通过铸体薄片、高压压汞、恒速压汞、X衍射、核磁共振及渗流实验等多种实验手段,分析研究了周长地区长8致密砂岩储层孔喉结构特征及其对渗流特征的影响.结果表明,研究区储层主要发育粒间孔和长石溶孔,孔隙面孔率低;喉道类型以片状-弯曲片状和缩颈式喉道为主;岩石排驱压力低,进汞饱和度高,但退汞效率低,一方面是由于孔喉连通性差,另一方面储层中的黏土矿物也对退汞效率产生了影响.孔喉结构是影响致密砂岩储层渗流特征的主要因素,其中,喉道半径、孔喉比及连通性等决定储层渗流能力的关键.大喉道主要提供储层的渗流能力,而中-小孔喉则对储集能力的贡献更大.%Cast thin section analysis, high-pressure mercury porosimetry, constant-speed mercury porosimetry, X-ray diffraction, NMR and seepage experiments were adopted to investigate the pore structure and its influence on precolation of the Chang 8 tight sandstone reservoir in the Zhouchang Area.The result shows that the reservoir space is dominated by intergranular pore and feldspar dissolved pore with a low average surface porosity.Throat type mainly develops flaky-curved lamellar and necking throat.The reservoir exhibites a low displacement pressure and the mercury injection saturation is high, but the mercury ejection is low because of poor pore-throat connectivity and clay minerals.The main factor affect percolation characteristics with tight sand reservoir is the pore structure features.Among the pore structure parameters, throat size, pore-to-throat ratios and connectivity between pores and throats are the key impacting percolation capacity.Research also indicates that the large throats is the more contribution to the reservoir percolation.Whereas, middle to small sized pore throat is relatively contributes more to reservoir quality.
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