With the growing directional drilling market and the huge diversity of drive types encompassing both rotary steerable systems (RSSs) and positive displacement motors, the need for drill bits designed specifically for these applications is becoming more and more critical to delivering optimized directional drilling performance. The drill bit design is only one factor, however. Fitting drill bits with the correct cutter technology to solve drilling challenges such as abrasive resistance, thermal resistance, or impact damage due to high torsional and lateral vibrations also is a critical part of providing a complete drill bit solutions package.

ReedHycalog’s Seeker Directional drill bit product line from NOV Downhole recognizes that a single drill bit design will not work for every drive type and well profile. Seeker drill bits, in conjunction with NOV Downhole’s advanced cutter technology, Helios Thermal Tough Cutters, have set multiple field records by outperforming similar bits in the same geological location. Seeker drill bits are designed to match the bit to the specific drive type, well profile, and lithology by using the most comprehensive range of products in the industry coupled with proprietary bit selection software.

Seeker drill bits in conjunction with the NOV Downhole advanced cutter technology have set multiple field records outperforming similar bits. (Image courtesy of NOV ReedHycalog)

Design features such as cutting structure, profile, bit length, and gauge geometry are customized to offer a system-matched approach derived from long-term, intensive interaction with directional tool suppliers in combination with an understanding of the performance limitations of various well profiles. Seeker bits are equipped with the company’s latest cutter technology. Since launching this new cutter technology, engineers have been able to significantly improve overall bit performance, in many cases enabling operators to reach total depth (TD) with one bit. Helios Thermal Tough Cutters have already set multiple records in the field, including 194% increase in the average footage drilled, 52% decrease in cost per foot, and more than 100% increase in ROP, providing dramatic savings to the customer.

Bit selection also is one of the areas that has become very critical to overall drilling performance. Assuring proper bit selection can be challenging with the variety of options in the market today. The various RSS and motor configurations have different drill bit requirements. However, with the large variation in characteris- tics of cutting structures, in combination with a diverse range of gauge lengths and geometries, how can a driller select what bit is suitable for which tool?

To ensure consistent and accurate matching of the drill bit to specific drive type and trajectory, NOV Downhole developed an interactive software tool for optimal bit selection. The ReedHycalog System-Matcher software incorporates logic regarding tool operation and trajectory requirement and assesses these against key characteristics of the drill bit including bit length, profile, gauge geometry, cutting structure, and side cutting capability. Combining this software with the correct cutters for the application will deliver enhanced performance.

Single trip advantages

With field results displaying improved dull condition, improved ROP, increased interval drilled, and lowered drilling costs, the NOV Downhole advanced cutter technology provides enhanced performance through the impact, abrasion, and thermal resistance found in ReedHycalog Helios Thermal Tough Cutters.

The 8½-in. Seeker bit with Helios cutters in combination with an RSS successfully drilled a main bore and three openhole sidetracks without pulling to surface for a total of 4,827 m (15,836 ft), which set a new field interval record in the Troll field. The formation was mainly Sognefjord, consisting of medium to coarse grained sand with hard calcite stringers. Improved directional control – requiring less steering forces than offsets – was reported. The Seeker bit displayed excellent durability, drilling the challenging interval and coming out in good condition ( 0-1-WT-N/S-X-I-ER/CT-TD).

The 8?-in. Seeker SKH716D coupled with Helios cutters achieved the top three drill-out to kickoff point (KOP) runs for an operator in Montague and Cooke counties in Texas. The formations drilled included the Caddo, Atoka, Upper Barnett, Forestburg, and Barnett, comprising limestone, sandstone, siltstone, conglomerate, and shale. The 8?-in. SKH716D was run on an NOV mud motor drilling an average interval of 1,957 m (6,421 ft) with an average ROP of 60.6 m/hr (198.9 ft/hr). Overall, when compared to its nearest offsets’ ROP, the Seeker bit showed a 20% improvement.