Petroleum Production Systems

Chapter 14. Matrix Acidizing: Acid/Rock Interactions

14.1. Introduction

Matrix acidizing is a well stimulation technique in which an acid solution is injected into the formation in order to dissolve some of the minerals present, and hence recover or increase the permeability in the near-wellbore vicinity. The most common acids used are hydrochloric acid (HCl), used primarily to dissolve carbonate minerals, and mixtures of hydrofluoric and hydrochloric acids (HF/HCl), for attacking silicate minerals such as clays and feldspars. Because traditional drilling fluid (drilling “mud”) was a suspension of bentonite clay, the mixture HF/HCl, effective in dissolving bentonite particles, has been known in the vernacular as mud acid. Other acids, particularly ...