ULTRAHIGH PRESSURE HYDROCUTTER CUTS KILL TIME FOR KUWAIT WELLS

A British manufacturer reports a dramatic reduction in time required to kill Kuwaiti oil wells.

Harben Systems Ltd., Salisbury, Wiltshire, says its ultrahigh pressure hydrocutting system has slashed to 4 hr the time required to remove damaged wellheads by severing the well's casing. Traditional cutting methods such as swab rigs pulling a sandline back and forth across the casing can require 5-10 days.

Confirmation of the effectiveness of hydrocutters comes from Pride Petroleum Services Inc., Houston.

About midmonth Pride began demobilizing seven swab rigs after Kuwait Petroleum Co. said it had decided not to renew a contract on the units.

Pride said, "High pressure water cutters have proven to be more efficient than swab rigs in cutting off wellheads."

So far, in a deal worth more than 650,000, cutting contractor Hytorc has bought four sets of the pipe cutting equipment from Harben, a member of the British Fittings Group.

HOW IT WORKS

Harben's hydrocutter uses a remote controlled Jet Edge high pressure system working at 36,000 psi and mounted on a steel track fixed around the pipe. Harben said the cutter simultaneously cuts through as many as six thicknesses of 1/2 inch steel pipe, often with concrete infill. Solid steel as thick as 12 in. has been cut.

The cutting ability of the jet stream is increased by addition of an abrasive, in this case garnet.

Once the damaged valve mechanism has been removed, leaving a clean cut section of pipe, the well is capped with a Killspool valve assembly or by stinging into the production pipe with a tapered plug and then killing the flow with mud.

Ultrahigh pressure water jetting is not new, Harben points out, but what made it a viable proposition in the capping of wells was design of the cutting head support track developed and manufactured by Harben in 5 days.

It consists of a circle of high tensile spring steel that can be opened for positioning around the pipe.

Once reclosed and with four centralizing clamps tightened, the track acts as a stable platform around which the hydraulically powered tractor unit, which supports the jet cutting head, can move.

Movement around the track, pressure selection, and water on/off are controlled remotely from a safe distance.

The pump producing the water pressure is a skid mounted Harben Jet Edge 536 intensifier powered by a 250 hp Cummins diesel engine.

Water is drawn from a bowser. Harben says the low flow rate of 4.75 gpm assures economical use of "good" water, a precious commodity in the desert.

Compressed air delivers the garnet abrasive to the cutting head.

Copyright 1990 Oil & Gas Journal. All Rights Reserved.