Coiled tubing drilling for geothermal heating and cooling applications

A system for constructing geothermal boreholes, comprising:

• a power unit;
• a coiled tubing (CT) reel for spooling a CT string;
• a drill bit coupled to a first end of the CT string;
• a CT injector configured to inject the CT string from a surface into a subsurface via the first end of the CT string to construct a geothermal borehole, the CT injector including a gooseneck positioned between the CT reel and the CT injector, the gooseneck configured to guide the CT string into a body of the CT injector as the CT string is unspooled from the CT reel;
• a first arm for coupling the CT reel and the power unit;
• and
• a second arm for coupling the CT injector and the power unit, wherein:
• during operation of the system, the system is configured to:
• obtain a drilling speed and a drilling force of the drill bit;
• determine, based on a correlation between the drilling speed and the drilling force, whether the CT string is straight or helical;
• and
• in accordance with a determination that the CT string is helical, modify a distance between the CT reel and the gooseneck by adjusting at least one of (i) a length of the first arm or (ii) a length of the second arm, so as to straighten the CT string as the CT string enters the body of the CT injector via the gooseneck.