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Tool-Tech’s SS HPU technology is an attractive alternative to the all electric Sub Sea control system approach and can provide the same advantages for standard hydraulic systems.
All electric Sub Sea Control Systems have come as an addition to the traditional Electro Hydraulic systems. The main applications are deep water and very long distances to the surface installation. The advantages are umbilical cost reduction, zero control fluid discharge, fast response, etc.
A subsea hydraulic pump module has been developed by Tool-Tech AS and a test prototype was built and qualification tested for StatoilHydro in 2007/2008 through our subsidiary company, MultiControl Hydraulics AS. Tool-Tech AS has developed our Sub Sea pump module solution further and we are working on other core technology elements for complete subsea HPU solutions, high quality Sub Sea pressure regulator, subsea fluid condition instrumentation (with Hydac), filters, Sub Sea hydraulic fluid conditioning, including seawater removal from synthetic hydrocarbon-based hydraulic fluid (patent pending), bladder reservoirs, etc. Our Sub Sea hydraulic pump module and Sub Sea hydraulic pressure regulator can also be used in Hydraulic Pressure Intensifier solutions, typically on existing Sub Sea installations.
Tool-Tech AS believes that this technology will have a huge future potential for new Sub Sea installations, because it can reduce umbilical cost and is ideally suited for long distances between the surface controls and the Sub Sea installation. The technology can be used in upgrade projects for the Sub Sea aftermarket, where it can also improve performance of existing control system with regards to fast start-up of wells after shut-downs and Sub Sea hydraulic fluid conditioning.
A subsea HPU can be made fully redundant, so a failure does not interrupt production. The change out cost of a SS HPU in case of failure will be a small compared with change-out of an all electric Sub Sea X-mas tree with an actuator failure.
A Sub Sea HPU with a closed hydraulic system gives great freedom in the choice of hydraulic fluid as the control fluid is not released into the sea. With the Sub Sea HPU solution all valves are hydraulically operated. One aspect of the all electric approach is that although electrical actuators can be an alternative for Sub Sea use, electrical actuation of the down hole safety valve (SCSSV) is not reliable enough. With the all electric Sub Sea control system, there must still be a local hydraulic source for operating this valve hydraulically at the Sub Sea installation.
Tool-Tech AS has developed a Sub Sea hydraulic pressure regulator to be installed downstream of the accumulators. The output pressure from the accumulator module is adjusted to the operation pressure. When there is hydraulic consumption from actuation of valves, the system pressure falls to a level where the pressure regulator releases stored energy into the system. One big advantage with Tool-Tech’s Sub Sea Hydraulic Pump module is that we use a frequency controlled induction motor (AC motor) and when the pump is charging the hydraulic accumulators to store hydraulic energy, the hydraulic accumulator charging time can be adapted to the available electrical power. This is particularly important if the equipment is introduced on existing installations where availability of electrical power is limited.
The SS HPU can be replaced during regular operation with SCM replacements at the Sub Sea field, when an intervention vessel is mobilised anyway. X-mas trees with hydraulic actuators are field proven and very reliable. There is less experience with electrically operated X-mas trees and control system with Sub Sea electrical battery back-up. If there is a major problem with the actuators on a Horisontal X-mas tree, this can result in production loss and the tubing in the well must be recovered before the X-mas tree can be recovered to surface. Re-installation is equally expensive.
For more information regarding our solutions for Sub Sea hydraulic power generation, please contact Magne Rød, tel. +47 95784570 |