西湖凹陷保俶斜坡中部深部储层控制因素分析

通过铸体薄片、扫描电镜、X衍射、物性等分析化验资料及岩心观察、测井资料，对西湖凹陷保俶斜坡中部深部（4 000 m以下）储层的岩石学特征、孔隙特征及物性特征进行分析认为:研究区平湖组深部储层岩性以长石岩屑质石英砂岩为主，不稳定组分平均达31.66%，孔隙类型以次生溶蚀孔隙为主，仅保存少量原生粒间孔，孔隙度主要分布在10%~18%之间，渗透率从小于0.1×10-3 μm2到大于100×10-3 μm2均有分布，说明研究区4 000 m以下发育有一定量的优质储层。成岩作用的两对矛盾:压实与抗压实、溶蚀与胶结共同作用、相互影响，是影响研究区深部储层物性的主要因素；而储层内部有效流动单元的三维空间展布则受制于沉积成因的致密层理、泥质披盖等非渗流性夹层。综合分析认为:保俶斜坡中部埋深4 200 m左右存在物性甜点。

Research on Controlling Factors of Deep Reservoirs in the Central Part of Baochu Slope,Xihu Sag

Based on the analytical data of casting thin section, scanning electron microscope, X-ray diffraction, physical properties, core observation and well logging, the author analyzed the petrological characteristics, pore characteristics and physical properties of deep reservoirs in the central part of Baochu slope, Xihu Sag. The results show that the reservoir lithology of deep reservoirs in the study area is feldspar detritus quartz sandstone, and the average content of unstable components is 31.66%. The predominant pore type is secondary dissolution pore while only a few of the residual primary intergranular poresare well preserved. The reservoir porosities are between 10% and 18%, and the permeability is distributed from less than 0.1×10-3 μm2 to more than 100×10-3 μm2, indicating that a certain number of high-quality reservoirs are well developed below the depth of 4 000 m in the study area. The compaction and anti-compaction, the dissolution and cementation are two sets of contradictory diagenesis, and they are the main factors affecting physical properties of deep reservoirs in the study area which occurred at the same time and influenced each other. The 3D spatial distribution of effective flow unit in the reservoir is controlled by dense bedding, mud drape and other impermeable interlayers caused by deposition. According to comprehensive analysis, there may be physical desserts in the reservoir at the depth of 4 200 m in the central part of Baochu slope.