Offshore staff

HOUSTON -- A drastic reduction in wellbore vibration is possible with a sturdy new expandable reamer called GaugePro XPR, which can be used in the BHA to ream the borehole while drilling.

The Hughes Christensen tool was designed to solve many of the chronic reamer problems faced by the industry such as complexity, activation, downhole failures and vibration/stability dysfunction, the company says.

"After evaluating other reamers in the marketplace and talking to operators about their experiences with them, our design team was determined to engineer a tool that would remain closed until triggered, open on command, ream an in-gauge hole, and then close and come out of the hole properly," says Steve Radford, GaugePro XPR project manager for Hughes Christensen.

Designed by a bit company, the expandable reamer has a balanced cutter profile that was tested and found to be equal to or to exceed the stability of a typical, same-diameter drill bit. The stabilization pads in the body of the tool immediately below the cutting structure further enhance this stability.

"These replaceable hard-faced pads eliminate the need to weld directly onto the tool body, preventing potential heat-affected-zone crack propagation found on other underreamers," Radford says.

The manufacturer conducted reaming and drilling tests through 27,500 ft of mixed formations in 20 wells at the Baker Hughes Experimental Test Area (BETA) near Tulsa, Oklahoma. Testing at other Baker Hughes laboratories included extreme torque, high axial load, stability, high temperature, erosion, and fatigue, which also proved the design's ruggedness and reliability.

The new 10 5/8 in. x 12 1/4 in. and 12 1/4 in. x 14 3/4 in. expandable reamers have already been deployed for use in deepwater and shelf areas of the Gulf of Mexico in 2008, as well as on land. The 14 1/2 in. x 17 1/2 in. and the 8 1/2 in. x 9 7/8 in. tools will be available in 2009.

One of the unique aspects of the tool is synchronization of the pilot bit and reamer to achieve a dramatic decrease in vibration.

A paper on the topic presented at the SPE showed that bit and reamer whirl and stick-slip vibration were isolated and reduced by 40-80% with increased WOB and ROP compared with industry-standard methods.

GaugePro XPR has roughly half the moving parts and seals, Radford says.

11/25/2008