Reservoir Stimulation's Effect on Depletion‐Induced Seismicity

Abstract

Depletion‐induced seismicity can pose a problem in some fluid‐producing subsurface reservoirs, in some cases requiring production rate control in order to limit the seismicity. This study investigates the use of reservoir stimulation to reduce the depletion‐induced seismicity rate. Depletion‐induced stress and pore pressure changes are evaluated in a shale cap rock, sandstone reservoir, and shale underburden system, which contains a horizontal well, all modeled in plane strain conditions. The seismicity rate is then predicted based on an existing seismicity model and is found to be dependent on the direction the well is drilled in with respect to the principal stresses. The case where the reservoir has first been stimulated is compared to the case where stimulation has not been performed (using the same production rates) for normal, reverse, and strike‐slip faulting stress regimes. Seismicity is reduced in the case of reservoir stimulation for both reverse and strike‐slip faulting stress regimes. The seismicity rate is only slightly reduced for the normal faulting stress regime. Stimulation also increases the distance that changes in pore pressure dominate over poroelastic stress changes in the reservoir. Further, it is found that the optimal orientation of a horizontal well, in terms of induced seismicity, is parallel to the minimum principal stress in normal faulting stress regimes and parallel to the maximum principal stress in reverse faulting stress regimes. The orientation of a horizontal well determines where the seismicity is located in a strike‐slip faulting stress regime.

Hydraulic Transport Through Calcite Bearing Faults With Customized Roughness: Effects of Normal and Shear Loading

“…We can conclude that changing the state of stress will improve fluid production in a larger scale than generating significant offsets in the fault (which can be technologically difficult). This can be done for example through stress preconditioning (Fryer et al, 2018(Fryer et al, , 2020.…”

“…Further work is nevertheless needed to estimate at which stress levels this prediction stops being accurate and to predict the change at high normal stress. Indeed, by preconditioning the reservoir (reducing the effective stress on it; Fryer et al, 2018Fryer et al, , 2020, the predictions of transmissivity should become more accurate. We can speculate that the use of more complex models that include shear stress and wear processes can strongly improve the prediction of transmissivity with shear displacement (Aghababaei et al, 2016;Frérot et al, 2019;Milanese et al, 2019;Molinari et al, 2018;Shvarts & Yastrebov, 2018a, 2018bShvarts, 2019;Yastrebov et al, 2017).…”

Hydraulic transport through calcite bearing faults with customized roughness: Effects of normal and shear loading.

“…Further work is nevertheless needed to estimate at which stress levels this prediction stops being accurate and to predict the change at high normal stress. Indeed, by preconditioning the reservoir (reducing the effective stress on it; Fryer et al, 2018Fryer et al, , 2020, the predictions of transmissivity should become more accurate. We can speculate that the use of more complex models that include shear stress and wear processes can strongly improve the prediction of transmissivity with shear displacement (Aghababaei et al, 2016;Frérot et al, 2019;Milanese et al, 2019;Molinari et al, 2018;Shvarts & Yastrebov, 2018a, 2018bShvarts, 2019;Yastrebov et al, 2017).…”