Evaluation of Main Pay- Zubair Formation after Operations Re-Injection of Produced Water Directly In Rumaila Oil Field Norths under Matrix Condition

The water injection program is a key part of Rumaila oilfield long-term development plan to raise pressure levels in reservoirs. This water injection program has involved project of produced water re-injection (PWRI) directly. Although PWRI is most economical method for disposal of produced water and reduces environmental pollution risks but it can causes impairment in formation permeability due to contain it on suspended and dissolved solids that can plug porous media. Therefore, it is essential conduct fluid-rocks compatibility experiments and analysis to evaluation PWRI. The experimental work was carried out in Department of Laboratory and Quality Control in Basra Oil Company, using waterflooding apparatus. The compatibility experiments were applied on five core selected from Main Pay - Zubair formation that has very high permeability with 40 liter produced water at North-Rumaila oilfield. The main purpose of this work is evaluation of PWRI by studying the reduction of permeability(formation damage). The maximum damage degree is 71% and the minimum damage degree is 55% with average value 68.2%. The main causes to impairment permeability are present high concentration from suspended solids in PW.  The damage is start from maximum degree  near wellbore and  gradually decreasing away from injection well and the permeability start jump up. The damage zone is propagate symmetrical around axial wellbore injector and connect together formed roughly circular dish. In this paper we establish table of monitor for help to minimize formation damage.  Based on these results, we can concludes, direct injection of produced water into Zubair formation without surface treatments or  washing of formation or acidizing treatment  or injection under fracture conditions causes formation damage and increases with time.