Seismic Imaging Method for Subsurface Fluid Movement Mapping
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Solution Overview
Problem
Conventional seismic surveying methods lack the necessary resolution to accurately characterize fluid-induced changes and hydraulic fractures in subsurface rock formations, particularly in optimizing fluid flow properties of wellbores during hydraulic fracturing operations.
Innovation Solution
The method employs a seismic sensor array with high-frequency seismic energy and coherent stacking, combined with beam steering and focused data processing to enhance lateral and vertical resolution, allowing for time-lapse imaging of subsurface reservoirs during fluid pumping operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional seismic surveying methods are used, then the surveying process is simple and cost-effective, but the spatial resolution is insufficient to accurately characterize fluid-induced changes and hydraulic fractures
Solution Approach 1:
The patent combines active source seismic imaging and passive seismic imaging into a single integrated workflow. The active source component provides high-resolution structural imaging through coherent stacking and beam steering, while the passive source component captures microseismic events from fluid movement. By merging these two imaging modes and processing them together with joint migration techniques, the system achieves comprehensive high-resolution characterization of both static formation properties and dynamic fluid movement that neither method could achieve alone.
Solution Approach 2:
The patent implements dynamic beam steering that adapts to subsurface velocity variations. The beam steering angles and timing are continuously adjusted based on measured travel times and updated velocity models. This dynamic adaptation allows the system to maintain optimal spatial resolution throughout the survey, compensating for heterogeneities in the subsurface formations that would otherwise degrade image quality.
2Measurement precision
If high-frequency seismic energy with coherent stacking and beam steering is employed, then lateral and vertical resolution are enhanced, but data processing complexity and computational requirements increase
Solution Approach 1:
The patent segments the seismic data processing into distinct modules: active source processing, passive source processing, and integrated joint migration. Each module handles specific aspects of the data independently, allowing for optimized processing algorithms in each segment. The active source data undergoes coherent stacking and beam steering, while passive source data is processed through location algorithms, and finally both are integrated through joint migration to produce the unified high-resolution image.
Solution Approach 2:
The patent transforms the seismic data from the time domain to the frequency-wavenumber domain through Fourier transformation. This parameter change enables more efficient processing of high-frequency components and facilitates beam steering operations. By working in the frequency domain, the system can apply filtering and enhancement techniques that preserve high-resolution information while reducing computational complexity compared to time-domain processing.
3Loss of information
If time-lapse imaging of subsurface reservoirs is performed during fluid pumping operations, then fluid movement monitoring capability is improved, but acquisition time and operational complexity increase
Solution Approach 1:
The patent enables continuous monitoring of fluid movement by performing seismic acquisitions at multiple time points during the fluid pumping operation. Rather than conducting separate discrete surveys, the system continuously captures active source data and passive source data throughout the pumping process, creating a time-lapse sequence that tracks fluid migration in real-time. This continuous action provides comprehensive temporal coverage without significant interruptions.
Solution Approach 2:
The patent implements periodic seismic surveys at strategically selected time intervals during the fluid pumping operation. These periodic acquisitions are synchronized with the pumping schedule to capture key moments such as fracture initiation, proppant placement, and fluid front advancement. By timing the surveys to coincide with critical events, the system maximizes the information gained from each acquisition while minimizing the total time required.
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 provides improved spatial resolution and faster data processing, enabling better monitoring of fluid movement and characterization of petrophysical property changes in subsurface formations, optimizing fluid flow and reservoir management.
Implementation Method 1
seismic energy is detected at the sensors that emanates from various seismic events occurring within the Earth's subsurface
Implementation Method 2
directing seismic energy, by repetitive operation of a seismic source such as a vibrator or air gun array... and detecting seismic energy from the source after its interaction with the formations
Implementation Method 3
coherent stacking from multiple actuations of a seismic energy source is used to mitigate the attenuation of such higher frequency energy
Implementation Method 4
The sensitivity of the array may be beam steered to a selected position within the subsurface
Implementation Method 5
Repetitive actuation of the source and stacking of the detected energy combined with beam steering the array response may result in higher frequency seismic energy being detected
Data Source
Figure 1~1A
Figure 1B
Figure 2
AI summary
A method for characterizing fluid pumping effects on a subsurface formation includes (a) during pumping of fluid into the subsurface formation, detecting passive seismic signals related to fractures created in the subsurface formation. (b) A place of origin of the passive seismic signals is determined. (c) A seismic energy source is actuated for a plurality of actuations and an output thereof is beam steered toward the place of origin. (d) At least one acoustic property is determined for the place of origin using signals detected as a result of the plurality of actuations. The detected signals are beam steered toward the place of origin and are stacked over the plurality of actuations. (a), (b), (c) and (d) are repeated until the pumping is completed.