As activity in the Eagle Ford shale play continues to increase, Varel International has ramped up its support for the operators in the area with new drill bit designs to meet specific applications. PDC designers and field engineers recently have introduced a new five-bladed Navigator series set of bits in the Eagle Ford with tremendous success. These designs are the new generation of Varel’s product line for directional applications.

The bits have been developed to address the challenges in the Eagle Ford play, including erosion, gauge wear, and most importantly, the need for both trajectory holding and directional responsiveness.

Steerability, directional behavior
Using proprietary design tools, engineers focused on making the bits extremely responsive to directional inputs while maintaining trajectory when drilling ahead. This is accomplished by combining a tightly balanced cutting structure with an aggressive side cutting capability. The bits also have combined features that minimize torque and torque variations while allowing for high rates of penetration.

The newly designed five-bladed Navigator bit was recently deployed in the Eagle Ford shale. The bit is shown post-run after drilling a total of 10,087 ft (3,075 m) and completing all directional objectives. (Image courtesy of Varel International)

The result is a product that builds angle as required, limits bit walk, holds trajectory in hole, and allows for smooth “in the zone” drill ahead in lateral sections.

The bits use Varel’s proprietary Vulcan class PDC cutters, combining high thermal abrasion resistance with impact resistance. These cutters hold up well to wear and impact, which is imperative with the heavy side load requirements encountered during the curve and lateral sections of Eagle Ford wells. This new technology has proven scalable to other bit diameters for Eagle Ford applications with comparable success.

Single-run performance
In a recent Eagle Ford well in Live Oak County, Texas, the operator’s goal was to complete the entire section with one drill bit. A key concern in meeting the goal was bit durability in light of the heavy side forces the bit would experience in the curve section of the well. A number of previous operations used steel-bodied products and saw premature gauge and shoulder wear due to the loads created by the directional requirements. The other key concern was the directional characteristics of the bit, both steerability and trajectory holding. These issues historically cost valuable rig time due to tripping and the replacement of drill bits and components.

Varel field engineers studied previous drilling logs in addition to extensive dull evaluation reviews. Using earlier iterations of Varel’s Navigator technology, the bits were modified to add shock studs to smooth out torque, upgraded with Vulcan class PDC cutters, and redesigned to incorporate “ultra-force balancing.”

Upon completing the upper section with a 12¼-in.Varel PDC bit, the 8.50 VM513H Navigator PDC bit was run in hole. The bit built the curve, held the tangent, and then made the lateral section without dropping.

The bit drilled 6,246 ft (1,904 m) to a depth of 11,986 ft (3,653 m), where the bottomhole assembly was modified per plan for a 200-hour motor change. Post-run evaluation graded the bit’s cutting structure at 1-1, and the bit was returned to the assembly to continue drilling.

With the completion of the run, the bit drilled a cumulative 10,087 ft (3,075 m) to a total depth of 15,827 ft (4,824 m). The run required very little correction other than limited corrections made at formation changes. After 101 hours of drilling and completing the section with an overall ROP of 37ft/hr (11.3 m/hr), the bit was graded 1-4-BT-G-X-I-TD and met the directional, durability, and ROP goals set out for the section.

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