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.
One of the greatest historically unsolved challenges to date in the United Arab Emirates is the failure to effectively cure the severe losses due to poor zonal isolation during drilling and cementing aquifer formations in particular the Dammam, UER & Simsima formations in the BAB field. Continuous efforts have been made to seek and pilot new technologies in UAE land operations to overcome drilling operation challenges, specifically chronic lost circulation in aquifer formations with the commitment to drive a more cost-effective operation and reduce the risk of Non-Productive Time (NPT). The current practice was not providing proper zonal isolation in the surface and intermediate sections. Most of the time aerated drilling was utilized while drilling the lost zones and conduct a top-up cement job to improve zonal isolation, but this results in limited reliability. It was necessary to identify a different approach to cure or significantly reduce the losses which would enable the hole section to be drilled successfully while minimizing operational risks, in a cost-effective manner. A technique combining two different technologies was selected: a swelling polymer lost-circulation material (LCM) that hydrates and helps reduce flow velocity into the formation, followed by a shear-rate rheology-dependent cement system. This cement system is a tunable and tailored slurry with thixotropic properties and has shown very cost-effective results with high success rates. It was then decided to tailor this approach to Abu Dhabi land operations to maximize wellbore asset value. After four subsequent trials targeting two different aquifer formations, the technique has shown tremendously promising results by successfully curing the losses providing above 80% returns. These combined technologies aim to eliminate or reduce effect of losses during cementing by performing the primary cementing job with complete returns or minor losses across aquifers thus enhancing wellbore integrity during the lifecycle of the well. It is hoped that this will eliminate, or at a minimum reduce production deferrals and subsequently improve plug and abandon (P&A) operations at end of field life. This paper aims to describe the challenges faced on the first three trials utilizing this technique and the solutions assigned for each trial based on the inputs, such as loss rate, formations interval exposed, design and lab testing for the pumped treatments as well as job execution details along with lesson learned for future jobs.
Extended reach drilling (ERD) can facilitate the development of untapped resources, reduce greenhouse gas emissions, surface congestion, and drilling costs. This ERD project with lower completion was started with an aim to lower well cost indicators including $/ft and $/bbl. Therefore, the challenge was to drill Slimhole ERD (6-1/8″ lateral) wells with water-based mud (WBM). WBM is more cost-effective, environmentally friendly, and less damaging to the reservoir than OBM (oil-based mud). The use of WBM instead of OBM can save $2MM per well. The major challenges in drilling Slimhole (6-1/8″ size) ERD well with lateral le include higher torque and failure to deploy lower completion due to high friction factors. The first pilot well was planned with a liner-less design considering the low friction factors required to drill 15,000′ of 6-1/8″ lateral hole and run the lower completion. The second pilot well was targeting a deeper and tighter reservoir zone with higher downhole temperatures. This involved drilling 12-1/4″ intermediate hole to the landing point with larger 5-1/2″ drill pipe. It enabled a push-pipe technique for drilling the lateral hole with improved weight transfer through the curved profile. The 6-1/8″ lateral hole was drilled with 4″ high-torque drill pipe, tandem high-flow circulating subs, and specially formulated drilling fluid lubricant. A conventional OBM system provides sufficient lubricity to reduce friction factors as low as 0.10. In this application, a low cost WBM system was made feasible by introducing stable high-temperature lubricant and unique hole cleaning practices. Following this successful achievement, the 5-year business plan has been revised to include 63 similar wells with a projected total savings of ~ $250MM. The Slimhole ERD project has demonstrated substantial value with a 35% reduction in CAPEX. The delivery of these two Slimhole ERD wells overturned conventional drilling and completion practices. The implemented project resulted in saving up to 35% of the well cost and saved 20 days per well compared to a conventional ERD well with 8-1/2″ hole and OBM. These two Slimhole ERD (15,000′ lateral) wells were drilled with a challenging Directional Difficulty Index (DDI) of 7.2. The wells were both completed successfully by running the 4-1/2″ lower completion to reach the total depth.
An active filter cake technology (AFT) was chosen to improve production performance in the tight reservoir following a comprehensive laboratory study to determine formation damage impact caused by previous non-damaging fluids (NDF). The AFT was successfully field trialed on two wells with production improvement vs. acid stimulated offset wells. This paper discusses laboratory data and improved field productivity. It documents reduction of torque/drag with increased rate of penetration without using a lubricant during drilling. Comprehensive laboratory testing to identify origins of deficient production was completed by thoroughly reviewing drilling and completion practices, and completion type implemented. Compatibility of base brine with formation water; formation damage impact of drilling fluids used in reservoir and effectiveness of hydrochloric acid (HCl) solution pumped through coiled tubing to destroy the filter cake constituted the first phase of the investigation. Assessment of several fluids capable of mitigating concerns was performed in the second phase. The optimization and customization of candidate fluids to address all challenges was the third phase. Last phase consisted of field trials and assessment of production results. Testing identified a potential incompatibility of calcium chloride brine and the formation water. The brine was replaced with monovalent halides brine. The previous NDF system exhibited elevated filtrate volume and a high concentration of acid insoluble materials which together significantly impacted productivity. Review of the completion operation and laboratory results proved filter cakes of reservoir drill-in fluids (RDF) cannot be homogenously and entirely removed with HCl solution using coiled tubing. Only less than 50% of the wellbore length can be accessed with coiled tubing and treated with acid. The acid treatment dissolved less than 10% of filter cake when sumulated field conditions in the laboratory. Likewise, the filter cake breaker cannot be implemented on barefoot completion as its volume is totally lost to the formation after breakthrough before complete filter cake dissolution occurs. The study recommended AFT with 100% organophilic bridging materials. The AFT was successfully field trialled in two wells. Post analysis of drilling parameters with AFT exhibits lower torques without addition of lubricant compared to previous fluid along with 186% increase in average rate of penetration which saved 79 hours of ILT/well. Production kicked-off without assistance from lighter fluid (N2 gas) or stimulation showing promising results compared with near-by wells. The 100% organophilic bridging materials were used for first time in field. It proved acid stimulation can be eliminated for the tight reservoir while improving the oil production rate compared to the offset wells. In addition to inherent productivity improvement characteristics, AFT is appropriate where cheesing and greasing of RDF are common problems with lubricants. AFT demonstrates reduced torque without lubricant addition in extended horizontal deviated wells and excellent production while eliminating post stimulation.
Extended reach drilling (ERD) can facilitate the development of untapped resources, reduce greenhouse gas emissions, surface congestion, and drilling costs. This ERD project with lower completion was started with an aim to lower well cost indicators including $/ft and $/bbl. Therefore, the challenge was to drill Slimhole ERD (6-1/8″ lateral) wells with water-based mud (WBM). WBM is more cost-effective, environmentally friendly, and less damaging to the reservoir than OBM (oil-based mud). The use of WBM instead of OBM can save $2MM per well. The major challenges in drilling Slimhole (6-1/8″ size) ERD well with lateral le include higher torque and failure to deploy lower completion due to high friction factors. The first pilot well was planned with a liner-less design considering the low friction factors required to drill 15,000’ of 6-1/8″ lateral hole and run the lower completion. The second pilot well was targeting a deeper and tighter reservoir zone with higher downhole temperatures. This involved drilling 12-1/4″ intermediate hole to the landing point with larger 5-1/2″ drill pipe. It enabled a push-pipe technique for drilling the lateral hole with improved weight transfer through the curved profile. The 6-1/8″ lateral hole was drilled with 4″ high-torque drill pipe, tandem high-flow circulating subs, and specially formulated drilling fluid lubricant. A conventional OBM system provides sufficient lubricity to reduce friction factors as low as 0.10. In this application, a low cost WBM system was made feasible by introducing stable high-temperature lubricant and unique hole cleaning practices. Following this successful achievement, the 5-year business plan has been revised to include 63 similar wells with a projected total savings of ~ $250MM. The Slimhole ERD project has demonstrated substantial value with a 35% reduction in CAPEX. The delivery of these two Slimhole ERD wells overturned conventional drilling and completion practices. The implemented project resulted in saving up to 35% of the well cost and saved 20 days per well compared to a conventional ERD well with 8-1/2″ hole and OBM. These two Slimhole ERD (15,000’ lateral) wells were drilled with a challenging Directional Difficulty Index (DDI) of 7.2. The wells were both completed successfully by running the 4-1/2″ lower completion to reach the total depth.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.