Beam Pumping Unit Load Sensing via Samson Post Strain
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Solution Overview
Problem
Beam pumping units face challenges in accurately measuring and controlling the dynamic loads on sucker rod strings due to interference from traveling stress waves, which affects the efficiency and reliability of fluid extraction, and existing load cell installations are often elevated and costly to maintain.
Innovation Solution
A control system that includes a strain gauge coupled to the Samson post of the beam pumping unit to measure Samson post strain, allowing the beam pumping unit controller to compute and induce variable loads, thereby eliminating the need for elevated load cells and improving maintenance safety and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If load cells are installed at elevated positions to measure rod load, then measurement capability is achieved, but maintenance cost and safety risks increase
Solution Approach 1:
The patent uses strain gauges mounted on the Samson post as a surrogate measurement system. Instead of directly measuring rod load with elevated load cells, the strain gauges measure the bending strain on the Samson post, which is correlated to the rod load through a transfer function. This creates an indirect measurement copy that eliminates the need for elevated load cell installations.
Solution Approach 2:
The patent replaces the mechanical load cell system with an electrical strain gauge measurement system. Strain gauges convert mechanical strain on the Samson post into electrical signals that can be processed by the controller, substituting direct mechanical load measurement with an electrical sensing approach mounted at ground level.
2Ease of repair
If strain gauges are used on the Samson post instead of load cells, then maintenance safety and cost are improved, but measurement complexity increases due to transfer function requirements
Solution Approach 1:
The controller automatically performs the transfer function computation and surface card generation without requiring external intervention. The system self-calibrates and processes the strain gauge data into meaningful rod load measurements and diagnostic information, eliminating the need for manual calculations or complex external measurement systems.
Solution Approach 2:
The transfer function acts as an intermediary mathematical model that bridges the strain gauge measurement and the desired rod load information. This computational mediator translates the indirect strain measurements into accurate load data, managing the complexity within the control system rather than requiring complex physical measurement apparatus.
3Ease of operation
If surface measurements are used for controlling the beam pumping unit, then control capability is achieved, but measurement accuracy is reduced due to traveling stress waves interference
Solution Approach 1:
The patent extracts the measurement location from the rod-string system (where stress waves interfere) and places it on the Samson post foundation (where measurements are stable). By taking the measurement point out of the dynamic rod-string environment and locating it on the stationary Samson post, the system eliminates interference from traveling stress waves while maintaining control capability.
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 reduces the costs of load sensors, enhances maintenance safety, and improves load sensor reliability by using lower-cost strain gauges on the Samson post, providing accurate load measurements and control for the beam pumping unit.
Implementation Method 1
The strain gauge is coupled to the Samson post and is configured to measure a Samson post strain
Data Source
AI summary
A control system for operating a beam pumping unit includes a strain gauge and a beam pumping unit controller. The strain gauge is coupled to a Samson post of the beam pumping unit, and is configured to measure a Samson post strain. The beam pumping unit controller is coupled to the strain gauge and is configured to operate the beam pumping unit to induce a variable load on a rod of the beam pumping unit. The beam pumping unit controller is further configured to receive the Samson post strain from the strain gauge and compute the variable load based on the Samson post strain.