TRSSSV
A Tubing-Retrievable Surface-Controlled Subsurface Safety Valve (TRSSSV or TR-SCSSSV) is a critical downhole safety device installed as an integral part of the production tubing string. Its primary function is to provide emergency well shut-in capability in the event of surface equipment failure, loss of well control, or damage to the production facilities. By automatically closing when control pressure is lost, the valve prevents uncontrolled flow of hydrocarbons to the surface, thereby protecting personnel, equipment, and the environment.
Its primary function is to provide emergency well shut-in capability in the event of surface equipment failure, loss of well control, or damage to the production facilities.
The TRSSSV is operated hydraulically from the surface. Under normal producing conditions, hydraulic control pressure is transmitted through a small-diameter control line attached to the outside of the production tubing. This pressure overcomes the spring force inside the valve and keeps it in the open position. If hydraulic pressure is intentionally bled off or accidentally lost (e.g., due to fire, line rupture, or emergency shutdown), the internal spring forces the valve to fail-safe closed, isolating the wellbore.
Structurally, the TRSSSV contains several key components such as a flapper or ball closure mechanism, a spring package, hydraulic control chamber, and flow tube. During normal operation, the flow tube pushes the flapper or ball into the open position. When control pressure is removed, the flow tube retracts, allowing the flapper to swing shut and form a high-integrity seal against the seat.
TRSSSVs are installed at depths typically ranging from 150 to 300 meters (or deeper depending on regulatory requirements). They are designed to withstand high pressures, corrosive environments, and rapid pressure-transient events. Various materials and elastomers are selected based on reservoir conditions such as temperature, CO₂/H₂S content, and production fluid composition.
WRSSSV
Because TRSSSVs are tubing-retrievable, major servicing or repairs generally require pulling the entire tubing string. For this reason, some wells also include a secondary wireline-retrievable safety valve (WRSSSV) that can be installed inside the TRSSSV in case of malfunction.
Summary
In summary, the TRSSSV is a fail-safe, surface-controlled downhole safety device that plays a vital role in well integrity, regulatory compliance, and overall safety of production operations.
