TY - JOUR
T1 - Coupled poroelastic solutions for the reservoir and caprock layers with the overburden confinement effects
AU - Su, Xing
AU - Mehrabian, Amin
N1 - Funding Information:
The Petroleum Research Fund of the American Chemical Society under Grant 59894-DNI9 is gratefully acknowledged. The authors wish to thank the editor and anonymous reviewers for their constructive criticism of this work.
Publisher Copyright:
© 2020 Elsevier Ltd
PY - 2021/3
Y1 - 2021/3
N2 - Coupled theory of poroelasticity is used to develop a generic analytical solution for the time-dependent solid stress and pore fluid pressure of the subsurface rocks. A uniaxial model comprising three layers of rock formations, namely, the reservoir, caprock and burden rock is considered. The model entails different mechanical and flow properties for the considered rock layers. A linear stress–displacement formulation at the interface of the caprock and overburden defined and is calibrated to account for the confinement effect of the burden rock. The closed-form solution to the considered coupled, poroelastic problem is derived in Laplace transform space. The time-domain solution is retrieved by numerical inversion of the solution in Laplace transform space. The obtained general solution is used to assess the coupled pore fluid pressure and stress evolution of rock layers in the following applied problems. (1) Caprock integrity upon fluid injection into the reservoir. (2) Seal rock efficiency of containing fluid transport from an abnormally pressured reservoir compartment. Findings indicate that the time evolution of pore fluid transport within and in between the rock layers is influenced by the relative magnitude of both flow and mechanical properties of the reservoir and caprock. In particular, the contrast between the elastic moduli of the reservoir and caprock are found to have substantial effect on the rate and magnitude of overpressure dissipation from the reservoir. Coulomb's shear failure criterion, together with Terzaghi's effective stress criterion for tensile failure, is used to assess the time-dependent failure tendency of the caprock upon exposure to excess pressure of the reservoir in the case of fluid injection problem. Findings suggest that higher injection rate, stiffer overburden, thinner reservoir and stiffer reservoir rock would enhance the failure tendency of the caprock.
AB - Coupled theory of poroelasticity is used to develop a generic analytical solution for the time-dependent solid stress and pore fluid pressure of the subsurface rocks. A uniaxial model comprising three layers of rock formations, namely, the reservoir, caprock and burden rock is considered. The model entails different mechanical and flow properties for the considered rock layers. A linear stress–displacement formulation at the interface of the caprock and overburden defined and is calibrated to account for the confinement effect of the burden rock. The closed-form solution to the considered coupled, poroelastic problem is derived in Laplace transform space. The time-domain solution is retrieved by numerical inversion of the solution in Laplace transform space. The obtained general solution is used to assess the coupled pore fluid pressure and stress evolution of rock layers in the following applied problems. (1) Caprock integrity upon fluid injection into the reservoir. (2) Seal rock efficiency of containing fluid transport from an abnormally pressured reservoir compartment. Findings indicate that the time evolution of pore fluid transport within and in between the rock layers is influenced by the relative magnitude of both flow and mechanical properties of the reservoir and caprock. In particular, the contrast between the elastic moduli of the reservoir and caprock are found to have substantial effect on the rate and magnitude of overpressure dissipation from the reservoir. Coulomb's shear failure criterion, together with Terzaghi's effective stress criterion for tensile failure, is used to assess the time-dependent failure tendency of the caprock upon exposure to excess pressure of the reservoir in the case of fluid injection problem. Findings suggest that higher injection rate, stiffer overburden, thinner reservoir and stiffer reservoir rock would enhance the failure tendency of the caprock.
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U2 - 10.1016/j.gete.2020.100215
DO - 10.1016/j.gete.2020.100215
M3 - Article
AN - SCOPUS:85089969446
VL - 25
JO - Geomechanics for Energy and the Environment
JF - Geomechanics for Energy and the Environment
SN - 2352-3808
M1 - 100215
ER -