Real-Time EM Survey Depth and Resistance Estimation
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Solution Overview
Problem
Conventional electromagnetic surveying techniques for determining sub-bottom resistivity are time-consuming and tedious, requiring days to produce reliable resistivity maps from acquired data.
Innovation Solution
A real-time method for estimating target depth and transverse resistance using a towed EM system, which involves determining a one-dimensional resistivity background model and applying non-linear minimization procedures to process EM data during data acquisition, allowing for rapid computation of resistivity information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electromagnetic surveying techniques are used to determine sub-bottom resistivity, then reliable resistivity maps can be obtained, but the process is time-consuming and requires days to produce results
Solution Approach 1:
The patent applies preliminary action by pre-determining a one-dimensional resistivity background model before processing the electromagnetic survey data. This background model serves as a foundation that enables rapid real-time estimation of target depth and transverse resistance, significantly reducing the time required to produce reliable resistivity maps while maintaining measurement precision.
2Productivity
If real-time processing of EM data is implemented, then rapid estimation of target depth and transverse resistance is achieved, but the complexity of data processing increases
Solution Approach 1:
The patent segments the complex resistivity inversion problem into two distinct parts: (1) determining a one-dimensional resistivity background model, and (2) using this model to rapidly estimate target depth and transverse resistance. This segmentation enables real-time processing by separating the computationally intensive background modeling from the rapid real-time estimation, thereby achieving high productivity while managing processing complexity.
Solution Approach 2:
The one-dimensional resistivity background model acts as an intermediary between the raw electromagnetic survey data and the final real-time estimates of target depth and transverse resistance. This intermediary model simplifies the complex inversion process, enabling rapid computation while maintaining accuracy, thus resolving the contradiction between processing speed and computational complexity.
3Loss of information
If conventional inversion techniques are used, then comprehensive resistivity information is obtained, but the process is tedious and time-consuming
Solution Approach 1:
The patent extracts the essential information needed for rapid estimation by focusing on the key parameters of target depth and transverse resistance, rather than performing a complete comprehensive inversion. By taking out only the critical information elements and using the background model to infer the rest, the method maintains sufficient information completeness while dramatically reducing processing time.
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 rapid estimation of target depth and transverse resistance in real-time during EM data acquisition, significantly reducing the time lag between data collection and obtaining useful resistivity information, facilitating dynamic adjustments to the survey plan.
Implementation Method 1
Electromagnetic geophysical surveying of the Earth's subsurface involves imparting an electric field or a magnetic field into subsurface Earth formations... and measuring electric and/or magnetic fields by measuring voltage differences induced in electrodes, antennas and/or interrogating magnetometers
Data Source
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AI summary
Disclosed are apparatus and methods for determining characteristics of a target region which is embedded in background material below a body of water. In accordance with one embodiment, a resistivity background is determined. In addition, characteristics of an electric dipole due to the target region are determined. A resistance for the target region is then computed using the characteristics of the electric dipole and the resistivity background. Other embodiments, aspects and features are also disclosed.