高石梯—磨溪区块灯影组碳酸盐岩气藏孔隙结构特征

四川盆地高石梯-磨溪区块震旦系灯影组气藏的储层以白云石为主,孔洞缝发育,非均质性强,对气藏孔隙结构特征进行研究是开发方案编制和开发动态预测的基础。因此,以工区内不同井位所取得的直径为2.5 cm柱塞样和直径7 cm全直径岩心为研究对象,进行岩心基础物性、铸体薄片、核磁共振、CT扫描等一系列的测试;并进行了相关的分析。结果表明:灯影组储层基岩低孔(2.76%)、低渗(0.8 m D),孔渗相关性差;储层孔隙类型以裂缝-孔隙型为主;储层裂缝以缝网形式存在,但仅在局部层段发育,裂缝以构造溶蚀缝为主;储集空间以大、中孔隙为主(约共占65%),储层可动流体饱和度与孔隙度呈正相关性;溶蚀孔洞分布满足(对数)正态分布,算数平均后得到确定的概率密度函数,为更大尺度储层定量表征奠定基础。

Pore structure characteristics of Dengying Formation carbonate gas reservoir of Gaoshiti-Moxi block

Natural gas was usually found in pores and caves in Sinian Dengying Formation dolomite gas reservoir of Sichuan Basin Gaoshiti-Moxi block, which is a serious area of the fissure formation. Because of its strong heterogeneity, the research of pore structure characteristics is necessary to programming development plan and predicting development dynamic. Therefore, we choosed many cores from this area for a series of tests, such as basic physical properties, cast thin section, nuclear magnetic resonance and CT scan, and then analyzed the experimental results. The findings were summarized as follows: the Dengying Formation reservoir rock is low porosity(2.76%), and low permeability (0.8mD), and there is poor correlation between porosity and permeability; the main pore type is fracture-pore; fracture network is only developed in local layer, and most of the cracks are structural dissolution fractures; the reservoir space are mainly large or medium pores (about 65%), and there was a positive correlation between movable fluid saturation and porosity; corrosion pore distribution satisfies the ( logarithmic ) normal distribution, and we could obtain the determining the probability density function after the arithmetic average, which lays the foundation for quantitatively characterize the reservoir layer in lager scale.