Abstract
The viability of carbon capture sequestration (CCS) is dependent on the secure storage of CO2 in subsurface geologic formations. Geomechanical failure of caprock is one of the main reasons of CO2 leakage from the storage formations. Through comprehensive assessment on the petrophysical and geomechanical heterogeneities of caprock, it is possible to predict the risk of unexpected caprock failure. To describe the fracture reactivation, the modified Barton–Bandis model is applied. In order to generate hydro‐geomechanically heterogeneous fields, the negative correlation between porosity and Young’s modulus/Poisson’s ratio is applied. In comparison with the homogeneous model, effects of heterogeneity are examined in terms of vertical deformation and the amount of leaked CO2. To compare the effects of heterogeneity, heterogeneous models for both geomechanical and petrophysical properties in coupled simulation are designed. After 10‐year injection with petrophysically heterogeneous and geomechanically homogeneous caprock, CO2 leakage is larger than that of the homogeneous model. In contrast, heterogeneity of geomechanical properties is shown to mitigate additional escape of CO2. Vertical displacement of every heterogeneous model is larger than homogeneous model. The model with compressive tectonic stress shows much more stable trapping with heterogeneous caprock, but there is possibility of rapid leakage after homogeneous caprock failure.
Highlights
CO2 sequestration in aquifer is an effective and a verified method to reduce the atmospheric CO2 airborne fraction. e world’s first commercial approach of CO2 storage project is attempted at the Sleipner gas field in the North Sea, and CO2 sequestration in a saline aquifer has been regarded as the feasible technology [1]
Rutqvist et al [8] conducted coupled reservoirgeomechanical simulations to evaluate the shear and tensile failure in order to accurately estimate the potential of fracture reactivation for a geomechanical CO2 storage formation, and they suggested that long-lasting observation is needed to geomechanical changes resulting from the injected fluid pressure
We constructed a carbon capture sequestration (CCS) model with heterogeneous caprock and compared the flow and geomechanical responses to CO2 injection with particular focus on the risks to storage security posed by geomechanical deformation. e correlations between geomechanical and petrophysical properties were regarded as a function of porosity, and several numbers of numerical simulations were conducted to evaluate the effects of the heterogeneous caprock during CCS. e amount of stored CO2 and vertical deformation of caprock within a two-dimensional formation models were compared for several rock properties including parameters such as Poisson’s ratio, Young’s modulus, porosity, and permeability
Summary
CO2 sequestration in aquifer is an effective and a verified method to reduce the atmospheric CO2 airborne fraction. e world’s first commercial approach of CO2 storage project is attempted at the Sleipner gas field in the North Sea, and CO2 sequestration in a saline aquifer has been regarded as the feasible technology [1]. Us, it is important to monitor the geomechanical change of storage formation to evaluate the stability of CO2 injection. Rutqvist et al [8] conducted coupled reservoirgeomechanical simulations to evaluate the shear and tensile failure in order to accurately estimate the potential of fracture reactivation for a geomechanical CO2 storage formation, and they suggested that long-lasting observation is needed to geomechanical changes resulting from the injected fluid pressure. We constructed a CCS model with heterogeneous caprock and compared the flow and geomechanical responses to CO2 injection with particular focus on the risks to storage security posed by geomechanical deformation. E correlations between geomechanical and petrophysical properties were regarded as a function of porosity, and several numbers of numerical simulations were conducted to evaluate the effects of the heterogeneous caprock during CCS.
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