RockForce slimhole bits achieve superior reliability through designs optimized for the smaller sizes.

Slimhole drilling uses a variety of directional drilling technologies that were previously cost-prohibitive or unavailable. Bit reliability during these operations is of extreme importance. NOV ReedHycalog RockForce bits, now in slimhole diameters, are providing greater reliability at higher run parameters than ever before.

Re-engineered from the ground up, the RockForce bearing system uses advanced machining techniques and lubrication technology to achieve record-setting performance.

Rock-Force slimhole bits also include additional technologies such as MudPick hydraulics, SuperTuff inserts, MatchFit insert retention, and Ventrite pressure compensation.
A field study of 149 61?8-in. 537 type bits in Oklahoma on directional and rotary applications showed R30A RockForce bits delivered seal effective rate 94% compared to 85% for the next best comparable bit with an 800 KRev life versus 528 KRev for the next best.

Another field study of 46 43?4-in. 517 bits in South Texas in directional motor applications at 200+ rpm showed that R22A RockForce inserts delivered 79% more average hours over similar models with 90% more average KRevs.

While extraordinary bit parameters may reduce bearing life, many of the parameters previously considered to be extreme are now the norm. RockForce reliability in slimhole roller cones commands a second look when selecting bits for deep slimhole applications.

Controlling fixed cutter torque and cutting costs

Controlling the torque response of a fixed cutter bit is widely regarded as one of the greatest challenges when drilling on a directional assembly. Aspects such as a torsional vibration and toolface control are closely related to the amount of torque generated by the bit. NOV ReedHycalog introduced a number of features within its SystemMatched directional products.

Two recent fixed cutter design innovations allow optimization of this torque.

SmoothTorque Torque Control Components (TCC) are flat-top polycrystalline diamond compact inserts strategically located in the center of the bit to prevent the cutting structure from taking excessive bite into the formation.

The company’s SmoothSteer Gauge’s use slightly tapered gauge geometry to reduce the resistance to tilt on a directional assembly without sacrificing gauge length of the bit.
To clearly demonstrate the reduced torque benefits provided by these features, a series of controlled tests was conducted in the Rockies of Western Canada. The testing included use of the company’s BlackBox dynamic recorder. The high-quality data recorded can be used to determine both the lateral and torsional stability of the assembly.

In this case it was used to evaluate the implementation of SmoothTorque TCC and SmoothSteer compared to a direct offset. The baseline fixed cutter (FC) offsets with conventional design produced severe stick-slip with a downhole bit rpm ranging between 0 and 385. Dull condition was poor with noticeable impact damage. Progessive implementation of TCCs demonstrated significantly less torque variation, excellent dull, and improved drilling efficiency.

Testing with BlackBox data analysis also included evaluation of SystemMatcher “recommended” FC bits. SystemMatcher software takes into account the specific tool characteristics and trajectory requirements along with bit design parameters including bit length, profile, gauge geometry, cutting structure, and side cutting capability. It produces a list of recommended bits and quantifies how each matches the requirements. For these field tests, system-matched bits with TCC and SmoothSteer features were compared to runs of insert bits on nearby baseline offsets. BlackBox data revealed smooth and constant torque while sliding with the SystemMatched FC bit, comparable to that achieved with the baseline roller cone bits.

Torque control is just one aspect of the directional drilling equation. NOV ReedHycalog’s directional solutions were derived from long-term, intensive interaction with directional tool suppliers and have led to the company’s constantly evolving understanding of the effect of drive characteristics, lithology, well trajectory, and bit design features on the four fundamental drillbit characteristics of rate of penetration, stability, durability, and steerability.

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