What are the subsurface devices designed to prevent an uncontrolled release of hydrocarbons from the well if something catastrophic occurs at surface?

• A. Subsurface safety valves
• B. Surface safety valves
• C. Blowout preventers
• D. Chokes

Answer: (A)

Subsurface safety valves act as the downhole barrier that can shut off flow in the well if surface equipment fails or a problem occurs at the surface. Installed in the tubing, they close to isolate hydrocarbons from reaching the surface, providing a last line of defense against an uncontrolled release.

Surface safety valves sit at the surface, so they’re not the subsurface device in question. Blowout preventers are critical for preventing kicks during drilling and are part of surface or subsea well-control systems, not the downhole barrier meant specifically for catastrophic surface events. Chokes simply restrict flow to control speed, not seal off the well.