A Novel Approach to Matrix Acid Stimulation for ESP Wells: Overcoming Challenges and Enhancing Productivity. Case Studies in Two Wells

Abstract During lifespan of electric submersible pumps (ESP), reservoir productivity often declines, either due to the induced damage during work over or production related issues that causes reduction in reservoir PI. Traditional matrix acid stimulation techniques, to restore the initial productivity index and remove induced damage, can be challenging to implement while the ESP is downhole, leading to additional cost for work over and replacement of the damaged string. This paper introduces a novel technique to matrix acid stimulation that targets damaged reservoir while ESP is in place downhole, by developing a new treatment includes mixing acid with retarding agent to overcome the challenges of pumping highly corrosive chemicals via coiled tubing through ESP without causing any damage for ESP string, pump stages, cables or even the motor. also, casing side which maintained with minimum reaction with acid treatment till reaching the proposed previously inaccessible damaged formation that requires productivity enhancement. Optimizing the treatment pumping is distinctively crucial to ensure the customized delivery of treatment into formation. Implementing this new technique in two oil producing wells in the western desert in EGYPT, with two diversified formation types, one is sandstone reservoir and the other is carbonate reservoir, both had ESP installed string, and both had productivity reduction due to severe damage while work over. As a result of using the new treatment, productivity index in both wells was restored to their initial productivity index, and ESP pumps properly operated after a period of intermittent performance due to the reservoir damage. This approach saved work over cost for each well, and also protected the ESP and increased its life time, as they were working outside their recommended operating range in their low thrust range which intensely leads to pump failures. This presented technique in matrix acid stimulation promotes a wide range of applications, where the productivity index of the wells running with ESP could be enhanced, without the need to work over or to retrieve the existing ESP string to accommodate acid stimulation treatment for the reservoir.