Next Steps in Hydraulic Fracturing in the Clair Field – An Evolving Story

Abstract

Abstract Due to its complexity the Clair Field is a phased development. It consists of the Clair Phase 1 and Clair Ridge Platforms with prospects of Clair Phase 3 in future. The original development plan for the Clair Field was based on wells successfully targeting natural fracture networks to deliver enhanced production rates well above those the low-permeability matrix alone could deliver. Natural fractures drive productivity in Clair Field producers, so no hydraulic fracturing stimulation was envisaged. Therefore, it is unsurprising that initial stimulation efforts on the Clair Field targeted intervention-based hydraulic fracturing after the wells had been completed and put on production. However, several recent wells which did not encounter sufficient natural fractures have delivered production results below expectations. Consequently, this increased appetite for hydraulic fracturing to protect the base and provide additional production. Hydraulic fracturing has demonstrated its value in terms of production uplift for the Clair Field since the first well was hydraulically fractured in 2019. The first platform-based multistage fracturing on the Clair Phase 1 Platform was undertaken from the drill floor when no development well construction was taking place. It has highlighted that fracturing offshore as a wellwork campaign is an intensive and complex scope. On the Ridge platform the continuous drilling program is ongoing, driving requirements for simultaneous operations (SIMOPS). Increasing operational challenges to the next level, the next step was to perform hydraulic fracturing alongside an ongoing development drilling and completion campaign, driving the requirement to conduct all intervention operations simultaneously (SIMOPS) with minimal impact both to the rig and production operations. The first SIMOPS fracturing project was successfully delivered on the Clair Ridge Platform in 2022. It demonstrated the capability to perform a complex hydraulic fracturing intervention concurrently with an ongoing drilling campaign and production operations all while ensuring safe and reliable execution. Future intervention-based stimulations are planned on Clair Phase 1 and Clair Ridge and the lessons learned from the first two operations are key to delivering those efficiently. Striving for continuous improvement, the Clair team have developed plans to transfer stimulation operations from an intervention to an integral part of the well construction phase, immediately following lower completion installation. Changing to an ‘online’ fracturing execution approach greatly reduces both equipment and personnel on board (POB) required on the platform. New insights also include considerations on fracturing design and placement in naturally fractured reservoir as Ridge area of the Clair Field. This paper details lessons learned for dealing with pressure dependent leak-off for hydraulic fracturing in naturally fractured reservoir.