Drill bit technology is in a continuous state of evolution. Many operators have experienced better performance in drilling operations by matching bit design to highly advanced bottomhole assemblies and using bits specifically designed to contend with specific types of formations, including improved cutter strength, hybrid combinations of roller cones and PDC technology, and more aggressive cutter profiles. With an improved capacity influencing bit selection, more options are leading to more efficient drilling projects.

When it comes to analysis, more rock equals more data. While coring provides optimal samples, the trips needed to acquire cores are not always considered the best investment, especially in tight markets such as unconventional gas. While MWD/LWD can assist drilling engineers in optimizing the trajectory of the well, geologists often are left out of the process with only a limited amount of information garnered from cuttings. Where PDC bits are used, these cuttings often are referred to as “rock flour.” While cuttings can provide a limited amount of reservoir data, larger samples are needed to provide more downhole data.

Encore Bits LLC currently is making headway with what is known as the Micro-Coring Bit. The new bit provides all the advantages of PDC capability, while allowing the generation of a micro-core of the formation being drilled in the center area of the bit where the cutting structure is interrupted. Conventional cores are acquired by running a standard coring bit, which requires an extra trip with no gains in ROP or total depth. By adding micro-coring capability to an engineered PDC bit, the coring process takes places automatically with each successive “plug” or micro-core circulated to surface through the annulus. Having a legitimate section of rock can open a wide range of information on downhole conditions throughout the entire well bore, giving geologists something to work with. The design allows for an improvement in cuttings quality, especially in hard rock environments where standard cutting sizes are reduced due to the low depth of cut achieved in these formations.

In addition to providing geologists with better rock samples at surface, the “No Center Bit Design” also saves a significant portion of the energy used in the bit’s cutting action. While this bit currently is being tested domestically, it already has shown the ability to generate larger rock fragments than conventional bits in Pakistan’s Lumshiwal sandstone. Coring operations soon might be carried out simultaneously with the drilling operation, reducing trips and nonproductive time in the process.

Drill bit design will continue to improve the speed at which fields are developed. Breaking down the barriers that exist between drilling productivity and reservoir characterization can only enhance the profitability of field operations.

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