digilib@itb.ac.id +62 812 2508 8800

Matrix acidizing is a common well stimulation technique in which acid is injected into the producing reservoir. The main purpose of the process is to remove wellbore formation damage and/or dissolve a portion of the rock and hence, enhance the permeability in the near well-bore region. It is however, important to optimize many treatment parameters to execute an efficient acidizing job. This study are undertaken to investigate the influences of acid injection rate, acid concentration, variation of rock permeability, and acid volume injected on the recovery of damaged rock permeability using matrix acidizing of oil carbonate reservoirs. Nine core flood experiments are undertaken to investigate the above-mentioned effects on matrix acidizing process using actual cores and reservoir liquids. Every core sample was cleansed, evacuated, saturated with brine, flooded with crude oil, and damaged with bentonite water-base mud. Then, the designed acidizing run was carried out. The rock permeability was measured before and after acidizing to quantify the success of the process and to identify the effect of every factor. Models of prediction for permeability damaged factor and permeability improvement factor were developed. The results of the study indicated that the increase of acid concentration and/or the flow rate increases the recovery of damaged permeability. Furthermore, initial rock permeability has minor effect on permeability enhancement by matrix acidizing of damaged carbonate oil reservoir rocks. The increase of acid injection rate increases the required acid volume injected regardless of the reservoir temperature under acidizing.