First Time in Kuwait: Successful Hybrid Multistage Completion Accelerates Production of Najmah Unconventional Jurassic Gas Reservoir

Abstract

Abstract North Kuwait Jurassic Gas asset development has strategic value of gas independency for Kuwait as it is the only non-associated gas producing asset. This paper will share the experience, added value, challenges and lessons learned from the successful implementation of first ever Hybrid 15k Multi-Stage Completion in Kuwait across Najma unconventional gas carbonate reservoir commingled with lower cemented liner completion in conventional Middle-Marrat tight carbonate reservoir. This completion configuration enables acceleration of selective stimulation and testing of Najma unconventional production potential in existing wells, and simultaneous comingled production from both reservoirs to maximize well production potential. The development of North Kuwait Jurassic deep unconventional gas carbonate reservoirs is key to compensate the production decline from conventional producing Middle-Marrat reservoir and to achieve the production target of Jurassic gas asset. The recovery from such unconventional reservoirs is extremely challenging if conventional development strategies are applied. Therefore, a dedicated full development plan applying integrated upstream and downstream technologies is important to achieve commercial production. The NK field development team has initiated a study to test the potential of unconventional Najmah formation in existing wells to evaluate the production potential and accelerate production from such reservoirs. The typical completion of Jurassic wells include Najmah reservoir in the 7-5/8″ cemented liner section followed by the Marrat reservoir completed in 5″ or 4.5″ cemented liner section. The multidisciplinary team efforts have yielded an innovative hybrid completion solution of 15K rated cased-hole ball-drop multistage completion across Najma reservoir layers and cemented liner across Middle-Marrat reservoir layers that allows selective commingled production of Middle-Marrat and Najmah with ensuring full selective stimulation potential across Najmah reservoirs through the multistage completion. Many completion design, operations and installation challenges were resolved to ensure mechanical isolation of lower depleted conventional reservoir before perforation the upper unconventional reservoir and running the multistage across it. This is to mitigate the challenges of high differential pressure of approximately 5,000 psi between the two reservoirs in completion phase to avoid high formation damage to the depleted Middle-Marrat lower reservoir plus well control during rig operation. This innovative hybrid completion has been installed successfully in one well as first time ever in Kuwait. Najmah and Middle Marrat reservoirs have been selectively stimulated and tested individually then commingled production from both reservoir as first time in Jurassic gas fields and Kuwait. PLT showed positive production contribution from Najma open frac ports and no cross flow among open reservoirs. There is a plan to expand such Hybrid completion to other candidates. This innovative completion configuration can be used in similar application for commingling production to minimize cost of new wells for different reservoirs.