Abstract

The improvement of PCD cutting tools requires a better understanding of rock cutting mechanism. For the moment, the study of this mechanism is based on laboratory tests and numerical modeling. For the numerical aspect, distinct element method seems to be more efficient than finite element method by taking into account the granular aspect of the rock. A new methodology in DEM modeling, the clump logic, tends to give the best results to model the rock mechanical behavior. As this type of model was never used for the rock cutting modeling, the aim of this work is to study the improvement of rock cutting modeling by the use of clump logic. The most important aspect of the study is to verify the destruction mechanism of the rock, ductile or brittle, depending on the depth of cut and to compare this mechanism with laboratory observations made on the Rock Strength Device.

1 Introduction

The need of improving PCD drilling tools requires a better understanding of rock cutting mechanism. In this context, different methods as laboratory tests, field results and numerical modeling are used to study the rock-tool interaction.

In the rock cutting modeling, the distinct element method is increasingly used. This is because this type of modeling takes into account the granular aspect of the rock, which allows a better modeling of the development of cracks and fractures in small samples of rock.

This DEM modeling, often used with PFC2D software, was generally used in rocks mechanics to model mechanical characterization tests (Potyondy & Cundall 2004) or to study the rock mass stability (Jing & Hudson 2002). Several models were worked out to obtain the best representation of rock behavior. One of this models, the Clump model proposed by Cho et al. (2007), tends to give the best results to model the behavior of rock material.

As this methodology was never been used before, this work aims to study if the clump models have a benefit impact on the rock cutting modeling. The study is divided into three parts:

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