Effective means to alleviate the greenhouse effect: case study of history match simulations on a brief CO2 injection into less-deep low-rank coal seams

Abstract

Injecting carbon dioxide into coal seams for storage is an effective means to solve environmental problems such as the greenhouse effect. A history match study on a case of originally designed multi-well pilot CO 2 -ECBM field testing is introduced in this article. Numerical simulations were undertaken to study the primary productions of two existing offset wells, initial production of a newly drilled injection well, followed by two short-term CO 2 injection testing with a post-CO 2 production and a nitrogen slug between them. Through the history match study, a few specific model parameters, which were in no way to be directly measured or hardly interpreted through geophysical monitoring in the case of field scales, were accordingly determined. Parameters include initial reservoir water saturation, coal swelling, and shrinkage strains by the adsorption and desorption of gas components which govern coal cleat porosity and permeability changes, gas sorption time constants, and well skin factors during series of testing periods. The numerical simulations were additionally used to predict afterwards CO 2 storage volume, gaseous CO 2 distribution, and reservoir pressure in the field. Due to CO 2 price doubled up than its budget, meanwhile, hydraulic communication from upper stratum implied a leakage risk, the CO 2 injection was suspended. Available data recorded from this eventual micro-pilot case was worthwhile of being carefully studied. It would contribute to understanding the process of injecting CO 2 into relatively shallow but less saturated low-rank coal seams.

Recent Advances and Perspectives of CO2-Enhanced Coalbed Methane: Experimental, Modeling, and Technological Development

“…This model takes into account the effective stress gradient between the matrix and fractures and the fracture aperture. Gou et al 174 studied the matching of the field test and numerical results of multi-point well testing and determined some parameters that cannot be interpreted 54 applied the state module EOS7C-ECBM in TOUGH2 to model the CO 2 -ECBM process on the assumption that the coal seam is homogeneous, isotropic, and isothermal and concluded that the key challenge of CO 2 -ECBM is to balance the coal matrix swelling caused by CO 2 injection.…”

“…This model takes into account the effective stress gradient between the matrix and fractures and the fracture aperture. Gou et al studied the matching of the field test and numerical results of multi-point well testing and determined some parameters that cannot be interpreted through geophysical exploration or field research. The numerical simulation was also used to predict the amount of CO 2 subsequention, gas distribution, and gas pressure in reserviors.…”

Low Subcritical CO2 Adsorption–Desorption Behavior of Intact Bituminous Coal Cores Extracted from a Shallow Coal Seam

“…Subcritical CO 2 adsorption in shallow coal seams is poorly understood. 10 − 13 CO 2 adsorption capacity of coal generally increases with pressures at subcritical conditions (<7.38 MPa and <304.15 K). 9 , 14 − 22 Micropores provide most of the surface area for gas adsorption, and it is higher in high-rank coals.…”

“…Subcritical CO 2 adsorption in shallow coal seams is poorly understood. − CO 2 adsorption capacity of coal generally increases with pressures at subcritical conditions (<7.38 MPa and <304.15 K). ,− Micropores provide most of the surface area for gas adsorption, and it is higher in high-rank coals. However, the presence of channel-like pores and matrix swelling properties influence adsorption behavior of bituminous coals. − Ozdemir et al estimated the adsorption capacity of eight powdered Australian bituminous coal samples at 22 °C and pressures up to 4.0 MPa, and the reported values varied between 1.07 and 1.97 mmol/g of coal.…”