Wireline Resistivity Tool with Selectable Depth of Investigation
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Solution Overview
Problem
Existing well logging tools with fixed spacings between transmitters and receivers are limited in their ability to provide sufficient data for determining formation properties, especially in complex invasion profiles and for measuring resistivity at varying depths, as they cannot effectively characterize anisotropy or provide detailed measurements beyond the invaded zone.
Innovation Solution
A wireline tool string with selectively spatially separated transmitter tools, each equipped with triaxial coils and a receiver tool also with triaxial coils, allowing for variable spacings and multi-frequency operations to achieve deeper depths of investigation and more detailed measurements, enabling characterization of formation properties beyond fixed depths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed spacing between transmitters and receivers is used, then device structure is simple, but depth of investigation is limited and cannot be adjusted
Solution Approach 1:
The patent implements a telescopic boom structure that allows the spacing between the transmitter tool and receiver tool to be dynamically adjusted. The boom can extend to multiple predetermined lengths, enabling the system to achieve different depths of investigation by changing the physical distance between measurement components, thus resolving the contradiction between fixed structure and adjustable depth.
Solution Approach 2:
The measurement system is divided into separate transmitter tool and receiver tool components that can be independently positioned along the telescopic boom. This segmentation allows flexible configuration of the spacing between components to achieve desired investigation depths while maintaining a relatively simple overall device structure.
2Measurement precision
If multiple fixed arrays with different spacings are used, then sufficient data for complex invasion profiles is obtained, but device complexity increases
Solution Approach 1:
Instead of incorporating multiple fixed arrays with different spacings, the patent uses a single transmitter-receiver pair on a telescopic boom that can be dynamically positioned at multiple spacing configurations. This dynamic adjustment capability provides the measurement precision of multiple fixed arrays while avoiding the complexity of permanently integrating multiple arrays into the device.
3Adaptability or versatility
If telescopic boom with adjustable spacing is implemented, then flexible depth of investigation is achieved, but device complexity increases
Solution Approach 1:
The telescopic boom is designed with segmented sections that can be extended to predetermined lengths. This segmentation allows the boom to achieve multiple fixed spacing configurations without requiring a complex continuously variable mechanism, thus balancing adaptability with device simplicity.
Solution Approach 2:
The telescopic boom provides dynamic spacing adjustment capability, allowing the system to adapt to different measurement requirements by extending to appropriate lengths. The predetermined extension positions simplify the control mechanism while maintaining flexibility in depth of investigation.
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 configuration allows for more comprehensive and accurate determination of formation resistivity and properties, including anisotropy, by providing flexible depth of investigation and improved signal-to-noise ratio, resulting in enhanced 3D imaging of the formation surrounding the borehole.
Implementation Method 1
Induction logging tools measure the resistivity (or, more accurately, its inverse, conductivity) of the formation by inducing eddy currents in the formations in response to an AC transmitter signal
Implementation Method 2
The eddy currents induce secondary magnetic fields that in turn induce voltages in receiver antennas. Because the magnitudes of the eddy currents depend on formation conductivities, the magnitudes of the received signals thus reflect the formation conductivities
Data Source
AI summary
A wireline tool string used in a wellbore to determine formation properties is disclosed which comprises one or more transmitter tools disposed within the tool string, each transmitter tool having three linearly independent coils; a receiver tool disposed within the tool string, wherein the receiver tool has three linearly independent coils; and a tool string component disposed between the one or mole transmitter tools and the receiver tool; wherein the one or more transmitter tools are selectably spatially separated from the receiver tool along the tool string to provide a desired depth of investigation and measurements made using the one or more transmitter tools and receiver tool are used to determine formation properties.