Upcoming Reservoirs in North Kuwait will play significant role for meeting NK’s strategic production target. Recent full field study of Sabryia Tuba carbonate reservoir makes it the largest Oil in-Place of the Upcoming Reservoirs in NK. Sabriyah Tuba, though discovered in the 60’s, is still relatively under exploited presently with only 13 active wells with very low total production rate compared to other reservoirs. High reservoir heterogeneity, tightness and poor fluid properties necessitate the application of new stimulation technology targeting good frac conductivity and deep penetration for effective productivity and recovery enhancement. With efforts of a multidisciplinary team, new acid frac fluid, diverter and high leak off control technologies have been designed and executed successfully in two stages covering multiple reservoir layers for the first time in Tuba. Tuba is tight multilayer limestone reservoir. Owing to the low reservoir transmissibility, even low average well production assisted by Artificial Lift causes near-wellbore (not regional) rapid decline in pressure. Full-scale commercial exploitation of the Tuba reservoir therefore requires advanced technologies for productivity enhancement. The well under study is vertical, drilled in 2012 and completed in Upper and Lower Tuba with conventional matrix acid stimulation which had a very steep post-treatment decline rate. It was selected for first application of acid fracturing due to its excellent reservoir development in higher structure position with high initial pressure and medium oil quality, but low production rate. The job was designed to implement a 3-stage acid frac. The first stage was successfully executed. The second and third stages were combined into one stage due to the vertical communication between all 4 Upper Tuba layers during the data fracture treatment. Many technical and operational challenges were faced and properly handled through integrated communication between different participating teams with lessons learned are to be considered in next designs and executions. Post acid Frac, a production log (PLT) was recorded and showed greater contribution from the Upper Tuba intervals. The well has been monitored closely where stabilization was observed in short time period represented in stabilized Pump Intake pressure and production rate that has been tripled post stimulation with an estimated reservoir productivity improvement of about ~3 folds from nodal analysis. The positive result of first acid frac reinforces the action plan to proceed with such stimulation technology. It is expected that the oil gain potential will be significantly more in horizontal completions. Therefore, acid frac stimulation for 2 Horizontal Tuba’s wells is under study. The success of such application will formulate the drilling, completion and stimulation development strategy for the entire Tuba reservoir including early stimulation to improve initial productivity that will contribute significantly to the NK production target. This paper describes the design, implementation and production impact of an advanced fiber based acid fracturing treatment that was successfully executed across the cased-hole of a pilot vertical well that is shaping the production enhancement strategy for Sabriya’s Tuba tight reservoir in North Kuwait field. The paper also focuses on the acid fracturing technique that delivers hydraulic acid fractures with deep, infinitely conductive channel compared to conventional acid stimulation techniques previously employed and their immense impact on production.

This paper will demonstrate how the acid fracturing stimulation using different technologies in multidisciplinary team integration helped un-locking the production potential and setting up development strategy for Tuba tight carbonate reservoir, with case histories. Upcoming Reservoirs in North Kuwait (NK) oil fields will play significant role for meeting NK's strategic production target. Recent full field study of Tuba carbonate reservoir makes it the largest Oil in-Place of the Upcoming Reservoirs in NK. Tuba, though discovered in the 60's, is still relatively under-exploited presently with only 12 active wells with very low total production rate compared to other reservoirs. High reservoir heterogeneity, tightness and poor fluid properties necessitate the move from conventional matrix stimulation to Acid Fracturing technology targeting better Frack conductivity and deep penetration for effective productivity and recovery enhancement. With efforts of multidisciplinary team, Acid Frac fluid, diverter and high leak off control technologies have been designed and executed successfully in 9 wells (7 vertical and 2 multistage horizontal) covering multiple reservoir layers with very positive results that proved the concept and supported more TUBA development. Many technical and operational challenges were faced and properly handled with lessons learned are to be considered in next designs and executions. Despite the close results yielded from the multistage acid fracturing in two horizontal wells compared to the results from 7 vertical wells, it is still early to evaluate stimulation potential of horizontal against vertical wells. It needs more production history and more wells to evaluate long term sustainability. The results of such evaluation will formulate the drilling, completion and stimulation development strategy for the entire TUBA reservoir including early fracturing stimulation to improve initial productivity that will contribute significantly to the NK production target.

Artificial lift is widely used by Kuwait Oil Company (KOC) to both accelerate and increase oil production. The electrical submersible pump (ESP) is one of the most commonly used artificial lift systems in oil and water wells. The ESP is a multistage centrifugal pump placed down in the wellbore, capable of delivering high pressure increments for large oil rates. Reservoir oil is always saturated with natural gas, which will be separated from the oil as the pressure is decreased below the bubble point pressure. Since oil production is based on pressure drawdown, ESPs are likely to experience free gas in the suction fluid. Due to free gas present, several gas locking and ESP trips are observed. This technology is taken into consideration to minimize the free gas produced into the pump. Application of this technology can lead to more stable flow, less ESP trips and increased its run life of ESP. More over, suitable cooling mechanism has to be set up for the motor protection.