Time-lapse Seismic Processing Using Kinematic Invariants
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Solution Overview
Problem
Current 4D seismic data processing methods are inefficient, requiring lengthy processing times and necessitating repeated survey acquisition geometries, which hinders the timely delivery of production-related time-lapse information for reservoir management.
Innovation Solution
The method involves characterizing changes in a subsurface volume by obtaining and processing seismic data at two different times, reversing relevant processing steps to estimate changes between the two data sets, and using kinematic invariants to shortcut laborious processing, allowing for real-time delivery of time-lapse information without requiring identical survey geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional 4D seismic data processing methods are used, then measurement precision is improved, but processing time increases significantly
Solution Approach 1:
The processing workflow is segmented into distinct stages: initial full processing for the first seismic survey to establish accurate velocity models, followed by streamlined processing for subsequent surveys that leverages the pre-established models. This segmentation allows comprehensive processing where needed while skipping redundant steps in later surveys, thereby reducing overall processing time without sacrificing accuracy.
Solution Approach 2:
Velocity models and processing parameters are determined in advance during the initial survey processing. These preliminary results are then reused for subsequent surveys, eliminating the need to repeat computationally intensive velocity analysis and parameter optimization steps. This preliminary action significantly reduces processing time for time-lapse surveys while maintaining measurement precision through the use of validated models.
2Measurement precision
If repeated survey acquisition geometries are required, then measurement precision is improved, but device complexity and operational difficulty increase
Solution Approach 1:
The methodology transitions from static, rigid requirements for identical survey geometries to a dynamic approach where velocity models are updated to accommodate actual acquisition variations. The system adapts to changing survey conditions by recalibrating velocity models for each survey, allowing flexibility in acquisition geometry while maintaining measurement precision through model-based compensation.
Solution Approach 2:
Velocity model parameters are changed and updated between surveys to reflect actual acquisition conditions and subsurface changes. Rather than requiring identical geometries, the methodology allows parameter adjustments in the velocity models to account for geometric variations, thereby maintaining measurement accuracy without imposing rigid operational constraints.
3Measurement precision
If comprehensive seismic data processing is performed, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The processing workflow is divided into comprehensive initial processing for the first survey and streamlined processing for subsequent surveys. The segmentation allows the system to perform thorough analysis where needed (initial survey) while using efficient, targeted processing for time-lapse surveys, thereby improving productivity without compromising the precision of reservoir evolution characterization.
Solution Approach 2:
All comprehensive processing steps are performed in advance during the initial survey, including velocity model building, parameter optimization, and quality control. Subsequent surveys then use these pre-established models and parameters, requiring only minimal updates and comparisons. This preliminary action enables rapid delivery of time-lapse information while maintaining comprehensive processing standards.
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 significantly reduces processing duration and costs, enabling faster and more cost-effective delivery of time-lapse information while maintaining accuracy, even with changes in acquisition geometries between surveys.
Implementation Method 1
one or several sources emit elastic waves in the form of pressure or ground motion modulation from specific locations (wavefield), at or below the land or sea surface or in a borehole. This wavefield propagates away from the source(s) through the subsurface. Along with this propagation, a fraction of the incident wavefield is reflected from the heterogeneities in the elastic material properties of the subsurface
Implementation Method 2
a fraction of the incident wavefield is reflected from the heterogeneities in the elastic material properties of the subsurface (such as acoustic impedance). This excitation by the incident wavefield generates a reflected wavefield from the heterogeneities
Data Source
AI summary
Disclosed is a method and associated computer program and apparatus for characterising changes within a subsurface volume between a first time and a second time. The method comprises obtaining first seismic data corresponding to the first time and processing this data to obtain a seismic image of the subsurface volume. This processing is reversed for relevant portions of the seismic image to obtain relevant portions of first seismic data. Changes within the subsurface volume between the first time and the second time are characterised by estimating the changes between second seismic data corresponding to the second time and the relevant portions of first seismic data.