Paradigm Shift from Cemented Completions to Multi-Stage Completion Strategy for Managing Tight Gas Development Challenges

Abstract

Abstract The development of North Kuwait Jurassic gas assets has strategic importance for Kuwait's production strategy as the only non-associated gas-producing field in Kuwait. This paper demonstrates the benefits, challenges and lessons learned of the recent paradigm shift in Jurassic tight gas wells’ completion strategy from cemented liner to multi-stage completion. Successful expansion of Multi-Stage Completion (MSC) technology is achieved at the field level led by the integrated team efforts in 2020/21, despite challenging constraints of COVID-19. MSC's help to enhance overall well production potential, overcome reservoir and intervention operation challenges, and allow early production delivery, which is a key factor to achieve a strategic asset production target of 70-80% by 2024/25. Many technical and logistic challenges were experienced during first installations of which the relevant learnings will be shared in this paper. The Jurassic gas asset produces mainly from deep high pressure and temperature, conventional and unconventional tight carbonate reservoirs. The recovery from such complex heterogeneous 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 the strategic production target. Due to the excessive Jurassic carbonate reservoir tightness, permeability contrast and dual permeability effect (matrix and natural fractures), well productivity potential significantly depends on the effectiveness of subsequent stimulation treatments of such complex heterogeneous reservoirs to improve well productivity and potentially connect with natural fractures. Selecting proper well completion design is critical to overcome such reservoir challenges and ensure effective acid stimulation treatments for the mix of conventional and unconventional formations that need convenient diversion mechanism during stimulation to enhance the productivity of each individual reservoir flow unit and enable selective future flexibility of re-stimulation and reservoir management. The asset team has recently applied a step change in completion strategy to open hole multi-stage ball drop completions using state of the art MSC technologies including closeable frac sleeves, full 3.5-in monobore ID post frac sleeves milling and debris sub enclosure to protect the MSC string during casing tie-back operations. This is to overcome reservoir complexity, eliminate wellbore cleaning and decrease the challenges and risks that accompany multiple perforation intervention operations. As well as, eliminate cement quality risks and uncertainties, improve overall cost, and fast track well delivery to production to meet asset production targets by significantly reducing operation time from approximately one month for plug and perf techniques to less than one week when using continuous and less subsurface intervention operations. Recently, a total of 13 new MSC installations and subsequent multi-stage stimulations were achieved in seven months, fromQ3-2020 to Q1-2021, with positive overall production results, significant improvement of intervention operation efficiency and faster well delivery to production. This paper will describe the details of progress to date, and the plan forward for optimization and new technology trials to further improve well performance.