College of Earth Sciences, Jilin University, Changchun 130061, China

A systematic study was undertaken on the geological conditions of shale gas reservoirs of dark mud shale in the Lower Cretaceous Muling Formation, using organic geochemical analysis, X-ray diffraction analysis, high pressure mercury injection, scanning electron microscopy and low temperature nitrogen adsorption. The results show that the dark mudstone of the Muling Formation is widely developed, with significant cumulative thickness and medium TOC content. The organic matter that mainly consists of ��2 kerogen is in the mature to over mature stage, indicating that the organic matter has entered the stages of significant gas production. The content of brittle minerals such as quartz, feldspar and carbonate in shale is high. There exists certain amount of pore porosity and micro fractures, which is a type of pore structure with low porosity and low permeability. According to drilling data, the dark mud shale of Lower Cretaceous Muling Formation has a good gas-bearing ability. Compared with major shale oil and gas fields in the US and continental shale gas deposits in China, parameters of Muling Formation reach the standard, indicating that it has a good potential for shale gas exploration.