Variable Speed Drive Beam Pump Rod Load Smoothing
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Solution Overview
Problem
In deeper wells, diagnosing pump performance from surface dynamometer cards is challenging due to the complex dynamics of long sucker rod strings, leading to inefficient rod loading and increased energy consumption.
Innovation Solution
A method that involves monitoring surface linear speed of rods and adjusting the motor speed using a variable speed drive to smooth rod loading by slowing down during peak loads and accelerating during valleys, thereby reducing energy consumption and gearbox loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If constant speed operation is used in beam pump, then equipment structure is simple, but rod loading is uneven and energy consumption is high
Solution Approach 1:
The patent applies variable speed drive technology to convert the constant speed rotation of the prime mover into variable speed rotation, allowing the motor speed to dynamically adjust during the pump cycle. This enables the system to operate at optimal speeds during different phases (upstroke, downstroke), smoothing rod loading and reducing peak loads while lowering overall energy consumption. The dynamic speed adjustment resolves the contradiction by making the system adaptable to varying load conditions.
Solution Approach 2:
The patent changes the operational parameter of motor speed from constant to variable. By using a variable speed drive, the motor speed can be adjusted as a controllable parameter to match the varying load requirements throughout the pump cycle. This parameter change allows the system to reduce energy consumption by operating at lower speeds during high-load periods while maintaining necessary production rates, thus resolving the energy consumption contradiction.
2Productivity
If high speed operation is used to increase productivity, then production rate increases, but rod loading peaks increase and cause excessive stress
Solution Approach 1:
The variable speed drive enables dynamic speed adjustment during the pump cycle, allowing the system to maintain higher average speeds for productivity while reducing peak speeds during critical phases. The motor speed is dynamically controlled to smooth out loading peaks on the rods, preventing excessive stress while maintaining overall production rates. This dynamic control resolves the contradiction between productivity and rod strength.
Solution Approach 2:
The patent applies periodic speed modulation synchronized with the pump cycle phases. The variable speed drive periodically adjusts motor speed to match the cyclical nature of beam pump operation, reducing speed during upstroke (when rod loading peaks) and maintaining or increasing speed during downstroke. This periodic action pattern allows sustained productivity while protecting rod strength through rhythmic speed variation.
Data Source
AI summary
A well has a wellbore extending from a surface. Tubing extends within the wellbore for supporting a downhole pump. Sucker rods extend within the tubing for reciprocating a travelling valve. A load calculator determines loading on the sucker rods during a pump cycle. A variable speed driver reciprocates the sucker rods and travelling valve. A real time speed controller varies a speed of the driver in response to loading information from the load calculator for smoothing the rod load in a beam pump cycle. A target rod load is obtained and a surface linear speed of rods is varied by either slowing or speeding a driver for varying a surface linear speed of the rods when rod loading is above or below the target rod load.