Formation Damage Analysis of Organic Acids with Limestone Rocks during Acidizing: A Case Study on an Iranian Carbonate Formations

Acidizing of carbonate reservoirs is widely used to improve well productivity. HCl is commonly used for carbonate acidizing due to its low cost and high dissolving power. There are some limitations in using this acid like high reaction rate with calcite and corrosion of tubbing at high temperature. Therefore, organic acids are used as alternatives to HCl to overcome these limitations. However, Organic acids have some disadvantages. These acids are more expensive than HCl and cannot be used at higher concentrations than a specific value because of formation damage due to the precipitation of calcite salts. This study presents experiments to investigate the reaction of these acids with calcite in accordance with the conditions of the Iranian oil reservoirs and to evaluate the probability of calcium salts precipitation. The results indicate that calcium citrate precipitation forms on the surface of calcite, even if the concentration of the citric acid is less than ۱ wt%.

Keywords:

Limestone rocks , Acid injection , Organic acids , pH changes , Calcium citrate precipitation