Abstract: Shale gas has its own accumulation mechanism and requires secific geological conditions. Its formation is mainly controlled by such factors as thickness, area, total organic content (TOC), organic matter maturity, mineral composition, pressure and temperature of the mud shale. Shale gas assessment is summed up in three aspects: gas generating capacity, gas accumulating capacity and easy exploitation. Shale from bottom to up is mainly distributed in Sinian Doushantuo Formation, Lower Cambrian, Middle Cambrian, Upper Devonian and Permian in Southern Guizhou Depression. Through geochemical analysis, it is considered that this area has the basic conditions for shale gas accumulation. Mud shale features in wide distribution, big thickness, high organic matter content an high thermal evolution degree, and more silicastone in the high-carbon shale series of Lower Cambrian (∈1) and Permian Wujiaping Formation (P2w) which are most favorable for exploration.

Key words: shale gas, Southern Guizhou Depression, mud shale, adsorption, accumulation condition