Autonomous untethered well object

1. A method comprising:

deploying an untethered object through a passageway of a string in a well;

sensing a pressure in the passageway as the object is being communicated through the passageway, wherein sensing a pressure comprises sensing a differential pressure between an uphole end of the untethered object and a downhole end of the untethered object;

determining a position of the object based at least in part on the sensing of the pressure; and

selectively autonomously operating the untethered object in response to the determined position.

2. The method of claim 1 , wherein selectively autonomously operating the untethered object comprises transitioning the object from a first state to a second state.

3. The method of claim 2 , wherein transitioning the object comprises transitioning the object from a radially contracted state to a radially expanded state in response to the sensing.

4. A method comprising:

communicating an untethered object though a passageway of a string in a well;

sensing a pressure as the object is being communicated through the passageway, wherein sensing a pressure comprises sensing a differential pressure between an uphole end of the untethered object and a downhole end of the untethered object; and

selectively radially expanding the untethered object in response to the sensing.

5. The method of claim 4 , further comprising detecting at least one valve of the string based on the sensing, wherein selectively radially expanding the untethered object further comprises selectively radially expanding the untethered object in response to the detecting.

6. The method of claim 4 , wherein sensing the pressure comprises sensing a differential pressure across the object.