Metal sealing device

1. A method comprising:

deploying an untethered object through a passageway of a string in a well to cause the untethered object to travel along the passageway; and

operating the untethered object as the object travels in the passageway to expand a metal sealing device of the untethered object to cause the object to become caught at a downhole location,

wherein the metal sealing device is an expandable slotted ring comprising a plurality of axially extending beams, and

wherein each beam of the plurality of axially extending beams remains in an elastic state during enlargement.

2. The method of claim 1 , wherein operating the untethered object comprises extending an expansion member inside the metal sealing device to transition the metal sealing device from a first outer diameter to a larger second outer diameter.

3. The method of claim 1 , wherein operating the untethered object comprises autonomously operating the untethered object in response to sensing a property of an environment of the string as the object travels through the passageway.

4. The method of claim 1 , wherein operating the untethered object comprises communicating with the untethered object from an Earth surface of the well.

5. The method of claim 1 , wherein operating the untethered object comprises operating the untethered object in response to sensing at least one marker in the well.

6. The method of claim 1 , wherein operating the untethered object comprises sensing a repeating pattern as the object travels along the passageway.

7. The method of claim 1 , wherein deploying the untethered object comprises pushing the object with fluid.

8. The method of claim 1 , wherein operating the untethered object comprises operating the object to perform a downhole operation selected from the group consisting essentially of performing a stimulation operation, operating a downhole tool and operating a downhole valve.

9. The method of claim 1 , further comprising causing the untethered object to travel through a plurality of seats and subsequently causing the metal sealing device to expand to cause the untethered object to be caught by another seat.

10. The method of claim 1 , wherein operating the untethered object comprises at least one of the following:

shifting a sleeve;

forming a downhole obstruction; and

operating a well tool.

11. A system usable with a well, comprising:

a string comprising a passageway; and

an untethered object adapted to be deployed in the passageway such that the object travels in the passageway, the object comprising:

a metal sealing device;

an actuator; and

a controller to operate the actuator to selectively radially expand the metal sealing device as the untethered object travels in the passageway,

wherein the metal sealing device is an expandable slotted ring comprising a plurality of axially extending beams, and

wherein each beam of the plurality of axially extending beams remains in an elastic state during enlargement.

12. The system of claim 11 , wherein the string comprises a plurality of seats, each of the seats being sized to catch an object having substantially the same size, and the untethered object is adapted to pass through at least one of the seats and controllably expand to said same size to cause capture of the untethered by one of the seats.

13. The system of claim 11 , wherein the metal sealing device comprises:

a first pressure receiving side to circumscribe an axis of the sealing device;

a second pressure receiving side to circumscribe the axis;

first axially-extending slots in the first pressure receiving side; and

second axially-extending slots in the second pressure receiving side, the second axially-extending slots being offset from the first axially-extending slots to form axially-extending beams.

14. The system of claim 13 , wherein the actuator comprises a tapered expansion member to extend inside the metal sealing device to transition the metal sealing device downhole in the well from a first outer diameter to a larger second outer diameter.