川南长宁地区五峰组和龙马溪组页岩储层差异性分析

Difference analysis of shale reservoirs of Wufeng Formation and Longmaxi Formation in Changning area, southern Sichuan

文中通过扫描电镜和分析化验资料,对长宁地区五峰组—龙马溪组页岩储层差异性进行了研究,结果表明:五峰组与龙马溪组一段1亚段页岩矿物种类相同,但质量分数差异大,五峰组页岩碳酸盐矿物质量分数最高,龙一1亚段页岩石英质量分数最高。矿物组分特征的差异导致龙一1亚段页岩脆性指数明显高于五峰组。有机碳质量分数和含气量两者略有差异,龙一1亚段页岩有机碳质量分数垂向变化幅度更大,非均质性更强。五峰组与龙一1亚段页岩储层的孔隙类型基本一致,以有机质孔为主,但孔隙发育特征不同。五峰组页岩有机质孔多呈长条状、扁平状,孔径较小;龙一1亚段页岩有机质孔多呈圆柱状、椭圆状,孔径较大。两者之所以具有这样的差异性,是因为沉积环境不同。总体上,龙一1亚段储层优于五峰组,更有利于页岩气的勘探开发。

In this paper, the differences of Wufeng-Longmaxi Formation shale reservoir in Changning area were studied by scanning electron microscope and analysis of laboratory data, and the results show that the Wufeng Formation and Long1-1 sub-member shale have the same mineral compositions, but the mass fractions are quite different. The content of carbonate minerals in Wufeng Formation shale is the highest, while the content of quartz in Long1-1 sub-member shale is the highest. Due to the difference of material basis, the brittleness index of Long1-1 sub-member shale is significantly higher than that of Wufeng Formation. The TOC and the total gas content have little difference, but the Long1-1 sub-member shale has a large change range and stronger heterogeneity than that of Wufeng Formation shale. The pore types of the two reservoirs are basically the same, mainly organic pores.The organic pores of Wufeng Formation are mostly long strip and flat shape with small pore size, while those of Long1-1 sub-member is mostly cylindrical and elliptical shape with large pore size. The difference between the two reservoirs are mainly due to the different sedimentary environments. Generally, the reservoir physical property of Long1-1 sub-member is better than Wufeng Formation, which is more favorable for shale gas exploration and development.