Borehole Receiver Depth from Longest-Wavelength Seismic Waves
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Solution Overview
Problem
Existing seismic monitoring methods fail to accurately determine the optimal depth for borehole receiver placement, leading to suboptimal signal-to-noise ratio (SNR) and ineffective noise reduction, particularly for weak seismic events, due to reliance on empirical data or simplified models that do not consider precise wavelengths and frequencies of seismic waves.
Innovation Solution
A method and system that analyze seismic noise attenuation and signal-to-noise ratio patterns by generating surface waves with varying frequencies, determining the longest wavelength, and installing borehole receivers at this depth to enhance detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If borehole receivers are deployed in deep boreholes to reduce background seismic noise, then noise reduction is improved, but drilling costs and technical complexity increase
Solution Approach 1:
The patent applies parameter changes by determining the optimal borehole depth based on the longest wavelength of surface waves in the frequency band of interest. This quantitative approach transforms the qualitative decision of depth selection into a precise parameter-based solution, balancing noise reduction with economic and technical constraints.
Solution Approach 2:
The patent replaces traditional empirical or simplified models for depth selection with a physics-based wave propagation model. By using the relationship between wavelength, frequency, and wave velocity, the invention substitutes mechanical trial-and-error approaches with a theoretical calculation framework.
2Ease of operation
If borehole receivers are placed at arbitrary depths based on empirical data, then deployment is simplified, but signal-to-noise ratio deteriorates
Solution Approach 1:
The patent performs preliminary calculations of the longest wavelength before actual receiver deployment. By determining the optimal depth in advance using wave propagation theory, the system prepares the precise installation parameters before field operations, ensuring both ease of deployment and optimal signal-to-noise ratio.
Solution Approach 2:
The patent uses measured surface wave velocities and frequencies as feedback to calculate the optimal depth. This measured data feeds into the wavelength calculation, creating a closed-loop system that adapts to actual subsurface conditions rather than relying on fixed empirical rules.
3Device complexity
If simplified models are used for depth selection, then calculation process is simplified, but detection accuracy of weak seismic events deteriorates
Solution Approach 1:
The patent replaces simplified empirical models with a physics-based wave propagation model that uses the fundamental relationship between wavelength, frequency, and velocity. This substitution maintains relatively simple calculations while dramatically improving detection accuracy for weak seismic events.
Solution Approach 2:
The patent changes the approach from using fixed empirical depth values to calculating dynamic depth parameters based on measured wave characteristics. By using the longest wavelength as the depth parameter, the system adapts to different geological conditions while maintaining calculation simplicity.
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 improves the SNR and enhances the detection of seismic activities by minimizing background noise and mitigating signal attenuation, balancing economic feasibility with monitoring efficiency.
Implementation Method 1
generating, with a seismic source, a set of surface waves having a plurality of frequencies in a frequency band of interest
Implementation Method 2
receiving, by at least one seismic receiver placed at a distance d from the seismic source, the set of surface waves
Data Source
AI summary
A system for determining a depth z to install a borehole receiver in a monitoring borehole includes a seismic source, a seismic receiver, an antenna, a computing device and a drilling system. The seismic source generates surface waves having multiple frequencies in a frequency band of interest within a geologic formation such as a subterranean reservoir. The seismic receiver is placed at a distance d from the seismic source, to receive the surface waves. The computing device determines a smallest frequency f1 of the multiple frequencies. The computing device further determines a surface wave velocity v for the smallest frequency f1. The computing device further calculates a longest wavelength WL of the surface wave in the frequency band of interest based on WL=v/f1. The borehole receiver is installed, e.g., with the drilling system, in the monitoring borehole at the depth z equal to the longest wavelength WL.