Logging Tool Electrode Capacitance Tomography
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Solution Overview
Problem
Existing logging tools struggle to accurately determine the distribution and position of oil, gas, and water phases in a well fluid, particularly in detecting leaks and water influx through perforations, due to limitations in capacitance measurement techniques and assumptions required for processing data.
Innovation Solution
A logging tool with a cylindrical shape and electrodes arranged around its periphery, measuring capacitance between all possible electrode combinations without grounded guards, allowing for a higher resolution image of fluid distribution and enabling the detection of leaks by creating tomograms that show the size and position of each phase without relying on assumptions about fluid distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grounded guards are used to ensure radial electrical field distribution, then measurement independence from gas phase distribution is improved, but measurement precision of fluid distribution is worsened
Solution Approach 1:
The patent removes the grounded guards from the electrode assembly, extracting the element that was limiting measurement precision. By taking out the guards, the electrical field is no longer constrained to radial distribution only, allowing the field to extend axially and capture three-dimensional fluid distribution information, thereby improving measurement precision while maintaining reliability through alternative field distribution patterns
Solution Approach 2:
Instead of using grounded guards to constrain the electrical field radially, the invention inverts the approach by allowing the electrical field to distribute freely in three dimensions without radial constraint. This inversion enables the capacitance measurements to capture actual three-dimensional fluid distribution rather than radial averages, improving the precision of fluid phase location determination
2Measurement precision
If capacitance measurements are taken between all electrode combinations, then image resolution of fluid distribution is improved, but device complexity is worsened
Solution Approach 1:
The patent divides the measurement system into discrete electrode elements arranged around the tool perimeter. By segmenting the measurement into multiple electrode combinations (with each electrode paired with every other electrode), the system captures comprehensive three-dimensional capacitance data. This segmentation approach enables high-resolution fluid distribution imaging while managing complexity through modular electrode configuration and systematic measurement sequences
Solution Approach 2:
The electrode array serves multiple functions: each electrode acts as both a measurement electrode and a reference electrode in different measurement combinations. This multi-functionality allows the same physical electrodes to generate comprehensive three-dimensional capacitance data without requiring separate dedicated electrodes for each measurement type, thereby improving image resolution without proportionally increasing device complexity
3Device complexity
If assumptions about fluid distribution are made to simplify data processing, then processing complexity is reduced, but measurement precision is worsened
Solution Approach 1:
The patent replaces the mechanical/mathematical assumption-based processing system with a direct three-dimensional capacitance measurement system. Instead of using assumptions about radial or layered fluid distribution to simplify calculations, the invention uses the raw three-dimensional capacitance data from multiple electrode combinations to directly reconstruct fluid phase positions, eliminating the need for simplifying assumptions and thereby improving measurement precision without excessive processing complexity
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 solution provides more accurate and detailed images of fluid distribution, enabling precise detection of leaks and water influx, allowing for smaller, less expensive patches to seal leaks and reducing the risk of internal diameter reduction in wells.
Implementation Method 1
measuring means for measuring the capacitance of the fluid between two electrodes in all possible combinations
Data Source
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AI summary
The invention relates to a logging tool (1) for determining properties of a fluid (2) surrounding the tool arranged downhole in a casing (3) comprising a wall (4) and having a longitudinal extension. The logging tool has a substantially longitudinal cylindrical shape with a longitudinal axis and, when seen in cross-section, a periphery (5). Moreover, the logging tool comprises a plurality of electrodes (6) arranged spaced apart around the longitudinal axis in the periphery of the tool so that the fluid flows between the electrodes and the casing wall, and a measuring means for measuring the capacitance between two electrodes in all possible combinations giving n*(n-1)/2 capacitance measurements for n electrodes.