South Morecambe well structures safely extracted

March 17, 2010
InterAct has completed the abandonment of an `observation’ well in the East Irish Sea for Centrica Hydrocarbon Resources.

Offshore staff

NORWICH -- InterAct has completed the abandonment of an `observation’ well in the East Irish Sea for Centrica Hydrocarbon Resources.

Well 110/2-7 was drilled in 1983 and was used to monitor temperatures and pressures in the South Morecambe gas field. The well was enclosed within a bathymetric chamber to give divers periodic access to its various gauges. Later, the well was suspended and in 1999, part of the chamber was removed with the remainder left flooded.

According to InterAct, full abandonment a decade later raised various concerns. The well had been fitted with a surface tree and there were question marks over its condition after such a long period of immersion in seawater. Also, only limited design data were available on the chamber; the condition of the tubing in the well was uncertain; and three mandrel control lines extended into the completion string, potentially hampering efforts to seal the well correctly.

According to GM Stuart Wordsworth, InterAct responded by drawing up contingency measures to deal with problems that might arise offshore. Centrica Energy Upstream well engineer Roman Sitek adds: “Good planning and technical analysis provided us with diving and abandonment programs that were sufficiently detailed to include anticipated problems and appropriate mitigation measures, which minimized any ‘management of change’ requirements.”

The project was undertaken during December 2009 and January 2010. In addition to designing the abandonment program, InterAct assembled many of the services required and also supervised the offshore work with Centrica’s offshore drilling representative. Sister Acteon group companies Claxton, OIS, and 2H respectively provided tooling, marine procedures management, and riser analysis.

The well was killed and plugged from the Ensco 92 jackup, and the 65-metric ton (71.6-ton) bathymetric chamber and wellhead were extracted using a diving team working from a separate support vessel. Removed well equipment was despatched to Aberdeen for disposal.