濮城油田南区沙二上4-7砂层组储层孔隙结构及与驱油效率的关系

利用薄片、铸体薄片、扫描电镜、岩石物性和压汞资料，对濮城油田南区沙二上4—7砂层组储层岩石特征及其微观孔隙结构进行了全面的研究．结果表明，储层岩性混杂、属低渗储层；发育原生粒间孔、残余粒间孔、晶间及晶内微孔、溶蚀孔及微裂缝5类孔隙类型，以中细孔细、微细喉孔隙结构类型为主；储层孔隙小、喉道细，分布区间宽，孔喉参数变化范围大，分选和均质程度低，孔喉比偏大，孔隙结构的非均质性较强．在此研究的基础上，利用相关分析法定量分析了储层退汞效率与孔隙结构参数的关系，认为储层退汞效率与各孔隙结构参数之间存在负相关关系；其中，随孔隙度、渗透率增大退汞效率迅速降低，而随孔喉增大退汞效率缓慢减小，喉道分选性与驱油效率呈负相关，但相关性较差，另外，驱油效率随岩样束缚水饱和度增加而增大，随岩样孔隙体积的增加而降低．总体上，储层驱油效率随孔隙结构的变好而降低．

Reservoir Pore Structure and Its Effect on Displacing Efficiency,4-7 Sand Sets of the Upper 2nd Member of the Shahejie Formation, Nanqu, Pucheng Oilfield

Reservoir characteristics and pore structure of the 4-7 sand sets of the upper 2^nd member of the Shahejie Formation, Nanqu, Pucheng Oilfield, are fully studied based on analysis of rock physical properties, sections, cast sections, scanning electron microscope and mercury intrusion data. The lithology of the reservoir of the 4-7 sand sets is multiplex, and intergranular pores, intercrystalline micro-pores, dissolved pores as well as micro-fracture develop. The reservoir has low-permeability, and the main pore structure is mean pore and thin throat. Pore and throat widely distribute; pore and throat parameters changed greatly; the sorting and homogeneity are low, the pore and throat size ratio tends to be on the high side; the heterogeneity of the pore structure is heavy. The relationship between efficiency of mercury withdrawal and pore structure parameters was analyzed quantitatively through correlation analysis method; the result indicates that the efficiency of mercury withdrawal is negatively correlated to every pore structure parameter; that the efficiency of mercury withdrawal decrease sharply with the increases of porosity and permeability, while decreases slowly with the increase of the sizes of the porethroat ; that the sorting of the pore-throat is negatively correlated to displacement efficiency, but such correlation is poor. In addition, the efficiency of mercury withdrawal increases with the increases of irreducible water saturation, and decreases with the increases of pore volume of the reservoir. As a whole, the displacement efficiency of the 4-7 sand sets reservoir decreased with the melioration of pore structure.