At-Bit Antenna for Low-Latency Geosteering
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Solution Overview
Problem
Existing logging while drilling (LWD) technologies face latency issues in detecting bed boundaries, which impairs the utility of azimuthally-sensitive resistivity logs for precise geosteering in petroleum drilling operations.
Innovation Solution
The implementation of an at-bit loop antenna within three feet of the drill bit, in conjunction with a resistivity tool and mud motor, enables low-latency geosteering by acquiring azimuthal resistivity measurements proximate to the bit, using non-parallel loop antennas to calculate and display bed boundary indicator signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resistivity tool is positioned at a distance from the drill bit, then the tool structure is simpler and easier to manufacture, but the latency in detecting bed boundaries increases and measurement precision deteriorates
Solution Approach 1:
The system is divided into separate functional modules: an at-bit antenna module positioned near the drill bit for signal transmission, and a resistivity tool module positioned above for measurement and processing. This segmentation allows the antenna to be close to the bit (improving precision) while keeping the main tool structure manageable (controlling complexity).
Solution Approach 2:
A mud motor is introduced as an intermediary component between the at-bit antenna and the resistivity tool. The mud motor serves multiple functions: it drives the drill bit rotation, positions the antenna relative to the formation, and mechanically connects the separated modules. This intermediary enables the precision benefits of close positioning while maintaining structural feasibility.
2Loss of time
If an at-bit antenna is positioned within three feet of the drill bit, then the latency in detecting bed boundaries is reduced, but the device complexity increases
Solution Approach 1:
The at-bit antenna is positioned and configured in advance within three feet of the drill bit before drilling begins. This preliminary positioning ensures that electromagnetic signals are transmitted and received at the optimal location for detecting bed boundaries as they are encountered, minimizing detection latency from the moment the bit encounters a boundary.
Solution Approach 2:
The mud motor serves multiple functions simultaneously: it acts as a drive mechanism for the drill bit, a positioning mechanism for the at-bit antenna, and a structural connector between the antenna module and the resistivity tool. This multi-functionality reduces the need for additional dedicated components, thereby limiting the increase in overall device complexity despite the close positioning requirement.
3Loss of information
If non-parallel loop antennas are used for azimuthal resistivity measurements, then the information quality for geosteering is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The system deliberately uses non-parallel (asymmetric) loop antenna orientations rather than symmetric parallel arrangements. By positioning the at-bit loop antenna and the resistivity tool loop antenna at different angles relative to each other, the system captures azimuthal variations in formation resistivity. This asymmetric configuration provides rich directional information for geosteering decisions.
Solution Approach 2:
The system measures azimuthal resistivity variations using the non-parallel antenna configuration and provides feedback to the drilling operation. The measured resistivity logs are analyzed to determine borehole orientation relative to formation bedding planes, and this feedback information is used to adjust drilling direction in real-time, compensating for any manufacturing orientation variations through active control.
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 precise and timely geosteering by providing real-time information on current drill bit position, enhancing drilling precision and reducing the latency in detecting bed boundaries.
Implementation Method 1
the at-bit antenna is part of an at-bit module that, in some embodiments, transmits periodic electromagnetic signal pulses for the resistivity tool to measure
Implementation Method 2
one or more antennas for transmitting an electromagnetic signal into the formation and one or more antennas for receiving a formation response
Data Source
AI summary
Logging tools and methods employing an at-bit loop antenna to acquire azimuthal resistivity measurements proximate to the bit enable low-latency geosteering signals to be generated. In some embodiments, the at-bit antenna is part of a bottom hole assembly that includes a drill bit, a mud motor, and a resistivity tool. The mud motor is positioned between the at-bit antenna and the resistivity tool. The resistivity tool includes at least one loop antenna that is not parallel to the at-bit loop antenna. The at-bit antenna is part of an at-bit module that, in some embodiments, transmits periodic electromagnetic signal pulses for the resistivity tool to measure. In other embodiments, the at-bit module measures characteristics of electromagnetic signal pulses sent by the resistivity tool and communicates the measured characteristics to the resistivity tool via a short hop telemetry link.