Systems and methods for microwave-based drilling employing coiled tubing waveguide

A method for drilling a borehole into a subsurface formation, comprising:

• deploying coiled tubing from a spool of coiled tubing such that the coiled tubing extends from the spool into the borehole, wherein the coiled tubing has a surface end disposed at the spool;
• injecting, via a coupler, microwave radiation generated by a microwave generator into the surface end of the coiled tubing, wherein the coiled tubing functions to guide propagation of the microwave radiation into the borehole, and wherein the coiled tubing has a continuous inner diameter surface having a diameter greater than two times the characteristic wavelength of the microwave radiation injected into the surface end of the coiled tubing;
• and
• using microwave radiation that propagates inside the coiled tubing to vaporize rock and extend the borehole into the formation.

A system for drilling a borehole into a subsurface formation, comprising:

• a spool of coiled tubing, wherein the coiled tubing has a surface end disposed at the spool, and wherein the coil tubing extends from the spool into the borehole;
• a microwave generator;
• a coupler for injecting microwave radiation generated by the microwave generator into the surface end of the coiled tubing, wherein the coiled tubing functions to guide propagation of the microwave radiation into the borehole, and wherein the coupler is further configured to inject a pressurized fluid into the surface end of the coiled tubing;
• a waveguide operably coupled between the microwave generator and the coupler;
• and
• an injection manifold having multiple legs that supply the pressurized fluid to the waveguide through corresponding ports in the waveguide.