Near Field Developments with an Upgraded Brown-Field Platform Rig: Sharing the Learning from a Three-Well Extended Reach Drilling (ERD) Program

Abstract

Abstract This paper will summarize the concept selection, concept definition, and modifications for a two-stage upgrade of a 35-yr old platform rig on a production platform to extend the drilling radius from 15 to 25 kft (Cutt 2007), the maximum working pressure (MWP) from 5 to 10 ksi, and how combined projects enabled the development of new fields which could not support subsea infrastructure. The paper will highlight the lessons learned at each stage of the upgrade and the drilling programs, focusing on how the legacy limitations of the original rig design and inherited constraints of 200% well slot utilization were mitigated to enable the drilling of a next generation of wells. The upgrade of the rig in two separate projects allowed the lessons learned from the first extended reach drilling (ERD) upgrade (Cutt 2007) to be applied to the second 10-ksi upgrade. This approach also allowed different approaches to be taken to achieve improved results. The drilling of redrilled wells on an old platform through depleted reservoirs constrained many aspects of well design; most specifically, casing sizes and maximum mud weights through intervals of reactive shale and depleted sands (Bennett et al, 1998). The company has global experience in new field developments with world class ERD wells (Elks et al, 2002; Walker 2008; Armstrong et al, 2011; McDermott et al, 2005; Viktorin et al, 2006; Elsborg et al, 2005; Woodfine et al, 2011) and the different approaches for new wells and redrilled wells will be compared. The paper will show how the challenges of ERD operations to 25 kft in a 6-in. hole size were overcome and will comprehensively address how some risk mitigations introduced new risks, with specific emphasis on managing an operation where the extreme requirements did not allow any fallback contingencies in the event of a problem.