Downhole tool expert helps with fishing expedition

Paul Boughton

Advanced technology from specialist downhole tool provider, Peak Well Systems, has been instrumental in successfully fishing a parted tubing retrievable safety valve lockout tool for a major oil company in a Southern North Sea well. The Downhole Safety Valve (DHSV) is a vital component on the completion that will isolate the surface from wellbore fluids in the event of an emergency. 

A fishing package including a high-strength, high-temperature magnet and retrievable overshot performed a text-book recovery of the safety valve lockout tool, which had parted downhole in the safety valve at 534 ft well depth. Video footage established that the ‘bean can’ mechanism (part of the safety valve lockout tool that keeps the flapper permanently in open position) had successfully locked out the DHSV. The sub-assembly housing on the bean can had fallen and was expected to be sitting in the 3.688” nipple at 8,155ft.

To complicate matters, it was identified that the actuation dog of the lockout tool might hinder the retrieval of the housing by sitting across the top of the fish, thus preventing retrieval with a spear.

In response to the situation, Peak worked in close collaboration with the operator, providing technical support and discussing all the fishing options. Peak provided layout drawings for various overshots and spears, operational procedures, rapid manufacture and delivery of the fishing tools to Great Yarmouth.

For one contingency, a gauge cutter was heavily modified to act as a sweeping tool for the actuation dog. In the event that it was needed, the gauge cutter would be rotated around the top of the sub assembly by an indexing tool and would push the actuation dog back into the sub assembly. A high-strength, high-temperature magnet was supplied for retrieval of the actuation dog and a 2.720” releasable spear for retrieval of the sub assembly.

Steve Moir, technical sales manager, commented: “Our close collaboration with the client resulted in the fishing operation going exactly to plan. The magnet picked up the actuation dog and the releasable overshot speared the inner spring mandrel on the first attempt and pulled the fish to surface. The operator was delighted with the successful outcome.” 

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