Step Change in West of Shetland Offshore Fracturing. First Online Multistage Fracs in Clair Delivers Operational Efficiency and Production Uplift

Abstract In the Greater Clair Area, the largest oil field in Europe, Hydraulic Fracturing (HF) has demonstrated its value in terms of delivering initial production uplift increases of 3 to 6 times with the first HF wells being installed in Clair Phase 1, 2019, and Clair Ridge, 2022. Clair Ridge platform started production in 2018; however, some wells have not encountered sufficient natural fractures (NF) to replicate oil production rates from the initial appraisal wells, increasing the appetite for HF. SPE 216632 (Bird, 2023) documented successful production delivery from intervention-based HF in Clair, while highlighting these operations were inefficient on platforms not specifically designed to support HF operations. SPE 216632 expressed the case to move away from delivering HF in Clair as intense and complex well work campaigns to instead efficiently deliver HF ""online"" via drill pipe as part of the lower completion installation. This paper will document the successful planning, design, and execution of the first ""online"" HF completion operation delivered for Clair Ridge. 5 HF were executed, including record breaking efficiency for Clair with 4 treatments in 4 days. This entire process will be reviewed from completion concept selection, supplier / equipment selection, completion design, operational execution, and lessons learned. The paper will document the potential to incorporate sleeves designed for hydraulic fracturing in addition to multiple additional sleeves designed to provide proppant retention, sand control, and remote activated sleeves for intervention-less production start-up. Providing such functionality currently requires two additional sleeves per zone (e.g., increasing from 8 to 24 sleeves in an 8 zone well). Work is underway to incorporate either 3 sleeves per zone or full functionality into a single sleeve. The pros and cons of each approach will be presented outlining the risks associated, such as accidental sleeve shifting or proppant blockage around sand control sleeve annulus. Clair Unit III has historically been completed with passive sand control standalone screens (SAS) which was a borderline decision. This is the first Unit III well to be completed without SAS, with HF providing additional mitigation for this decision. The process to install a robust sand-face completion will be documented. Details will be provided of solids production monitoring on startup through a temporary well clean-up package designed to remove solids and water and ensure smooth plant operations, including the use of Cutting Re-Injection (CRI) well to dispose of flow back fluids. "Online" HF operations have been operationally and technically successful, the production performance predicted post-drill and actual production post HF will be reviewed including installing a remote activated downhole choke inserted to control production from a NF zone at risk of water production. Analysis of tracers to compare production splits between naturally fractured zones and HF zones will be presented.