| CPC E21B 7/24 (2013.01) [E21B 7/003 (2013.01); E21B 47/04 (2013.01); E21B 47/07 (2020.05)] | 18 Claims |

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1. A method comprising:
monitoring a rate of penetration of a drilling apparatus during formation of a first portion of a borehole of a well using the drilling apparatus, wherein the drilling apparatus includes a drill bit for mechanical removal of material from within the borehole, the monitoring further comprising generating a spatial orientation of a bottom hole assembly of the drilling apparatus and determining the rate of penetration based on the generated spatial orientation of the bottom hole assembly;
determining a depth of the first portion of the borehole at which the rate of penetration of the drilling apparatus falls below a rate of penetration threshold;
determining, based at least on the rate of penetration of the drilling apparatus falling below the rate of penetration threshold, to utilize a millimeter drilling apparatus including a waveguide configured for insertion into the borehole; and
forming a second portion of the borehole utilizing the millimeter wave drilling apparatus, wherein the second portion of the borehole is formed starting from the depth at which the rate of penetration fell below the rate of penetration threshold.
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