Model based adaptive control scheme for pump down operation

A system for a pump down operation comprising:

• a controller disposed on an information handling system and configured to identify a difference between a downhole tension set-point to an actual downhole tension;
• a pump drive connected to the information handling system and configured to adjust a desired flow rate of the pump drive based at least in part on the difference from the controller to create an actual flow rate from the pump drive to follow the downhole tension set- point;
• a parameter estimation unit disposed on the information handling system and connected to at least the pump drive, configured to produce a fluid drag coefficient, a friction coefficient, and a line speed delay constant;
• and
• a controller design unit disposed on the information handling system and connected to at least the parameter estimation unit and the controller, configured to send one or more control gains to the controller based at least in part on the fluid drag coefficient, the friction coefficient, and the line speed delay constant, wherein the line speed delay constant identifies a time delay between a line speed of the motor drive and a velocity of a downhole tool and is calculated using a depth of the wireline in the wellbore and a speed of sound in the wireline.

A method for controlling a tension on a conveyance downhole comprising:

• inputting a downhole tension set-point into a controller;
• identifying a difference between the downhole tension set-point and an actual downhole tension with the controller;
• adjusting a line speed set-point of a motor drive and a desired flow rate of a pump drive based at least in part on the difference from the controller to follow the downhole tension set-point;
• producing a fluid drag coefficient, a friction coefficient, and a line speed delay constant with a parameter estimation unit that is connected to the motor drive and the pump drive;
• and
• sending one or more control gains to the controller based at least in part on the fluid drag coefficient, the friction coefficient, and the line speed delay constant, wherein the line speed delay constant identifies a time delay between a line speed of the motor drive and a velocity of a downhole tool and is calculated using a depth of the wireline in the wellbore and a speed of sound in the wireline.