Multi-component Induction Logging Selected Frequency Inversion
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Solution Overview
Problem
Resistivity logging systems face challenges in achieving accurate inversion of formation parameters without increasing computational complexity, particularly in real-time monitoring and embedded systems, due to the complexity of multi-spacing, multi-frequency, and multi-component measurements.
Innovation Solution
The implementation of multi-component induction (MCI) logging systems using selected-frequency inversion, which employs multiple inversion models and adapts measurement strategies based on frequency and antenna spacing to balance accuracy and computational complexity, including the use of radial and vertical 1D models to derive formation properties efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multi-spacing, multi-frequency, and multi-component logging tools are used to increase measurement complexity and improve system performance, then measurement precision and reliability are improved, but device complexity and computational burden increase significantly
Solution Approach 1:
The patent segments the inversion process by dividing the formation model into discrete layers (e.g., N layers with varying thicknesses and properties) and processes measurements from different antenna spacings and frequencies separately. This allows the complex multi-component inversion to be broken into manageable sub-problems that can be solved more efficiently while maintaining overall accuracy.
Solution Approach 2:
The patent implements dynamic selection of inversion models based on the specific logging conditions. Different inversion models (e.g., homogeneous model, layered model, anisotropic model) are chosen adaptively according to the formation characteristics and measurement quality, allowing the system to balance computational complexity with inversion accuracy in real-time.
2Measurement precision
If higher model complexity is used to achieve accurate inversions, then measurement precision is improved, but ease of operation and real-time processing capability deteriorate
Solution Approach 1:
The patent performs preliminary processing of the raw measurements including calibration, noise filtering, and initial parameter estimation before the main inversion process. This preliminary action prepares the data in an optimized format that reduces the computational burden of the subsequent inversion, enabling faster real-time processing while maintaining accuracy.
Solution Approach 2:
The patent transforms the inversion problem by changing parameters from the raw measurement domain to a processed domain that is more suitable for inversion. This includes transforming measurements into apparent resistivity values and using optimized parameterizations that reduce the dimensionality of the inverse problem, thereby improving computational efficiency.
3Productivity
If simple inversion models are used to reduce computational burden, then ease of operation is improved, but measurement precision deteriorates in complex formations
Solution Approach 1:
The patent dynamically adjusts the inversion model complexity based on the specific geological conditions being encountered. In simple homogeneous formations, a basic model is used for fast processing, while in complex formations with thin beds or strong anisotropy, the system automatically switches to more sophisticated layered or anisotropic models to maintain accuracy.
Solution Approach 2:
The patent segments the formation into multiple thin layers and uses a layered inversion model that can resolve fine-scale variations. This segmentation allows the system to capture complex formation characteristics that simple models would miss, while still maintaining computational efficiency through the use of efficient numerical algorithms for layered media.
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 accurate formation property estimation with reduced computational burden, enabling effective real-time monitoring and improved logging results by selectively using shorter spacings/lower frequencies and short-to-middle spacings/higher frequencies depending on the formation type.
Implementation Method 1
The transmitter antenna creates electromagnetic fields in the surrounding formation, which in turn induce an electrical voltage in each receiver antenna
Data Source
AI summary
Formation properties may be more efficiently derived from measurements of multi-frequency, multi-component array induction tools, by emphasizing the measurements associated with shorter spacings/lower frequencies in certain regions and short-to-middle spacings/higher frequencies in other regions. In at least one embodiment, a disclosed logging system includes a logging tool that when conveyed along a borehole through a formation obtains multi-component transmit-receive antenna coupling measurements with multiple arrays having different antenna spacings; and a processing system that operates on the measurements. The processing system derives from said measurements one or more formation parameter estimates; determines measurement weight coefficients for a cost function based on said one or more formation parameter estimates; and inverts said measurements with said cost function to obtain one or more enhanced parameter estimates.