Geomechanics of carbon dioxide sequestration in coalbed methane reservoirs.

摘要

Coalbeds in the Western Sedimentary Basin of Canada could potentially trap over 12 trillion cubic meters of carbon dioxide which is equal to decades of Canada's CO2 production. The injection of CO 2 into deep coalbed methane reservoirs is appealing because of its offsetting benefit in the production of methane. Successful implementation of the CO 2 disposal/CH4 recovery process will require a fundamental understanding of the geomechanical and hydraulic characteristics of the coal.; A special multiphase geomechanic testing facility, which included a high pressure, double wall triaxial cell, was developed to accommodate the testing conditions of this research. Fundamental experiments were carried out to study permeability variations in coal during the CO2 sequestration process. Increasingly complex tests were conducted to gain an understanding of the coal response to variations in effective stress and gas pressure. At constant effective stress levels, a 75% reduction in intrinsic permeability was measured as CO2 pressure increased from 3.5 and 12 MPa. Permeability reductions of 51% to 90% were measured over an isotropic effective stress range of 6 to 16 MPa. Coals of increasing rank show larger reduction in permeability. Permeability variation due to CO2 pressure displayed a bi-linear relationship.