Knowing Subsurface Safety Valve- API14A
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<strong>Valve</strong>-System Considerations<br />
Since the 1980s, several oil and gas companies have collaborated on a major<br />
study of SCSSV reliability, including data from valve manufacturers and<br />
operating companies with offshore interests in Brazil, Denmark, The<br />
Netherlands, Norway and the UK. The study, originally undertaken by the<br />
Foundation for Scientific and Industrial Research at the Norwegian Institute of<br />
Technology (SINTEF) and currently managed by Wellmaster, remains the<br />
largest yet undertaken into subsurface safety-valve operational experience.<br />
Conclusions of the SINTEF report from 1989 have influenced safety-valve<br />
development in the years since. These conclusions include the following<br />
findings:<br />
• Tubing-retrievable safety valves are more reliable than slicklineretrievable<br />
valves.<br />
• Flapper valves are more reliable than ball valves.<br />
• Non-equalizing valves are more reliable than self-equalizing valves.<br />
• The need for routine functional testing to identify problems should be<br />
balanced against the risk of imposing conditions or damage during testing<br />
that affect the operation or reliability of safety valves.<br />
Charlie Chong/ Fion Zhang
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