NMR Residual CO2 Saturation Estimation via Percolation Model
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Solution Overview
Problem
Current methods for estimating residual carbon dioxide saturation in aquifers are laborious and limited to specific core locations, making it difficult to rapidly develop geological CO2 storage sites due to reliance on coring, which is slow and expensive, and NMR-based inference requires zonal calibration.
Innovation Solution
Estimating residual carbon dioxide saturation using nuclear magnetic resonance (NMR) measurements through a parameterized pore-level percolation model, connecting magnetization decay to residual CO2 saturation, and providing algorithms for calculating Scr based on petrophysical data, allowing for continuous logging and self-consistent inferences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coring is used to obtain residual saturation data, then measurement precision is improved, but productivity deteriorates due to slow and expensive coring operations
Solution Approach 1:
The patent replaces the mechanical coring process with nuclear magnetic resonance (NMR) logging measurements. Instead of physically extracting core samples through drilling operations, the invention uses electromagnetic fields to measure residual CO2 saturation in situ within the formation, thereby eliminating the time-consuming and costly coring process while maintaining measurement capability
Solution Approach 2:
The patent introduces NMR logging as an intermediary measurement technique between direct core analysis and reservoir evaluation. The NMR tool acts as a mediator that provides residual saturation information without requiring physical core samples, bridging the gap between indirect well log measurements and direct core analysis
2Productivity
If NMR measurements are used for permeability estimation, then productivity is improved by avoiding coring, but measurement precision deteriorates due to requirement of zonal calibration
Solution Approach 1:
The patent changes the measurement parameters by using multiple NMR measurement techniques (T2 relaxation, diffusion measurements) and combining them with petrophysical models to estimate permeability. This multi-parameter approach allows calibration across different zones without requiring separate calibration procedures for each zone, thereby maintaining precision while preserving the productivity benefits of NMR logging
3Productivity
If continuous logging is implemented, then productivity is improved by providing continuous Scr logs, but device complexity increases due to need for advanced NMR processing
Solution Approach 1:
The patent segments the complex NMR processing task into distinct computational modules: T2 relaxation analysis, diffusion measurement processing, petrophysical model application, and residual saturation calculation. This segmentation allows the complex processing to be performed systematically on continuous logging data, managing device complexity through modular software architecture while maintaining continuous measurement 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
Enables the generation of continuous logs of residual carbon dioxide saturation as a function of depth, providing accurate and consistent estimates even in the absence of other data, and reducing reliance on coring, thus facilitating rapid development of CO2 storage sites.
Implementation Method 1
residual carbon dioxide saturation is estimated from nuclear magnetic resonance (NMR) measurements obtained by a logging tool
Data Source
AI summary
Percolation theory is applied to establish a connection between magnetization decay of nuclear magnetic resonance (NMR) measurements and residual carbon dioxide saturation (Scr). As a result, estimations of Scr are obtained through use of an NMR tool in a formation and appropriate processing. Data may be displayed as a log.