Coiled Tubing Intervention for the Actuation of Reservoir Formation Isolation Valve in a High-Pressure Gas Well

Abstract

Abstract Well – K1 is one of 6 gas wells drilled and completed in an over-pressured gas reservoirs in-line with SPDC aspirations to leverage on the opportunities presented by deep and over-pressured gas plays in a bid to develop hydrocarbon reserves to meet existing gas supply commitments and growing domestic demands (driven by power and manufacturing sectors). The well sand-face completions incorporated a Formation Isolation Valve (FIV) which provided a temporary isolation of the high reservoir pressure (circa 9,400psi) allowing the safe deployment of the upper completions in a lower density fluid, thus creating a 3,200psi underbalance without the well flowing. Post well construction and prior to hooking up the well for production, an evaluation was made on the best well intervention method to actuate the closed FIV open, especially because the hydraulic "trip-saver" option of opening the FIV was deactivated during well construction making the mechanical option the only means. After due considerations of the well configuration, high reservoir and surface pressures, high differential pressure across the FIV and possibility of mud solids settlement on the FIV shifting profile hindering access, Coiled tubing (CT) was selected to deploy the FIV shifting tool to mechanically open the FIV. After many months of careful planning and preparation, the intervention was carried out successfully and the well tested to planned rate. This paper discusses the detailed job design and planning towards deployment of coiled tubing in a deep over-pressured well. Also highlighted are the key challenges and experiences gained which can be referred to as a benchmark for CT deployment in HPHT environment in the Niger delta.