DAS Borehole Seismic Inversion for Meter-Scale Wave Impedance
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Solution Overview
Problem
Existing methods fail to effectively utilize high-density optical fiber DAS data for precise inversion of formation wave impedance, limiting the accuracy of seismic exploration.
Innovation Solution
A method and apparatus for inverting formation wave impedance using DAS borehole seismic data by performing high-precision first arrival picking, mapping first arrival amplitudes to relative wave impedance, and correcting using linear coefficients determined through well-logging data, with optional statistical averaging and spherical diffusion compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional geophone acquisition is used, then the acquisition process is simple, but the sampling density and wave impedance inversion precision are insufficient
Solution Approach 1:
The patent replaces conventional mechanical geophone acquisition systems with optical fiber DAS (Distributed Acoustic Sensing) technology. The DAS system uses optical backscattering signals to detect formation vibrations, eliminating the need for discrete mechanical geophones. This substitution enables high-density sampling along the optical fiber trajectory, providing abundant amplitude information for wave impedance inversion and significantly improving measurement precision while the processing methods handle the data complexity
Solution Approach 2:
The patent transforms the measurement approach by changing from discrete point measurements (geophones) to continuous distributed measurements (DAS). By utilizing the high-density spatial sampling capability of DAS and applying specific processing techniques (first arrival picking, amplitude extraction, spherical diffusion compensation, and linear inversion), the system converts optical signal intensity variations into formation wave impedance values, achieving meter-level inversion precision
2Loss of information
If optical fiber DAS is laid outside casing for direct formation coupling, then formation information abundance is improved, but the difficulty of effective inversion increases
Solution Approach 1:
The patent extracts the essential amplitude information from the complex DAS wavefield data by focusing on first arrival events. By identifying and isolating the first arrival amplitudes from direct waves, the method separates the useful formation impedance information from the complex multi-wavefield DAS data, making the inversion process manageable while preserving complete formation information
Solution Approach 2:
The patent introduces an intermediary processing framework that bridges the gap between raw DAS data and formation impedance parameters. The method uses first arrival amplitude extraction as an intermediate step, followed by spherical diffusion compensation and linear inversion with correction coefficients. This intermediary processing chain transforms the difficult direct inversion problem into a series of manageable steps, reducing inversion difficulty while utilizing all available formation information
3Productivity
If existing well-logging based inversion is used, then the inversion process is straightforward, but the utilization of high-density DAS data is insufficient
Solution Approach 1:
The patent creates a universal inversion method that works with both traditional well-logging data and high-density DAS data. By establishing a linear inversion framework with correction coefficients that can be determined from well-logging data, the method enables DAS data to be processed using a generalized approach that maintains compatibility with existing workflows while fully utilizing the high-density amplitude information for improved precision
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
Improves the precision of wave impedance inversion to a meter-level resolution, enhancing the accuracy of seismic exploration and reservoir interpretation.
Implementation Method 1
The DAS technology mainly uses Rayleigh backscattering (RBS) generated when a laser pulse propagates in an optical fiber. When a formation around the optical fiber vibrates, RBS will carry information of formation vibration changes.
Data Source
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AI summary
A method for inverting a formation wave impedance using DAS borehole seismic data, comprising: acquiring an initial magnitude at a time window after the initial arrival time of seismic wavefield data in a well (101); mapping the initial magnitude to a relative wave impedance (102); and correcting the relative wave impedance to obtain an inverted wave impedance (103). Also provided are an apparatus for inverting a formation wave impedance using DAS borehole seismic data, a device, and a computer-readable storage medium. wavefield