroded, and had developed into collapse breccias which display weak reservoir properties, and the karst upland reservoir is generally superior; (2) lithologic differences determine the extent of dolomite reservoir dissolution, with gypsum dolomite being simultaneously corroded and collapsed and it is distributed in a comparatively wide area. However, serious collapse may occur vertically, which contributes to karst development. Solution pores and cracks, which are conducive to reservoir development, can easily develop in gypsum-bearing dolomite; (3) different dolomitization causes dolomite reservoir heterogeneity. Micrite dolomite in the penecontemporaneous period is tight and more pore spaces have developed powder-fine dolomite. Both types are interbedded, which makes the reservoir vary greatly laterally, but relatively continuous horizontally.