This paper presents the methodology and results from a major research project on well completion equipment reliability. Historical data were collected and analysed from a large number of installations represented by 17 participating oil companies.
The data were analysed using a purpose designed software package for reliability analysis (CERED). A standardized reliability data collection format was defined for the most critical items of downhole completions and implemented in this software package.
Generic and detailed reliability data are presented for entire completions as well as specific items, such as tubing, annulus safety systems, electrical submersible pumps and downhole permanent gauge systems. The paper also discusses the potential benefit of using reliability data as a decision basis, with consideration of limitations in data quality. The database established in this project represents nearly 800 completion equipment failures covering some 6600 well years of operation.
A separate database is established and maintained by SINTEF on Surface Controlled Subsurface Safety Valves (SCSSV). The paper also describes some long term trends in SCSSV reliability extracted from this database which now holds information on some 1400 failures. The latest update of this database was completed and reported in February 1992 as an integral part of the well completion study.
The cooperation with the participating oil companies and the major completion equipment manufacturers was instrumental in obtaining useful results in the study and is described in detail in the paper.