A prolific gas-condensate well in the Caspian Sea was forced to shut in due to a leak in a premium connection of the 7 in. production tubing resulting in loss of well integrity. Immediate repair was required to re-establish production. An expandable tubing patch (solid expandable cased-hole liner) was selected to provide a high-pressure, gas-tight, and potentially long-term repair of the leak while minimizing the loss of wellbore internal diameter (ID). In a very short time frame, engineering teams successfully collaborated to design, manufacture, and qualify the expandable tubing patch to a V0 (zero-bubble acceptance criterion) test protocol.
The tubing patch was successfully installed without killing the well using a single downhole barrier and a snubbing unit. The well was returned to production in May 2007, and has been on continuous production without any evidence of a re-occurrence of the tubing leak. This paper will review the well engineering, design engineering, qualification testing, QA/QC, and operational installation planning. Close teamwork between the end user and the expandable provider resulted in the successful repair of the well and allowed the operator to progress the return of the well to service.
The Shah Deniz field, confirmed in 1999, is a giant high-pressure gas condensate field containing approximately 30 TCF of gas and a significant amount of condensate offshore Azerbaijan in the Caspian Sea (Figure 1). Shah Deniz Stage 1 sanctioned 12 wells with further development planned in the field with a life estimated to more than 30 years. Well conditions are near HPHT with a reservoir pressure of 12,500 psi at 20,000 ft (~6,100m) TVD and a static reservoir temperature of 212°F. Drilling and production occur from the Shah Deniz Alpha (SDA) platform in water depth ~330 ft (~100m) (Figure 2). Licensees and subsequent interests in the Shah Deniz Exploration, Development, and Production Sharing Agreement (EDPSA) include the following:
BP, operator - 25.5%
StatoilHydro - 25.5%
State Oil Company of the Azerbaijan Republic (SOCAR) - 10%
LUKoil - 10%
Nico - 10%
Total - 10%
TPAO - 9%
Wells producing from the Shah Deniz field are among the most prolific in BP's global portfolio. As such, the integrity of these wells is essential to the company's strategy for exporting gas from the Caspian Sea.