ESP Motor Voltage Control for Changing Downhole Conditions
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Solution Overview
Problem
Conventional electric submersible motors (ESMs) face inefficiencies due to discrepancies between laboratory-derived operating guidelines and actual downhole conditions, leading to unpredictable power usage and increased operating costs, primarily because they do not account for changing environmental and operational conditions such as temperature and gas composition, and voltage drops in long electrical cables.
Innovation Solution
A dynamic power optimization system and method that involves a variable speed drive (VSD) controller with non-transitory memory storage, which dynamically adjusts voltage output based on real-time measurements of pump performance variables and motor current, using a feedback loop to optimize power usage by increasing or decreasing voltage in response to changes in current and performance variables, thereby maintaining optimal operation within defined thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional motors operate based on laboratory-derived operating guidelines, then motor rating and BEP are established, but actual downhole operating conditions cause discrepancies leading to inefficient operation
Solution Approach 1:
The system dynamically adjusts motor operating parameters (voltage, frequency, speed) in real-time based on actual downhole conditions detected by sensors, transitioning from static laboratory ratings to adaptive field operation. The VSD continuously modifies motor operation to match changing temperature, pressure, and load conditions.
Solution Approach 2:
The system implements closed-loop feedback by measuring actual motor current, voltage, temperature, and pump performance parameters, then using this data to adjust VSD output and maintain optimal operating point. This feedback mechanism corrects deviations from efficient operation caused by changing downhole conditions.
2Ease of operation
If VSD adjusts voltage and frequency to control motor speed, then motor speed varies to accommodate performance requirements, but power consumption changes dynamically increasing operating costs
Solution Approach 1:
The system optimizes power consumption by dynamically adjusting voltage and frequency parameters independently rather than maintaining constant V/Hz ratio. The VSD modifies these parameters based on actual motor load and efficiency characteristics to minimize power consumption while maintaining required motor speed and pump performance.
Solution Approach 2:
The system uses feedback from current sensors and power measurement to continuously monitor and adjust VSD output parameters, ensuring motor operates at optimal efficiency point under varying load conditions. This prevents excessive power consumption when full speed or power is not required.
3Length of stationary object
If long electrical cables connect surface power source to downhole motor, then power can be delivered to deep wells, but voltage drop occurs making power delivery unpredictable
Solution Approach 1:
The system measures actual voltage and current at the motor terminals using downhole sensors and communicates this data to the surface VSD. This feedback enables real-time compensation for cable voltage drop by adjusting VSD output to maintain accurate and predictable power delivery to the motor despite long cable lengths.
Solution Approach 2:
The system uses communication signals transmitted through the power cables themselves to convey information about actual motor operating conditions back to the surface VSD. This intermediary use of the power cables for both power and data transmission enables real-time adjustment without additional sensing infrastructure.
4Adaptability or versatility
If motor operates under changing environmental conditions such as temperature and gas composition, then motor must adapt to maintain efficiency, but conventional systems lack real-time adjustment capability
Solution Approach 1:
The VSD system performs multiple functions: speed control, power optimization, condition monitoring, and adaptive adjustment. By consolidating these functions into a single integrated control system, the patent achieves environmental adaptation without proportionally increasing overall system complexity.
Solution Approach 2:
The system automatically adjusts motor operating parameters in response to detected environmental changes without requiring manual intervention. The VSD self-regulates voltage, frequency, and power output based on sensor feedback, enabling the motor to service itself across varying operating conditions.
Data Source
AI summary
A method comprises operating an electric submersible pump (ESP) motor downhole in a well. The ESP motor is electrically connected to a variable speed drive (VSD) proximate to the well. The operating comprises measuring a revolution rate and a motor current of the ESP motor for a first period of time and performing a first adjustment of a voltage output of the VSD. The method comprises measuring, after the first adjustment, the revolution rate and the motor current of the ESP motor for a second period of time determining a difference between the motor current measured for the first period of time and the motor current measured for the second period of time; and performing a second adjustment of the voltage output of the VSD based on a change in the revolution rate and the motor current between the first period of time and the second period of time.