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为研究渤海湾B油田沙三段致密砂岩储层孔隙结构,进一步了解孔隙演化过程及控制因素,利用铸体薄片、扫描电镜、X衍射、高压压汞、物性分析、粒度分析等资料,总结出3种孔隙类型和4种孔隙结构;同时,根据成岩作用研究成果,采用定量分析方法分析孔隙演化史。研究区储层孔隙以混合孔、次生孔、原生孔为主,喉道具有特细喉和微细喉的特点属于典型的致密砂岩储层,物性较差。运用未固结砂岩原始孔隙度与砂岩的分选系数的统计关系,恢复计算出研究区砂岩原始孔隙度平均为32.25%。在沉积成岩过程中机械压实及胶结作用造成原生孔隙大量丧失,是储集层物性变差的最主要原因。区内溶蚀作用较为发育,溶蚀强度中等,所形成的溶蚀孔隙一定程度上改善了储层的物性,为认清该油田储层致密原因提供了可靠依据。
In order to study the pore structure of the tight sandstone reservoir in the third member of the Bohai Bay B Oilfield, and to further understand the pore evolution process and control factors, the authors summarized the casting thin slices, scanning electron microscopy, X-ray diffraction, high pressure mercury intrusion, physical property analysis and particle size analysis Three kinds of pore types and four kinds of pore structure. At the same time, according to the research results of diagenesis, the quantitative analysis method was used to analyze the evolution history of the pores. The reservoir pores in the study area are dominated by mixed pores, secondary pores and primary pores. The throat has the characteristics of fine throat and fine throat, which belongs to the typical tight sandstone reservoir with poor physical properties. Using the statistical relationship between the original porosity of unconsolidated sandstone and the sorting coefficient of sandstone, the original porosity of the sandstone in the study area is calculated to be 32.25% on average. During the process of sedimentary diagenesis, mechanical compaction and cementation result in a large loss of primary pores, which is the most important reason for the deterioration of reservoir physical properties. The dissolution in the area is relatively developed, and the dissolution strength is medium. The dissolved pores formed to some extent improve the physical properties of the reservoir, which provides a reliable basis for understanding the densification reason of the reservoir.