Method of automatically controlling the trajectory of a drilled well

A method of controlling the trajectory of a drill string comprising:

• providing a steering behavior model having a build rate equation or a turn rate equation;
• calibrating the steering behavior model by minimizing any variance between an actual build rate or an actual turn rate of the drill string generated by a first tool setting and a first estimated build rate or a first estimated turn rate generated by inputting the first tool setting into the steering behavior model;
• and
• determining a second estimated build rate or a second estimated turn rate by inputting a second tool setting into the steering behavior model.

A method of controlling the trajectory of a drill string comprising:

• providing a steering behavior model having a build rate equation and a turn rate equation of a bottom-hole assembly;
• providing an actual azimuth and inclination at a first interval of drilling;
• determining an actual build rate and an actual turn rate at the first interval;
• calibrating the steering behavior model by minimizing any variance between the actual build rate and the actual turn rate and a first estimated build rate generated by inputting a first set of tool settings into the steering behavior model;
• and
• determining a second estimated build rate and a second estimated turn rate with the calibrated steering behavior model for a subsequent second interval drilled with a subsequent second set of tool settings.