Pressure balanced Telescopic Riser Safety Joint

摘要

Safe operation is fundamental and a prerequisite for all subsea well operations including drilling,completion and well intervention. With an intensified demand for well interventions on mature and livewells globally, there is an increased need for improved system and component safety functions. It shallbe known which barriers are established and which function they are intended to fulfill. The pressurebalanced Telescopic Riser Safety Joint (TSJ) will become a critical safety element within these systemsand replace the traditional Weak Link(s). The TSJ can be configured in a drilling- or workover risersystem and is designed to increase the safety and operating envelope of well interventions and drillingoperations in the case of unintended operational event. There is no overloading due to accidental excessivetop tension, while containing well bore fluids, solving the following fundamental risk elements; 1)Protection of well barriers 2) Protection of rig and personnel and 3) Protection of environment. This newlydeveloped TSJ is the first system which significantly reduces operational risk from severe accidents dueto loss of rig station-keeping or top compensator lock-up. The TSJ enables an automatic overloadprotection system based on the following functions; Tensile bolts with predefined capacity control theactivation. In an accidental event, the bolts get overloaded (rupture) and the TSJ starts telescoping whilemaintain pressure balance. The telescopic length is longer than the rig heave movements to avoid riserseparation. The TSJ will also prevent spill to sea after activation. It includes a bore membrane separatingclean hydraulic control fluid from dirty bore fluid for pressure compensation. Once the Safety Joint isactivated as a result of excessive top tension, it will provide sufficient time to safely shut in the well andperform a controlled riser disconnect. The Safety Joint can be instrumented and included in a SafetyInstrumented Systems (SIS). A full scale workover riser prototype has been built and tested to validate thefundamental principles. This paper provides an overview of the development and testing performed on thepressure balanced Telescopic Safety Joint.