Downhole Wireline Cable Diameter Measurement Using Eddy Current Sensors
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Solution Overview
Problem
Existing diameter measurement devices for wireline cables in oil and gas field operations are inaccurate in dirty and rough handling conditions, failing to provide reliable dynamic measurements due to environmental interference and mechanical damage.
Innovation Solution
A diameter measurement device with opposed shafts and resilient members, utilizing eddy current sensors to measure cable deformation, which is resistant to environmental interference and capable of accurate diameter measurement in harsh conditions, with digital output for precise weight and stretch calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If optical methods (laser caliper) are used to measure cable diameter in real time, then measurement speed and real-time capability are improved, but measurement precision deteriorates in dirty environments due to stray light interference and laser instability
Solution Approach 1:
The patent replaces optical measurement methods with electrical measurement methods. Specifically, it uses应变 gauges (strain gauges) bonded to the cable surface to directly measure diameter changes through electrical resistance changes, eliminating the need for optical systems that are sensitive to stray light and environmental dirt. This substitution of measurement principle resolves the contradiction by providing real-time measurements without the precision limitations of optical methods in dirty environments.
Solution Approach 2:
The patent introduces应变 gauges as an intermediary element bonded to the cable surface. These gauges act as a mediator that converts mechanical diameter changes into electrical signals that can be measured accurately regardless of environmental conditions. The应变 gauges are positioned and wired to provide direct measurement of cable diameter changes without being affected by stray light or dirt, thus resolving the measurement precision issue while maintaining real-time capability.
2Reliability
If cable diameter is measured dynamically during cable movement in and out of borehole, then operational safety and failure prevention are improved, but device reliability deteriorates due to rough handling and harsh downhole conditions
Solution Approach 1:
The patent applies measurement devices (strain gauges and wiring) to the cable surface before the cable is lowered into the borehole. This preliminary preparation ensures that the measurement system is already in place and protected by the cable's own structure before exposure to harsh downhole conditions. The cable is then lowered with the measurement system already integrated, avoiding the need to deploy complex protective structures during cable retrieval operations.
Solution Approach 2:
The patent uses thin应变 gauge films bonded to the cable surface to create a measurement system that is both sensitive to diameter changes and resistant to harsh environments. These thin film sensors conform to the cable surface and are protected by the cable's own jacketing and structure, providing reliable measurements without requiring bulky protective housings that would increase device complexity and interfere with cable flexibility.
3Measurement precision
If multiple pairs of shafts and resilient members are used to measure cable deformation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the measurement function from a complex mechanical structure and concentrates it in the应变 gauges bonded to the cable surface. Instead of using multiple pairs of shafts and resilient members that would require complex assembly and calibration, the measurement function is extracted and implemented through simple electrical sensors that directly bond to the cable, providing precise measurements with minimal structural complexity.
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
The device provides accurate and reliable dynamic diameter measurements of wireline cables, resistant to environmental interference and mechanical damage, enabling precise weight and stretch calculations, and recalibration of cable position, thus enhancing operational safety and reducing costly failures.
Implementation Method 1
The sensor is an eddy current sensor having a sensing face that faces the resilient member
Data Source
AI summary
A diameter measurement device for measuring the diameter of a wireline cable dynamically during moving in and out of a borehole. The measurement device has a first pair of opposed shafts, a rotating roller on each shaft of said first pair of opposed shafts, a first resilient member mounted to urge at least one of the shafts of said first pair of opposed shafts toward the wireline cable to be measured, and a first intrinsic measuring unit operatively associated with the first resilient member to measure the displacement thereof. The measuring device further has at least a second pair of opposed shafts angularly displaced with respect to the first pair of opposed shafts, a rotating roller on each shaft of said second pair of opposed shafts, a second resilient member mounted to urge at least one of the shafts of said second pair of opposed shafts toward the wireline cable to be measured, and a second intrinsic measuring unit operatively associated with the first resilient member to measure the displacement thereof as the wireline cable is moved lengthwise between the rollers; each of said first and second intrinsic measuring devices outputting to a digitizer for generating digital measurements of the diameter at various positions on the circumference of and along the length of said wireline cable, which measurements are transmitted to and stored in a logging device. At least one of the first and second intrinsic measuring units can be an eddy current measurement device to measure deflection of at least one of the first and second resilient members using eddy currents.