Rotary drill bit with nozzles designed to enhance hydraulic performance and drilling fluid efficiency

A rotary drill bit for forming a wellbore, comprising:

• a bit body having an upper portion adapted for engagement with a drill string for rotation of the bit body;
• a number of cutting structures engaged with the bit body;
• a fluid cavity formed in the bit body and sized to receive drilling fluid from an attached drill string;
• a plurality of fluid flow passageways extending from the cavity to respective nozzles engaged with exterior portions of the bit body;
• each nozzle having a nozzle body with a fluid flow passageway extending between an inlet portion and an outlet portion of the nozzle body;
• and
• a first Coanda surface formed within each fluid passageway extending between the associated inlet portion and the associated outlet portion.

A rotary drill bit operable to form a bore hole comprising:

• a bit body having a plurality of cutting structures;
• the cutting structures operable to engage adjacent portions of a downhole formation to form the bore hole in response to rotation of the rotary drill bit;
• one end of the bit body having a threaded connection operable for engagement with a bottom hole assembly;
• the rotary drill bit and the bottom hole assembly generally aligned with each other along a longitudinal axis during formation of a vertical bore hole;
• a plurality of nozzles formed in the bit body and operable to direct fluid flow from a drill string attached to the rotary drill bit to exterior portions of the bit body;
• the nozzles cooperating with each other to create respective fluid flow streams in an annulus formed between exterior portions of rotary drill bit and the attached bottom hole assembly and adjacent interior portions of the bore hole;
• and
• the fluid flow streams moving at an angle of approximately twenty-eight (28°) degrees to thirty-eight (38°) degrees relative to the longitudinal axis.

A system operable to form a wellbore extending from a well surface through at least one downhole formation comprising:

• a drill string having a bottom hole assembly attached with one end of a drill string;
• a rotary drill bit attached with the bottom hole assembly opposite from the drill string whereby rotation of the drill string and bottom hole assembly results in rotation of the rotary drill bit;
• a plurality of nozzles disposed in the bit body;
• each nozzle having at least a first Coanda surface;
• and
• the nozzles cooperating with each other to form respective swirling fluid flow paths on exterior portions of the rotary drill bit and the bottom hole assembly.

A method for designing a rotary drill bit and associated nozzles to improve efficiency of drilling fluids exiting from the nozzles during drilling of a wellbore in a downhole formation comprising:

• selecting a first drill bit design including cutting structures, nozzle locations, nozzle orientation and direction of fluid flow exiting from each nozzle;
• identifying any stagnate regions of drilling fluid developed between the cutting structures of the first drill bit design and adjacent portions of an associated wellbore;
• selecting a second drill design with the same cutting structures and a change in direction of fluid flow exiting from each nozzle;
• identifying any stagnate regions of drilling fluid developed between the cutting structures of the second drill bit design and adjacent portions of an associated wellbore;
• comparing the location of each stagnate region associated with the first drill bit design with the location of each stagnate region associated with the second drill bit design;
• and
• repeating the above steps until the location of any stagnate regions of drilling fluid have been removed from between the cutting structures of the associated drill bit design and adjacent portions of the wellbore.

A method of forming a rotary drill bit and associated nozzles to improve efficiency of drilling fluids exiting from the nozzles during drilling of a wellbore in a downhole formation comprising:

• forming a bit body having an upper portion operable for releasable engagement with a drilling string;
• forming an enlarged cavity within the bit body operable to receive drilling fluid from an attached drill string;
• forming at least one fluid passageway extending from the bit body to a respective nozzle receptacle;
• forming at least one nozzle receptacle in an exterior portion of the bit body;
• forming each nozzle with a nozzle body having a fluid flow passageway extending therethrough;
• and
• forming at least one Coanda surface within each fluid flow passageway with an optimum configuration to minimize turbulent fluid flow through the fluid flow passageway and to optimize hydraulic performance and efficiency of fluid flow exiting from the nozzle.