Is it necessary to install a downhole safety valve in a subsea ... - NTNU
Is it necessary to install a downhole safety valve in a subsea ... - NTNU
Is it necessary to install a downhole safety valve in a subsea ... - NTNU
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Reliabil<strong>it</strong>y data dossier<br />
Component: Tub<strong>in</strong>g hanger seals, wellhead seal and cas<strong>in</strong>g hanger seals<br />
Failure rate<br />
(10 -6 /hours)<br />
Failure mode<br />
Data source/comment<br />
0.62 Leakage, EXL Reliabil<strong>it</strong>y of well completion<br />
equipment - Phase II p.18.<br />
Operational time 2403.71 years,<br />
failures 13.*<br />
Recommended values for calculations:<br />
Failure rate (10 -6 /hrs):<br />
EXL: 0.6<br />
Test<strong>in</strong>g and ma<strong>in</strong>tenance:<br />
The Tub<strong>in</strong>g hanger and cas<strong>in</strong>g hanger seals are never tested. Repair and replacement would require<br />
a well workover.<br />
Comments and leakage paths:<br />
The tub<strong>in</strong>g hanger failure rate is approximated <strong>to</strong> be identical <strong>to</strong> the cas<strong>in</strong>g hangers. The tub<strong>in</strong>g<br />
hanger is component tested <strong>in</strong> the “Reliabil<strong>it</strong>y of well completion equipment - Phase II”<br />
rapport. The leakage is though the seals at the cas<strong>in</strong>g/ tub<strong>in</strong>g hanger and <strong>in</strong><strong>to</strong> the annulus or<br />
wellhead.<br />
* The value does not <strong>in</strong>clude <strong><strong>in</strong>stall</strong>ation failures (i.e. failure occurr<strong>in</strong>g dur<strong>in</strong>g the first six days<br />
after <strong><strong>in</strong>stall</strong>ation).<br />
D-4
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