ESP Motor Control for Pump-Off Detection via Current Monitoring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional artificial lift systems using sucker rods require bulky and expensive physical load sensors to measure pumping force, making them inefficient and costly, while ESP systems lack methods to detect pump-off conditions and prevent fluid pound effectively.
Innovation Solution
Monitoring the current drawn by the ESP motor using current sensors to determine instantaneous force and detect pump-off conditions, controlling the motor to prevent fluid pound by re-initializing it when sudden force decreases are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical load sensors (strain gauges or load cells) are incorporated into the sucker rod pump system to measure pumping force, then force measurement capability is improved, but system complexity and cost increase
Solution Approach 1:
The patent replaces mechanical load sensors (strain gauges, load cells) with an electrical measurement system. The linear permanent magnet motor's controller measures electrical parameters (current, voltage, power) to determine the force produced by the motor, thereby eliminating the need for physical force measurement devices on the sucker rod pump assembly.
Solution Approach 2:
The patent uses electrical parameters as an intermediary to indirectly measure force. Instead of directly measuring mechanical force with sensors, the system measures electrical consumption and performance metrics of the motor, which correlate to the force output, providing a non-intrusive measurement method.
2Measurement precision
If physical load sensors are installed on the sucker rod pump to detect pump-off conditions, then detection accuracy is improved, but installation complexity and cost increase
Solution Approach 1:
The patent replaces mechanical sensing systems with electrical sensing. The controller monitors electrical parameters (current draw, power consumption) that change when pump-off conditions occur, eliminating the need for physical sensors on the pump assembly and simplifying installation.
Solution Approach 2:
The motor's electrical system serves dual purposes: driving the pump and detecting pump-off conditions. The same electrical infrastructure used to operate the motor also provides the data needed for detection, eliminating the need for separate detection hardware.
3Productivity
If the motor operates at high speed during pump-off conditions, then productivity is maintained, but fluid pound damage occurs
Solution Approach 1:
The controller continuously monitors electrical parameters and detects pump-off conditions in real-time. When pump-off is detected, the controller provides feedback to adjust motor operation, reducing speed or changing operational mode to prevent fluid pound, thereby protecting the system while maintaining productivity when conditions are normal.
Solution Approach 2:
The system dynamically adjusts motor operation based on real-time conditions. The controller can change speed, torque, or operational mode in response to detected pump-off conditions, allowing the system to adapt its behavior to prevent damage while maximizing productivity during normal operation.
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 simplifies the system by eliminating the need for physical load sensors, allowing for efficient and cost-effective detection and prevention of fluid pound in ESP systems, extending the motor's lifespan and maintaining oil flow stability.
Implementation Method 1
a linear permanent magnet motor to lift oil from the well
Implementation Method 2
The drive includes a controller that receives instantaneous current measurements from the current sensors and determines an instantaneous current vector for each of the phases of the output power. The controller then determines an instantaneous force generated by the motor based on the instantaneous current vectors.
Data Source
AI summary
Systems and methods for determining the existence of a pump-off condition in an ESP system and controlling the motor to prevent fluid pound that would otherwise result from the pump-off condition. The current drawn by the ESP motor during a power stroke is monitored and the instantaneous force generated by the motor is determined from the instantaneous current. Pump-off conditions may be indicated by sudden, large decreases in the generated force, smaller decreases in force that occur over a longer period, or forces below those seen during a dwell time. In response to detecting a pump-off condition, the motor may be stepped through the rest of the stroke, temporarily halted and re-initialized, thereby preventing potentially damaging fluid pound that would otherwise result from the pump-off condition.