新安边地区长7致密油储层孔隙结构对可动流体赋存的影响

Effect of pore structure on the occurrence of movable fluid in Chang 7 tight oil reservoir in Xin′anbian Area

利用铸体薄片分析、扫描电镜、恒速压汞及核磁共振等测试技术,对延长油田定边采油厂新安边地区长7储层微观孔隙结构和可动流体赋存特征进行详细研究,并探究可动流体赋存的影响因素。结果表明,研究区长7储层发育残余粒间孔、溶蚀孔、晶间孔和微裂隙,以片状及弯片状喉道为主,孔喉匹配类型有粒间孔缩颈型喉道,粒间孔片状、弯片状喉道,溶蚀孔片状、弯片状喉道及晶间孔管束状喉道,具有微中孔隙、微细喉道的特征;目标层孔隙结构可划分为Ⅰ、Ⅱ、Ⅲ三种类型,3种类型孔隙结构对应的孔隙空间和渗流能力逐渐变差,不同类型储层间的可动流体赋存特征存在较大差异,其中Ⅱ类储层是挖潜的主要方向。研究认为,储层物性、孔喉类型、孔隙结构是影响流体可动性的3大因素,不能单一用来评价储层可动流体赋存特征;喉道半径大小、分布形态,孔喉半径比及分选系数是影响可动流体赋存特征的主要因素。

In this study,the microscopic pore structure and movable fluid occurrence characteristics of Chang 7 oil reservoir in Xin′anbian area of Dingbian Oil Production Plant of Yanchang Oilfield were investigated with thin slice analysis of cores,SEM,constant rate mercury penetration and NMR testing,and the factors affecting the occurrence of movable fluid were also investigated.The results show that:①The primary pore type of Chang 7 reservoir is residual intergranular pore,dissolution pore,intergranular pore and micro crack,the primary throat type is flake and curved lamellar throat.There are intergranular pore-necking throat,intergranular pore-flake,curved lamellar throat,dissolution pore-flake,curved lamellar throat and intergranular hole-bundle throat,which has the characteristics of micromedium porosity pores and fine throat.②The pore structure of the target layer can be divided into three types:Ⅰ,ⅡandⅢ,and their corresponding storage capacity and flow ability become worse of the three types gradually,there is big difference among the occurrence characteristics of movable fluid in the different reservoirs types.The typeⅡis the main direction of tapping potential.③The reservoir physical property,pore-throat type and pore structure are the three major factors affecting the occurrence characteristics of movable fluid,which cannot be used to evaluate the occurrence characteristics of movable fluid only.Throat radius size,distribution form,pore-throat radius ratio and sorting coefficient are the main factors affecting the occurrence characteristics of movable fluid.