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根据岩心与铸体薄片观察、扫描电镜观测及岩石矿物学、物性资料分析,研究了鄂尔多斯盆地东北部地区太原组砂岩储层特征及影响因素。研究区储层的岩石类型以粗粒岩屑石英砂岩为主,成分成熟度好,结构成熟度中等—好,储层物性差,属于低孔、低渗储层,储集空间以次生孔隙为主,发育极少的成岩裂隙对改善储层渗透性贡献不大。储层的储集性受沉积相和成岩作用综合控制,沉积作用分析表明潮坪潮道砂体是最有利储层发育的沉积微相;压实作用、胶结作用、溶蚀作用控制了储层孔隙演化,其中压实作用是导致原始孔隙损失的主要原因,硅质胶结与自生伊利石进一步降低了孔隙度与渗透率,碳酸盐的胶结作用持续到了晚成岩A期,早期胶结增强了岩石抗压实能力,晚期胶结充填则损害次生孔隙。
Based on the observations of core and cast thin slices, scanning electron microscope observation, rock mineralogy and physical data analysis, the characteristics and influencing factors of sandstone reservoirs in Taiyuan Formation in the northeastern Ordos Basin are studied. The rock types of the reservoirs in the study area are mainly coarse-grained lithic quartz sandstones, with good maturity, moderate structural maturity and poor reservoir properties. They belong to low-porosity and low-permeability reservoirs with secondary pores Dominated, the development of very few diagenetic fractures to improve permeability of the reservoir little contribution. The reservoir property is controlled by sedimentary facies and diagenesis. Sedimentation analysis shows that the tidal flat sand body is the most favorable reservoir for sedimentary microfacies. Compaction, cementation and dissolution control the porosity of reservoir The compaction effect is the main reason for the loss of primary porosity. The siliceous cementation and authigenic illite further reduce the porosity and permeability. The cementation of carbonate lasted until late diagenetic stage A, and the early cementation enhanced the rock resistance Compaction ability, late cementing damage secondary pores.