Reservoir characteristics of mud shales from Upper Permian Linxi Formation in Suolun-Linxi area, Inner Mongolia

In the Suolun-Linxi regions of the Inner Mongolia, extensive mud shales with a good hydrocarbon potential occur in the Upper Permian Linxi Formation. The thickness of the mud shales reaches a peak in the northwest of the Guandi-Bayanhua-Suolun areas. The total thickness is up to 911 m, and the maximum thickness of a single layer is 63 m.Field scanning electron microscopy and X-ray diffraction show that the mud shales are rich in brittle minerals, with an average content of 62.9% and a maximum content of 70.8%. The average content of clay minerals is 37.1%, and the maximum content is 41.5%. Micro pores and micro cracks are common. The pores are mainly intergranular and intragranular ones, with an average diameter of 1-3 μm and the maximum diameter of 8 μm. The average and maximum porosities of the mud shales are 1.288% and 4.42%, respectively. The average and maximum permeabilities of the matrix are 0.026 2×10^-3μm² and 0.275 8×10^-3μm², respectively. Compared to the shale gas basins already found in China and abroad, the mud shales of the Linxi Formation are favorable for shale gas accumulation, and possess the petrological characteristics of development. In conclusion, the northwest of the Chagannaoer-Baiyinnuoer area has a good exploration potential.