An Innovative Approach to Well Intervention and Workover Operations on Platforms With Limited Structural Capacity

Abstract

The challenge faced when identifying and planning the requirement for intervention and workover operations on small platforms or single caissons is significant. Typically drilled via a jack up rig, there are limited opportunities to install hardware to the platform directly. With an increasing well stock reaching maturity, there is a requirement to perform operations at a reduced cost on wells with increasing deviation and complexity. This scenario would typically be addressed by a jack up rig being installed over the well site, or with a HWU (Hydraulic Workover Unit) being installed if there are capping beams/availability to install them. Each has its merits; however, they also have cost and safety implications respectively. To address the market of platforms with limited structural capacity, a new WHWOU (Wellhead Mounted Workover Unit) has been developed to facilitate intervention, workover and abandonment operations in a safe and efficient manner on platforms with structural limitations.

This paper describes the market challenges facing mature basins and assesses the opportunities arising to perform intervention and workover operations on the ageing well stock to stimulate well production. It also presents key design parameters driving the new technology, principally: Safety, Efficiency and Cost reductions. Each is achieved through lessons learned allied with a novel approach to the use of new technology. Operational flexibility facilitates wireline, coiled tubing, pumping and fishing operations for example to aid wellbore stimulation activities. It also facilitates heavy workover such as re-completion, re-perforation, and whipstock setting in preparation for multilateral well development. Plugging and Abandonment operations are achievable with section milling, primary isolation plug setting, and tubular recovery through the design.

The operational capability is supplemented by a flexible philosophy - deployment through appropriate well control equipment to the surface wellhead. Further, the ability to be installed on light beams or by cantilever beams from a lift barge or boat gives the end client numerous scenarios for a campaign and platform stock. The WHWOU will allow operators to successfully conduct operations on a wide range of platforms from single wells to downgraded structures with multiple well slots and active process facilities.