Surface Controlled Subsurface Safety Valves (SCSSV) are a critical component of well completions, preventing uncontrolled flow in the case of catastrophic damage to wellhead equipment. SCSSV’s are strategically positioned within the tubing string beneath the surface, or mudline in offshore scenarios. Their primary function is to automatically close and secure the well in the event of a catastrophic incident at the surface that poses a risk of severe damage or loss to the wellhead. These valves are governed by a slender steel control line, running externally from the surface down to the valve. In the unfortunate scenario where the wellhead sustains significant damage, leading to the rupture of the control line, the resulting loss of pressure prompts the valve to close, effectively sealing off the tubing. The image below show the actual SCSSV prepared for completion string.
There are primarily 2 designs for these valves: wireline retrievable and tubing retrievable. Wireline retrievable valves offer the advantage of extracting and servicing or replacing the major components of the valve (excluding the body) without the need to pull the entire tubing string from the well. On the other hand, the tubing retrievable model necessitates the removal of the tubing string from the well to gain access to the valve. These valves, often referred to as “flapper type,” can be secured in the open position using wireline tools. This facilitates access to the tubing string beneath the valve, enabling additional wireline operations as needed.
Surface Controlled Subsurface Safety Valves (SCSSV) can be called in different names ie Tubing Retrievable Valve (TRSV), Down Hole Safety Valve (DHSV), Sub Surface Safety Valve (SSSV). If you see these names, they are (SCSSV).
Cormack, D. (2007). An introduction to well control calculations for drilling operations. 1st ed. Texas: Springer.
Crumpton, H. (2010). Well Control for Completions and Interventions. 1st ed. Texas: Gulf Publishing.
Grace, R. (2003). Blowout and well control handbook [recurso electrónico]. 1st ed. Paises Bajos: Gulf Professional Pub.