Multi-vintage seismic inversion using time shift maps
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Solution Overview
Problem
Current 4D seismic inversion methods face challenges in accurately determining geophysical properties such as P-wave velocity, S-wave velocity, and density across multiple vintages, leading to inconsistent estimates and reduced accuracy in subsurface layer characterization.
Innovation Solution
The introduction of a time shift map as a 4D hard constraint and a term in the cost function, calculated through cross-correlation or knowledge of the reservoir, helps balance P-velocity variations with density variations, improving the interpretation of seismic data and allowing for global inversion of multi-vintage seismic data by aligning seismic traces and using simulated annealing to minimize a multi-term cost function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If independent inversion of base and monitor surveys is performed, then processing complexity is reduced, but estimation accuracy and consistency deteriorate
Solution Approach 1:
The patent merges base and monitor surveys into a single simultaneous inversion process, treating them as an integrated system rather than separate operations. This combining approach allows the inversion algorithm to consider all seismic data from both surveys together, ensuring consistent elastic property estimates across different time points while maintaining processing efficiency through unified mathematical formulation.
2Measurement precision
If global inversion of all vintages is performed simultaneously, then estimation accuracy and consistency improve, but processing complexity and computational requirements increase
Solution Approach 1:
The patent segments the global inversion problem into manageable components by organizing data from multiple vintages into a structured simultaneous inversion framework. This segmentation allows the complex problem to be solved through systematic mathematical operations on divided datasets, reducing computational burden while maintaining the benefits of global inversion for improved accuracy and consistency.
3Manufacturing precision
If time shift corrections are applied during inversion, then alignment accuracy between vintages improves, but processing complexity increases
Solution Approach 1:
The patent applies time shift corrections as a preliminary step before performing the main inversion process. By pre-aligning seismic traces from different vintages using calculated time shifts, the method ensures proper temporal registration of data without adding complexity to the core inversion algorithm. This preliminary alignment action simplifies the subsequent inversion by providing well-prepared input data.
Data Source
AI summary
Global inversion of multi-vintage seismic data uses simulated annealing to minimize a cost function simultaneously for all vintages and all angle stacks to yield values of geophysical properties. Each vintage is generated from an independent seismic survey of a subsurface structure conducted over a distinct period of time and includes seismic traces and angle stacks. An initial model of the subsurface structure is used and includes values for geophysical properties and time shift maps between vintages. The time shift map contains shifts in the seismic trace between vintages. The cost function includes a time shift map term for the difference between the time shift map and a calculated time shift of the seismic trace between vintages and is based on a proposed perturbation to at least one of the geophysical properties. The time shift map is also used as a global constraint on proposed perturbations of subsurface properties.