1D Inversion in 3D Subsurface Formations
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Solution Overview
Problem
Current methods for determining formation parameters in geological formations using electromagnetic measurements are limited by the assumption of a 1D structure, which does not accurately represent the complex 2D or 3D nature of subsurface formations, leading to inaccurate results.
Innovation Solution
A method is developed to apply 1D processing in non-1D formations by obtaining a 3D model of the subsurface earth formation, defining processing windows for 1D inversion, building a local 1D model, performing 1D inversion to generate formation parameters, and updating the 3D model with these parameters, allowing for more accurate representation of complex geological structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 1D processing algorithms are used for computing electromagnetic induction and propagation responses, then processing speed is improved and analytical solutions are obtained within reasonable time, but measurement precision deteriorates because the earth is assumed to be a 1D layered structure which does not represent real 2D or 3D subsurface formations
Solution Approach 1:
The patent divides the 3D or 2D subsurface formation into multiple local 1D processing windows along the wellbore trajectory. Each window is treated as a separate 1D inversion problem, allowing fast processing while capturing local formation variations. The windows are segmented based on formation heterogeneity and electromagnetic tool depth of investigation, enabling accurate representation of complex geology through piecewise 1D modeling.
2Device complexity
If 1D layered mud cake model is assumed for inversion, then device complexity is reduced and practical solutions are achieved, but adaptability deteriorates because real subsurface formations are 2D or 3D structures with complex geometry
Solution Approach 1:
The patent transitions from traditional 1D inversion to a multi-dimensional approach by defining processing windows in 3D space that account for wellbore trajectory, formation dip, and electromagnetic tool orientation. The windows are oriented perpendicular to bedding planes and adjusted for formation anisotropy, effectively adding spatial dimensionality to the 1D inversion framework while maintaining computational efficiency.
3Loss of time
If traditional 1D inversion is applied to non-1D formations, then processing time is reduced and computational efficiency is improved, but reliability deteriorates because the underlying assumption of 1D layered structure does not match actual 2D or 3D formation geometry
Solution Approach 1:
The patent applies local quality by making the inversion model properties vary spatially across different processing windows. Each window has its own 1D model parameters (resistivity, thickness, dip) that are optimized independently based on local formation characteristics. This allows the inversion to adapt to local geological variations while maintaining the computational efficiency of 1D processing, thereby improving reliability without sacrificing processing speed.
Data Source
AI summary
Methods, computer-readable media, and systems are disclosed for applying 1D processing in a non-1D formation. In some embodiments, a 3D model or curtain section of a subsurface earth formation may be obtained. A processing window within the 3D model or curtain that is suitable for 1D inversion processing is determined, and a local 1D model for the processing window is built. A 1D inversion is performed on the local 1D model, and inverted formation parameters are used to update the 3D model or curtain section.