UDAR 3D Inversion Using Discrete Voxel Segmentation
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Solution Overview
Problem
Existing 3D processing methods for ultra-deep azimuthal resistivity (UDAR) measurements employ approximate computational domain discretization, leading to smoothened formation mapping with artifacts away from the borehole, compromising higher resolution and accuracy.
Innovation Solution
The method involves receiving UDAR measurements from a downhole tool, determining a data processing window based on the relative location of the transmitter, performing a three-dimensional (3D) inversion of the measurements, and generating an anisotropic resistivity distribution output. This approach uses exact full 3D EM solvers for accurate and high-resolution processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If approximate computational domain discretization is used for 3D processing, then processing speed is improved, but measurement precision deteriorates due to smoothened formation mapping and artifacts
Solution Approach 1:
The invention segments the 3D processing domain into discrete computational elements (voxels or finite elements) with exact geometric boundaries. This segmentation allows the electromagnetic field equations to be solved precisely at each discrete location without approximation, eliminating the smoothening artifacts that occur with continuous approximate discretization while maintaining computational efficiency through systematic grid-based processing.
Solution Approach 2:
The invention changes the discretization parameter from approximate continuous domain representation to exact discrete voxel/element representation. By transforming the mathematical model from continuous approximate solutions to discrete exact solutions on a computational grid, the method achieves both high processing speed through algorithmic efficiency and high measurement precision through exact field calculations at each discrete point.
2Measurement precision
If exact full 3D EM solvers are used for accurate processing, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The invention transforms the complex full 3D electromagnetic inversion problem into a more manageable form by changing parameters: (1) discretizing the continuous 3D space into a finite voxel grid, (2) formulating the forward model using efficient finite difference or finite element methods on this grid, and (3) applying regularized inversion algorithms that exploit the structured nature of the discretized system. This parameter transformation reduces computational complexity while maintaining exactness in the forward modeling stage.
Solution Approach 2:
The invention segments the complex 3D inversion problem into smaller, more manageable computational tasks: (1) forward modeling at each voxel location, (2) Jacobian matrix computation for sensitivity analysis, and (3) iterative inversion updates. This segmentation of the computational process allows exact full 3D EM solving to be performed through systematic, modular operations rather than as a single complex monolithic calculation.
3Loss of information
If high resolution 3D reservoir mapping is achieved, then asset recovery is increased, but well construction costs increase
Solution Approach 1:
The invention applies partial action by processing only the essential UDAR measurements that provide the most critical reservoir information. Rather than attempting to process all possible measurements or achieve maximum theoretical resolution, the method selectively processes the subset of measurements that deliver sufficient reservoir characterization for drilling decisions, thereby reducing computational costs while maintaining adequate asset recovery information.
Solution Approach 2:
The invention performs preliminary 3D processing and formation evaluation before actual drilling operations. By obtaining high-resolution resistivity maps in advance through rapid 3D inversion of UDAR data, the system allows for optimal well path planning and reservoir targeting, which reduces unnecessary drilling operations and associated costs while maximizing asset recovery from productive zones.
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
The method achieves high accuracy and resolution in real-time, providing precise 3D reservoir mapping that enhances drilling performance, increases asset recovery, and reduces well construction costs.
Implementation Method 1
an electromagnetic downhole tool configured to generate electromagnetic measurements associated with a volume within a geological formation
Data Source
AI summary
The present disclosure relates to a method that includes receiving ultra-deep azimuthal resistivity (UDAR) measurements from a downhole tool within a geological formation. The method also includes determining a data processing window based on a relative location of a transmitter of the downhole tool with respect to a location of one or more components of the downhole tool. Further, the method includes performing a three-dimensional (3D) inversion of the UDAR measurements based on the relative location of the transmitter. Further still, the method includes generating an anisotropic resistivity distribution and relative formation dip output based on the 3D inversion.