US 4,901,806 A · Apparatus for controlled absorption of axial and torsional forces in a well string

Abstract

A drill string apparatus for the controlled absorption of both axial and torsional forces exhibited on the well string during drilling operations. The device is adapted to be connected in the drill string above the drilling tool in order to control the forces acting on the bit and to arrange the mean weight on bit for the selected drilling operation. Generally, the apparatus includes an outer casing coupled at its upper end to the drill string and an inner assembly telescopically received within the outer casing and connected at its lower end to the lower part of the bottom hole assembly or the drilling tool. Rotational torque is transferred from the drill string and outer casing to the inner assembly and drill bit by a series of helical splines. The mean weight on bit is controlled through an interchangeable pressure control nozzle mounted at the top of the inner assembly. Dual pistons with corresponding fluid chambers dampen axial forces while the helical splines decouple the torsional forces from axial vibrations to ensure proper control of the drill bit. In addition to attenuating vibration in conventional drilling operations, the present invention can be utilized in highly deviated holes and in drill strings using coiled tubes.

Claims22

Dependent claims

An apparatus for the controlled absorption of axial and torsional forces associated with the drilling work loads applied to a drill string, said apparatus adapted for series connection in a drill string to formation cutting means, said apparatus comprising:

an outer casing connected at its upper end to the drill string, said outer casing having an axial opening formed at its lower end;
an inner mandrel assembly having the formation cutting means connected to the lower end thereof and an axial fluid passageway for the controlled supply of drilling fluid from the drill string to the formation cutting means, said inner assembly telescopingly received in said outer casing such that the lower end of said assembly extends through said axial opening of said outer casing;
upper and lower pistons on said inner assembly adapted to sealingly engage an inner surface of said outer casing, said pistons forming an enclosed fluid chamber therebetween;
and
a torque retractor assembly disposed within said fluid chamber between said upper and lower pistons, said torque retractor assembly adapted to absorb the torsional forces associated with said drill string.

2 more elements

An apparatus for the controlled absorption of axial and torsional forces associated with the drilling work loads applied to a drill string, said apparatus adapted for series connection in a drill string with a bottom hole assembly having a drill bit, said apparatus comprising:

an outer casing connected at its upper end to the drill string, said outer casing having an axial opening formed at its lower end;
an inner mandrel assembly having the bottom hole assembly connected to the lower end thereof, said inner assembly telescopingly received in said outer casing such that the lower end of said assembly extends through said bottom opening of said outer casing, said inner assembly comprising:
an axial fluid passageway for the controlled supply of drilling fluids from the drill string to the bottom hole assembly and drill bit, said axial fluid passageway having an interchangeable pressure control nozzle mounted at the upper end of said passageway to vary the fluid pressure supplied to the bottom hole assembly;
upper and lower pistons adapted to sealingly engage an inner surface of said outer casing, said pistons forming an enclosed fluid chamber therebetween, said upper piston being exposed to the drilling fluid pressure from said drill string and said lower piston being exposed to the downhole fluid pressure environment through said bottom opening in said outer casing, said pistons adapted to absorb the axial load forces associated with said drill string;
a torque retractor assembly adapted to absorb the torsional load forces associated with said drill string and disposed within said fluid chamber between said upper and lower pistons, said torque retractor assembly including an outer member having a helically cut surface with a substantially sinusoidal surface configuration, said outer member forming the inner surface of said outer casing, and a mating inner member having a mating helically cut surface with a substantially sinusoidal surface configuration, said inner member forming the outer surface of said inner mandrel assembly between said upper and lower pistons.

2 more elements

Dependencies are inferred from the claim text.

Apparatus for controlled absorption of axial and torsional forces in a well string

Life of this patent

Apparatus for controlled absorption of axial and torsional forces in a well string

Life of this patent

Abstract

Claims22