While the emphasis in diamond bit technology has increasingly shifted toward PDC and TSP technology, two recent innovations, detailed in the paper, are directly applicable to the improvement of natural diamond bits.
Use of numerically controlled milling machines, in conjunction with computerized bit design, allows a reduction in the number of diamonds used on a bit, thus increasing penetration rates through increased diamond loading. The development and use of diamond coating techniques, which offers the possibility of improving the bit-to-matrix bond, allows increased diamond exposure on the face of the bit. When these enhanced bits are coupled with a medium speed, medium torque drilling motor, significant performance increases are realized.
The paper provides analysis of bit runs employing a significant number of enhanced diamond bits in a variety of sizes, hole intervals and well applications, primarily in western Oklahoma’s Red Fork formation, which is typically a medium to hard alternating sand/shale sequence. These runs are compared to more than 100 conventional natural diamond bit motor and rotary runs.
In addition, operating limitations and recommendations are outlined for the use of enhanced natural diamond bits, which is shown to have resulted in savings of two to three days per well versus conventional diamond bit motor applications.