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A/S Norske Shell needed to carry out tubing hanger crown plug (THCP) removal from a riserless light well intervention (RLWI) vessel in the Norwegian sector of the North Sea. There were concerns that the conventional application of mechanical jarring with slickline tools could not be used due to the combination of deep water and high sea currents in the specific field. A safer, more controlled and assured method was needed to withstand this extreme environment and provide the certainty of task success. Theoretical studies and practical testing were conducted at the supplier's test site to verify the impact sea current had on cables and toolstring assemblies. Different scenarios were analysed and the most effective and lowest cost solution was determined. An electric line deployed and powered electrohydraulic stroker device was selected, which did not require any cable actuation to generate the pull forces required to unseat the crown plug. Toolstring space-out was critical to ensure the stroker anchor was above and clear of the well control package (WCP) and positioned to prevent any inadvertent damage to the lubricator. In addition, a release tool and a shearable stem provided back-up safety capability for well control. A modification to an existing stroker was designed and a prototype built and tested at the onshore facility. The final stroker toolstring design was tested out successfully on a more benign shallow subsea well, where the highly accurate force and movement control of the stroker, coupled with real-time surface readout, enabled a safe and secure crown plug pulling and installation operation. The targeted operation in a deep-water, high-sea current environment was then carried out successfully, applying many lessons learned and process improvements from the trial well. In conclusion, the use of electrohydraulic stroker technology was proved to be a viable alternative for crown plug retrieval and setting operations, whilst bringing heightened visibility and control to such an operation.
A/S Norske Shell needed to carry out tubing hanger crown plug (THCP) removal from a riserless light well intervention (RLWI) vessel in the Norwegian sector of the North Sea. There were concerns that the conventional application of mechanical jarring with slickline tools could not be used due to the combination of deep water and high sea currents in the specific field. A safer, more controlled and assured method was needed to withstand this extreme environment and provide the certainty of task success. Theoretical studies and practical testing were conducted at the supplier's test site to verify the impact sea current had on cables and toolstring assemblies. Different scenarios were analysed and the most effective and lowest cost solution was determined. An electric line deployed and powered electrohydraulic stroker device was selected, which did not require any cable actuation to generate the pull forces required to unseat the crown plug. Toolstring space-out was critical to ensure the stroker anchor was above and clear of the well control package (WCP) and positioned to prevent any inadvertent damage to the lubricator. In addition, a release tool and a shearable stem provided back-up safety capability for well control. A modification to an existing stroker was designed and a prototype built and tested at the onshore facility. The final stroker toolstring design was tested out successfully on a more benign shallow subsea well, where the highly accurate force and movement control of the stroker, coupled with real-time surface readout, enabled a safe and secure crown plug pulling and installation operation. The targeted operation in a deep-water, high-sea current environment was then carried out successfully, applying many lessons learned and process improvements from the trial well. In conclusion, the use of electrohydraulic stroker technology was proved to be a viable alternative for crown plug retrieval and setting operations, whilst bringing heightened visibility and control to such an operation.
An operator required straddle related interventions to be carried out on one of their platforms in the North Sea, for both straddle retrieval and straddle deployment purposes. For these they were seeking innovative solutions to deliver more efficient and effective operations providing time and cost savings. The first operation described in the paper was a straddle packer deployment, which, done conventionally using coiled tubing, would have required nine runs to install the 100-meter assembly. This was due to the limited rig up height available. The second operation was to pull a shallow set straddle before setting a plug and punching the tubing as part of a plug and abandon operation. Here, scale had accumulated above the straddle which first needed to be removed to enable the removal of the straddle itself. For both operations, a solution was devised that overcame the challenges and inefficiencies of the more traditional methods, be that using coiled tubing or slickline. In the first (straddle packer deployment), an electric line tractor was used to aid in-well straddle assembly. The tractor's real-time tension/compression readings would provide accurate and controlled deployment and a precise measurement of the over-pull verification once set. The solution provided more rig up height, enabling surface assembly of spacer pipe sections, hence fewer runs for the full straddle system deployment. For the second (straddle packer retrieval), historically such scale removal would be performed by slickline broaching—a time consuming multi-run method. Instead, an electric line powered debris removal tool string was used, removing the scale in hours instead of days. Critical toolstring space-out through the blowout preventer (BOP) stack was managed. Furthermore, an electric line powered stroker was used to retrieve the straddle sections. The application of electric line based intervention technologies provided direct and indirect efficiencies. In the first operation, the electric line deployment of the straddle packer assembly was completed in only six runs compared to the nine runs required if coiled tubing was used, which delivered a time saving of almost two days. Pre-job simulations were carried out to optimise the deployment tool string design. During the second operation, the cleanout mill string, with collection chambers added purely to manage the string space out through the BOP stack, also provided better centralisation for the milling operation. With this operation occurring within the marine riser section, hydraulic oil specification was optimised for 1 °C operation. Advantages brought about through the use of electric line deployed powered mechanical tools were apparent in both operations. The depth resolution, coupled with the real-time surface read-out toolstring command—provided by electric line—enabled fast, precise and controlled operations, including delicate straddle tagging without risk of damage. Both operations were executed successfully.
Manipulation of downhole completion components such as formation isolation valves, inflow control valves and sliding sleeves has become a regular phase of both new well initiation and existing well production optimisation scope. This often occurs in deviated and extended reach well trajectories frequently involving mono-bore completions. Although primarily done by pressure activation, electric line deployment of linear actuators that engage with associated shifting profiles of such valves and sleeves offers a secondary means of manipulation, one that is often relied upon. Deployment of these devices through smaller ID restrictions located higher up in the completion string necessitates in-situ activated high expansion anchoring and shifting capabilities. The electric line powered tractor-stroker-shifting device toolstrings capable of high deviation conveyance coupled with precise and real-time controlled completion component manipulation are desired, providing visibility throughout the operation. Furthermore, sufficient force to cover not only the shifting specification of the valve or sleeve design but also to overcome sleeve seizing commonly encountered downhole from scale or debris infringement is necessary to maximise the certainty of these operations. The technology platform presented in this paper has been designed to provide conveyance, positioning, anchoring, and high bi-directional force and stroke generation in a slim tool architecture offering high expansion shifting capability. Its downhole logic for optimised electric and hydraulic power distribution and a high degree of instrumentation and sensors has brought reliable target search, device engagement and real-time operational visibility and control to completion manipulation operations. Extensive system integration tests done on replica valve sleeves using the full tractor-stroker-shifting device toolstring to confirm the functionality and effectiveness will be described in the paper. This has been done within a reconstructed horizontal completion configuration to confirm successful string conveyance, shifting dog engagement and stroker shifting action, collaborating toolstring sensor measurements with those incorporated in the test jig configuration. A single run multi-sleeve shifting operation carried out in the North Sea will also be described, with real-time surface readout information which allowed the engineer to better understand the in-situ situation and take immediate and controlled corrective actions, circumventing a false shift scenario due to sleeve seizing and delivering an efficient operation. The seamless integration and interaction between the tractor, stroker and shifting device that make up the full manipulation toolstring assembly presented in this paper are transformative. Tractor wheels are kept in an extended mode whilst setting the stroker anchors, aiding optimal centralisation of the toolstring throughout the stroker anchoring and manipulation sequence. This reduces the risk of the shifting dogs unlatching from the profile of the completion component being manipulated as is often the case with a sequential tool operation scenario—the intervention technology platform providing a true convey-position-inspect-act-verify ethos.
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