牛圈湖油田储层孔隙结构对注水开发的影响

Effect of Micro-pore Structure and Controlling Factors on Waterflooded Development in Niujuanhu Oilfield

针对牛圈湖油田西山窑组油藏低孔隙度、低渗透率、低压力的储层特征以及高含水储层开发现状，运用铸体薄片、扫描电镜、高压压汞、核磁共振、恒速压汞等实验方法，研究牛圈湖油田西山窑组储层微观孑L隙结构特征，并从微观角度分析影响注水开发效果的主要因素。西山窑组储层孔隙类型主要为溶蚀孔、残余粒间孔和高岭石晶间孔，晶问孔的出现使恒速压汞统计结果显示出喉道体积大于孔隙体积的假象特征。研究区储层孔喉半径比大，孔隙与喉道分异性强，孔喉连通性差是导致储层可动流体饱和度低、油田整体开发难度大的主要原因。

The reservoir is characterized by low-porosity, low-permeability, low-pressure and high water cut in Xishanyao group of Niujuanhu oilfield. Based on studying the microscopic pore structure in the group and from microscopic point, the main impact factors on water injection development are analyzed with experimental methods, such as casting section, SEM, high-pressure mercury penetration, nuclear magnetic resonance and constant rate mercury penetration. Resear- ches indicate that the main pore styles are carven-erosion, penitent intergranular pore and kaolinite intercrystal pore in Xishanyao reservoir. The intercrystal pore gives a false feature that throat volume is larger than pore volume in the statistics of constant rate mercury penetration. The main reasons that lead to low mobile fluid saturation and difficult oilfield development are large reser- voir pore-throat ratio, acute pore-throat differentiation and bad connectivity between pore and throat in the studied area.