Multi-Component Induction Logging Tool Eccentricity Correction
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Solution Overview
Problem
Conventional electromagnetic induction well logging tools are limited in measuring vertical conductivity and anisotropy of earth formations, as they are sensitive only to horizontal conductivity, and do not account for tool eccentricity or fractures, which affect multi-component measurements in deviated boreholes.
Innovation Solution
A method and apparatus for determining resistivity properties of earth formations using a logging tool displaced from the borehole center, making multi-component measurements at various frequencies, and employing a processor to estimate resistivity properties, including horizontal and vertical resistivity, relative dip angle, and azimuthal angles, while correcting for tool eccentricity and fractures using rotation techniques and multifrequency focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional electromagnetic induction well logging tools are used with coils aligned along the well axis, then the measurement process is simple and straightforward, but the tools can only measure horizontal conductivity and cannot determine vertical conductivity or anisotropy
Solution Approach 1:
The patent segments the measurement capability by introducing separate transmitter and receiver coils oriented in different directions (horizontal and vertical). The horizontal coils measure horizontal conductivity while vertical coils measure vertical conductivity, allowing independent measurement of each component rather than relying on a single aligned configuration.
Solution Approach 2:
The patent adds a vertical dimension to the coil orientation by positioning transmitter and receiver coils with vertical axes in addition to the conventional horizontal alignment. This dimensional addition enables the tool to sense both horizontal and vertical conductivity components, providing three-dimensional conductivity measurement capability.
2Loss of information
If multi-component measurements are made in deviated boreholes with tool eccentricity, then more comprehensive formation properties can be determined, but the measurements become affected by tool eccentricity and fractures
Solution Approach 1:
The patent employs feedback by using the measured multi-component signals to calculate apparent resistivity values, which are then used to determine tool orientation and eccentricity. This calculated information feeds back into the measurement process to correct the raw data, compensating for the effects of tool eccentricity and borehole deviations.
Solution Approach 2:
The patent changes the measurement parameters by taking measurements at multiple frequencies and with different coil orientations. By analyzing how the measured signals vary with frequency and orientation, the system can separate formation properties from tool position effects, maintaining measurement reliability despite eccentricity.
3Quantity of substance
If transverse induction logging tools are used to determine average resistivity, then shale and sand fraction volumes can be determined, but the relatively lower conductivity of hydrocarbon-bearing sand layers dominates the estimation
Solution Approach 1:
The patent applies local quality by using specifically oriented coils (both horizontal and vertical) to probe different directional conductivity properties at each measurement location. This allows the tool to detect the distinct conductivity characteristics of sand layers versus shale layers, with the vertical coils being particularly sensitive to the conductivity of hydrocarbon-bearing zones.
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 accurate determination of resistivity properties, including anisotropy, in deviated boreholes by correcting for tool eccentricity and fracture effects, improving the reliability of resistivity measurements and providing detailed petrophysical parameters such as sand fraction, water saturation, and permeability.
Implementation Method 1
One or more transmitter coils are energized by an alternating current. The oscillating magnetic field produced by this arrangement results in the induction of currents in the formations which are nearly proportional to the conductivity of the formations. These currents, in turn, contribute to the voltage induced in one or more receiver coils.
Data Source
AI summary
Measurements made by a multi-component induction logging tool are corrected for tool eccentricity in a deviated borehole. The eccentricity angle is determined from single frequency skin-effect corrected data and is then used to correct multifrequency data. Multifrequency focusing is then applied to the corrected multifrequency data. An inversion is then used to recover formation resistivity and relative dip and azimuth of the borehole.