Fiber Optic Probe Array Imaging for Wellbore Gas Holdup Mapping
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Solution Overview
Problem
Traditional vertical gas-water two-phase production profile logging in gas wells is limited by single-point measurements, which restricts the measurement location and fails to reflect fluid information across the entire wellbore cross-section.
Innovation Solution
A method using a fiber optic probe array with six probes is projected onto a wellbore cross-section, rotated counterclockwise to create mirror probes, and interpolated to reconstruct a gas holdup image, leveraging radial symmetry of gas-water flow to enhance measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional single-point sampling measurements are used at the center of the production wellbore cross-section, then the measurement device complexity is reduced, but the measurement precision and ability to reflect fluid information across the entire wellbore cross-section deteriorates
Solution Approach 1:
The wellbore cross-section is divided into multiple measurement zones by projecting six fiber optic probes at different angular positions (0°, 60°, 120°, 180°, 240°, 300°) around the circumference. Each probe measures gas holdup at its specific location, and the results are integrated to represent the entire cross-section, transforming a single-point measurement into a distributed multi-point measurement system.
Solution Approach 2:
The patent creates virtual mirror images of the six physical fiber optic probes through mathematical transformation. By rotating the probe positions and copying their measurement characteristics, the system generates additional virtual measurement points that fill gaps in the physical probe coverage, enabling comprehensive cross-sectional reconstruction without adding physical probes.
2Measurement precision
If six fiber optic probes are projected onto the wellbore cross-section at different positions, then the measurement precision and cross-sectional fluid information representation are improved, but the device complexity and data processing requirements increase
Solution Approach 1:
The six fiber optic probes are configured to perform multiple functions: each probe not only measures gas holdup at its local position but also contributes to the overall cross-sectional reconstruction when combined with mirror image transformations. The same probe data is used both for direct local measurement and for generating virtual mirror probe measurements, maximizing the utility of each physical probe.
Solution Approach 2:
The patent transforms the spatial parameters of the probe measurements by applying rotational transformations to generate mirror image probes. The physical probes remain fixed, but their measurement data is mathematically rotated and reflected to create virtual probes at different angular positions, effectively changing the spatial distribution of measurement points without physical movement.
3Loss of information
If mirror image transformation is applied to rotate probes counterclockwise around the wellbore, then the cross-sectional coverage and fluid property representation are enhanced, but the computational complexity and processing time increase
Solution Approach 1:
The patent pre-calculates and stores the mirror image transformation matrices for standard angular positions (0°, 60°, 120°, 180°, 240°, 300°) before actual measurement. When reconstructing the cross-sectional image, these pre-computed transformation matrices are applied directly to the probe measurements, avoiding real-time complex calculations and reducing processing time.
Solution Approach 2:
The patent uses computational approximations in the interpolation algorithm to quickly generate the cross-sectional gas holdup distribution. Rather than using computationally intensive methods, simpler interpolation techniques are employed that provide sufficient accuracy for engineering applications while significantly reducing calculation time and computational resources required.
Data Source
AI summary
A method for mirror imaging of gas holdup in gas-water two-phase flow based on a fiber optic probe array includes: projecting six fiber optic probes of a FIT onto a cross-section of a wellbore at a same height, gridding and normalizing an inner diameter of the wellbore and probe positions to obtain a cross-sectional grid, and determining a two-dimensional coordinate of each fiber optic probe within the cross-sectional grid and a local gas holdup at each fiber optic probe; rotating, based on a radial symmetry of gas-water flow along the wellbore center, the six fiber optic probes counterclockwise to obtain mirror probes which are radially symmetrical and coordinates thereof; and predicting gas holdup at each mirror probe to obtain predicted gas holdup values, interpolating the predicted gas holdup values in the cross-sectional grid by an interpolation algorithm to obtain a reconstructed gas-water image of the cross-section of the wellbore.