Acoustic Core Sample Testing with Elastic Pressure Cell
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Solution Overview
Problem
Conventional methods for testing large core samples from wellbores face challenges such as sample size limitations, disturbance to the sample during testing, and inconsistent transducer attachment, which affect the accuracy and efficiency of measuring acoustic properties.
Innovation Solution
A testing apparatus with a sample chamber and ultrasonic transducers that applies consistent pressure and ensures stable, consistent contact with the sample, using a pressure-retaining case and lock mechanisms to securely hold the transducers in place, allowing for quick and easy loading and unloading of large samples while minimizing disturbance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional triaxial test apparatus is used to measure acoustic properties, then mechanical properties can be derived, but sample size is limited and transducer attachment is inconsistent
Solution Approach 1:
The apparatus divides the sample chamber into modular components including end caps, a pressure cell, and a removable sample chamber assembly. This segmentation allows large core samples to be accommodated by configuring the chamber dimensions appropriately, while maintaining the ability to apply controlled pressures and attach transducers systematically.
Solution Approach 2:
The pressure cell serves multiple functions: it applies confining pressure to the sample, provides a sealed environment for pore pressure control, and supports the mounting of acoustic transducers. This multi-functionality allows the same apparatus to handle both mechanical testing and acoustic property measurement without requiring separate specialized equipment for each function.
2Reliability
If conventional testing methods are used, then mechanical properties can be measured, but sample disturbance occurs during testing
Solution Approach 1:
The apparatus allows transducers to be attached to the sample before the actual acoustic measurement begins. The sample is first placed in the pressure cell, confining pressure is applied, and then transducers are mounted on the sample surface. This preliminary attachment ensures stable contact during the measurement process without requiring disturbance of the sample during data acquisition.
Solution Approach 2:
The pressure cell uses an elastic impermeable membrane to enclose the sample, providing a flexible yet sealed containment. This flexible membrane allows uniform application of confining pressure while maintaining sample integrity, and facilitates stable transducer attachment without rigid constraints that could disturb the sample structure.
3Measurement precision
If transducers are attached to sample surface, then acoustic measurements can be taken, but attachment consistency varies
Solution Approach 1:
The pressure cell applies uniform confining pressure across the entire sample surface through the elastic membrane. This equipotential pressure distribution ensures that transducers attached to the sample surface experience consistent contact conditions, eliminating variations in attachment quality that would otherwise occur with non-uniform pressure or manual positioning alone.
Solution Approach 2:
The elastic impermeable membrane acts as an intermediary between the pressure cell and the sample. It transmits confining pressure uniformly to the sample surface while providing a consistent interface for transducer attachment. This intermediary layer ensures that all transducers are attached under identical pressure conditions, improving attachment consistency across the sample surface.
4Volume of moving object
If large core samples are tested, then comprehensive acoustic properties can be measured, but loading and unloading becomes time-consuming
Solution Approach 1:
The sample chamber is designed as a removable assembly that can be detached from the pressure cell. Large core samples can be loaded into the sample chamber outside the pressure cell environment, and then the entire chamber assembly is quickly installed into the pressure cell. This segmentation eliminates the need to manually handle and position large samples inside the pressurized environment, significantly reducing loading and unloading time.
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
Enables efficient and accurate measurement of acoustic properties of large core samples with consistent transducer attachment, reducing testing time and maintaining sample integrity by ensuring minimal disturbance and consistent pressure application.
Implementation Method 1
A pressure-retaining case surrounds a radial surface of the central member. The pressure-retaining case is configured to contain a pressurized fluid between an annulus formed between the pressure-retaining case and the central member.
Implementation Method 2
acoustic transmitters configured to emit sounds waves in the central member. The acoustic transmitters are ultrasonic emitters and the acoustic receivers are ultrasonic acoustic sensors.
Implementation Method 3
acoustic receivers configured to detect sound waves in the sample chamber
Data Source
AI summary
A central member defines a sample chamber and includes an elastic material configured to enclose at least a portion of a sample, acoustic sensors configured to detect sound waves in the sample chamber, and acoustic emitters configured to emit sounds waves in the central member. A pressure-retaining case is configured to contain a pressurized fluid between an annulus formed between the pressure-retaining case and the central member. A switch is configured to connect or disconnect a pulser and receiver circuit to a specified emitter of the acoustic emitters. A data acquisition unit is configured to receive a signal from each of the acoustic sensors. A pulser and receiver circuit is configured to send an electric pulse to an acoustic emitter and a control signal to the data acquisition unit.