New Cutter Technology for Faster Drilling in Hard/Abrasive Formations

Abstract

Drilling the hard, abrasive and interbedded Travis Peak and Cotton Valley formations in East Texas creates a difficult challenge for polycrystalline diamond compact (PDC) bits. Historically, conventional PDC cutting elements dulled quickly due to abrasive wear, impact damage and thermal fatigue. Thus, cutter technology has been the limiting factor for efficient PDC bit drilling in the East Texas Basin.Recent technological developments have produced a new, highly abrasion resistant cutter that has increased rate of penetration (ROP) and total footage drilled in addition to producing better dull grades. Further, the sections that normally require two/three PDC bits can now be drilled in one fast PDC bit run. The new cutter technology is designed and manufactured utilizing an innovative process which delivers superior properties both in laboratory testing and field trials. The manufacturing process involves a two-step high pressure/high temperature (HPHT) technique. The first step is to make a polycrystalline diamond table (PCD) using conventional HPHT parameters. The second step is to re-attach the PCD synthetic diamond wafer on a new tungsten carbide (WC) substrate under extreme HPHT parameters. The advantages of this method compared to the conventional one-step process are as follows:1. The residual stress in the PCD table is reduced by the additional second process 2. The two-step HTHP process increases the microstructure strength of the PCD Laboratory tests have indicated the new type of PDC cutter has increased resistance to abrasive wear and thermal fatigue by approximately 100% over standard PDC cutters while not compromising impact resistance. Extensive field tests in the East Texas Basin have documented that drilling efficiency could be improved by 20% in the hard/abrasive application. The cutters are expected to have a positive economic impact on other hard/abrasive applications worldwide.

Working characteristics research on the impacting–cutting hybrid bit

“…Nevertheless, due to its structural characteristics, it is usually difficult for the hammer bit to discharge rock debris; moreover, the rock-breaking mode of the bit makes the teeth wear easily or even fracture and fall off the bit body, which is harmful to an efficient drilling process. [5][6][7][8][9][10] The rotary cutting elements in the hybrid bit impact, break, and scrape the rock in a rotating manner, which has the advantages of high breaking efficiency, high ROP, and better kinetic performance; moreover, the structure of the bit bearing is improved to ensure increased rock-breaking efficiency while increasing bit life; different hybrid structure in the hybrid bit can achieve high center rock-breaking performance, high ROP, and fine gauge protection effect. 11,12 Aiming at solving the problems existing in PDC bits and hammer bits, the authors of this article put forward a cutting-percussion hybrid bit to improve the ROP of bit drilling in poor-drillability formation.…”