in the industry, especially in deep well completions and completions with sand control, such as gravel pack or stand alone screens. FIVs are deployed to provide temporary isolation between the reservoir and the main wellbore section, typically to act as fluid loss prevention device or as a well control barrier while deploying the upper completion. Well-K1 is one of 6 gas wells drilled and completed in 2 high-pressured reservoirs in the Niger Delta, with reservoir pressures in the range of 9,300 – 9,400 psi.The reservoir section was drilled with a heavy mud weight of 14ppg POBM to provide the required overbalance. It was required to isolate the reservoir section while deploying the upper completions, therefore an FIV was incorporated into the lower sand face completions for the purpose of isolating the reservoir section.
This allowed the section above the closed and tested FIV to be displaced to a lighter completions brine of 9.23 ppg, prior to deploying the upper completions. The FIV successfully held a differential of 3,200 psi across it.Post well construction & prior to hooking up the well for production, an evaluation had to be made on the best well intervention method to use to actuate the closed FIV open, considering the well configuration and high pressures, especially because the hydraulic “tripsaver” option of opening the FIV was deactivated during well construction making the mechanical option the only means to access the reservoir. After due considerations, Coiled tubing (CT) was selected to deploy the FIV shifting tool to open the FIV.
Risk assessment during the planning stage of Well-KI revealed top technical risks to be managed such as:• ability to open FIV with high differential pressure across it, • possibility of mud solids settlement on the FIV shifting profile hindering access• Complexities due to simultaneous operations (SIMOPs) with an active rig in an adjacent slot on the same location.This paper presents the job design, the preparation process, HSE considerations, and challenges, in addition to lessons learnt while carrying out this successful CT intervention.
