Geomechanical Coupling for Well-Test Diagnostics Near Partially Communicating Faults Applied to Underground Geological CO2/H2 Storage and Compaction Formation Damage

Summary The modeling of the pressure diffusivity in oil and gas reservoirs with geomechanical coupling is fundamental for the adequate reservoir performance estimation. The applications of this modeling rely upon geosciences, petroleum engineering, and energy transition [e.g., underground geological carbon dioxide (CO2)/hydrogen (H2) storage and geothermal projects]. In this paper, we present a transient 2D analytical model for well-reservoir diagnostics with unequal formation thickness effect during oil production near partially communicating faults. Moreover, the response of the compaction caused by depletion in production is also simulated. The method developed combines the Laplace and Fourier transforms to compute the solution of two hydraulic diffusivity equations. The results show that the total pressure drop (Δp) is modeled by two Ei(U) and erfc(U) functions. The first function is coupled with the source raised from the real well (production well), and the second is related to the image well (no source effect). The geomechanical elastic parameters, Young's modulus (E), Poisson ratio (ν) and Biot's coefficient (α), are coupled with the depletion solution of the hydraulic diffusivity equation. Therewith, the depletion and effective stress derivatives for the observation region (∂ΔpD1/∂tDL and ∂σDL′/∂tDL) and for the active one (∂ΔpD2/∂tDA and ∂σDA′/∂tDA) are used to identify potential leakage and sealing zones for underground geological CO2/H2 storage. A computational code was developed in Python software, and the results were highly convergent compared with a numerical method. The main advantages of the proposed model are graphical well-reservoir diagnostics, its ease of implementation in Python and the quick run of the code, which saves computational costs during the simulation. Furthermore, the model presented can be used for potential sites identification for underground geological CO2/H2 storage.