(132c) On the Relationship Between Mechanical Specific Energy and Rate of Penetration

A technique to measure the efficiency of a drilling operation consists of the examination of how the Mechanical Specific Energy (MSE) input is translated into the drilling rate of operation (ROP). This study investigates such relationship from laboratory-scale single cutter test to full drilling test. We initially carried finite element method modeling to provide insight on the mechanics involved. We then computed the mechanical specific energy using two volumes: the actual volume being cut and the volume computed based on the region swept by a cutter. Our finite element method analysis of a circular cutting by a sharp single disk PDC cutter provided a nearly constant mechanical specific energy when the rock failed in ductile mode. We have derived a general correlation of the mechanical specific energy versus the drilling rate of penetration. The correlation has been tested using data from the National Energy Technology single cutter ultra-deep drilling simulator at elevevated pressure of 138 MPa as well as data from rock cutting at ambient pressure. These comparative results will be presented.