Abstract
Injectivity of water disposal wells is decreasing with time as tar accumulates in the wellbore and/or within the vicinity of the wellbore. The tar deposit reduces and deteriorates the effective wellbore length in addition to increasing mechanical skin across the sand face. The injectivity of water disposal wells can be effectively enhanced/stimulated by doing special chemical treatment mainly for sand stone reservoir. This helps to reduce injection bottom-hole pressure and consequently increase the pumping rates. This proposed chemical treatment was used for the first time in Saudi Arabia for sandstone reservoir to remove tar accumulation. The chemical treatment fluid (recipe) was tested in the lab and showed promising results. In this trial test, a water disposal well candidate with a low injection rate was selected to be implemented for the trial test. The treatment was aimed at enhancing well injectivity and the initial results of the field implementation demonstrate a significant improvement in the injection rate. This result was confirmed from the rate measurement before and after the treatment in addition to well testing analysis. Key results were consolidated with fall-off tests conducted before and after the treatment proving the effectiveness of the chemical treatment at reducing the skin and increasing the injection rate. In addition, this chemical is cost effective compared to other chemicals previously used for the same treatment objective. This paper also illustrates the current procedures and provides recommendations for future job execution with new procedures and steps to improve results.
