A multi-dimensional percussion method for efficient drilling in HDR formations: Rock fragmentation mechanism, drilling energy analysis, and performance optimization

• Multi-dimensional percussion (axial + torsional) enhances rock fragmentation in HDR formations, promoting brittle-ductile mixed failure in granite and brittle fragmentation in carbonatite. • Frequency-domain analysis of penetration force signals reveals increased net drilling energy and intensified fragmentation under multi-dimensional percussion. • Optimal impact frequency combinations are 15 Hz axial + 15 Hz torsional for granite and 30 Hz axial + 15 Hz torsional for carbonatite, maximizing drilling efficiency. • Field validation in geothermal well Fushen-1 confirms the reliability of the optimization approach for practical HDR drilling.