Shale gas has become a promising source of energy in recent years, especially in North America, giving rise to abundant of field applications and research. Compared with the oil or conventional gas reservoirs, shale reservoirs are usually deeper in depth, lower in permeability with higher clay content, resulting in its difficulty for exploration. Hydraulic fracturing is the most frequently used technique to stimulate the low-permeability shale reservoirs. And most of the fracturing fluids are water-based due to low cost. However the mechanism of the interaction between fracturing fluid and the gas-shale is not fully uncovered, like the fracture initiation and propagation, fracture geometry, evolution of reservoir permeability. Many field application results are unsatisfactory due to our poor understanding.

The effects of the hydro-fracturing is influenced by shale reservoir properties (TOC content, clay content, porosity and permeability, brittleness index), injection regime and in-situ stress field etc.. My PhD research concentrates on the optimization of fracture network formation based on hydro-fracturing. It involves to investigate the impacts of these influencing factors by literature review, lab tests and modelling, and to optimize the fracturing designs. The output of my research will contribute to the understanding of hydro-fracturing used in shale reservoirs and provide guidelines for the field trials.