| Title | Three-dimensional numerical study of DTH bit–rock interaction with HPWJ downhole slotting: influence of bit design and bottom hole geometric conditions on rock breaking efficiency in percussive drilling |
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| Authors | Stéphane Dumoulin, Nicolas Morin, Térence Coudert, Alexandre Kane, Laurent Gerbaud, Naveen Velmurugan, Emad Jahangir, Hedi Sellami, John-Paul Latham, Sadjad Naderi, Jiansheng Xiang |
| Year | 2023 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | The present study is carried out within the context of the ongoing research project ORCHYD where a novel hybrid drilling technology is being developed and customised for deep hard rock geothermal reservoirs access. The hybrid development, combining High Pressure Water-Jetting (HPWJ) and percussive drilling technologies, requires slotting circumferential stress relieving grooves on the bottom of the hole (using HPWJ) to improve the efficiency of rock breaking during impact. A three-dimensional finite element bit–rock interaction model is therefore built to investigate the influence of bit design and bottom-hole geometry conditions on the rock breaking efficiency for an impact from percussive drilling. A pressure and rate dependent elastoplastic damage model is calibrated using a full-scale laboratory drilling test under high confining pressure and applied on a granite rock. The role of geometric conditions of the bit-rock interface is assessed considering various slot dimensions (i.e. depth, width) at the bottom-hole wall-rock and various bit profiles (flat, parabolic, and concave). Parametric percussive impact simulations are performed and an optimal bit rock interface configuration is proposed. |