Method and apparatus for drilling boreholes in earth formations (drilling liner systems)

A drilling liner system for use in continued drilling of a borehole having a casing therein, the casing having a drilling tubular and a liner hanger/packer assembly at the bottom, the drilling liner system comprising:

• (a) an inner bottom hole assembly including:
• (i) a drilling motor adapted to be operated by mud conveyed downhole by the drilling tubular;
• and
• (ii) a drive shaft on the drilling motor coupled to a male sub with retractable drive splines thereon, the male sub coupled to a pilot bit for drilling a pilot hole upon operation of the drilling motor;
• (b) a liner coupled at a first end to the liner hanger/packer and the drilling tubular, and at a second end to an outer bottom hole assembly, the outer bottom hole assembly including:
• (i) a female sub adapted to engage the drive splines on the male sub and rotate with the male sub upon being engaged thereto, and
• (ii) a core bit surrounding the pilot bit and coupled to the female sub for drilling an enlarged hole;
• and
• (c) a releasing tool for releasably coupling the inner bottom hole assembly to the liner.

A drilling liner system for use in continued drilling of a borehole having a casing therein, a drilling tubular inside the casing, and a liner hanger/packer assembly at the bottom of the casing, the drilling liner system comprising:

• (a) a tubular coupled to the drilling tubular and to an inner bottom hole assembly, the inner bottom hole assembly including:
• (i) a drilling motor coupled to the tubular and adapted to be operated by mud carried by said tubular;
• (ii) a thruster coupled to a drive shaft on the drilling motor and to a male sub, the thruster adapted to extend and retract the position of the male sub relative to the drilling motor
• (iii) retractable drive splines on the male sub, and
• (iv) a pilot bit coupled to the male sub for drilling a pilot hole upon operation of the drilling motor;
• and
• (b) a liner coupled at a first end to the liner hanger/packer and at a second end to an outer bottom hole assembly, the outer bottom hole assembly including:
• (i) a female sub adapted to engage drive splines on the male sub and rotate with the male sub upon being engaged thereto,
• (ii) a core bit surrounding the pilot bit and coupled to the female sub for drilling an enlarged hole, and
• (iii) a telescopic suspension sub coupled to the drilling motor and the female sub, said telescopic sub adapted to move the female sub in conjunction with the motion of the thruster.

A method of drilling a borehole comprising:

• (a) setting a casing in a section of the borehole;
• (b) passing a drilling tubular through the casing and a liner hanger/packer assembly at the bottom of the casing;
• (c) operating a drilling motor coupled to a lower end of the tubular by passing mud carried by said tubular;
• (d) coupling a first end of a liner to the liner hanger/packer and at a second end to an outer bottom hole assembly;
• (e) coupling a drive shaft on the drilling motor to a male sub with retractable drive splines thereon and to a pilot bit for drilling a pilot hole upon operation of the drilling motor;
• (f) engaging a female sub on the outer bottom hole assembly to the drive splines on the male sub and rotating with the male sub upon being engaged thereto, thereby operating a core bit on the outer bottom hole assembly for drilling an enlarged hole.

A method of drilling a borehole comprising:

• (a) setting a casing in a section of the borehole;
• (b) coupling a first end of a liner to a liner hanger/packer at the bottom of the casing;
• (c) coupling a second end of the liner to an outer bottom hole assembly having a core bit thereon;
• (d) using a releasing tool to couple the outer bottom hole assembly to an inner bottom hole assembly having a mud motor therein;
• (e) coupling a drive shaft on the drilling motor to a male sub with retractable drive splines thereon and to a pilot bit for drilling a pilot hole upon operation of the drilling motor;
• (f) engaging a female sub on the outer bottom hole assembly to the drive splines on the male sub thereby enabling the core bit to drill an enlarged hole upon operation of the drilling motor;
• (g) conveying mud through a drilling tubular in the casing through the liner hanger/packer into the liner and using the mud to operate the drilling motor, thereby causing the pilot bit to drill a pilot hole and the core bit to drill an enlarged hole.