Numerical evaluation of a fracture acidizing treatment in a three-dimensional fractured carbonate reservoir

Abstract

A fracture acidizing treatment, as an effective way to enhance the well performance, is commonly used in fractured carbonate reservoirs operated with hydraulic fracturing stimulation. A fracture acidizing simulator is developed to model the fracture acidizing process in a fractured carbonate rock mass embedded with randomly distributed natural fractures. Mathematical models incorporating the hydro-chemical coupled process together with the material compressibility are discretized based on a unified pipe-network method. An implicit time scheme is employed in the proposed simulator, and the model reliability is verified against the results obtained from a commercial software. Sensitivity analyses are carried out in respect of the Sherwood number, matrix porosity, and closure stress considering the acidizing along a single hydraulic fracture in a carbonate domain. The proposed model is applied to the simulation of the fracture acidizing considering highly interconnected fracture network system. Two stages in the production estimation, the oil development with constant production rate in the first stage and with constant bottom-hole pressure in the second stage, are operated. It is concluded that the increase of either the injection concentration or the injection pressure in the acidizing treatment process achieves better acidizing efficiency and thus improves the productivity potential.