Rotary drill bit

An improved rotary drill bit comprising:

• an elongated generally cylindrical outer drill member having an upper end and a lower end forming an annular cutting face and having a plurality of vertically spaced rows of diamond-shaped openings formed in the wall thereof, the diamond-shaped openings in adjacent rows being offset from each other and overlapping at their upper and lower ends whereby as said lower end of said outer drill member wears away, cutting edges are continuously formed therein by said diamond-shaped openings;
• a plurality of elongated generally cylindrical inner drill members concentrically disposed one within the other and within said outer drill member, each of said inner drill members having upper ends and lower ends forming annular cutting faces and having a plurality of vertically spaced rows of diamond-shaped openings formed in the wall thereof, the diamond-shaped openings in adjacent rows being offset from each other and overlapping at their upper and lower ends whereby as the lower ends of said inner drill members wear away, cutting edges are continuously formed thereon by said diamond-shaped openings therein;
• a non-perforated drilling fluid conduit concentrically disposed within the innermost of, and along the entire length of, said inner drill members for conducting drilling fluid from the upper ends of said inner and outer drill members to the lower ends thereof, said fluid conduit having a plurality of diamond-shaped recesses formed in the outer surface thereof;
• and
• means for connecting said outer drill member, inner drill members and drilling fluid conduit to a string of drill pipe and for conducting drilling fluid to said drilling fluid conduit.

An improved rotary drill bit comprising:

• an elongated generally cylindrical outer drill member including a plurality of elongated semi-cylindrical members connected to each other at the sides thereof, said connected semi-cylindrical members having an upper end and a lower end forming an annular cutting face and having a plurality of vertically spaced rows of diamond-shaped openings formed in the walls thereof, the diamond-shaped openings in adjacent rows being offset from each other and overlapping at their upper and lower ends whereby as said lower end of said connected semi-cylindrical members wears away, cutting edges are continuously formed thereon by said diamond-shaped openings;
• a plurality of elongated generally cylindrical inner drill members disposed within said outer drill member, each of said inner drill members having upper ends and lower ends forming annular cutting faces and having a plurality of vertically spaced rows of diamond-shaped openings formed in the wall thereof, the diamond-shaped openings in adjacent rows being offset from each other and overlapping at their upper and lower ends whereby as said lower ends of said inner drill members wear away, cutting edges are continuously formed thereon by said diamond-shaped openings;
• a drilling fluid conduit disposed within said outer drill member for conducting drilling fluid from the upper ends of said inner and outer drill members to the lower ends thereof;
• and
• means for connecting said outer drill member, said inner drill members and said drilling fluid conduit to a string of drill pipe and for conducting drilling fluid to said drilling fluid conduit.

An improved rotary drill bit comprising:

• an elongated generally cylindrical outer drill member having an upper end and a lower end forming an annular cutting face and having a plurality of vertically spaced rows of diamond-shaped openings formed in the wall thereof, the diamond-shaped openings in adjacent rows being offset from each other and overlapping at their upper and lower ends whereby as said lower end of said outer drill member wears away, cutting edges are continuously formed thereon by said diamond-shaped openings;
• at least one elongated generally cylindrical inner drill member disposed within said outer drill member having a length corresponding to said outer drill member, an upper end and a lower end forming an annular cutting face and having a plurality of vertically spaced rows of diamond-shaped openings formed in the wall thereof, the diamond-shaped openings in adjacent rows being offset from each other and overlapping at their upper and lower ends whereby as said lower end of said inner drill member wears away, cutting edges are continuously formed thereon by said diamond-shaped openings;
• a non-perforate drilling fluid conduit disposed in said outer drill member for conducting drilling fluid from the upper ends of said outer and inner drill members solely to the lower ends thereof;
• means for connecting said outer drill member, inner drill member and drilling fluid conduit to a string of drill pipe and for conducting drilling fluid to said drilling fluid conduit;
• and
• a plurality of rotatable grinding members positioned between said outer drill member and said inner drill member.