Resistivity Imager Antenna Coils for Non-Conductive Mud
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Non-conductive mud in wellbore drilling presents difficulties for effective imaging of earth formations during electrical logging, as existing technologies lack the capability to accurately measure resistivity properties in such conditions.
Innovation Solution
A downhole assembly with a resistivity sensor comprising multiple antenna coils arranged radially and a processor to image the earth formation, where the antenna coils are oriented to minimize direct coupling and operate at varying frequencies to measure dielectric constant or resistivity, with magnetic materials used to enhance signal levels and control magnetic flux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional electrical logging devices are used in non-conductive mud, then the drilling operation can proceed, but the imaging capability and resistivity measurement accuracy are lost
Solution Approach 1:
The patent changes the operating frequency parameter of the antenna coils to optimize performance in non-conductive mud. By operating at higher frequencies, the device can maintain effective electromagnetic coupling with the formation despite the non-conductive mud, thereby preserving resistivity measurement accuracy while allowing continuous drilling operations
Solution Approach 2:
The patent introduces an intermediary approach by using multiple antenna coils arranged in specific configurations (push-pull, orthogonal) that can couple electromagnetic energy through the non-conductive mud to the formation. This intermediary configuration allows the system to overcome the mud's non-conductive properties and maintain imaging capability
2Measurement precision
If antenna coils are arranged to minimize direct coupling, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent segments the antenna system into multiple discrete coils (first antenna coil, second antenna coil, third antenna coil) arranged in specific patterns. This segmentation allows each coil to be independently controlled and positioned to minimize direct coupling while maintaining the overall imaging capability, thereby improving measurement accuracy through a systematic breakdown of the antenna array
Solution Approach 2:
The patent employs asymmetric arrangements of antenna coils, such as push-pull configurations where coils are positioned and oriented to create differential electromagnetic fields. This asymmetric design minimizes direct coupling between adjacent coils while maintaining effective interaction with the formation, achieving improved measurement accuracy through purposeful asymmetric geometry
3Measurement precision
If multiple antenna coils are used to enhance signal levels, then imaging quality improves, but the device size and complexity increase
Solution Approach 1:
The patent merges multiple antenna coils into integrated assemblies that can be collectively controlled to enhance signal levels. By combining the electromagnetic fields from multiple coils in coordinated patterns (push-pull, orthogonal arrangements), the system achieves improved signal-to-noise ratio and imaging quality while managing the overall device complexity through unified control mechanisms
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 high-quality imaging of earth formations by compensating for direct coupling and enhancing signal levels, allowing for accurate measurement of resistivity properties even in non-conductive mud environments, thereby improving the resolution and accuracy of borehole imaging.
Implementation Method 1
an antenna (coils) with a current source within the measuring instrument induces eddy current within the earth formation. The induced current generates signals that can be detected using either the same antenna or a separate receiver antenna
Implementation Method 2
transmitting electromagnetic energy between about 10 KHz and about 10 GHz through the fluid in the annulus about the drill pipe from a transmitter located in the drill pipe section, receiving a portion of that energy which has traveled through the fluid but not through the surrounding formation
Data Source
AI summary
An apparatus, method and computer-readable medium for imaging an earth formation. A downhole assembly having a resistivity sensor is conveyed in a borehole penetrating the earth formation. The resistivity sensor includes a plurality of antenna coils arranged along a radial line that is substantially perpendicular to a longitudinal axis of the downhole assembly and configured to obtain measurements of a resistivity property of the earth formation. A processor images the earth formation using the obtained measurements.