Furmanite develops specialist cutting equipment for Harriet Bravo well abandonment
Posted: 7 November 2005
Apache Energy needed to perform a well abandonment procedure on the Harriet Bravo platform --- cemented casing had to be cut and retrieved.
Furmanite, with its in-situ machining expertise and offshore industry experience, developed specialist equipment with purpose-designed features to meet the project requirements.
The procedure, undertaken on the Harriet Bravo platform on the Australian North West Shelf using the Ensco 106 offshore rig, required cemented 20 x 133/8 x 95/8 inch casing strings installed in the Harriet-B3 well to be cut, retrieved, and returned to the mainland to recover the platform slot.
No hotwork could be undertaken given the potential for trapped gas in the cement between the casing strings, so Furmanite used cold-cutting equipment. Specialist double trepanning drilling and casing cutting machines were deployed, driven by a purpose-developed intrinsically-safe hydraulic power pack for safe and efficient execution of the work. The drill unit was designed in two halves with a removable hinge pin so it could be split for easy installation onto the casing, and special heavy duty cutters were manufactured to drill through the cemented strings.
An operation by the Ensco rig crew saw drill pipes made up and run in hole (RIH) to 130 metres with an 8-inch casing cutter installed to cut through the three sizes of casing in a single operation. Furmanite technicians then began operations to cut and retrieve the casings in 12 metre lengths.
Furmanite’s hydraulically-operated 600kg double trepanning drill unit was used to drill 100mm holes through the casings to allow retaining pins to be installed. The drill unit was clamped around the outside of the casing with the drills positioned at 180 degrees to each other, to ensure that the holes were drilled directly in line with each other to allow the lifting pin to be fitted. The pin was then installed to hold the two different sized casings together and allow the cut casings to be lifted off the rig floor.
With the retaining pins in place the weight of the casing (approximately 6,000kg) was taken up by the rig’s hoisting system, and Furmanite’s 1,500kg cutting machine was installed and clamped around the outside of the 20 inch casing, to cut through the casing strings. In total six cutting procedures were carried out, to produce the required 12 metre sections to be separated and retrieved.
The project was successfully completed over six days.
Commenting on the work, Apache Energy senior drilling engineer Brett McIntyre said: “The Furmanite equipment and personnel performed very professionally. The operations were conducted safely and efficiently, cutting and handling the multiple cemented casing strings.”
David Arnold, Furmanite sales manager said: “This is a typical example of the way Furmanite is able to apply its experience, engineering expertise and technology to develop solutions to meet specific requirements. We offer a wide range of on-site and on-line services to the offshore oil and gas industry, geared to helping customers maximise asset uptime and keep their assets earning efficiently.”
For more information see www.furmanite.com
Posted by Richard Price, Editor, EnergyME.com
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