Permeable Fracture Imaging Using Low-Pressure Seismic Stimulation
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Solution Overview
Problem
Current methods for mapping subsurface fluid flow channels and structures, such as permeable fracture networks, require high-pressure fluid injection, which is costly and risky, and often fail to detect the volumetric distribution of connected permeable fracture networks due to their spatial complexity and the limitations of microearthquake monitoring.
Innovation Solution
A method using low fluid-pressure increases to stimulate small-amplitude seismic emissions from permeable fractures, recorded by seismic sensors and processed to image the connected permeable fracture network, utilizing ambient seismic Permeable Fracture Imaging (PFI) techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-pressure fluid injection is used to map subsurface fracture networks, then the detection capability is improved, but the cost and risk increase significantly
Solution Approach 1:
The patent changes the pressure parameter from high-pressure injection to low-pressure injection (below fracture pressure), combined with using ambient seismic noise as the signal source. This parameter change allows detection of fracture networks without the high costs and risks associated with high-pressure injection, while still achieving mapping capability through the unique fingerprint signals generated by low-pressure fluid movement in fractures.
Solution Approach 2:
The patent replaces the traditional active high-pressure mechanical injection system with a passive ambient seismic noise-based detection system. Instead of using high-pressure fluid injection to stimulate fractures, the method uses naturally occurring ambient seismic waves that interact with the fracture network, eliminating the need for expensive and risky high-pressure equipment while maintaining detection capability.
2Device complexity
If microearthquake monitoring is used to locate permeability, then the method is simpler, but it fails to detect the volumetric distribution of connected permeable fracture networks
Solution Approach 1:
The patent introduces low-pressure fluid as an intermediary between the ambient seismic noise source and the fracture network. The low-pressure fluid acts as a mediator that transmits the ambient seismic signals through the fracture network, generating unique fingerprint signals that reveal the volumetric distribution of connected fractures. This intermediary enables the simple ambient noise method to capture three-dimensional spatial information that traditional microearthquake monitoring misses.
Solution Approach 2:
The patent changes the pressure parameter to below-fracture-pressure levels, which allows the fluid to move through existing permeable fractures without creating new fractures or triggering microearthquakes. This parameter change enables the system to detect the volumetric distribution of connected fractures through the unique seismic fingerprint signals generated by low-pressure fluid flow, providing comprehensive spatial mapping while maintaining method simplicity.
3Productivity
If high-pressure injection is used to stimulate fractures, then fluid flow channels can be activated, but new permeable fractures may be induced causing fluid loss
Solution Approach 1:
The patent applies partial action by using low-pressure injection below the fracture pressure threshold. This pressure level is sufficient to activate fluid flow in existing permeable fractures and stimulate seismic emissions for detection, but insufficient to induce new fracture formation. This partial action approach achieves the goal of mapping existing fracture networks without the harmful side effect of creating new fractures and losing injection fluid.
Solution Approach 2:
The patent converts the typically harmful high-pressure injection process into a beneficial low-pressure detection method. By using low-pressure injection combined with ambient seismic noise, the method transforms what would normally require high-pressure stimulation into a passive detection process, eliminating fluid loss from induced fractures while still achieving fracture network mapping through the unique seismic fingerprints generated by low-pressure fluid movement.
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 approach reduces costs and risks by using low-pressure fluid injection to stimulate seismic emissions, providing a comprehensive and less risky tool for locating connected permeable fracture networks, enhancing reservoir development and resource extraction efficiency.
Implementation Method 1
increase the minimal pressure...selected to produce an instantaneous elastic deformation of the rock and stimulate a small-amplitude seismic emissions
Implementation Method 2
establishing a network of seismic sensors centered around at least one fluid injection site in the fluid reservoir for detecting small-amplitude seismic emissions
Data Source
AI summary
Provided herein is low fluid pressure stimulation of seismic emissions from permeable fractures. The low fluid pressure is selected to ensure the resultant stimulated seismic emissions are of a small amplitude such that no new fractures open up in the fluid reservoir that contains the relevant permeable fractures. The low fluid pressure stimulation of seismic emissions is used to image the permeable fracture network of the fluid reservoir. The image may then be used in a range of applications related to fluid injection and/or recovery, process improvement and the like.