鄂尔多斯盆地延长组特低渗透储层微观地质成因

Microscopic Geologic Origin for Ultra-Low Permeability Reservoir of Yanchang Groups,Ordos Basin

特低渗透储层开发潜力大,孔隙结构复杂。为明确该类储层的微观地质成因,以鄂尔多斯盆地典型特低渗透储层为例,综合运用常规薄片、铸体薄片、扫描电镜、X-衍射、高压压汞、恒速压汞、核磁共振等常规和先进的实验测试手段,从微观上探讨了该类储层的地质成因。研究结果表明,胶结物含量高、绿泥石含量较高且赋存形态复杂、岩盐含量及铁方解石含量较高、伊利石胶结物发育、浊沸石胶结物溶蚀效果差是导致特低渗透储层物性较差、孔隙结构复杂的关键因素,进而使特低渗透储层表现出面孔率低、排驱压力高、小喉道发育、可动流体饱和度低等特点。

Ultra-low permeability reservoirs have the characteristics of tremendous development potential and complex pore structure. In order to make definite the microscopic geologic origin of Yanchang Formation in Ordos basin, the authors integratedly use a lot of advanced technology test methods, such as convention thin section, cast thin section, X-ray, high pressure mercury penetration, constant rate mercury penetration, NMR, EMS techniques. The results show that the key elements of cause physical property variation are high cement content, high chlorite content and complex form, halite content, high ferrocalcite content, illite cement upgrowth, lomontite cement corrosion bad. All those elements cause ultra-low permeability reservoir showed the characteristics of poor scope-pore coefficient, high displacement pressure, fine pore-throat upgrouth, low movable liquid saturation.