Shell Norway, Envirex AS – Technical Presentation – ICoTA Stavanger Well Intervention Seminar
Envirex has for years been a Shell Norway technology provider. One of Envirex focus areas has been to design and manufacture systems which enables an ROV to supply hydraulics and controls directly to X-mas Trees. The technology used has enabled operations to be performed without other downline supplies than what is is related to a ROV system. Topside WOCS/HPU systems and umbilicals is no longer needed. This reduces personnel onboard and deck space offshore. Time spend for mob/demob onboard is also reduced.
The ROV is equipped with a undercarriage skid containing hydraulic fluid reservoirs, pumps, motors, control valves and a electronic control system. Ther system is based on standardized components and interfaces, whereas one system can work on a variety of X-Mas Trees without rebuilds. The system can also be applied to a wider range of subsea services and activities such as X-Mas Tree installation and testing, retrieval, module replacements and testing, commissioning, tree cap installation/retrieval and testing.
On Ormen Lange B-6, October last year this system was applied when fault-finding on a 7” Dual Carriage self-equalizing TRSSSV assembly. From operations at Nyhamna it was reported they could not flow the well. All X-Mas Tree valves were apperently in working condition (operated via SCM and control system), as well as the TRSSSV’s. After discussions it was concluded that most likely something had happened in the well reservoir or one of the TRSSSV’s filed to open- A riser less Intervention was then planned using the Island Constructor intervention vessel. This was the deepest water well ever intervented in Norway (approx. 900 meter sea depth). Some vessel modifications were carried out as well as some down hole method changes.
The Envirex Octopoda RWOCS skid were quickly set up with, among other things, high accuracy flow meter for the HP line supply.
X-Mas Tree where connected to the RWOCS skid to the XMT MQC plate with hydraulic jumpers(HFL’s), further the ROV valves were manipulated enabling isolation of the SCM and Tree control system – enabling direct control of both upper and lower TRSSSV. The TRSSSV’s where operated from the RWOCS skid, one by one and control fluids were accurately logged. It turned out that both valves were in good operating condition (i.e amount of flow corresponded to what was logges when well was completed). These trials further confirmed that the problem in the well were situated in reservoir.
Next the Upper/Lower crown plugs were pulled (Horizontal XMT) and a toolstring with camera was ran. HUD was reached approx. 80 meter above the TRSSSV assembly. The camera pictures confirmed a colomn of produced sand.
Further operations were aborted and well was left as is.
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