Modeling of Acid Fracturing

Abstract

Summary The paper presents a theoretical framework for modeling acid fracturing stimulations. Starting from the fundamental equations of fluid mechanics, fracture mechanics, convection, and diffusion, the paper outlines the steps necessary to derive simplified equations for an acid fracturing model. Unlike some existing models, the coupled problem of fracture geometry, acid transport, and diffusion is solved simultaneously in this paper. Although an infinite reaction rate is assumed in the solution of the problem, an empirical correlation is used to account partially for finite reaction rates. Errors in the governing equations of some of the existing models are identified. To assess the accuracy of the approximations used in the present model, exact solutions are used for comparison. Predictions from the present model are compared with a model in the literature, and the results are found to be in reasonable agreement. As in all existing acid fracturing models, not all the phenomena of the acid fracturing process have been incorporated into the present model. Nevertheless, the present model is improved over existing models because it is derived from fundamental equations and thus forms a basis from which further improvements can be made.