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塔里木盆地下古生界白云岩是重要的油气储层,由于经历了长期而复杂的成岩演化过程,其储集空间以次生孔隙为主,其中微孔储集体系分布广泛,很不均匀,并且规律性不强。通过对大量白云岩岩心薄片与显微照片的观察,结合电子探针分析,认为埋藏过程中白云石与方解石的差异溶蚀是微孔储集体系形成的主要方式,白云岩的物质组分与微观结构对白云岩微孔的形成具有重要的制约作用;从白云岩成分上来讲,含灰云岩与灰质云岩是白云岩储层的主要岩性;白云岩中方解石的溶解与否,受方解石赋存状态的制约。根据白云岩显微结构中方解石和白云石两者之间的关系,将储集物性较好的粒状白云岩大致分为3个亚类,即粒间填隙型、粒内包含型、包含—填隙混合型,其中以第1种形式即“粒间填隙型”分布的方解石最容易被溶蚀并形成次生孔隙,包含—填隙混合型次之,粒内包含型最差。
The Lower Paleozoic dolostone in the Tarim Basin is an important oil and gas reservoir. Due to its long-term and complicated diagenetic evolution process, the reservoir space mainly consists of secondary pores. The microporous reservoir system is widely distributed and inhomogeneous, And regularity is not strong. By observing a large number of dolomite cores and photomicrographs and combining with electron probe analysis, it is considered that the differential dissolution of dolomite and calcite during burial is the main mode of formation of micropore reservoir system. The composition and microstructure of dolomite Structure plays an important role in the formation of dolomite micropores. From the perspective of dolomite composition, dolomite-bearing dolomite-bearing dolomite dolomite is the main lithology. The dissolution of calcite in dolomite is dominated by calcite Presence of state constraints. According to the relationship between calcite and dolomite in the dolomite microstructure, granular dolomites with good reservoir properties can be divided into three subgroups: intergranular interstitial, intragranular inclusions, Among them, the calcite distributed in the first form of “interstitial interstitial” is most likely to be eroded and secondary pores are formed, followed by the inclusion-interstitial mixture followed by the worst-inclusion type.