Collocated Antenna Grooves for Resistivity Logging Tool Strength
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Solution Overview
Problem
Electromagnetic induction resistivity well logging instruments struggle to effectively measure non-conductive layers in earth formations, which are often hydrocarbon-bearing, as their responses are masked by conductive layers, leading to potential oversight of commercially interesting formations.
Innovation Solution
The use of collocated antennas with multiple orientations, including longitudinal and transverse axes, and high permeability magnetic materials in a downhole tool to measure cross-component magnetic fields, allowing for the estimation of electrical properties and distance to bed boundaries without the need for extensive grooves, which would weaken drill collars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple antennas with different orientations are placed in separate grooves, then multi-component resistivity measurements can be obtained, but the drill collar structure is weakened due to the large number of grooves required
Solution Approach 1:
The patent combines multiple antennas of different orientations (longitudinal and transverse) into a single integrated groove structure. The groove contains both a longitudinal antenna and a transverse antenna, reducing the total number of grooves needed and maintaining drill collar strength while enabling multi-component resistivity measurements.
Solution Approach 2:
The single groove structure serves multiple functions by accommodating both longitudinal and transverse antennas. This multi-functional groove design eliminates the need for separate grooves for each antenna orientation, resolving the conflict between measurement capability and structural strength.
2Device complexity
If traditional electromagnetic induction instruments with parallel coils are used, then the instrument structure is simple, but non-conductive hydrocarbon-bearing layers are masked by conductive layers and cannot be effectively detected
Solution Approach 1:
The patent introduces asymmetric antenna orientations (both longitudinal and transverse) rather than using only parallel coils. This asymmetric configuration enables the detection of electromagnetic responses from non-conductive hydrocarbon-bearing layers that would be masked by conductive layers in traditional symmetric parallel coil arrangements.
Solution Approach 2:
The patent adds a transverse dimension to the traditional longitudinal coil configuration. By incorporating antennas in both longitudinal and transverse orientations, the system can detect electromagnetic responses from multiple directions, enabling identification of non-conductive layers that were previously undetectable with single-orientation coils.
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 enables more accurate characterization of three-dimensional geological features and resistivity anisotropy, improving the detection of hydrocarbon-bearing layers without the limitations of traditional instruments, while maintaining tool strength and reducing the number of grooves required.
Implementation Method 1
positioned between the conductor and the tool body. The slots and the magnetic material cooperate to concentrate magnetic flux between the conductor and the tool body
Implementation Method 2
Eddy currents are induced in the earth formations from the magnetic field generated by the transmitter coil
Implementation Method 3
Voltages are then induced in the receiver coils related to the magnitude of the eddy currents
Data Source
AI summary
The disclosure provides a resistivity tool for use in a wellbore, wherein at least two orthogonal antennas are located at the same or substantially the same location of the tool. A single set of vertically aligned grooves is provided for the at least two orthogonal antennas. Each antenna may be configured to operate as a transmitter or receiver. A tool with collocated antennas may be used to provide azimuthally sensitive measurements even if the tool is non-rotating.