Ulterra Drilling Technologies and United Diamond have joined forces. The company is young, but their leadership and management have substantial drill bit and downhole tool experience. UlterraUnited is bringing to market fresh and renewed technology, ideas, and business processes to reduce drilling costs.

Stick-slip

In normal drilling conditions, polycrystalline diamond compact (PDC) bits can bore through formations with amazing speed and efficiency. However, PDC drill bits can lose depth of cut in harder, cemented lithologies. This means the PDC cutters must abrade the formation rather than cutting in shear, which slows rate of penetration (ROP) and substantially increases cutter wear.

As formation strength increases more weight on bit (WOB) is required to maintain efficient depths of cut. Increased WOB will often create stick-slip. When drilling these more difficult formations with aggressive PDC bits, the bit can momentarily stop turning until sufficient torque is developed to shear the rock. The drill string winds up as torsional energy is built up and stored in its length. Once the required torque is generated, the bit breaks free at rotational speeds much higher than normal. This violent action is called “stick-slip,” which eventually breaks down the integrity of the diamond inserts and results in cutter damage, bit failure, bottomhole assembly (BHA) component failure, and lost time.

Until now, eliminating stick-slip problems with PDC bits in difficult formations meant less WOB, less aggressive cutters, less efficient bit design features, or the use of roller cone bits.

In the field

TORKBUSTER has proven itself in a variety of formations all over the globe. While a relatively new technology, it is well into its development with over 2,100 runs since its conception in 2000. From the design of the impact mechanism, the internal fluid flow, assembly method, to the overall geometry of the housing, the entire tool has been fine-tuned to meet the drilling demands down hole. The compact length and design has minimal effect on BHA characteristics and has been very effective in rotary, directional, performance drilling, and rotary steerable applications.

Alberta drilling

Bonavista Petroleum drilled a directional well in Alberta’s Caroline field with a United Diamond UD513 steel-body PDC bit and Torkbuster. The 200-mm-diameter wellbore intersected Viking, Mannville, Glauconitic, Ostracod, Ellerslie, Basal Quartz, and Fernie formations. Although previous wells in this field required five bits to complete the interval, the United Diamond bit and Torkbuster drilled 10,007 ft (3,050 m) in a single run, saving the operator more than US $185,000.

Wyoming drilling

An operator was drilling wells in Fremont County, Wyoming at low ROP due to stick-slip conditions below 7,500 ft (2,286 m). When the operator coupled a 6.5-in. TorkBuster long hammer tool with the same bits it had used previously (16 mm, six-blade matrix), the instantaneous ROP increased 50-100% for most of the run. The operator was able to drill the bottom of the wells in two fewer days than normal.

Texas drilling

In Roberstson County, Texas, an operator drilled two vertical wells on the same lease with the same rig. An offset well required two PDC bits to drill a 6.5-in. hole through an interval from about 13,300 to 14,300 ft (4,055 to 4,360 m) depth with an average ROP of 8-10 ft/hr (2.4-3.0 m/hr). After switching to a United Diamond UD513 bit and TorkBuster on the second hole, the operator was able to drill 931 ft (284 m) at 17.7 ft/hr (5.4 m/hr) in a single run.

For more information, please visit www.ulterra.com.