Three-dimensional simulation of acidizing process in carbonate rocks using the Darcy–Forchheimer framework

Abstract

Acidizing is an economical and effective practice to remove the near wellbore damage, which is performed by injecting acid into the formation through the wellbore. The injected acid dissolves the rock, by which the permeability nearby the wellbore can be improved. For a carbonate reservoir, the injected acid dissolves some of the minerals and some narrow and long channels, named wormholes, are formed then. These wormholes can bypass the damaged zone and hence improve the productivity of the well. The process for acid dissolving rocks involves complex physicochemical change, including the chemical reactions at the pore scale and the fluid flow at Darcy scale. In this paper, a 3-D reactive flow model with non-Darcy framework is developed based on the two-scale continuum model, and is solved by using the finite volume method. Five types of dissolution patterns, named face dissolution, conical wormhole, wormhole, ramified wormhole, and uniform dissolution, are obtained as the injection velocity increases. The effect of non-Darcy flow on dissolution pattern and breakthrough volume is analyzed. It is found that there is no effect of non-Darcy on dissolution structure and breakthrough volume when the injection velocity is very low. However, when the injection velocity is very high, the generated wormhole has more branches when using the Forchheimer equation than using the Darcy equation. Moreover, the optimal injection velocity is found to be the same whether considering the non-Darcy flow or not.

Editorial: Advanced modeling and simulation of flow in subsurface reservoirs with fractures and wells for a sustainable industry

“…Acidizing is an economical and effective practice used to remove the near wellbore damage that is performed by injecting acid into a formation through the wellbore, dissolving the rock, and improving its permeability. In this special issue, Liu et al [1] developed a 3-D reactive flow model within a non-Darcy framework based on a two-scale continuum model. Five types of dissolution patterns, i.e., face dissolution, conical wormhole, wormhole, ramified wormhole, and uniform dissolution, were obtained as the injection velocity increases.…”