Methods to Estimate the Rock Strength and Tooth Wear While Drilling With Roller-Bits—Part 2: Insert Bits

Abstract

New methods to estimate both the rock strength and tooth wear while drilling with roller-bits were developed and proposed in Part 1. These methods were derived from the results of drilling tests using milled-tooth type three-cone bits with different amounts of tooth wear. In this report, these methods were extended and applied to insert type three-cone bits. The validity of the test and data analyses techniques of Part 1 were confirmed for insert bits. The methods to estimate the tooth wear proposed in Part 1 were based on the drillability strength of rock. A new approach to determine the tooth wear is presented. This new approach could be more readily applied to evaluating tooth wear when compared to the previous methods based on the drillability strength of rock.