STIMULATION FOR METHANE-GAS RECOVERY FROM COAL

During the past several years, a combination of data from field and la boratory experiments, published data from commercial treatments, and c oncurrent analysis and model development activities has led to a bette r understanding of the processes occurring in coal during stimulation operations, Ar the same time, better modeling capabilities have been d eveloped. For example, a new hydraulic fracture design model that incl udes pressure-dependent nonlinear leakoff, multiple interacting fractu res, and failure in the coal near the, fracture plane as a result of c hanges in effective stress is being developed and is being used to stu dy fracture propagation in coal. In addition, two- and three-dimension al (2D and 3D) discrete element and hybrid finite element models that couple the mechanical and multiphase fluid response of the coal have b een applied to analyzing problems arising from cavity completion opera tions. In this paper, we compare data obtained from field trials in co al seams with model simulations, and we discuss the implications for s timulation design and execution.