Deviation When Drilling Deep RC Holes

Back in 2011, Harley Hollier at Harlsan was approached by a customer regarding a problem they had drilling 360m deep Reverse Circulation holes.

Some of the holes had deviated more than 5 degrees off the intended azimuth when measured at the bottom of the hole. As the RC holes were to be used as pre-collars for much deeper diamond drilling they needed to be as accurate as possible.

While traditionally Dig-Out & Stabiliser Subs have been used to try and counter the problem of deviation in RC Drilling deep holes they have had mixed success.

Harley likes a challenge, he knew there must be a better way to get these holes back on target.

The Solution – Harlsan’s Spiral Stabilizer Sub

By using the precision manufacturing technology of a robot welder Harlsan created the Spiral Sub, an improved product that perfectly combines the benefits of a Dig-Out and Stabiliser Sub. The spiral arc hard facing tracks an exact curve around the body of the sub and it’s the precision of this curve that is the key to the Spiral Subs success.

There are various options when setting up a Spiral Sub on a drill string that will depend on a number of factors and specific drilling conditions. The experience Harlsan has had helping others drillers will be a valuable asset in helping you chose the correct set up.

Extensive operational testing shows that the Spiral Sub dramatically improves accuracy while significantly reducing drill string chatter. It has enabled many Harlsan customers to achieve drilling rates & accuracy that were otherwise unobtainable.

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