Simulation of Weak and Strong Acids Injection into a Carbonate Formation: Case Study of Acidizing in Two Hydrocarbon Layers of an Oil Field, South-West of Iran

Injection of different acids is one of the methods that can improve the permeability of the damaged near-wellbore areas. The efficiency of the carbonate acidizing processes depends on the propagation of wormholes in porous media. Creation of these high permeable flow paths is mainly dependent on the flow rate of the injected acids, the composition of the system, and the structure of the porous media. Indeed, experimental studies have indicated that there are optimum injection rates for different acids in different systems. In this study, the injection of several acids into the damaged formations in an oilfield is simulated using the Well book software. The results of this study indicate that it is probable to implement an optimized acidizing operation in this well. The obtained optimum injection rate for HCl is slightly higher than the maximum injection rate that the carbonate layers can tolerate. In addition, the simulation results indicate that using formic acid instead of acetic acid helps to achieve a higher reduction of the skin factor. Moreover, using coiled tubing can contribute toward the uniform distribution of acid in different sections, which results in the increase in the productivity index in all production layers. According to the simulation results, injection of hydrochloric, acetic and formic acid in the determined optimized condition can result in the increase in the oil production rate from the primary value of 300 bbl/day to 544, 511, and 441 bbl/day respectively.