First Deepwater Well Intervention with Hydraulic Workover Unit on a Tension Leg Wellhead Platform in Brazil

Abstract Production from a tension leg wellhead platform (TLWP) in the deepwater environment of Brazil led the operator to seek cost-effective well workover solutions after several projects were deemed uneconomical. The novel approach to diagnose, design, and deliver a customized hydraulic workover unit (HWU) solution to successfully change out a complex electrical submersible pump (ESP) completion on a TLWP with deck capacity and personnel restrictions is discussed. Using HWU for ESP changeouts from offshore production platforms would be considered a regular operation, but its application in a deepwater TLWP environment remains uncommon. According to Pollack et al. (2007), previous deepwater offshore operations on live wells have only been carried out in the Gulf of Mexico. To ensure technical feasibility for HWU installation and operation on a TLWP, the engineered customization of the HWU solution was required. This effort involved technical visits, structural studies, and a detailed analysis of the intervention scope to diagnose challenges and design a solution that met the economic objectives. The delivery of a customized HWU solution, tailored for the deepwater TLWP environment, enabled the successful changeout of an ESP well, which restored well production to 2,000 BOPD and achieved a 75% cost reduction compared to a conventional rig. To achieve this result in a challenging environment, the delivery of a customized design and installation of a modular and lightweight pulling unit that incorporates a hydraulic workover jack, load transfer system, skidding system, and temporary decks to enable the removal of tubulars from the wellbore was required. Operational challenges included blowout preventer (BOP) stabilization during adverse weather conditions while attempting an overpull requirement for unseating tubing hangers that exceeded HWU capacity. This situation was mitigated through the pre-planned integration of specialized equipment designed to provide a pull boost, which was successfully used to resolve the issue. The deployment of a HWU solution on a deepwater TLWP, to include problem diagnosis, solution design, and operational execution, is discussed in this case study. The objective is to establish a benchmark for similar operations and demonstrates the HWUs capability to deliver efficient and cost-effective interventions under difficult conditions with consistent operational efficiency.