US Patent 9879490 Methods and systems for drilling

A method of automatically placing a drill bit used to form an opening in a subsurface formation on a bottom of the opening being formed comprises a) increasing a flow rate in a drill string to a target flow; b) controlling a flow rate of fluid into the drill string to be substantially the same as a flowrate of fluid out of the opening; c) allowing a fluid pressure to reach a relatively steady state; and d) automatically moving the drill bit toward the bottom of the opening at a selected rate of advance until an increase in measured differential pressure indicates that the drill bit is at the bottom of the opening.