Decoupled velocity formulation for geothermal well and reservoir simulation.

Abstract

The energy transition is inevitable since approximately two-third of the current global emission is due to energy production. Subsurface can provide a great opportunity for innovative lowcarbon energy solutions such as geothermal energy production, hydrogen storage, carbon capture, and sequestration, etc. Well and borehole operations play an important role in all these applications. In order to operate wells intelligently, there must be a robust simulation technology that captures physics and the expected production scenario. We design a numerical framework for predictive simulation and monitoring of injection and production wells based on the general multi-segment well model. Our simulation model is based on the general unstructured grid framework in which the wells are segmented similar to finite-volume discretization of reservoir. Total velocity serves as an additional nonlinear unknown and it is constrained with the momentum equation. Moreover, transforming nonlinear governing equations for both reservoir and well into operator form benefits from operator-based linearization (OBL) techniques and reduce further the computational cost related to linearization. This framework was tested for several complex physical kernels including thermal compositional multiphase reactive flow and transport. The proposed model was validated using a comparison with analytic and numerical results.