CO2 Plume Characterization via Seismic Impedance Analysis
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Solution Overview
Problem
Current methods for monitoring CO2 geological storage sites are limited by their reliance on theoretical models and inability to perform a complete, quantitative analysis of seismic data, leading to inaccurate estimates of CO2 volume and mass distribution.
Innovation Solution
A method that constructs a CO2 saturation cube from relative density variations and uses seismic inversions to determine the volume and mass of free CO2 plumes by weighting the sum of CO2 saturation values with average porosity and density, without relying on elastic models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If theoretical models (Biot-Gassmann) are used to estimate CO2 volume and mass from seismic data, then the analysis can be performed, but the measurement precision and reliability are compromised due to model uncertainties and inability to perform complete quantitative analysis
Solution Approach 1:
The invention extracts and analyzes only the essential seismic data parameters (P-wave and S-wave impedances) directly from the seismic measurements, removing the dependence on complex theoretical elastic models like Biot-Gassmann. By directly computing CO2 saturation from impedance ratios, the method eliminates model-related uncertainties while maintaining measurement precision.
Solution Approach 2:
The invention replaces the mechanical/theoretical modeling approach (Biot-Gassmann elastic models) with a direct seismic attribute analysis approach. Instead of using theoretical frameworks to infer CO2 properties, the method directly computes saturation from measured P-wave and S-wave impedances, substituting model-based mechanics with empirical seismic data analysis.
2Reliability
If repetitive seismic campaigns are conducted to monitor CO2 plume evolution, then the monitoring capability is provided, but the productivity and time efficiency are reduced due to long intervals between campaigns
Solution Approach 1:
The invention performs a partial analysis using only P-wave and S-wave impedance data from seismic campaigns, rather than requiring complete elastic model inversion. This partial approach using selected seismic attributes enables faster processing and more frequent monitoring while maintaining sufficient reliability for CO2 plume tracking.
3Reliability
If complete monitoring of CO2 fate is performed to detect leaks and perform volume balance, then regulatory compliance is achieved, but the difficulty of detecting and measuring increases due to complex physico-chemical modifications of CO2
Solution Approach 1:
The invention segments the complex CO2 monitoring problem into distinct components by separately analyzing P-wave and S-wave impedance data. This segmentation allows the method to handle different CO2 forms (free gas, dissolved, mineralized) through distinct seismic responses, making the detection and measurement process more manageable while maintaining complete monitoring capability.
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 provides a more accurate and quantitative assessment of CO2 distribution, enabling precise monitoring of CO2 storage sites and detection of leaks, thereby enhancing regulatory compliance and societal acceptance of the technology.
Implementation Method 1
the analysis of seismic data... measurements of the delay taken by the seismic wave to cross the layers of the subsoil
Data Source
Figure 1
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AI summary
The method involves constructing a density variation cube and an incompressibility module variation cube from seismic impedance cubes in P and S waves before and after carbon-di-oxide injection, where the variation cubes discretize an underground area in a set of cells. The plume of the free carbon-di-oxide in the area is localized by identifying the cells in which the density variation and the incompressibility module variation are negative and an absolute value is higher than a given positive threshold, where the identified cells defines the plume of the free carbon-di-oxide.