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Dart-activated disconnect sub takes new approach to stuck pipe

By Linda Hsieh, Managing Editor

The HyPR HoleSaver provides a clean cut, which can be beneficial for the operator if it decides to reenter the wellbore with a secondary fishing assembly to pull it out. The operator also may decide to go around it with an immediate sidetrack. Churchill Drilling Tools offers two darts to accommodate both actions.

Churchill Drilling Tools has launched the HyPR HoleSaver, a full-strength disconnect sub, at the 2015 Offshore Europe in Aberdeen, UK. In May, the company invited more than 30 engineers from operator and service companies to witness the tool’s first full rig test, also in Aberdeen. The full-strength sub was cut in just 112 minutes, said Mike Churchill, Director for Churchill Drilling Tools.

When stuck pipe occurs, the HyPR dart can be pumped down to activate the sub, directing a milling jet at velocities of more than 300 ft/sec to make the cut. The darts are capable of producing more than 1,000 hydraulic horsepower, but require no special handling.

“Conventionally they would deploy explosives,” Mr Churchill said, noting that the time required to mobilize explosives and associated specialist personnel could be significant depending on location of the rig. “Whereas with these subs deployed in the string, if they do get stuck, they can pump one of those darts down. Within a couple of hours they could be free and begin the remedial action.”

Mr Churchill emphasized the full-strength aspect of the tool. “Any user’s first instinct must be that we’ve weakened it, that there is some weakness in it so we can break it, but that is not the case… There is absolutely nothing weak about the sub, and that is what we believe to be a first for this type of tool because it is a completely standard connection. We haven’t done anything to the tool in any way to compromise its integrity.”

Compared with explosives, which generates a very high energy for a very short period of time, the HyPR HoleSaver takes a different approach to stuck pipes. The force being generated “gradually works its way through the piece of metal and pulls it free. We’re doing a very strong force for a reasonably significant period of time versus an explosive force for an instant,” he said.

Since the first rig test in May, the company has seen growing interest from operators in the US Gulf of Mexico, Mr Churchill said. It’s already been run in the North Sea by three operators. “We’ve only had it available for a month or two, so I think this is a really exciting start. Some operators are experiencing quite a big cost risk for getting stuck, and this potentially can save them a lot of time and money.”

HyPR and HoleSaver are trademarked terms of Churchill Drilling Tools.

Click here to view a demonstration of the HyPR HoleSaver.

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