Polycrystalline diamond compact bit-rock interaction

Akbari, Babak (2011) Polycrystalline diamond compact bit-rock interaction. Masters thesis, Memorial University of Newfoundland.

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Abstract

A physical model of a single PDC (Polycrystalline Diamond Compact) cutter interacting with rock surface is developed, and its most important characteristic is the ability of inputting different force on cutter profiles and outputting cutter penetration. The model is developed in 2 dimensions simplifying the three dimensional cutter movement by a 2 dimensional plane. The model is simulated using the Distinct Element Method and simulation results for the single cutter are interpreted. Simple theories are then proposed to extend the results to a full PDC. -- Model inputs encompass parameters such as force profile and horizontal velocity profile on the cutter and also pressure on the rock specimen and the model outputs include dynamic parameters such as cut depth and penetration profile and energy consumed by the cutter. -- Relating different types of model inputs and outputs to drilling operational parameters is explained. Approaches to tackle a certain drilling problem relating to the efficiency of particular down-the-hole tools exerting dynamic force profiles on the bit using this model are also explained in detail. -- Results show that adding force oscillation generally improves the drilling performance; however, the improvement diminishes as the bottomhole pressure increases. Also, regardless of the force oscillations, the rate of penetration decreases linearly with logarithm of the bottomhole pressure.

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