TY - GEN
T1 - Gas production induced stress and permeability variations in coalbed methane reservoirs
AU - Liu, S.
AU - Harpalani, S.
PY - 2012
Y1 - 2012
N2 - A sound knowledge of stress and coal cleat permeability, both varying with continued gas production from coalbed methane (CBM) reservoirs, is critical in order to determine how to best produce the reservoir. CBM reservoirs are unique due to their exhibiting shrinkage of coal matrix associated with release of gas, resulting in increased permeability. This paper describes the work carried out focusing on the stress and cleat permeability variations as a function of declining reservoir pressure. A new experimental technique was developed to estimate the variation of permeability and monitor the stress evolution under best replicated in situ condition, namely the uniaxial strain. The experimental results showed that decreasing reservoir pressure resulted in a significant decrease in horizontal stress and increased permeability for methane. The horizontal stress decreased linearly for depletion. Using the laboratory established permeability trend, cleat compressibility was estimated by application of the exponential relationship between changes in effective stress and permeability. The results showed that the cleat compressibility was not a constant during the course of depletion and a bi-model variation was able to describe the variation well.
AB - A sound knowledge of stress and coal cleat permeability, both varying with continued gas production from coalbed methane (CBM) reservoirs, is critical in order to determine how to best produce the reservoir. CBM reservoirs are unique due to their exhibiting shrinkage of coal matrix associated with release of gas, resulting in increased permeability. This paper describes the work carried out focusing on the stress and cleat permeability variations as a function of declining reservoir pressure. A new experimental technique was developed to estimate the variation of permeability and monitor the stress evolution under best replicated in situ condition, namely the uniaxial strain. The experimental results showed that decreasing reservoir pressure resulted in a significant decrease in horizontal stress and increased permeability for methane. The horizontal stress decreased linearly for depletion. Using the laboratory established permeability trend, cleat compressibility was estimated by application of the exponential relationship between changes in effective stress and permeability. The results showed that the cleat compressibility was not a constant during the course of depletion and a bi-model variation was able to describe the variation well.
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M3 - Conference contribution
AN - SCOPUS:84873266028
SN - 9781622765140
T3 - 46th US Rock Mechanics / Geomechanics Symposium 2012
SP - 1857
EP - 1864
BT - 46th US Rock Mechanics / Geomechanics Symposium 2012
T2 - 46th US Rock Mechanics / Geomechanics Symposium 2012
Y2 - 24 June 2012 through 27 June 2012
ER -