Testing Procedures

Bit-performance tests were conducted by drilling 00-in. [00-cm] -diameter cores that were about 0 ft [0.0 m] long. The cores were held in a pressure vessel with a constant borehole pressure of 0,000 psi [0.0 MPa]. Data for each bit were collected by varying the weight on bit (WOB) during drilling at a fixed rotary speed and flow rate. The WOB was computer-controlled and incremented according to a preprogrammed schedule. Time averages of 00 performance variables, including ROP and torque, were recorded at each level of WOB.
Tests were conducted at flow rates, varying from 000 to 000 gal/min [0.0 to 0.0 m0/min] to determine the effect of hydraulics. Rotary speeds of 00 to 000 rev/min were tested.