An Innovative Wellbore Cleanup Solution for Non-Cemented Lower Completions Saves 27 Million$ in ADNOC Onshore

The long-term development of any mature field requires a fresh perspective of long MRC (Maximum reservoir contact) wells and increased well accessibility. To improve well accessibility the deployment of lower completion has been a mandate. Onshore UAE Field demands drilling Slim hole (6″ /6-1/8″ ) laterals and Slim Hole ERD (Extended reach drilling) wells with 4.5″ Uncemented Lower Completion. This paper highlights the innovative wellbore cleanout procedure prior installation of Lower Completions. Conventionally, using Water Based Mud (WBM) with high friction factors in 6″ Horizontal Hole (HH), two trips were required to reduce the friction factor prior running the Lower Completion. The optimized solution allowed wellbore clean-up and displacement of brine in one trip with drilling assembly (BHA). This innovative technique eliminated one dedicated trip for wellbore cleanout and thus saved millions in CAPEX and Business Plan days. The T&D data for 5 wells with dedicated cleanout trip were compared to clean-out with 6″ drilling BHA with viscous-lubricated brine. The 6″ BHA was optimized to fit with innovative dormant drilling scrapper and lubricated viscous brine was displaced in the Open Hole. A thorough hole cleaning procedure was formulated and was applied to all the wells. After analyzing over 5 wells, it was observed that in both runs, the one with 6″ BHA compared to dedicated cleanout-trip, the torque and drag values were similar and the effective reduction in friction factor was similar. This supported the elimination of planned dedicated cleanout trip and saved average 2 days/well and 27MM$ for year 2022. This optimized BHA design with enhanced hole cleaning procedure was a keystone in deploying slim 4-1/2″ lower completion in WBM system. This practice led to successful deployment of First Slim Hole ERD in UAE with 15000ft of 4-1/2″ lower completion with WBM system. This was a one-of-a-kind achievement in UAE.