Innovative Methodology to Riglessly Restore the Functionality of the Sub-Surface safety valves Sc-SSSV with Damaged Control Line

摘要

The company introduced a new era of Well Integrity Management system as a continuous assessment and verification process to ensure the integrity of the wells is designed, monitored and maintained throughout the well life cycle. Failure of any well barriers is not allowed. If a barrier fail , an immediate action should be taken to restore the well integrity, which is one of the important business elements in oil and gas fields; and hence according to well integrity standards utilizing well control devices are mandatory to protect human life, and reduce the potential for environmental pollution in addition to minimize the loss of production. The surface control subsurface safety valve (SC-SSSV) is an integral part of the overall safety system of any well and it is the only method that provides sub-surface isolation in case of emergency due to uncontrolled surface or sub-surface event. Therefore it is mandatory to have functional SC-SSSV installed in the production tubing in all gas and oil wells, irrespective of their location, to stop the flow in case of a catastrophic failure. The SC-SSSV is adjusted to be held in the open position by hydraulic positive pressure from surface. This pressure is applied through a control line in the tubing-casing annulus running from the valve to the surface. In case of an emergency shutdown the hydraulic pressure will be released forcing the safety valve to close. However the control lines could leak, plug or break leading to losing the functionality of the safety valves. The only way to rectify SC-SSSV C/L problems is by a rig work-over to replace with new C/L. This paper describes the innovative methodology, which is the first application in the UAE & Middle East, to install Baker Hughes system “Inject-safe” controlled sub-surface safety valve which has a similar operating philosophy to the conventional SC-SSSV. The “Inject-safe” C/L deployment is on the inside of the tubing which drastically reduces the cost. This unique approach has been successfully executed in one of the super giant onshore fields in Abu Dhabi through an extensive techno-economical study. The paper goes through the methodology of candidates’ selection, the system requirements and modification in wellhead and the trial results through specific testing criteria in one of the wells as part of a field pilot. The risk assessment is also discussed along with the execution process. The cost impact of installing the new system as proved in the pilot through a techno-economical evaluation well will be highlighted, in addition to well performance pre/post installation combined with the project conclusion and recommendation for future implementation.