A major customer in the Norwegian North Sea was performing a plug-and-abandon operation and sought to reduce the number of runs needed as well as operational costs. The customer needed to displace the well from brine to water-based mud, drill and tag a newly set 200 m (656 ft) long cement plug at 1794 m (5,885 ft) measured depth (MD), and cut 9 ⅝-in. 53,5# P-110 casing at 932 m (3,057 ft) MD. With conventional technology, one dedicated run would be needed to displace the fluids and dress of the cement plug, and a second run to cut the casing. In a deepwater well, the costs of multiple run are constantly escalating.
Drawing on a prior relationship, Baker Hughes, a GE company (BHGE), proposed the use of the Perseus™ pump–through cutter for this application. Hydraulically operated and designed to cut a single string of casing on command, the Perseus cutter is ideal for plug and abandonment (P&A) or slot recovery jobs. The knives are dressed with METAL MUNCHER™ Advanced Milling Technology (AMT) carbide that provide the industry’s most durable, effective cutting and swarf control tungsten-carbide knives to cut or mill even the toughest steels.
The Perseus cutter was picked up and run in hole to above the cement plug. Taking advantage of the pump-through capability of the Perseus cutter, the well was displaced with 2500 lpm (660 gal/min) and 50 rpm. After the displacement job was performed, the cement plug was drilled from 1794 to 1806 m (5,885 to 5,925 ft) MD and weight tested to 10 tons. The string was pulled up to a cutting depth of 932 m (3,057 ft), and the casing was successfully cut in less than one minute.
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