Multistage downhole anchor

Abstract

The disclosure provides a downhole anchoring apparatus for use in a downhole tool. In an example implementation, a system is provided to anchor downhole tools in a wellbore. The system may include a tool body that fits within a wellbore casing, a slip having a wedge surface, a linkage connecting the slip to the tool body, and an actuator assembly. The actuator assembly may include a first actuator having a wedge surface corresponding to the slip wedge surface and a second actuator having a wedge surface corresponding to the slip wedge surface.

What is claimed is: 
     
         1 . A downhole anchoring apparatus comprising:
 a tool body;   a slip having a wedge surface;   a linkage connecting the slip to a first section of a tool body;   a first actuator having a wedge surface corresponding to the slip wedge surface; and   a second actuator having a wedge surface corresponding to the slip wedge surface.   
     
     
         2 . A downhole anchoring apparatus as in  claim 1 , wherein the first actuator comprises a slip support surface located at a first radial distance from a centerline of the downhole anchoring apparatus. 
     
     
         3 . A downhole anchoring apparatus as in  claim 2 , wherein the second actuator comprises a slip support surface located at a second radial distance from the centerline of the downhole anchoring apparatus, the second radial distance being greater than the first radial distance when the second actuator is actuated. 
     
     
         4 . A downhole anchoring apparatus as in  claim 2 , wherein the wedge surface of the first actuator comprises a wedge angle that is different than a wedge angle of the second actuator wedge surface. 
     
     
         5 . A downhole anchoring apparatus as in  claim 1 , wherein the second actuator is positioned inside the first actuator when the second actuator is not actuated. 
     
     
         6 . A downhole anchoring apparatus as in  claim 1 , wherein the linkage comprises a spring. 
     
     
         7 . A downhole anchoring apparatus as in  claim 1 , wherein the second actuator is actuated by the relative movement between the slip and the first actuator or relative movement between either the slip or the first actuator with respect to the tool body. 
     
     
         8 . A method for anchoring downhole tools, the method comprising:
 positioning a downhole tool in a wellbore, the downhole tool including a slip and a first actuator;   moving the slip along a centerline of the downhole tool toward the first actuator until a wedge surface of the slip mates with a wedge surface of the first actuator;   when the wedge surface of the slip is in contact with the wedge surface of the first actuator, moving the slip further along the centerline so that the wedge surface of the slip slides against the wedge surface of the first actuator, causing the slip to move radially outward from the centerline to a first expansion radius;   actuating a second actuator having a wedge surface corresponding to the wedge surface of the slip;   moving the slip further along the centerline and toward the second actuator until the wedge surface of the second actuator mates with the wedge surface of the slip;   when the wedge surface of the slip is in contact with the wedge surface of the second actuator, moving the slip further along the centerline, so that the wedge surface of the slip slides against the wedge surface of the second actuator, causing the slip to move radially outward from the centerline to a second expansion radius.   
     
     
         9 . A method as in  claim 8 , wherein moving the slip further along the centerline and toward the second actuator until the wedge surface of the second actuator mates with the wedge surface of the slip further comprises moving the slip along a slip supporting surface of the first actuator. 
     
     
         10 . A method as in  claim 8 , further comprising controlling the force to set the slip in the casing using a difference between the wedge angle of the first actuator and the wedge angle of the second actuator, allowing multiple setting forces in the same downhole tool. 
     
     
         11 . A method as in  claim 8 , wherein actuating a second actuator further comprises moving the second actuator out of a location within the first actuator. 
     
     
         12 . A method as in  claim 8 , wherein actuating a second actuator further comprises locking the second actuator in place once actuated. 
     
     
         13 . A system for anchoring downhole tools in a wellbore, the system comprising:
 a tool body that fits within a wellbore casing;   a slip having a wedge surface;   a linkage connecting the slip to the tool body; and   an actuator assembly including a first actuator having a wedge surface corresponding to the slip wedge surface and a second actuator having a wedge surface corresponding to the slip wedge surface.   
     
     
         14 . A system as in  claim 13 , wherein the first actuator comprises a slip support surface located at a first radial distance from a centerline of the downhole anchoring apparatus. 
     
     
         15 . A system as in  claim 14 , wherein the second actuator comprises a slip support surface located at a second radial distance from the centerline of the downhole anchoring apparatus, the second radial distance being greater than the first radial distance when the second actuator is actuated. 
     
     
         16 . A system as in  claim 14 , wherein the wedge surface of the first actuator comprises a wedge angle that is different than a wedge angle of the second actuator wedge surface. 
     
     
         17 . A system as in  claim 13 , wherein the second actuator is positioned inside the first actuator when the second actuator is not actuated. 
     
     
         18 . A system as in  claim 13 , wherein the linkage comprises a spring. 
     
     
         19 . A system as in  claim 13 , wherein the second actuator is actuated by the relative movement between the slip and the actuator assembly or relative movement between either the slip or the actuator assembly relative to the tool body. 
     
     
         20 . A system as in  claim 13 , wherein both the second actuator comprises a locking mechanism to hold it in place when actuated by the movement of the slip axially toward the actuator assembly.