Cutting pipes in wellbores using downhole autonomous cutting tools

A downhole autonomous cutting tool configured to cut a pipe in a wellbore, the downhole autonomous cutting tool comprising:

• a body comprising a hydraulic motor with a rotor embedded inside a stator;
• a locking unit attached to the body, the locking unit actuable to engage inner surfaces of the pipe in the wellbore;
• a sensor module operable to detect interactions between the pipe and walls of the wellbore;
• and
• an actuation unit with a plurality of cutting elements moveable between a running position and a cutting position, the actuation unit rotationally fixed to the rotor.

A method for cutting a pipe in wellbores, the method comprising:

• dropping a downhole autonomous cutting tool in a pipe, a downhole autonomous cutting tool controlled by a flow rate and configured to identify a location where interaction between the pipe and walls of the wellbore limits a downhole movement of the pipe;
• sensing the pipe with a sensor module until it reaches the location where interaction between the pipe and the walls of the wellbore limits a downhole movement of the pipe;
• receiving a signal from the sensor module with an identified location;
• sending a signal to open a main valve to allow flow through the downhole autonomous cutting tool;
• locking the downhole autonomous cutting tool in position relative to the pipe and preventing the tool from moving further downhole;
• sending a signal to an actuation unit to engage and extend a plurality of cutting elements outwards and initiate cutting of the pipe;
• and
• retrieving the cut pipe.