The Development and Field Introduction of a Subsea Wellhead Connector for Intervention Operations

Abstract

Subsea operations in general, attract significant expense; from the requirement of a multi-disciplinary team, through to the logistics of equipment and service conveyance in a harsh offshore enviroment. Costs are typically recovered through the reservoir production potential value over a number of years – this is not the case in abandonment operations. Upon cessation of production, the cost of abandonment is absorbed as a liability; as such the focus on cost efficiency is stringent and acute. It is however an area where the adoption of new and novel technology, allied to an alternative approach to service vessel selected and campaign structure, can achieve significant cost savings.

This paper describes the development of a subsea wellhead connector intended for use in well abandonment operations, in rigless decommissioning projects conducted in the UK Continental Shelf. It presents one of alternative rigless approaches to field decommissioning, and through collaboration with operators, cost effective equipment is developed reactively to meet their operational requirements. Deviating from a Jack up/MODU based rig campaign to a Monohull based campaign has shown savings can be achieved through a significant reduction in vessel day rates and personnel costs. The requirement of rigless abandonment technologies and equipment is growing as the market adopts rigless abandonment; as such, collaboration is required to align equipment with operators requirements.

The development of the Subsea Wellhead Connector (SWC) was undertaken and delivered in 29 days, with design, application, fabrication, and commissioning expedited to meet an aggressive operations schedule. A dedicated project team allied to robust internal engineering and testing programs, facilitated the delivery and leveraged over twenty years of lessons learned in subsea operations. The SWC is intended for Intervention and well abandonment operations, including: conveyance for mechanical and abrasive cutting, wellbore communication and testing, subsea tree (XT) installation, and well barrier verification, and wellhead retrieval.

The SWC has now undertaken five campaigns in the first six months since its market entry, and displayed that collaboration and the pooling of creative talent, can provide tangible and discernible benefits to the stakeholders involved.