For drill bit manufacturers, a new normal in drilling practices is something of a “Catch-22.” Drill bits equipped with the latest in technology are drilling further, faster, and with more precision, but in the past, completing a section with one drill bit was considered a decent goal. Today, expectations have moved even higher. Operators are asking for bits that can complete the section in half the time at rates of penetration (ROP) maintaining, on average, 30.5 m/hr (100 ft/hr). The need for pure product toughness combined with newer requirements for meeting the objective at consistently high rates of ROP has led to a transformation in product design.

In revisiting the further, faster, and more precise model, it is understood that there must be some sort of give and take in design components. Increased durability features can adversely affect speed and agility and vice versa. The challenge in the producers’ corner is to find the sweet spot in this tradeoff in directional responsiveness, longevity, and speed.

Varel International has adapted to this challenge by adding a new Navigator PDC drill bit to its product line, providing a bit ready to meet the new normal in drilling parameters through advanced bit design.

This post-run evaluation image shows the 8? -in. VM716P Navigator bit after completing more than a mile of drilling with an average ROP of 79 m/hr (260 ft/hr). (Image courtesy of Varel International)

Cooke County success

An operator requested a drill bit that was capable of meeting the demanding revolutions per minute (rpm) requirements in an application in Cooke County, Texas. The energy inputs for this specific operator exceeded 180-200 rpm.

According to the Varel field engineer, bits in this area are required to meet the “new normal” expectations of drilling at extremely high energy levels. Designers first evaluated a six-blade design that previously had been used in the area. This proven platform had been successfully deployed to address these increased rpm demands when ROP is the primary concern. However, engineers knew intuitively that the 13-mm cutters did not sustain enough diamond volume to complete the objective.

To add durability and increase diamond volume, an additional blade was added to the design along with premium 16-mm cutters. This design added stability features through cone and profile refinements, resulting in an entirely distinct 8? -in. VM716P Navigator PDC bit design.

In two separate runs, the seven-bladed PDC bit has drilled more than a mile of footage in a 24-hour period. According to post-run reports, the bits were still drilling at a solid ROP of more than 30.5 m/hr when pulled.

On the first run report, the bit drilled more than the operator’s normal depth and required holding a greater than normal deviation of 11.4 degrees. The bit drilled 1,822 m (5,976 ft) in just over 27 hours for an average ROP of 75 m/hr (247 ft/hr). The closest comparison drilled 183 m (600 ft) less with an average ROP of 30 m/hr (98 ft/hr), a difference of more than 250%.

On the second run report, a VM716P design in the same area again drilled past the operator’s normal depth. This was accomplished while also holding a larger tangent of 10 degrees compared to competitive performances. The bit drilled approximately 1,800 m (5,900 ft) in 22.75 hours for an average ROP of 79 m/hr (260 ft/hr). In this case as well, the closest competitive offset came up short, drilling only 255 m (837 ft) with an average ROP of 60 m/hr (197 ft/hr).

To date, this new design has been used on multiple operations and is considered the top performer in the area due to depth, ROP, and tangent achievements.