陕北地区马家沟组五段7、9亚段白云岩储层特征及主控因素的研究

Research on Characteristics and Control Factors of Dolomitic Reservoir in the 7^th and 9^th Submembers of Majiagou Formation in the Northern Shaanxi Region

摘要: 通过镜下薄片鉴定、X衍射、物性及压汞测试，对陕北地区奥陶系膏盐下马家沟组五段7、9亚段的储层特征及主控因素进行了综合分析。结果表明：目的层岩性主要为粉–细晶白云岩、粉–细晶颗粒白云岩、泥粉晶白云岩；储集空间以晶间孔、晶间溶孔、溶孔为主，膏模孔及微裂缝次之；不同岩性、相带及成因的白云岩储集体，其物性特征具有较大的差异性，沉积相带、沉积层序及TSR反应(烷烃与膏岩的化学反应)对储层分布具有一定的控制作用。

Abstract: The reservoir characteristics and key control factors in 7th and 9th submembers of the 5th Member (Om5) of Ordovician Majiagou Formation in the northern Shaanxi Region were comprehensively analyzed through thin section analysis, X-ray diffraction, physical property analysis and mercury injection test. Study result indicates that the reservoir lithology is mainly powder-fine crystal dolomite, powder-fine crystal particle-sized dolomite and argillaceous powder crystal dolomite. The reservoir pore space is intergranular pore, intergranular dissolved pore and dissolved pore, followed by the gypsum meld holes and micro-fractures. The physical properties of dolomite reservoirs with different lithologies, facies belts and genesis are quite different. The differences of sedimentary microfacies, sequence stratigraphy and TSR reaction (the chemical reactions of alkanes and gypsum) have a controlling effect on the distribution of the reservoirs.