Modern Concepts of the Carbonate Acidizing Process: a Review of Experimental and Theoretical Research

Carbonate acidizing is a common technology for increasing the production index of reservoirs. The competition of reactant flow in porous media and reaction rate with matrix is the key issue of the improvement of this process. Many experimental and theoretical research are devoted to the analysis of the process. A variety of approaches leads to the relevant problem of identifying their main groups. The aim of the article is to unify the results of recent experimental and theoretical research of the process and create general ideas about the process. Three main types of experimental installations is analyzed, which consider the different sides of the reaction and filtration of an acid through carbonate cores. Among them the new instrument in the process study is the high-resolution x-ray tomography, analysis of the ability of which is the object of the review. Theoretical studies are also being considered to integrate the research results into the overall basis. It is established that the semi-empirical and twoscale continuum modeling approaches play the fundamental role in the understanding of chemistry and physics of the process. These approaches uncovered the nature of the dominant wormholes formation as the unstable displacement process. The authors highlight the problem of dominant wormhole density per squire unit as the most actual question. It has been established that the results of experimental studies of the critical rate of acid injection do not always correlate with field data and the simplified proxy models are more suitable for the design of acid treatments.