Quad-D Dual-Diameter Drift and Drill Bits

Quad-D dual-diameter drift and drill bits fulfill the two requirements of borehole enlargement—drift and drill—and provide hole opening below installed casing or liner sections. The drillout capability eliminates the need for a trip after drilling out the cement and casing shoe. Available in both steel and matrix constructions, these polycrystalline diamond compact (PDC) bits achieve superior performance in vertical and directional applications for a variety of formations.

Diamond-enhanced inserts ensure hole integrity

Diamond-enhanced inserts and carbide hardfacing provide maximum durability for maintaining pilot hole diameter and ensure stability and hole integrity. Cutting elements are strategically placed to promote stable drilling behavior, and the formation-specific design optimizes drilling efficiency. Vibration is controlled by force- and mass-balancing, use of spiral blades and gauge, and Lo-Vibe depth-of-cut control inserts. Consequently, bit rotation is maintained about the true bit axis, ensuring accurate finished hole diameter and superior borehole quality.

Because the hydraulics on the pilot and reamer are designed to work together for efficient cuttings removal and cleaning, by balancing the requirements of the two sections, flow rates to the pilot can be reduced—minimizing any tendency to wash out the pilot gauge—while remaining adequate for the reamer section.

These technologies increase durability, reduce torque response, maintain tangents, and reduce sliding time.

Drift gauge protects cutting structure

When a Quad-D bit trips through casing, no part of the cutting structure comes in contact with the casing wall. This is achieved through the creation of a second gauge surface, the drift gauge. All cutters are strategically located inside the drift gauge surface, which is protected by tungsten carbide and diamond-enhanced inserts.

In addition, the placement of the bit's drift axis—with respect to the cutting structure of the pilot section—is engineered to maximize drilling efficiency in both drillout and drill-ahead modes. The Lo-Vibe inserts protect cutters from impact damage during casing drillout, prolonging the life of the bit and enabling it to drill a longer openhole interval.

Quick directional response improves steerability

The directional success of Quad-D dual-diameter bits is largely because of the improved bit stability. These bits fulfill the requirements of

• producing good borehole quality while building or dropping angle
• holding tangents
• following well trajectories in which conventional bicenter bits cannot be considered.

The compact size of Quad-D bits, along with spiral blades, a unique profile, and optimal gauge design, enables quick directional response, enhancing steerability.