A review of numerical modelling techniques for reactive transport in subsurface reservoirs and application in mimetic finite difference discretization schemes

Reactive transport is an area of growing interest to the petroleum industry due to the need to develop efficient simulators for oil production in mature and fractured fields. The subsurface flow processes are highly dependent on the chemical reaction between fluid and rocks, and between fluids themselves. This means that fluid flow in a reservoir should be characterized by mass change and chemical reactions, and thus researchers are trying to account for both phenomena through their corresponding governing equations. In this work, we discuss the early efforts to couple mass transfer and chemical reaction equations through presenting key studies in the field of modelling reactive transport and suggest a new discretization scheme for geochemical reactions. Our main objective is to improve on the formulation and simulation of reactive transport problems and explain how to implement Mimetic Finite-Difference (MFD) discretization scheme in reservoir simulators. The paper outlines the steps to discretize the governing equations of reactive transport, and construct and solve the resultant Jacobian system. The purpose of this work is to provide a clear presentation of the main mathematical and theoretical concepts of reactive transport, and how they can be applied in reservoir simulation framework. Such framework can be utilized in the future to develop a state-of-art reservoir simulator that employs Mimetic Finite Difference schemes in unstructured grids and full tensor permeability structures to solve for fluid flow in porous media, while accounting for the geochemical reactions at the subsurface.