Fracture Length Determination via Resonance
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Solution Overview
Problem
The characteristics of fractures induced during hydraulic fracturing are unpredictable, making it difficult to determine the fracture length even after the process is completed.
Innovation Solution
A method and system that isolate a portion of the borehole using packers, increase fluid pressure with a piston, and deploy a low-frequency source to generate resonance oscillations, allowing for the determination of fracture length based on the resonance frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic fracturing is performed to create fractures in rock layers, then energy is created and new channels are formed in the rock, but the characteristics of the resulting fracture become unpredictable and not readily discernible
Solution Approach 1:
The patent applies mechanical vibration by using a vibration source to generate resonance oscillations within the fracture. The vibration source emits vibrations at varying frequencies, and when the frequency matches the natural resonance frequency of the fracture, resonance occurs. This resonance allows for the determination of fracture length based on the measured resonance frequency, thereby recovering information that would otherwise be lost.
Solution Approach 2:
The patent employs feedback by measuring the resonance frequency of the fracture and using this measurement to determine the fracture length. The system creates a feedback loop where the vibration source generates vibrations, sensors detect the resonance frequency, and this information is processed to provide feedback about the fracture characteristics, making the previously unpredictable fracture properties measurable and controllable.
2Measurement precision
If conventional hydraulic fracturing methods are used, then fractures are induced in the rock, but the fracture length and characteristics cannot be determined after completion
Solution Approach 1:
The patent uses mechanical vibration to enable precise measurement of fracture length. By introducing a vibration source that generates resonance oscillations at the fracture's natural frequency, the system transforms the invisible fracture into a measurable resonant system. The resonance frequency directly correlates with fracture length, providing a precise measurement method that overcomes the difficulty of detecting fracture characteristics after hydraulic fracturing.
Solution Approach 2:
The patent replaces direct mechanical measurement methods with a resonance-based acoustic measurement approach. Instead of attempting to physically measure the fracture length directly (which is difficult due to the fracture being embedded in rock), the system substitutes a mechanical vibration and resonance measurement method that can detect fracture characteristics indirectly through acoustic waves traveling through the fracture fluid.
3Measurement precision
If resonance oscillations are generated in the fracture, then the fracture length can be determined based on resonance frequency, but fluid pressure must be increased and borehole isolation required
Solution Approach 1:
The patent applies universality by using the same isolated borehole section for multiple functions: it serves as both the containment vessel for pressure increase and the resonating cavity for measuring fracture length. The isolation system created by packers is not just a preparatory step but becomes the actual measurement chamber, eliminating the need for separate measurement equipment and reducing overall device complexity.
Solution Approach 2:
The fracture itself serves as the resonating element that provides the measurement signal. The fluid within the fracture acts as both the medium for pressure transmission and the resonant oscillator. The system essentially uses the fracture's own physical properties (its length and fluid content) to generate the resonance signal, making the fracture self-diagnostic without requiring external measurement probes or complex sensing equipment.
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 accurate measurement of fracture length by utilizing resonance frequency measurements, correlating eigenfrequency with fracture length, volume, and fluid properties, providing a reliable method for post-fracturing analysis.
Implementation Method 1
varying a frequency of the low-frequency source to generate resonance oscillations at a resonance frequency in the fracture
Data Source
AI summary
A system and method to determine a length of a fracture induced from a borehole are described. The method includes isolating a portion of the borehole, the portion of the borehole including an end of the fracture at the borehole wall, increasing fluid pressure in the portion of the borehole, deploying a low-frequency source in the portion of the borehole, and varying a frequency of the low-frequency source to generate resonance oscillations at a resonance frequency in the fracture. The method also includes determining the length of the fracture based on the resonance frequency.