Permanent downhole gauge (PDG) systems have been installed in many oil and gas wells to date. These systems enable improved reservoir management and production optimisation. Currently, more complex downhole monitoring and control systems are being installed, in what is often called 'Intelligent Wells'. For all these systems reliability is a critical aspect. We have evaluated the performance of 952 pressure and temperature monitoring systems installed since 1987. It was found that the 5-year survival probability of these systems improved from 40% for systems installed in the period 87/88 to 75% for the period 91/92. As from 1992 no further improvements have been observed resulting in a 5-year survival probability of 69% for the period 1993-1998. Failure modes have been evaluated and could mostly be attributed to the downhole gauge and to the cable. Based upon these findings, recommendations have been made to achieve reliability improvements.
Reliability analysis of permanent downhole monitoring systems
1999
10 Seiten, 2 Quellen
Conference paper
English
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