Patent ID: 7147068

Claim:
A method of making a cased wellbore comprising at least the steps of: assembling a lower segment of a drill string comprising in sequence from top to bottom a first hollow segment of drill pipe, a latching subassembly means, a directional drilling means, and a rotary drill bit having at least one mud passage for passing drilling mud from the interior of the drill string to the outside of the drill string; periodically halting rotary drilling, introducing into said wellbore a directional surveying means to determine the direction of the wellbore being drilled, and thereafter removing said directional surveying means from said wellbore; rotary drilling the well into the earth in a desired direction to a predetermined depth with the drill string by attaching successive lengths of hollow drill pipes to said lower segment of the drill string and by circulating mud from the interior of the drill string to the outside of the drill string during rotary drilling so as to produce a wellbore; after said predetermined depth is reached, pumping a latching float collar valve means down the interior of the drill string with drilling mud until it seats into place within said latching subassembly means; pumping a bottom wiper plug means down the interior of the drill string with cement until the bottom wiper plug means seats on the upper portion of the latching float collar valve means so as to clean the mud from the interior of the drill string; pumping any required additional amount of cement into the wellbore by forcing it through a portion of the bottom wiper plug means and through at least one mud passage of the drill bit into the wellbore; pumping a top wiper plug means down the interior of the drill string with water until the top wiper plug seats on the upper portion of the bottom wiper plug means thereby cleaning the interior of the drill string and forcing additional cement into the wellbore through at least one mud passage of the drill bit; allowing the cement to cure; thereby cementing into place the drill string to make a cased welbore.