Virtual Transducer for Stick-Slip Control in Drilling Systems
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Solution Overview
Problem
Systems prone to stick-slip and resonant behavior, such as those in oil drilling and pumping, face challenges in controlling undesirable oscillations without the need for sensors near the driven element, which are costly and prone to failure in hostile environments.
Innovation Solution
A 'virtual transducer' method estimates and controls stick-slip behavior by measuring parameters like velocity, torque, and rotational angle at the drive apparatus, eliminating the need for sensors near the driven element and using regulators like linear quadratic and ITAE full state feedback to manage oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are located at the driven element to measure oscillatory behavior, then measurement precision is improved, but device complexity and cost increase, and reliability decreases due to hostile environment
Solution Approach 1:
The patent uses drive element parameters (torque, speed, position) as an intermediary to indirectly measure the oscillatory behavior of the driven element. Instead of placing sensors directly at the driven element, the system measures parameters at the drive element that correlate with the driven element's behavior through the compliance of the connection, thereby avoiding the need for sensors in the hostile environment while still achieving measurement capability
Solution Approach 2:
The patent creates a virtual model or copy of the driven element's behavior by using mathematical relationships and compliance characteristics to replicate what the driven element's motion would be based on drive element measurements. This virtual copy allows measurement of oscillatory behavior without physical sensors at the driven element location
2Measurement precision
If sensors are located at the driven element to detect oscillations, then measurement precision is improved, but reliability worsens due to hostile environment exposure
Solution Approach 1:
The patent uses drive element parameters (torque, speed, position) as an intermediary to indirectly measure the oscillatory behavior of the driven element. Instead of placing sensors directly at the driven element, the system measures parameters at the drive element that correlate with the driven element's behavior through the compliance of the connection, thereby avoiding the need for sensors in the hostile environment while still achieving measurement capability
Solution Approach 2:
The patent creates a virtual model or copy of the driven element's behavior by using mathematical relationships and compliance characteristics to replicate what the driven element's motion would be based on drive element measurements. This virtual copy allows measurement of oscillatory behavior without physical sensors at the driven element location
3Stability of the object's composition
If compliance in the connection is reduced to prevent oscillation, then stability is improved, but ease of operation worsens due to increased rigidity and stress
Solution Approach 1:
The patent implements feedback control by continuously monitoring drive element parameters and adjusting the driving force to counteract oscillatory behavior. The control system uses measured torque, speed, and position data to detect oscillations and applies corrective feedback to stabilize the system, allowing the compliant connection to remain in place while preventing harmful oscillations
Solution Approach 2:
The patent changes the operational parameters of the drive element (torque, speed, acceleration) dynamically to prevent stick-slip behavior and oscillations. By adjusting these parameters in real-time based on measured conditions, the system maintains stability without requiring reduced compliance or increased rigidity in the mechanical connection
4Ease of manufacture
If compliant connection is used to connect drive and driven elements, then ease of manufacture is improved, but stability worsens due to resonant oscillation
Solution Approach 1:
The patent implements feedback control by continuously monitoring drive element parameters and adjusting the driving force to counteract oscillatory behavior. The control system uses measured torque, speed, and position data to detect oscillations and applies corrective feedback to stabilize the system, allowing the compliant connection to remain in place while preventing harmful oscillations
Solution Approach 2:
The patent changes the operational parameters of the drive element (torque, speed, acceleration) dynamically to prevent stick-slip behavior and oscillations. By adjusting these parameters in real-time based on measured conditions, the system maintains stability without requiring reduced compliance or increased rigidity in the mechanical connection
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively prevents stick-slip and resonant behavior, reducing system strain and maintaining pumping capacity while minimizing costs and complexity by eliminating the need for downhole sensors.
Implementation Method 1
any drive connection in a mechanical system exhibits some degree of compliance, i.e. a tendency to yield or bend under load, within the elastic limit of the material
Implementation Method 2
the driving force will be slightly out of phase with a corresponding reaction of a driven element at the opposite end of the connection, due to inertia of the driven component
Implementation Method 3
stick-slip behavior refers to an undesired intermittent form of motion that sometimes occurs between relatively moving parts where the coefficient of kinetic friction between the parts is less than the coefficient of static friction between the parts
Implementation Method 4
the resilient element may cause the system to oscillate as energy is alternately stored and released in the resilient element
Data Source
AI summary
An apparatus is provided for estimating and/or precluding stick-slip, or other oscillatory or resonant behavior, through use of a virtual transducer, which precludes the need for having sensors located adjacent to a driven element of the system, or adjacent contact surfaces at which the stick-slip relative motion may occur. Parameters measurable at a drive mechanism are utilized for controlling a system in a manner which precludes stick-slip, or other oscillatory or resonant behavior, of a driven element of the system. Relative motion between contacting surfaces in the driven element, prone to stick-slip behavior, is controlled after sufficient force is applied by the drive element to overcome static friction forces between the contacting surfaces and break them free from one another, relative motion between the surfaces is maintained at a high enough relative speed that the surfaces are precluded from contacting one another, so that stick-slip behavior is precluded.