Rock Fracture Initiation Prediction via Double Fracture Model
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for predicting the initiation of rock fractures in deep reservoirs are inaccurate due to the inability to fully simulate the real geostress environment, leading to deviations in experimental results.
Innovation Solution
A method using finite element analysis to establish a double fracture model, applying confining pressures to simulate different horizontal stress differences, and analyzing stress changes to predict fracture initiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If indoor experimental tests are used to predict rock fracture initiation, then the initiation point can be accurately captured, but the real geostress environment cannot be fully simulated resulting in inaccurate prediction
Solution Approach 1:
The patent creates a physical model that copies and simulates the real geostress environment and fracture conditions. By building a scaled model with controlled stress fields that replicate in-situ conditions, the system achieves both measurement precision and reliability without needing full-scale field tests.
Solution Approach 2:
The patent introduces an intermediate physical model system that acts as a mediator between indoor experiments and field conditions. This model includes a loading device and stress control system that translates real geostress conditions into controllable laboratory-scale experiments, enabling accurate simulation of horizontal stress differences and fracture initiation.
2Loss of information
If microseismic monitoring is used to monitor fracture expansion, then the distribution characteristics can be restored, but the initiation behavior of fractures cannot be accurately captured
Solution Approach 1:
The patent uses digital image correlation technology to perform preliminary measurement of displacement and strain fields before fracture initiation occurs. This allows the system to detect and record the earliest signs of fracture development, capturing initiation behavior that would be missed by microseismic monitoring which only detects later expansion events.
Solution Approach 2:
The patent replaces microseismic wave-based detection with optical field-based digital image correlation technology. This substitution enables direct visualization and measurement of surface deformations and stress distributions, providing precise capture of fracture initiation behavior rather than relying on indirect acoustic signal detection.
3Adaptability or versatility
If three-dimensional stress field analysis is implemented, then the real form of ground stress can be represented, but the initiation mechanism of natural fractures has not been fully studied
Solution Approach 1:
The patent transitions from traditional two-dimensional stress analysis to three-dimensional stress field analysis by implementing spatially-resolved measurement systems. The digital image correlation technology captures full-field three-dimensional displacement and strain data, enabling comprehensive analysis of fracture initiation mechanisms under realistic polyhedral stress conditions.
Solution Approach 2:
The patent systematically varies key stress parameters including horizontal stress differences, confining pressures, and injection pressures to study their influence on fracture initiation. By changing these parameters in controlled experiments, the research fully explores the initiation mechanism under different three-dimensional stress states, moving beyond limited previous studies.
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 method improves the accuracy of fracture initiation prediction by simulating real geostress conditions and clarifying the fracture initiation law and characteristics.
Implementation Method 1
adopting a finite element software ANSYS to establish a double fracture model based on the fracture data
Implementation Method 2
analyzing the corresponding stress changes of maximum principal stresses and maximum shear stresses on both sides of a fracture and a fracture tip
Implementation Method 3
when the highest value of the maximum shear stresses at the fracture tip and both sides of the fracture is greater than a shear modulus of the reservoir, or the highest value of the maximum principal stresses at the fracture tip and both sides of the fracture is greater than a compressive strength of the reservoir
Data Source
AI summary
The present disclosure provides a method, system, device and storage medium for predicting the initiation of rock fractures. The method comprises: obtaining rock fracture data in the reservoir, establishing a double fracture model, applying confining pressures of different strata to the boundary of the double fracture model to change stress differences of horizontal confining pressures and obtain different horizontal stress differences, analyzing the corresponding stress changes of maximum principal stresses and maximum shear stresses on both sides of a fracture and a fracture tip as the horizontal stress differences change, and obtaining a stress state at the fracture tip and both sides of the fracture, predicting whether the fracture is initiating. The method can quickly clarify the fracture initiation law and characteristic, analyze the stress state at the fracture tip and both sides of the fracture, and thus improve the accuracy of fracture initiation prediction.