How top hole drilling can put you ahead of project plan

Published 23.06.2016

If you were guaranteed to save 30 hours rig time by investing NOK 250.000 extra – would you do it? Well, someone did and they saved close to NOK 3 million. And got ahead of plan already after drilling the top hole.

Conquer the boulders

The boulders of the Barents Sea are famous for putting challenges to the ones drilling top holes. The big stones hiding in the ground just below the sea bed threatens to give every drilling crew a tough start drilling a new well. To conquer the Barents Sea, drillers must conquer the boulders and minimize their impact on the hole opener.

Vertical top hole

When a hole opener hits a boulder at full speed, the impact might cause small deviations in direction every time introducing an angle to the well path. If the driller reduces the RPM, he or she needs to compensate with more weight on the bit to contain penetration rates. It’s the weight on the bit that is essential, and the heavy Boulder Buster enables the driller to keep the neutral point low.

Also, when drilling through boulders, you risk them falling into the well and hit the hole opener. That can easily knock off cutters.

Target design

Clients operating in the Barents Sea look to overcome these challenges with new technology. After introducing the Boulder Buster, OWS has been able to join their clients in the fight against boulders.

  • The most eye-catching fact of the Boulder Buster is its size. The 28″ – 42″ hole opener provides the driller with eight extra tons on the bit. Then he is able to drill faster without risking the boulders to push the bit out of path thus creating an angle.
  • The cutter design is built to withstand the impact from stones falling into the well and hitting the hole opener. The cutters are protected and attached to the body with 10 high quality steel bolts, making them nearly impact proof.

Save time drilling

The Boulder Buster solves the aforementioned issues very well and improve top hoe drilling performance in several ways:

  • More weight on the right place makes you drill faster without deviation
  • The maximum running speed is nearly double the speed of conventional hole openers, thus giving the driller the opportunity to vary speed. Optimal speed increases efficiency.
  • The Boulder Buster drills straight, removing the need for time consuming reaming.
  • The one-piece design leaves you with only one removal of the master bushing. That saves one hour going in the hole and one hour going out.

Time limit

Our trust in the Boulder Busters is, well – rock solid. This is why we accepted a rather unusual term when providing the tool for a client recently. They planned to use 80 hours for the top hole with conventional hole opener. Could OWS guaranty that the Boulder Buster could do the job in 50 hours, the job was ours.

Not only did we accept the terms, but the Boulder Buster delivered the top hole in 37,8 hours. The difference in rig time is 42,2 hours.

Even with the rig costs of the current down cycle market, this shaved close to 3 mill. NOK off the well cost. Not bad for an extra investment on 250000 NOK .

The Boulder Buster is not the cheapest of the hole openers at the starting line of a project. But passing the finish line, it is second to none. It has proven its value during 330 top holes in the Barents Sea.

 > Read also: Hole openers: When your black gold is between a rock and a hard place

Topics: Drilling, Down Hole

By: Tor Helge Hestetun & Trond Inge Mitchell

Tor Helge and Trond Inge work as Sales & Project Engineers at Odfjell Well Services in Stavanger, and worked together on the ENI Boulder Buster project.

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