Downhole tractor
AssigneeNational Oilwell Varco, L.P.
InventorsAlan Martyn Eddison, David Anderson Coull, Derek James Stuart
Life of this patent
Estimating the term…
Abstract
A method of translating a member through a bore involving moving fluid through a tubular member such as a drill string, and generating impulses on the member by varying the passage of fluid through the member using a valve which opens at a first rate and closes at a different second rate to urge the member to advance in a selected direction. The valve may close quickly and open slowly, or may close slowly and open quickly.
Claims33
A method of translating a member through a bore, the method comprising:
- moving fluid through a tubular member located in the bore;
- generating impulses on the member by varying passage of fluid through the member by opening a flow passage at a first rate and closing the flow passage at a different second rate to urge the member to advance in a selected direction;
- and
- operating a valve to interrupt flow of the fluid.
A downhole tractor, comprising:
- a fluid-transmitting member;
- and
- a valve comprising a rotating element to vary fluid flow in the member, the valve movable at a first rate to an open position and at a different second rate to a closed position to generate impulses from fluid flowing through the member and tending to urge the member in a selected direction.
A method of translating a member through a bore, the method comprising:
- flowing fluid through the member located in the bore;
- and
- repeatedly interrupting flow of the fluid at a location in the member to generate pressure variations in the fluid at said location, a variable length element of the member responding more quickly to one fluid flow condition and more slowly to another fluid flow condition to generate impulses whereby the member is urged to advance through the bore in the direction of fluid flow;
- wherein the element comprises a shock sub and is subject to a first level of damping on the shock sub from extending on experiencing an elevated pressure, and is subject to a higher second level of damping on experiencing the lower internal fluid pressure, whereby the element responds more quickly to the elevated pressure.
A downhole tractor, comprising:
- a fluid-transmitting member;
- a valve for varying a fluid flow condition in the member;
- and
- a fluid-responsive device responsive to changes in the fluid flow condition and such that the device responds more quickly to one fluid flow condition and more slowly to another fluid flow condition to generate impulses tending to urge the member in a selected direction.
A method of translating a member through a bore, the method comprising:
- moving fluid through a tubular member located in the bore;
- and
- generating impulses on the member by varying passage of fluid through the member by opening a flow passage at a first rate and closing the flow passage at a different second rate to urge the member to advance in a selected direction.
Dependencies are inferred from the claim text.