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通过铸体薄片、扫描电镜、X衍射等分析测试,对鄂尔多斯盆地吴堡地区长7储层的成岩作用研究。结果表明,研究区砂岩经过了机械压实作用、胶结作用和溶蚀作用等多种成岩作用。储层孔隙演化与成岩作用关系密切:机械压实作用、胶结作用是储层物性降低的主要因素,孔隙损失分别达到19.69%和15.30%,研究区长7烃源岩发育,相比于研究区其他相邻层位,溶蚀作用强烈,是形成此生孔隙的主要因素,提高了储层的储集性能,孔隙增生量为1.19%。结合成岩作用与孔隙结构的关系,对研究区长7致密油储层成岩相进行定量划分,研究区成岩相可以划分粒间孔-长石溶孔相、长石溶孔相、剩余粒间孔相、碳酸盐胶结相和伊利石胶结相。有利成岩相粒间孔-长石溶孔相、长石溶孔相和剩余粒间孔相发育在分流河道/水下分流河道中央,这些成岩相控制的储层是油气聚集有利场所;不利成岩相碳酸盐胶结相和伊利石胶结相分布在分流间湾沉积相带上,不利于油气聚集。
Diagenesis of Chang 7 reservoir in Wubao area, Ordos Basin, through the analysis of cast thin films, scanning electron microscopy and X - ray diffraction. The results show that the sandstone in the study area has undergone many diagenesis such as mechanical compaction, cementation and dissolution. The evolution of reservoir porosity is closely related to diagenesis: mechanical compaction and cementation are the main factors for the decrease of reservoir physical properties, with pore losses of 19.69% and 15.30% respectively. The source rocks of Chang 7 in the study area are developed. Compared with the study area The other adjacent layers have a strong erosion effect and are the main factors for forming this pore and improve the reservoir’s reservoir performance. The amount of pore growth is 1.19%. According to the relationship between diagenesis and pore structure, the diagenetic facies of Chang 7 tight oil reservoirs in the study area are quantitatively divided. The diagenetic facies of the study area can be divided into intergranular feldspar-feldspar facies, feldspar dissolved facies and remaining intergranular pores Phase, carbonate cemented phase and illite cemented phase. The favorable diagenetic facies intergranular pores-feldspar facies, feldspar facies and the remaining intergranular pores develop in the middle of distributary channel / underwater distributary channel. These diagenetic-controlled reservoirs are favorable sites for hydrocarbon accumulation; unfavorable diagenesis The facies of carbonate facies and illite cementation are distributed on the distributary bay sedimentary facies, which is unfavorable to hydrocarbon accumulation.