Earth-boring tools carrying formation-engaging structures

1. An earth-boring tool, comprising:

at least one blade located on a body of the earth-boring tool;

cutting elements positioned in respective cutting element pockets on an exposed outer surface of the at least one blade, wherein the cutting elements comprise a polycrystalline diamond compact;

a pocket opening onto the exposed outer surface of the at least one blade;

a tapped bore extending through the at least one blade from at least one of a rotationally leading surface and a rotationally trailing surface of the at least one blade to the pocket, the rotationally leading surface being a leading surface of the blade as the at least one blade rotates around an axis of rotation of the body of the earth-boring tool, the rotationally trailing surface being a trailing surface of the blade as the at least one blade rotates around the axis of rotation of the body of the earth-boring tool;

a formation-engaging structure received within the pocket of the at least one blade, the formation-engaging structure positioned intermediate at least two cutting elements along a radial axis of the body of the earth-boring tool, the formation-engaging structure having a distal end, a proximal end and a sidewall therebetween, and the distal end of the formation-engaging structure having a formation-engaging surface;

a receiving formation located in the sidewall of the formation-engaging structure; and

a threaded fastening element threaded within the tapped bore extending through the at least one blade, the threaded fastening element threadably engaging threads of the tapped bore, a first end of the threaded fastening element engaging the receiving formation of the formation-engaging structure, the threaded fastening element, as engaged, configured to retain the formation-engaging structure within the pocket of the at least one blade.

2. The earth-boring tool of claim 1 , wherein the receiving formation comprises a receiving surface configured to engage the first end of the threaded fastening element.

3. The earth-boring tool of claim 2 , wherein the receiving surface is oriented at a non-parallel angle in relation to a longitudinal axis of the formation-engaging structure.

4. The earth-boring tool of claim 3 , wherein the tapped bore is oriented at a non-perpendicular angle in relation to the longitudinal axis of the formation-engaging structure.

5. The earth-boring tool of claim 3 , wherein the receiving surface of the receiving formation is planar, and the threaded fastening element comprises a set screw with a swivel tip having a planar bearing surface oriented co-planar with the receiving surface.

6. The earth-boring tool of claim 1 , further comprising a second threaded fastening element threaded within the tapped bore, a second end of the threaded fastening element adjacent a first end of the second threaded fastening element, the second threaded fastening element retaining the threaded fastening element within the tapped bore.

7. The earth-boring tool of claim 1 , wherein the formation-engaging surface of the formation-engaging structure is ovoid.

8. The earth-boring tool of claim 1 , wherein the formation-engaging structure comprises a volume of superabrasive material disposed over a substrate, the formation-engaging surface comprising a surface of the volume of superabrasive material.

9. The earth-boring tool of claim 8 , wherein the volume of superabrasive material of the formation-engaging structure comprises polycrystalline diamond.

10. The earth-boring tool of claim 2 , wherein an outer surface of the receiving surface of the receiving formation is recessed relative to an outer surface of the sidewall of the formation-engaging structure.

11. The earth-boring tool of claim 1 , wherein the cutting elements are located on the rotationally leading surface of the at least one blade and the formation-engaging structure is located rotationally behind the cutting elements.

12. The earth-boring tool of claim 1 , wherein the formation-engaging structure is located at a rotationally leading position relative to the cutting elements.

13. The earth-boring tool of claim 1 , wherein the formation-engaging structure is an insert.

14. The earth-boring tool of claim 1 , wherein the formation-engaging structure is a non-cutting bearing element positioned and oriented on the body as a rubbing surface configured to rub against a formation as the body of the earth-boring tool is rotated within a wellbore.

15. The earth-boring tool of claim 1 , wherein the earth-boring tool comprises a fixed-cutter earth-boring rotary drill bit comprising a bit body having generally radially projecting and longitudinally extending blades, the pocket being located on a leading end of a respective blade.

16. The earth-boring tool of claim 1 , wherein the tapped bore comprises a blind bore extending through the at least one blade from the rotationally trailing surface of the at least one blade to the pocket.

17. The earth-boring tool of claim 1 , wherein each of the threaded fastening element and the receiving formation of the formation-engaging structure are sized and configured to rigidly retain the formation-engaging structure within the pocket of the at least one blade.

18. The earth-boring tool of claim 1 , wherein the formation-engaging surface of the formation-engaging structure comprises a wear-resistant material comprising cemented tungsten carbide.