VSP Migration Velocity Analysis via Iterative Residual Moveout
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Solution Overview
Problem
The challenge in vertical seismic profile (VSP) analysis is accurately determining the velocity model of the subsurface to effectively migrate seismic data, as incorrect velocities lead to misaligned and complex images of the subsurface, affecting the clarity and accuracy of the geophysical survey results.
Innovation Solution
A method involving iterative processes and criteria-based velocity estimation, using residual moveout analysis and depth migration techniques to determine an accurate migration velocity by analyzing the alignment, flatness, and complexity of seismic traces, and updating the velocity model to improve image alignment and clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a velocity model is used for depth migration of VSP data, then the seismic data can be migrated and imaged, but incorrect velocities lead to misaligned and complex images reducing clarity and accuracy
Solution Approach 1:
The patent implements an iterative feedback process where the velocity model is repeatedly adjusted and refined. Residual moveout analysis provides feedback on the accuracy of the velocity model, and this feedback is used to update the model until the seismic images achieve proper alignment and clarity. This feedback mechanism directly resolves the contradiction by continuously improving velocity model accuracy to ensure reliable image alignment.
Solution Approach 2:
The patent employs parameter changes by iteratively adjusting velocity parameters in the velocity model. Through residual moveout analysis, the system identifies inaccuracies in the velocity model and modifies the velocity parameters accordingly. This parameter adjustment process continues until the seismic traces achieve proper alignment, thereby resolving the contradiction between velocity model accuracy and image alignment reliability.
2Measurement precision
If iterative velocity estimation processes are performed to improve velocity model accuracy, then image clarity improves, but processing time increases
Solution Approach 1:
The patent applies preliminary action by performing residual moveout analysis and velocity model updates before the final depth migration. By conducting these preparatory steps iteratively to achieve an accurate velocity model in advance, the system ensures that subsequent migration operations produce clear and aligned images. This preliminary action resolves the contradiction by investing time upfront to improve velocity model accuracy, which ultimately enhances image quality.
Solution Approach 2:
The patent implements continuity of useful action through an iterative process where velocity model updates and residual moveout analysis are performed continuously until convergence is achieved. This continuous refinement ensures that the velocity model progressively improves in accuracy, leading to clearer seismic images. The continuous action resolves the contradiction by maintaining productive work throughout the process, transforming initial inaccurate models into accurate final models through sustained iterative improvement.
Data Source
AI summary
Vertical Seismic Profile (VSP) analysis is a technique commonly used to conduct geophysical surveys of subterranean features. The processing of a VSP includes several steps, usually including a final step of depth migration. In order to properly process and image VSP data using depth migration, a velocity model of the subsurface must be known or derived. A variety of criteria can be used to ascertain whether the velocity used for migration is accurate.