2.5D CSEM Inversion Algorithm for Subsurface Conductivity Imaging
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Solution Overview
Problem
Current marine Controlled Source Electromagnetic (CSEM) methods struggle to accurately determine the depth and geometry of hydrocarbon reservoirs, relying on assumptions that can lead to biased results and requiring computationally expensive inversion algorithms, resulting in low-resolution images and long processing times.
Innovation Solution
A fast and rigorous 2.5D forward and inversion algorithm that simultaneously solves all source-receiver configurations, using a data analysis methodology that does not require geometry estimates, employing a grid type and optimization approaches such as local or global optimization techniques to obtain conductivity images, and verifying their geological reasonableness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If fast imaging techniques such as migration wave-field imaging approaches are employed, then processing time is reduced, but image resolution and interpretability of true conductivity structure deteriorates
Solution Approach 1:
The patent replaces traditional iterative matrix solution techniques (mechanical/computational heavy approach) with a finite-difference time-domain (FDTD) based forward modeling scheme. This substitution enables simultaneous solution of all source-receiver configurations through a unified computational framework, achieving both fast processing and high-resolution conductivity images without the trade-off present in conventional methods
Solution Approach 2:
The patent changes the fundamental computational parameters by switching from frequency-domain iterative solvers to time-domain finite-difference methods. This parameter change allows parallel computation of all source-receiver pairs in a single simulation run, dramatically reducing processing time while maintaining or improving image resolution through the rigorous physical modeling of electromagnetic wave propagation
2Measurement precision
If rigorous inversion algorithms with iterative matrix solution techniques are employed, then inversion accuracy is improved, but computational cost and processing time increases
Solution Approach 1:
The patent performs preliminary action by computing the electromagnetic field response for all source-receiver configurations simultaneously in the forward modeling stage using FDTD methods. This preliminary computation of the complete data set enables the subsequent inversion process to work with pre-computed responses, avoiding the need for repeated forward modeling iterations and significantly reducing total computational cost while maintaining inversion accuracy
3Measurement precision
If 3D inversion is performed using massively parallel resources, then inversion capability is improved, but computational resource requirements and system complexity increases
Solution Approach 1:
The patent creates a universal computational framework using finite-difference time-domain methods that can simultaneously handle 2D, 2.5D, and 3D inversion problems within a single algorithmic structure. This multi-functional approach eliminates the need for separate massively parallel 3D inversion systems, achieving high-dimensional inversion capability with standard computational resources through the inherent parallelism of the FDTD method
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 enables rapid generation of conductivity images in minutes, improving the resolution and accuracy of subsurface conductivity structure interpretation, reducing computational time significantly compared to existing methods, and providing geologically reasonable results.
Implementation Method 1
Marine Controlled Source Electromagnetic (CSEM) methods have recently received increased attention as a hydrocarbon exploration tool
Implementation Method 2
the technique's ability to directly detect the presence of thin hydrocarbon bearing layers
Data Source
AI summary
A method of determining the nature of a submarine or subterranean reservoir having an electromagnetic characteristic is described. The method comprises analyzing data associated with the application of a time varying electromagnetic field from above the reservoir using a data analysis methodology that does not utilize an estimate of the reservoir's geometry in determining one or more characteristics of the reservoir.