Acidization-Induced Formation Damage: Experimental and Modeling Studies

Abstract

Abstract The results of laboratory experiments conducted to investigate the effect of matrix acidization on long berea sandstone cores (6"-12") and their theoretical analysis are presented. Both damaged and undamaged core samples were treated with different concentrations of HCl/HF acids (4%HCl/1.5%HF and 12%HCl/3%HF). One undamaged core sample was treated with 6%HF acid. The effect of spent acid on permeability was investigated. The treated cores were cut into four sections each and the mineralogy of each section was analyzed using an X-Ray Diffraction (XRD). A simplified model for matrix acidization induced formation damage was developed and facilitated to analyze the laboratory test data and to determine the relative affects of adverse processes in matrix acidization. The model developed takes into account the change in concentrations of both acid and minerals, thereby predicting the change in permeability. The results indicated that higher concentration of acid causes more formation damage due to the precipitation of silicates and/or iron oxides. In addition, when the spent acid resides in the core for a longer time it causes a severe formation damage. It is shown that the experimental and simulation results agree well within the accuracy of the simplified model.