Drilling penetration rate estimation using Rock Drillability Characterization index

Abstract

Rock drilling Penetration Rate (PR) is influenced by many parameters including rock properties, machine parameters of the chosen rig and the working process. Five datasets were utilized to quantitatively assess the effect of various rock properties on PR. The datasets consisted of two sets of diamond and percussive drilling and one set of rotary drilling data. A new rating system called Rock Drillability Characterization index (RDCi) is proposed to predict PR for different drilling methods. This drillability model incorporates the uniaxial compressive strength of intact rock, the P-wave velocity and the density of rock. The RDCi system is further applied to predict PR in the diamond rotary drilling, non-coring rotary drilling and percussive drilling. Strong correlations between PR and RDCi values were observed indicating that the developed drillability rating model is relevant and can be utilized to effectively predict the rock drillability in any operating environment. A practical procedure for predicting PR using the RDCi was established. The drilling engineers can follow this procedure to use RDCi as an effective method to estimate drillability.