致密砂岩气藏孔喉结构与可动流体赋存规律——以鄂尔多斯盆地苏里格气田西区盒8段、山1段储层为例

致密砂岩储层的研究中，可动流体赋存特征因能表征储层孔隙中流体的流动规律而备受重视。以鄂尔多斯盆地苏里格气田西区下石盒子组盒8段、山西组山1段核磁共振测试样品为研究对象，结合铸体薄片,扫描电镜,阴极发光,恒速压汞,黏土矿物X-射线衍射,高压压汞及气水相渗实验分析了研究区储层可动流体赋存特征，开展了可动流体赋存特征的影响因素研究.结果表明:研究区储层依据孔隙组合类型可分为粒间孔_溶孔型储层,溶孔_晶间孔型储层及孔隙+裂缝型储层，可动流体赋存能力及大孔喉发育情况依次变差;喉道越大且孔喉均质程度越好可动流体饱和度越高;储层亲水性能力提高造成水膜厚度增大导致喉道缩小甚至阻塞，可动流体饱和度降低。测井解释含气性与孔隙组合类型对应良好，为致密砂岩储层含气性评价提供了直接依据。

Features of pore-throat structures and movable fluid in tight gas reservoir: A case from the 8th member of Permian Xiashihezi Formation and the 1st member of Permian Shanxi Formation in the western area of Sulige Gasfield,Ordos Basin

In tight sandstone reservoirs,the study of accumulative regularity is very important in that it can represent flow regularity in pores.The movable fluid characteristics and the influence of micro-pore structures on it were studied by taking nuclear magnetic resonance as samples and supplemented by casting thin sections,scanning electron microscopic(SEM),cathode luminescence(CL),constant-rate mercury injection,clay mineral X-ray diffraction,high-pressure mercury injection and gas-water relative permeability experiments from the 8^th member of Permian Xiashihezi Formation (He 8) and the 1^st member of Permian Shanxi Formation (Shan 1) tight gas reservoirs in the western area of Sulige Gas Field as research objects.The study shows that,there are three types of reservoirs dominated by pore assembly types in research regions,including intergranular-dissolved pore type,dissolved-intercrystalline pore type and pore plus fracture type.The capacity of movable fluid occurrence becomes worse and the proportion of large pores decreases in turn.Movable fluid saturation is in positive correlation with the size of throats and pore-throat homogeneous degree.Hydrophilic enhancement contributes to the increment of thickness of water-film,which can block the throat and reduce the movable fluid saturation.The gas-bearing capacity predicted by well logging interpretations are well corresponding to pore assembly types,which provide a direct evidence to recognize the tight reservoir’s gas-bearing capacity.