Abstract: Shale gas reservoirs generally need to be fractured for the industrial production. However, the flowback of fracturing fluid is low. Residual fracturing fluid can induce fracture in shale gas reservoir, but it also occupy seepage channels in shale gas reservoirs. This paper takes typical organic rich shale samples from the Longmaxi Formation in the Sichuan Basin, and recoustructed the fractured shale gas reservoir by sand pack and granular shale. Through comparative experiments of water absorption of shales treated with water and oxidation liquid, we find out mechanism of oxidation effect on fracturing fluid imbibition and dispersion to pore of matrix near fracture. The experiment results show that the liquid imbibition range increase after oxidation of granular shale, free water in shale pore space decreases and water absorbtion of increases. It is concluded that the oxidation-induced dissolution of organic matter can increase the contact area between water and clay minerals, and promote the imbibition of clay minerals and the growth of micro-fractures. The water saturation of fractures decreases, and increase seepage channels of gas. It is suggested to optimize the formula of fracturing fluids and the soak system according to the specific engineering geological characteristics, and optimize the adding time and amount of oxidizing fluid. so as to improve to the fracturing capacity of the retained oxidizing fracturing fluid, promoting the dispersion of fracturing fluid, minimize the return of fracturing fluid, and to increase effective seepage channels of gas in fractures.

Key words: organic-rich shale, oxidation, imbibition, formation damage, fracture, zero-flowback