Triaxial Core Fracturing System for Hydraulic Fracture Evaluation
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Solution Overview
Problem
Current methods for evaluating hydraulic fracture initiation, propagation, and stress sensitivity in unconventional oil and gas reservoirs are limited by small core sizes, artificial fracture creation, and inability to simulate true triaxial confining pressures, leading to inaccurate representations of fracture behavior and permeability changes.
Innovation Solution
A device and method that apply triaxial confining pressures to a large-sized core, inject liquid carbon dioxide or fracturing fluid, and use acoustic emission monitoring and high-speed cameras to evaluate fracture initiation, propagation, and stress sensitivity, while also testing permeability changes before and after fracturing, simulating real hydraulic fracturing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If numerical simulation is used to simulate hydraulic fracture initiation and propagation, then the complete process can be well simulated and intuitively displayed, but the results are greatly affected by boundary conditions, initial conditions, parameter settings, and overly idealized assumptions, unable to truly reflect fracture states in inhomogeneous and highly random porous reservoir rock
Solution Approach 1:
The patent creates physical replicas of reservoir conditions by constructing a true triaxial core fracturing system that replicates underground stress states, fluid injection processes, and fracture propagation behavior. Instead of relying on idealized numerical models, the system uses actual core samples from reservoirs subjected to realistic triaxial confining pressures, allowing direct observation and measurement of fracture initiation and propagation under conditions that truly represent in-situ reservoir environments.
2Reliability
If indoor core fracturing simulation test with large-size cubic core and true triaxial confining pressures is used, then the hydraulic fracture propagation state under underground stress can be well simulated, but it requires complex equipment and cannot easily monitor fracture propagation path and permeability variation
Solution Approach 1:
The patent integrates multiple measurement and monitoring functions into a unified true triaxial core fracturing system. The device combines triaxial confining pressure application, fluid injection capability, acoustic emission monitoring, high-speed camera imaging, and permeability measurement systems into a single integrated platform. This merging of functions allows simultaneous observation of fracture propagation paths through transparent sidewalls, real-time acoustic emission signals indicating fracture events, and permeability changes before and after fracturing, all while maintaining realistic triaxial stress conditions.
3Ease of manufacture
If traditional fracture stress sensitivity test with small cylindrical core is used, then the test can be performed with simple equipment, but the core and fracture sizes are too small, artificial splitting is used instead of real hydraulic fracture, and only one-way seepage can be simulated
Solution Approach 1:
The patent fundamentally changes the scale parameter of the test system by transitioning from small cylindrical cores (diameter <10 cm) to large-size cubic cores (50 cm edge length). This parameter change enables the creation of realistic hydraulic fractures that propagate through the entire core volume, rather than artificial splits in small samples. The larger core size also allows simulation of bidirectional seepage (from wellbore to reservoir and vice versa), and the use of actual hydraulic fracturing processes instead of mechanical splitting, thereby improving the representativeness and precision of stress sensitivity measurements.
Data Source
AI summary
A device and method for evaluating fracture initiation and propagation, and a stress sensitivity of a propped fracture is provided. The device includes a core part, a confining pressure loading part, a fracturing fluid pumping part, a stress sensitivity testing part and a fracture monitoring part. The method evaluates fracture initiation and propagation, and a stress sensitivity of a propped fracture using the above device and is reliable and simple to operate and guides optimization of construction parameters of hydraulic fracturing, thus achieving improvement in productivity of an oil and gas well.