Novel Perforation and Stimulation Approach to Maximize Production from HPHT Sour Gas Wells: Kuwait Jurassic Best Practices

AbstractOptimized perforation and stimulation approach was developed to maximize production and overcome heavy oil based mud (OBM) associated damage for HPHT condensate wells (matrix-dominated flow) from Jurassic formation in Kuwait. This paper shares the challenges, approach and results of this novel methodology that led to significant production enhancement.Heavy OBM is the drilling and completion fluid for deep carbonate formation of Jurassic era reservoirs in Kuwait. Conventional tubing conveyed perforation (TCP)/Wireline perforation requires well killing to run final completion. Production tests carried out before and after running final completion showed significant drop in production of hydrocarbon. Conventional coil tubing acid jobs was performed to bypass the damage but still production was well below expectations. After analyzing pros and cons of multiple perforation and completion methodologies, finally gun hanger shoot and drop perforation system was re-introduced for Jurassic wells.Robust design and completion process was developed for successful execution as previous attempts of gun hanger shoot and drop system was not successful due to extreme environment (16,000 ft Depth, 11,500 psi Reservoir Pressure, 4% H2S, 3% CO2). Successful execution using gun hanger shoot and drop system with ‘just in time’ firing facilitated underbalanced perforation with immediate production tests and no requirement of further killing of well. Engineered perforation and gun design helped in optimizing space available below zone of interest for any well intervention activities. Initial well tests showed encouraging production result with significant oil and gas flow. Thick walled coil tubing was successfully deployed in live well to perform well activation in extreme environment to bypass formation damage caused during drilling process and improved acid placement. Combination of acid and produced hydrocarbon led to In-situ generation of emulsified acid providing deeper penetration of acid. Acid pumping rate and pressure was optimized to generate conductive acid etched channels and avoid creation of inefficient fractures. Cross-segment collaboration led to successful execution in challenging conditions leading to five-fold increase in production post stimulation.Gun hanger shoot and drop system was successfully re-introduced for underbalanced perforation in extreme Jurassic environment. Coil tubing operation was performed for the first time in a live Jurassic well with bottom hole pressure close to 15,000 psi and H2S close to 4%.