牛圈湖区块西山窑组储层微观孔隙结构研究

The microscopic pore structure studying on the reservoir of Xishanyao formation of Niuquanhu oilfield

通过常规物性分析、扫描电镜、铸体薄片和常规高压压汞实验等技术,对三塘湖油田牛圈湖区块西山窑组油藏储层微观孔隙结构进行深入分析和研究,提出了孔隙结构压力特征参数P,用以表征孔喉特征。研究结果表明:本区的储集层具有孔喉均值较大(平均10.23)、分选中等(平均2.72)、中值半径较小(平均0.27μm)、排驱压力较小(平均0.45MPa)、中值压力中等(平均5.22MPa)、退汞效率较低(平均31.05%)和残留汞饱和度较高(平均61.66%)等特点。依据孔隙结构特征参数及其与物性的相关性分析,将研究区毛管压力曲线分为四类,从Ⅰ类到Ⅳ类Pcd和PC50逐渐增大,孔喉分选性变好,指示了储层从较好到差的孔隙结构和渗流能力。

With the technique of the physical property analysis,scanning electron microscope,casting slice,and high pres-sure Hg injection,the microscopic pore structure of Xishan-yao formation reservoir in Niuquanhu area of Santanghu oil-field was thoroughly analyzed and investigated. Therefore,pressure characteristic parameter of pore-structure P has been proposed,which can be used for expressing pore -throat characteristics. The research results indicate: the res-ervoir of this area had the characteristics of great mean (an average of 10. 23),medium sorting (an average of 2. 72),small median radius(an average of 0. 27 μm),minor expul-sion pressure (an average of 0. 45 MPa),medium median pressure(an average of 5. 22 MPa),low ejection efficiency (an average of 31. 05%),and high residual Hg content(an average of 61. 66%). On the basis of characteristic parame-ters of pore structure and the correlation analysis of it and physical property,capillary pressure curve of this area are divided into four categories. From class Ⅰ to class Ⅳ ,Pcd and PC50 gradually increase,pore-throat sorting changed for the better,and these all instruct that the pore structure and the percolation of reservoir are from good to bad.