Jurassic Reservoirs in Abduliyah field of West Kuwait are characterized by abnormal pressure variation within and across Jurassic formations, which cause profound drilling problems such as well kicks and mud losses resulting in increased drilling time, cost and materials in addition to reservoir damages.
The development of Najmah –Sargelu (NJ/SR) unconventional fractured reservoir requires drilling through high-density fracture swarms to ensure well productivity, which in many instances result in "alternate loss & gain scenario," occasionally, making the well control options limited. On the other hand, drilling through Marrat section encounters drilling difficulties such as mud loss and differential sticking in depleted middle Marrat layers juxtaposed to high-pressure layers of upper intervals. Keeping the above problems in mind, Managed pressure Drilling (MPD) was applied first time in both 9-1/4″ NJ-SR & 6-1/2″ Marrat reservoir sections in a deviated well of Abduliyah field. The Use of MPD in this well offered several advantages and improvements in drilling and completion performance as given below:
Reduction in Operation Time: Successfully drilled through Base Gotnia, Najmah-Sarjelu & Marrat Formations to Target Depth smoothly without any Non-productive Time (NPT)
Down hole problem avoidance: No downhole complications experienced during drilling to Target Depth.
Implementation of new casing design: Drilled Najmah-Sarjelu, Dharuma, Up. Marrat and Upper part of Middle Marrat in the same section for the first time in Abduliyah field which allows future re-entry sidetracking using 6 ½″ horizontal wellbores to enhance productivity for cost-optimal development of NJ-SR & Marrat reservoirs.
Reduction in drilling fluid density: The sections were drilled with lower drilling fluid density by 1.5-2.0 ppg resulting in optimum overbalance pressure to avoid formation damage while reducing the risk of differential stuck pipe, with savings in mud cost.
Health Safety & Environment (HSE) Improvement: The MPD sections were drilled without any incident indicating improved HSE performance.
Reduction in overall well cost: Significant cost reduction was achieved by using MPD for drilling the sections.
The paper aims to share the successful case study of drilling through Jurassic reservoir sections of Abduliyah deviated well using MPD technology along with lessons learned and benefits for its future implementation in similar wells across all KOC assets