大牛地气田下石盒子组储层特征

RESERVOIR CHARACTERISTICS OF LOWER SHIHEZI FORMATION IN DANIUDI GAS FIELD

下石盒子组是鄂尔多斯盆地北部大牛地气田的主要勘探目的层。文章从沉积相和岩石学特征入手,结合常规薄片分析、孔渗分析、压汞试验分析成果,利用数理统计方法,对下石盒子组储层特征进行了分析研究,结果表明该套储层为低孔隙、低渗透率储层,具有较高的排驱压力,较小的孔喉半径,且孔喉分选性差。储集空间以残余粒间孔隙和溶蚀孔隙为主,有少量微裂缝和粒间孔隙。笔者利用孔隙度((?))、渗透率(K)、排驱压力(Pd)、饱和度中值压力(Pc50)和孔隙喉道半径(Rm)5个参数对储层进行了分类,划分出Ⅰ、Ⅱ、Ⅲ类。经压裂测试证明,Ⅰ、Ⅱ类储层是本区具有工业价值的储层,是增储上产的主要目的层。

Lower Shihezi Formation (P1) is the major exploration target zone in Daniudi gas field in North E'erduosi Basin. The research on reservoir characteristics is beneficial not only to reservoir identification and prediction, thus increasing the percentage of hits of exploration, but also to reservoir simulation and description, thus raising rolling development efficiency. Proceeding from sedimentary facies and petrological features,the authors analyzed and investigated the reservoir characteristics of Lower Shihezi Formation by use of mathematical statistical method in combination with the conventional thin-section analysis, porosity-permeability analysis and mercury injection test analysis achievements. It was shown that Lower Shihezi Formation reservoirs belongs in low-porosity and low-permeability ones, having high displacement pressures,small pore throat dadii and poor pore throat sorting i and containing a few microfissures and intergranular pores, the reservoir rooms are mainly composed of residual intergranular pores and solution pores. The reservoirs were divided in to kinds I , II and III in terms of five parameters as porosity, permeability , displacement pressure ,Saturation median point pressure and pore throat radii. Through fracturing and testing , it was proved that the reservoirs of Kinds I and II are the commercial reservoirs and also the major target zones of increasing reserves and productivity.