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Understanding stress and/or temperature sensitivity on permeability helps in predicting permeability distribution in space and its change with production. While permeability evolution with pressure...

Gas adsorption and desorption and displacement has a significant effect on coal deformation and permeability evolution during the primary recovery of coalbed methane (CBM) and enhanced coalbed methane recovery (ECBM). The objectives are to (1) quantify the coal deformation and permeability change caused by methane (CH4) displacement with carbon dioxide (CO2) and (2) model the transportation of CH4 and CO2 in deformed coalbed. In this study, the gas adsorption and desorption and displacement, coal deformation, and permeability evolution during CBM and ECBM recovery were described by an internally consistent adsorption-strain-permeability model, of which the simplified local density (SLD) adsorption theory, a theoretical strain model, and a matchstick-based permeability model were rigorous coupled. The coupled model was then verified with all of the CH4 and CO2 measured gas adsorption and desorption and coal strain data published in the past 60 years. Next, sensitivity analysis was further conducted on the ...

Due to geological complexity and the heel–toe effect, the production profiles of long horizontal wells are usually imbalanced, and as a result, premature water breakthrough is usually encountered. Once water breakthrough occurs, this phenomenon will reduce oil production. To maximize oil recovery, inflow-control devices (ICDs) are widely used to create a uniform inflow profile. To date, known ICDs cannot meet all the ideal requirements throughout the well’s life. In this study, based on the combination of a successive restriction mechanism and water swelling rubber, a novel autonomous inflow control device is proposed. Then, the rules of oil–water two-phase flow through the novel design are studied by a numerical simulation based on optimized structural parameters, and the fluid property sensitivities are analyzed. Upon integration of the novel design into the test apparatus, flow tests are conducted. The influences of water content, inflow rate, and injection rate on the pressure drop are further analyze...

Natural gas produced from coals, or coalbed methane (CBM), is a significant component of the energy portfolio for many countries. One challenge associated with CBM production is associated water. Specifically, coalbeds in situ contain significant amounts of water, and ideally this water is removed by pumping prior to the primary recovery of CBM to lower pressure and stimulate methane desorption. Such a prior water production can be challenging because desorption depends on the occurrence state of methane and water in situ, e.g., how much of each fluid is adsorbed or otherwise. Accordingly, primary objectives of this analysis include quantifying both the occurrence state of methane and water of different coals for a range of coalbed properties and conditions, and specifically quantifying the impact of coal moisture on methane desorption. Ultimate and proximate analysis and methane adsorption tests were first conducted on several coal samples from different basins. Simplified local density (SLD) theory was ...

Recovery of coalbed methane (CBM) can trigger a series of coal-gas interactions, including methane desorption, coal deformation, and associated permeability change. These processes may impact each other. A primary objective of this analysis is to simultaneously quantify these interactions and their impacts during CBM recovery. To achieve this and other objectives, a rigorously coupled adsorption–strain–permeability model was developed. Gas adsorption, coal deformation, and cleat permeability characteristics were described using simplified local density (SLD) adsorption theory, a theory-based strain model, and matchstick-based permeability models, respectively. The strain model was verified against measured methane-adsorption-induced coal strain data published during the past 60 years, and the coupled model was tested using well test data measured in the San Juan Basin of New Mexico in the United States. Results suggest that the strain model is very consistent with measured coal deformation data for fluid ...