DepthStar Surface Controlled Subsurface Safety Valve - Dexter Magnetic Technologies - #1

Technical Paper

The Problem — How Can the Industry Continue to Meet the Equipment Demands Imposed by the New Areas into which Development is Venturing?

The Answer — Be proactive! How? Develop new concepts instead of trying to stretch the limits of the old ones!

This idea has recently been used to solve the problems that have plagued the industry with tubing-retrievable safety valve (TRSV) performance as development has ventured into deep-water environments. The DepthStar™ is an example of this approach.

Although TRSV performance has been improved drastically over the last decade, development into deeper and more corrosive offshore environments has continued to push TRSVs to their limits. An example of the additional concerns that have surfaced for deep-set applications is the higher valve opening pressures required. Conventional solutions have focused on balancing the piston area, which called for additional seals and/or gas-charged chambers. To maintain reliability, these solutions depend heavily on elastomeric seals and/or the permanent, long-term containment of a dome charge or pressure counterbalance. Unfortunately, when designing for life-of-the-well reliability, dynamic elastomeric seals pose a major limitation.

In a revolutionary TRSV design, a floating-magnetic-coupler mechanism is used to position the hydraulic actuator in a dedicated chamber isolated from contact with well fluids and pressure. By separating the hydraulic actuator from the tubing wellbore, this valve

► is the first in the industry to have 100% metal-to-metal (MTM) sealing with no moving seals within the tubing wellbore,

► does not need high-pressure operating equipment since the low hydraulic operating pressure of the valve simplifies the complexity of the pressure source equipment,

► could completely eliminate high-pressure equipment and associated umbilical line, (often more expensive than the TRSV),

► increases the life of the well and environmental and personnel safety while reducing system costs and sealing requirements.

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