Method for drilling with casing

1. A method for drilling a well with a well casing as at least a portion of an elongated tubular drill string and a drilling assembly retrievable from the lower distal end of the drill string without withdrawing the well casing from a wellbore being formed by the drilling assembly, the method comprising:

providing the casing as at least a portion of the drill string;

providing the drill string with the drilling assembly engaged at the distal end thereof;

with the drill string and the drilling assembly in the wellbore, driving the drilling assembly to operate at the bottom of the wellbore to extend the wellbore, the wellbore being formed having a diameter greater than the diameter of the drill string;

actuating the drilling assembly to disengage from the distal end of the drill string including launching a release tool and manipulating the drilling assembly using the release tool;

removing the drilling assembly out of the wellbore through the drill string without removing the drill string from the wellbore;

leaving the casing of the drill string in the wellbore; and

wherein the release tool is fluid-conveyed.

2. The method of claim 1 wherein the release tool is launched without a connection to a work string.

3. The method of claim 1 wherein during the step of actuating the drilling assembly, fluid circulation is substantially maintained through the wellbore.

4. The method of claim 1 wherein after the step of actuating the drilling assembly, the drill string is advanced toward the bottom of the wellbore prior to removing the drilling assembly.

5. The method of claim 4 wherein the drill string is advanced substantially to the bottom of the wellbore prior to removing the drilling assembly.

6. The method of claim 1 wherein the casing is provided as the entirety of the drill string.

7. The method of claim 1 wherein the casing is a liner and is suspended on a string of drill pipe and the method further comprises releasing the drill pipe from the liner and prior to removing the drilling assembly.

8. A method for drilling a well with a well casing as at least a portion of an elongated tubular drill string and a drilling assembly retrievable from the lower distal end of the drill string without withdrawing the well casing from a wellbore being formed by the drilling assembly, the method comprising:

providing the casing as at least a portion of the drill string;

providing the drill string with the drilling assembly engaged at the distal end thereof;

with the drill string and the drilling assembly in the wellbore, driving the drilling assembly to operate at the bottom of the wellbore to extend the wellbore, the wellbore being formed having a diameter greater than the diameter of the drill string;

actuating the drilling assembly to disengage from the distal end of the drill string including launching a release tool and manipulating the drilling assembly using the release tool;

removing the drilling assembly out of the wellbore through the drill string without removing the drill string from the wellbore;

leaving the casing of the drill string in the wellbore; and

wherein removing the drilling assembly includes reverse circulation of fluid down through an annulus about the drill string and up through the drill string.

9. The method of claim 8 wherein removing the drilling assembly employs a retrieving tool.

10. A method for positioning a casing string within a wellbore, the wellbore having been drilled using the casing string as at least a portion of an elongated tubular drill string and a drilling assembly connected to the drill string and retrievable from the lower distal end of the drill string without withdrawing the casing string from the wellbore being formed by the drilling assembly, the method comprising:

after drilling a wellbore, releasing the drilling assembly from engagement with the drill string including launching a release tool and manipulating the drilling assembly using the release tool;

removing the drilling assembly from the wellbore through the drill string without removing the casing string of the drill string from the wellbore; and

wherein the release tool is launched without a connection to a work string.

11. The method of claim 10 wherein the release tool is gravity-conveyed.

12. The method of claim 10 wherein the release tool is fluid-conveyed.

13. The method of claim 10 wherein during the step of actuating the drilling assembly, fluid circulation is substantially maintained through the wellbore.

14. The method of claim 10 wherein removing the drilling assembly includes reverse circulation of fluid down through an annulus about the drill string and up through the drill string.

15. The method of claim 10 wherein removing the drilling assembly employs a retrieving tool.

16. The method of claim 10 wherein after the step of releasing the drilling assembly from engagement with the drill string, the drill string is advanced toward total depth.

17. The method of claim 16 wherein the drill string is advanced substantially to wellbore bottom prior to removing the drilling assembly.

18. The method of claim 10 wherein the casing string is provided as the entirety of the drill string.

19. The method of claim 10 wherein the casing string is a liner and is suspended on a string of drill pipe and the method further comprises releasing the drill pipe from the liner prior to removing the drilling assembly.

20. The method for positioning a casing string within a wellbore, the wellbore having been drilled using the casing string as at least a portion of an elongated tubular drill string and a drilling assembly connected to the drill string and retrievable from the lower distal end of the drill string without withdrawing the casing string from the wellbore being formed by the drilling assembly, the method comprising: after drilling a wellbore, releasing the drilling assembly from engagement with the drill string including launching a fluid-conveyed dart with a release functionality and manipulating the drilling assembly using the fluid-conveyed dart; and removing the drilling assembly from the wellbore through the drill string without removing the casing string portion of the drill string from the wellbore.

21. The method of claim 20 wherein during the step of actuating the drilling assembly, fluid circulation is substantially maintained through the wellbore.

22. The method of claim 20 wherein removing the drilling assembly includes reverse circulation of fluid down through an annulus about the drill string and up through the drill string.

23. The method of claim 20 wherein removing the drilling assembly employs a retrieving tool.

24. The method of claim 20 wherein after the step of releasing the drilling assembly from engagement with the drill string, the drill string is advanced toward total depth.

25. The method of claim 24 wherein the drill string is advanced substantially to wellbore bottom prior to removing the drilling assembly.

26. The method of claim 20 wherein the casing string is provided as the entirety of the drill string.

27. The method of claim 20 wherein the casing string is a liner and is suspended on a string of drill pipe and the method further comprises releasing the drill pipe from the liner prior to removing the drilling assembly.