Wavefield Travel-Time Inversion Using Eikonal First-Arrival Picks
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Solution Overview
Problem
Existing wavefield travel-time inversion methods face challenges in accurately determining near-surface velocity models due to computational inefficiencies and unreliable first-arrival picks, especially in complex geological structures, which can lead to errors in well location determination and increased computational costs.
Innovation Solution
Employing an eikonal solver to obtain synthetic first-arrival times, replacing traditional picker programs, and using a wavefield travel-time inversion process to update the near-surface velocity model, thereby improving computational efficiency and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional picker programs are used to determine first-arrival times, then the process can handle complex geological structures, but the reliability of first-arrival picks deteriorates and computational costs increase
Solution Approach 1:
The patent replaces traditional mechanical picker programs with an eikonal solver that uses mathematical optimization to determine first-arrival times. This substitution transforms the mechanical picking process into a computational optimization process, achieving both improved reliability through stable mathematical solutions and maintained computational efficiency through optimized algorithms.
Solution Approach 2:
The patent changes the fundamental parameter approach by using travel-time optimization through eikonal equations rather than amplitude-based picking. This parameter transformation from amplitude domain to travel-time domain provides more reliable first-arrival picks while the efficient eikonal solver implementation maintains computational productivity.
2Measurement precision
If traditional wavefield inversion methods are used, then the near-surface velocity model can be determined, but the computational cost increases and the inversion process becomes less robust
Solution Approach 1:
The patent extracts and focuses specifically on the first-arrival time information from the full wavefield data, using only this extracted component for the inversion process. This selective extraction of critical information maintains measurement precision for the near-surface velocity model while significantly reducing computational cost by avoiding processing of the entire wavefield.
Solution Approach 2:
The patent performs preliminary determination of first-arrival times using the eikonal solver before conducting the inversion process. This preliminary action prepares optimized travel-time data in advance, enabling the subsequent inversion to achieve high measurement precision with reduced computational cost by working with pre-processed, optimized input data.
3Productivity
If conventional inversion processes are used, then the velocity model can be updated, but the speed and robustness of the inversion process deteriorates
Solution Approach 1:
The patent replaces conventional iterative inversion mechanics with an optimization-based inversion approach using eikonal solver. This substitution achieves faster inversion speed through efficient optimization algorithms while improving robustness through the mathematical stability of the eikonal equations, which provide consistent and reliable solutions across different geological conditions.
Data Source
AI summary
Example methods and systems for wavefield travel-time inversion using eikonal solver are disclosed. One example method includes obtaining multiple first-arrival times of a seismic wavefield measured at multiple receiver locations. Multiple synthetic first-arrival times corresponding to the multiple measured first-arrival times of the seismic wavefield are determined based on an eikonal solver and a near surface velocity model of the seismic wavefield. The near surface velocity model of the seismic wavefield is updated using a wavefield traveltime inversion (WTI) process and based on the multiple synthetic first-arrival times and the multiple measured first-arrival times. The updated near surface velocity model of the seismic wavefield is provided for well location determination.