Shape memory alloy actuated steerable drilling tool

Abstract

A rotary steerable apparatus is provided having an actuator for pushing the bit or pointing the bit that includes a shape memory alloy. An elongated form of the alloy, such as a wire or rod, is employed in a mechanism that applies force in a direction transverse to the wellbore in response to a change in length of the alloy. Temperature of the alloy is controlled to change shape and produce the desired force on pads for operating the apparatus. The apparatus may be used with downhole power generation and control electronics to steer a bit, either in response to signals from the surface or from downhole instruments.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of one embodiment of the rotary steerable drilling tool disclosed herein.

FIG. 2 a is a section view of the rotary steerable drilling tool when not activated; FIG. 2b is a section view of the tool when activated to push the bit.

FIG. 3 is an isometric view of the SMA actuator module.

FIG. 4 a is a section view of the SMA actuator module when not activated; FIG. 4b is a section view of the activator when activated to exert a force.

FIG. 5 is an illustration of the use of an SMA actuator to push a bit using pads on a sleeve.

FIG. 6 is an illustration of the use of an SMA actuator to point a bit using a flexible shaft.

FIG. 7 is a schematic of an actuator design with straight SMA wires or rods.

FIG. 8 is a block diagram of a directional drilling system using SMA actuators. The same part is identified by the same numeral in each drawing.

Claims

1. A rotary steerable drilling apparatus for drilling a wellbore, comprising: a shaft adapted for joining to a drill string;a sleeve concentric with the shaft and being free to rotate independently around the shaft;a plurality of actuator modules fixed to the sleeve, the modules comprising a shape memory alloy formed such that a change in temperature of the alloy within a selected range of temperature causes the alloy to change from a first dimension to a second dimension; anda plurality of pads in proximity to the actuator modules and adapted to apply a force to a selected wall of the wellbore in response to the change of the alloy from the first to the second dimension.

2. The rotary steerable drilling apparatus of claim 1 wherein the shape memory alloy is in the form of a wire.

3. The rotary steerable drilling apparatus of claim 1 wherein the shape memory alloy is in the form of a rod.

4. The rotary steerable drilling apparatus of claim 1 wherein the change of the alloy from the first to the second dimension causes a transverse motion in the actuator modules.

5. The rotary steerable drilling apparatus of claim 1 wherein the actuator modules comprise linkage systems adapted to move outwardly from the sleeve in response to the change in dimension of the alloy.

6. The rotary steerable drilling apparatus of claim 1 further comprising a heating element in contact or in proximity with the shape memory alloy.

7. A rotary steerable drilling system, comprising: the rotary steerable drilling apparatus of claim 1 further comprising a downhole electrical power generator, electronics for controlling the electrical power generated, sensors for measuring force on the pads and electronics for controlling force applied to the pads.

8. The rotary steerable drilling system of claim 7 further comprising a downhole instrument to measure direction of a bit and send a responsive signal to the steerable drilling apparatus.

9. A rotary steerable drilling apparatus for drilling a wellbore, comprising: a shaft adapted for joining to a drill string;a sleeve concentric with the shaft and being free to rotate independently around the shaft;a plurality of actuator modules fixed within the sleeve, the modules comprising a shape memory alloy formed such that a change in temperature of the alloy within a selected range of temperature causes the alloy to change from a first dimension to a second dimension; anda plurality of pads in proximity to the actuator modules and adapted to apply a force to a bearing, the bearing having a shaft passing therethrough, the shaft being adapted for having a bit connected thereto.

10. The rotary steerable drilling apparatus of claim 9 wherein the shape memory alloy is in the form of a wire.

11. The rotary steerable drilling apparatus of claim 9 wherein the shape memory alloy is in the form of a rod.

12. The rotary steerable drilling apparatus of claim 9 wherein the change in dimension of the shape memory alloy is a shortening of an elongated shape.

13. The rotary steerable drilling apparatus of claim 9 wherein the actuator modules comprise linkage systems adapted to move inwardly from the sleeve in response to the change in the elongated shape of the alloy.

14. The rotary steerable drilling apparatus of claim 9 further comprising a heating element in contact or in proximity with the shape memory alloy.

15. A rotary steerable drilling system, comprising: the rotary steerable drilling apparatus of claim 9 further comprising a downhole electrical power generator, electronics for controlling the electrical power generated, sensors for measuring force on the pads and electronics for controlling force applied to the pads.

16. The rotary steerable drilling system of claim 15 further comprising a downhole instrument to measure direction of a bit and send a responsive signal to the steerable drilling apparatus.