NEW FRONTIERS IN PIPELINE PRESSURE ISOLATION - NON-INVASIVE, WITHOUT DE-PRESSURIZING, PRODUCTION LOSS OR FLOW INTERRUPTION

摘要

There are several methods for pressure isolating pipelines. Along with hot tapping and stopple and freeze plugging, there is another common method known as remote controlled (tether-less) pipeline plugging, whose use is increasing - both offshore and onshore.This paper will review piggable tether-less plugging technology, provided by TDW Offshore Services using the SmartPlug~(TM), and case histories whereby a bi-directionally piggable, remotely actuated (tether-less) plug is deployed to allow pipeline operators to perform repair work, modifications, or tie-ins on pipeline systems without interrupting production in the remaining part of the pipeline system, i.e., while operating live and at production pressure.Specifically this paper will address two new technologies: First, allowing high pressure isolation of thin wall pipe, and second, of spiral wound pipe, both without welding, tapping or leaving any trace of the fact that an isolation occurred.Some advantages of tether-less plugging technology are:1. Plugging tools have higher pressure containment capacity than other plugging methods, typically up to 3,000 psi.1. Bi-directionally piggable, able to negotiate as small as 1.5D bends, operated and monitored entirely via remote control (tether-less through-wall control and communication system).3. Compared to hot tapping, welding a fitting on the pipeline is not required, and no need to hot tap (drill) into the pipeline, no future leak path and no issues regarding cuttings or coupon.This latest frontier of pressure isolation allows for plugging tools that are fail-safe (the higher the differential pressure the harder they set) with zero leakage tolerance. They can be configured for job specific requirements such as double or single block, and can allow for hydrotesting the completed work.The most important advantage is that they eliminate the time needed and lost production cost of displacing pipeline product, flaring, depressurizing, emptying the line, and re-commissioning the line.In addition, specifically this paper will address the latest technology advances allowing high pressure isolation of thin wall (8mm/0.32 inch) spiral wound pipe using external pressure reinforcement clamps over the pressure isolation tool during an onshore project on a 24" methane gas pipeline.During the isolation, a portion of the upstream pipeline was removed and replaced while the entire pipeline downstream of the pressure isolation remained under full operating pressure, thus requiring no loss of production from downstream assets during the repair. Once complete the tools were released and pigged from the line, leaving no holes, no welds, no future leak path and no trace that any event occurred on the pipeline in that location.