Downhole Dynamometer for Accurate Rod Pumping Diagnostics
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Solution Overview
Problem
Rod pumping units face inaccuracies in downhole dynamometer measurements due to varying well conditions, leading to inefficient operation and delayed diagnostic feedback, especially in highly-deviated wells where computational models based on surface measurements can be inaccurate.
Innovation Solution
A downhole dynamometer equipped with sensors and a controller that measures and stores downhole accelerations, load, temperature, and pressure, enabling the computation of a downhole dynamometer card directly from actual downhole measurements, rather than relying on surface measurements, and allowing for calibration of conventional computations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If surface measurements are used with wave equation models to compute downhole dynamometer cards, then the device complexity is reduced, but the measurement precision deteriorates especially in highly-deviated wells
Solution Approach 1:
The patent replaces complex computational mechanical models (wave equation solutions) with direct physical measurements using accelerometers and load cells. Instead of computing downhole conditions through complex surface measurements and mathematical modeling, the invention directly measures downhole acceleration and load with sensors attached to the sucker rod string, eliminating the need for complex computational transformations and providing accurate measurements even in highly-deviated wells.
2Ease of operation
If conventional surface-based computational methods are used, then the ease of operation is maintained, but the reliability of diagnostic feedback deteriorates due to inaccuracies
Solution Approach 1:
The patent enables the downhole measurement system to be self-sufficient by directly measuring downhole conditions with accelerometers and load cells attached to the sucker rod string. The system independently captures acceleration, load, and positional data at downhole locations without requiring complex surface-based computational transformations, providing reliable diagnostic feedback that accurately reflects actual downhole pump operating conditions.
3Measurement precision
If direct downhole measurements with sensors are implemented, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent achieves measurement precision by attaching multi-functional sensor assemblies to the sucker rod string that simultaneously measure acceleration, load, and position. The accelerometers and load cells serve multiple diagnostic purposes including pump performance monitoring, rod string condition assessment, and fluid dynamics analysis, providing comprehensive downhole measurements without requiring separate specialized devices for each parameter.
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 solution improves the accuracy of dynamometer card calculations, enhances the performance of sucker rod string models, and provides more reliable diagnostic feedback by using direct downhole measurements, reducing inefficiencies and delays in rod pumping unit operations.
Implementation Method 1
The plurality of sensors is configured to measure downhole accelerations of the sucker rod string
Implementation Method 2
The plurality of sensors is configured to measure downhole accelerations of the sucker rod string and to measure a downhole load on the sucker rod string
Data Source
AI summary
A downhole dynamometer for a rod pumping unit is provided. The downhole dynamometer includes a shell within which a plurality of sensors, a non-transitory memory, and a dynamometer controller are located. The shell is configured to be coupled to a sucker rod string of the rod pumping unit and disposed in a well opposite a wellhead of the well. The plurality of sensors is configured to measure downhole accelerations of the sucker rod string and to measure a downhole load on the sucker rod string. The dynamometer controller is coupled to the plurality of sensors and the non-transitory memory. The dynamometer controller is configured to periodically collect measurements from the plurality of sensors and store the measurements in the non-transitory memory.