Synergy Leads to Bit Innovations

Feb. 20, 2006
Maybe it’s a better understanding of rock mechanics and hydraulics. Maybe it’s material science and manufacturing innovations.

Maybe it’s a better understanding of rock mechanics and hydraulics. Maybe it’s material science and manufacturing innovations. More likely it’s just natural evolution or synergy at work. In either case, a marriage between roller cone and diamond technology has led to a new generation of drill bits that carry genes from both parents, combining elements of roller cone and PDC on the same bit. Today, many drill bits utilize technology between the two disciplines to optimize bit performance and attributes.

Ongoing research and development (R&D) efforts by major bit manufacturers continues to yield advances in bit performance while re-establishing material standards for the entire industry. Significant new materials have directly improved bit life, durability, ROP and allowed greater WOB.

Fixed Cutter Advancements

Improvements in the cutting elements themselves have been a catalyst for fixed cutter advancements. As mentioned, tougher, more abrasion resistant and thermally stable PDC cutters have expanded the application range for PDC bits into much harder, abrasive formations. Most major bit manufacturers have their version of these new cutters. PDC-cutter development reached a new level when it was shown impact resistance does not have to be compromised to gain abrasion resistance. Technologies continue to be developed that enable both impact and abrasion resistances to be maximized.

ReedHycalog has a new class of synthetic diamond TReX® cutters on the leading edge of the diamond table. As the TReX cutter wears, an ultra wearresistant, thermostable layer forms a distinct lip that increases contact stress at the rock interface, providing typically 30% more rate of penetration than a premium PDC cutter bit. New fixed cutter designs benefit from significant material advances that keep the bit sharper, longer.

More than two years ago, Hughes Christensen introduced new cutter technology with Genesis® PDC bits that combined comprehensive research in diamond interface design, diamond table thickness, and diamond edge geometry. The result has been an entire series of Genesis XT, HCM, HCR and other bit types with new cutter technology and design, better hydraulics, and improved bit stability for enhanced performance in diverse applications.

Smith Bits has developed innovative high operating temperature (HOT) cutters to provide a significant increase in cutter wear resistance. They are reportedly very cost-effective in applications where cutter wear rates are excessive.

Security DBS has a new line of Z3® PDC cutters that offer a step change in abrasion resistance without sacrificing impact resistance. They also deliver a third dimension of performance with Thermal Mechanical Integrity (TMI) qualified PDC cutters to handle extreme heat situations such as hard rock drilling.

Roller Cone Advancements

The development of tungsten carbide materials to improve roller cone bit performance in specific applications is also noteworthy. Carbide shapes, grades and composition are constantly being fine tuned and changing dramatically. Work with coarse-grain carbides has resulted in a wide range of proprietary carbide grades that combat heat checking and insert breakage that occurs as a result of thermal damage. The various grades of coarse-grain tungsten carbide particles provide extreme toughness and impact resistance, while withstanding high operating temperatures without thermal damage. These new carbide shapes and grades are increasing TCI bit ROP and life so bits drill longer without suffering catastrophic damage.

Hughes Christensen ZX PDC bits provide greater durability without sacrificing ROP when drilling hard and abrasive formations.
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There is also more use of diamond inserts, trimmers, and gage protection on roller cone bits. New generation elastomer seals and metal face seals are additionally extending seal and bearing life in high RPM and load applications. On a further note, materials research has extended the evolution of hard facing technologies for the protection of roller cone bits and milled tooth bits. Unique hard facing formulations and deposition techniques are being developed to increase the wear resistance and durability of existing hard facing materials.