Abstract
This paper describes the successful application of a rigless well abandonment method that isolated the well's production interval using resin-based sealant, without cement and without latching a conventional subsea blowout preventer (BOP).
An offshore operator needed to permanently abandon a subsea well that had become uneconomic due to excessive sand production. Several subsea wellhead and downhole conditions would have made killing the well by conventional means difficult if not impossible. Wellhead fatigue and soil erosion around the wellhead meant that a conventional drilling BOP could not be used in the operation due to the equipment's weight. Fluids to kill the well and permanently seal the formation could only be pumped down the tubing, and an obstruction in the flow path would limit the injection rate. Typical wireline and coiled tubing intervention tooling and circulation could not be used. Cement and micro-cement have particles that could potentially bridge at the downhole obstruction, preventing it from sealing the formation.
Considering these factors, the operator and service provider designed, tested, obtained regulatory approval, and successfully implemented a rigless abandonment operation using a service vessel and well stimulation tool to inject resin-based sealant into the well to seal the formation and enable safe final abandonment and tree removal using a light intervention vessel. These results suggest that this method can potentially be used during abandonment of subsea wells with smaller trees and wellheads that have experienced fatigue.
