A New Innovative Approach for an Independent Protection Layer (IPL) in Offshore Piping Network

This paper details an additional Independent Layer of Protection (IPL) concept and innovative approach which can be applied to both existing unmanned oil offshore Well-Head Platforms (WHP) and new unmanned offshore WHP to be tied-in to existing Pipeline (PL) network. This IPL which can be installed as a second layer of protection between existing Hydraulic Emergency Shut Down (HESD) system and a Safety Integrity Level (SIL) rated High Integrity Protection System (HIPS), will provide protection against over-pressure scenarios in pipelines downstream of unmanned offshore WHP due to Electrical Submersible Pump's (ESP) deadhead pressure. A new IPL approach was developed for the installation of a new 2 out of 3 (2oo3) Pressure Indicator Transmitters (PIT) with a new independent Programmable Logic Controller (PLC) safety logic solver type, for improving adequacy, safety and integrity. This option utilizes power Circuit Breaker (CB) inside Automatic Frequency Drive (AFD) inlet circuit for ESP shutdown purpose. This IPL does not require extensive programming on the PLC, Remote Terminal Unit (RTU) and Supervisory Control and Data Acquisition (SCADA) and it also optimizes shutdown requirements with minimum cable layouts, conduits, cable trays, fittings, grounding and cable tray supports. Normally, safety within a minimum acceptable risk is the main concern for the transportation of product oil to onshore from unmanned offshore WHP to Tie-in Platform (TP) and then to Gas Oil Separation Plant (GOSP). This approach would overcome challenges for the protection of possible rupture scenarios in topside piping, pipelines, flowlines, and trunk lines due to overpressure from WHP with ESP. Traditionally, only two protection layers are provided, namely, HESD system which is considered as the first layer of protection and a SIL rated HIPS. HESD comprises of electronic transmitter on each flow arm (initiator), Safety PLC (logic solver) for offshore multi-well platform and SSV (Master valve) and export ZV as final elements and the HIPS system is considered as the second layer of protection. However, the risk of scenarios of over-pressures still existed.