Relative Bearing Estimation Using 3D Model and Polarization Vector Comparison
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Solution Overview
Problem
Existing methods for determining the relative bearing angle of a non-gimbaled directional receiver in a borehole are prone to errors due to geological complexity and systematic errors, especially in multi-azimuth surveys, which affects the accuracy of seismic data interpretation and formation property analysis.
Innovation Solution
A method that uses a directional receiver to receive direct compressional arrivals, generates 3C data, and iteratively adjusts the relative bearing angle by comparing polarization and incident ray vectors within a 3D model to minimize their angular difference, ensuring accurate orientation in the true earth frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used to determine relative bearing angle, then the process is simpler, but measurement precision deteriorates due to geological complexity and systematic errors
Solution Approach 1:
The patent implements an iterative feedback mechanism where the relative bearing angle is repeatedly adjusted and re-evaluated. The polarization angle derived from seismic data is compared with the relative bearing angle, and the difference feeds back into the next iteration to refine the angle estimate. This feedback loop continues until convergence, systematically eliminating errors caused by geological complexity and improving measurement precision.
Solution Approach 2:
The patent performs preliminary data processing steps before final angle determination. Seismic data is first processed to extract polarization angles, and initial relative bearing angle estimates are obtained before the iterative refinement process. This preliminary action prepares the data in a form suitable for the subsequent iterative optimization, reducing the impact of systematic errors.
2Measurement precision
If iterative optimization is applied to minimize angular difference between polarization and incident ray vectors, then measurement precision improves, but loss of time increases due to repeated calculations
Solution Approach 1:
The patent applies partial action by performing a limited number of iterative optimizations rather than exhaustive search. The iterative process continues until the angular difference between polarization and incident ray vectors converges to an acceptable threshold, rather than exploring all possible angle values. This approach achieves sufficient measurement precision while significantly reducing computational time compared to exhaustive methods.
Solution Approach 2:
The patent changes the parameter being optimized from direct relative bearing angle to the angular difference between polarization and incident ray vectors. By minimizing this angular difference through parameter transformation, the optimization process becomes more efficient and converges faster, reducing computational time while maintaining high measurement precision.
3Measurement precision
If data is rotated to true earth frame using estimated relative bearing angle, then interpretation accuracy improves, but systematic errors propagate if the initial estimate is inaccurate
Solution Approach 1:
The patent uses feedback to correct systematic errors in the initial relative bearing angle estimate. The polarization angle extracted from rotated seismic data is compared with the input relative bearing angle, and the difference feeds back to adjust the angle in subsequent iterations. This feedback mechanism automatically compensates for inaccurate initial estimates, improving both interpretation accuracy and reliability.
Solution Approach 2:
The patent performs preliminary rotation of seismic data to the true earth frame using an initial estimated relative bearing angle before extracting polarization angles. This preliminary action allows the system to work with properly oriented data from the start, and subsequent iterative refinement corrects any errors introduced by the initial estimate, ensuring both accuracy and robustness.
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 reduces systematic errors and improves the accuracy of seismic data interpretation and formation property analysis by optimizing the relative bearing angle, leading to more precise orientation and better agreement between modeled and acquired data.
Implementation Method 1
a directional receiver to receive a direct compressional arrival generated by at least one source
Data Source
AI summary
A method is disclosed for more accurately determining the relative bearing angle of a directional receiver in a borehole using an existing three-dimensional (3D) geological model, one or more seismic sources and a three component (3C) directional receiver. A disclosed method includes: receiving direct compressional arrivals generated by multiple source events at the directional receiver disposed in the borehole; rotating the seismic data into the true earth frame using an estimated relative bearing angle; measuring a polarization vector of the rotated seismic data; estimating an incident ray vector of the direct compressional arrivals at the directional receiver using ray-tracing through the 3D model; calculating the weighted sum of an angular difference between the polarization vector and the incident ray vector; and adjusting the estimated relative bearing angle until the angular difference between the polarization and incident ray vectors is minimized.