Combined NMR-Resistivity Transceiver Antenna for Well Logging
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Solution Overview
Problem
The challenge in oil and gas exploration is to reduce the size, complexity, and cost of well logging while maintaining detailed information about geological formations, as additional tools increase the length and complexity of the subsurface tool string, and existing combined NMR/resistivity measurements do not provide significant advantages over separate instruments.
Innovation Solution
A compact apparatus using transceiver antennae capable of emitting and receiving both NMR and resistivity signals, allowing for multi-volume NMR and resistivity measurements without the need for additional resistivity sensors, which reduces the number of sensors required and minimizes direct field signal coupling errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple separate instruments are used for NMR and resistivity measurements, then measurement precision is improved, but device complexity and length increase
Solution Approach 1:
The patent combines NMR and resistivity measurement instruments into a single integrated tool, merging previously separate instruments into one unified device that performs both measurement functions simultaneously, thereby reducing overall device complexity and length while maintaining measurement precision
Solution Approach 2:
The transceiver antenna is designed to perform multiple functions: it serves as both an NMR transmitter and receiver, and simultaneously functions as a resistivity transmitter and receiver. This multi-functionality eliminates the need for separate dedicated sensors for each measurement type, reducing device complexity
2Measurement precision
If additional resistivity sensors are added to combined NMR/resistivity tools, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The transceiver antenna performs dual functionality by serving as both NMR and resistivity sensors simultaneously. The same antenna structure and signal processing circuitry are used for both measurement types, eliminating the need for additional dedicated resistivity sensors and reducing overall device complexity
Solution Approach 2:
The system uses parameter changes in the antenna operation to differentiate between NMR and resistivity measurements. By varying frequency, pulse duration, and signal processing parameters, the same physical antenna can accurately perform both measurement types without requiring additional hardware
3Device complexity
If transceiver antennae are used for both NMR and resistivity measurements, then device complexity is reduced, but measurement precision may deteriorate due to direct field signal coupling
Solution Approach 1:
The patent extracts and removes the direct field signal coupling effect from the resistivity measurement by using the NMR transmitter signal as a reference. The system separates the desired resistivity signal from the harmful direct coupling signal through signal processing, effectively taking out the interference component
Solution Approach 2:
The system uses feedback by monitoring the NMR transmitter signal and using it as a reference to subtract the direct field coupling component from the resistivity measurement. This feedback mechanism allows the system to compensate for the coupling effect and maintain measurement precision
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 solution enables efficient, cost-effective, and detailed characterization of geological formations by combining NMR and resistivity measurements in a single tool, reducing the length and complexity of the tool string and enhancing the accuracy of resistivity data by minimizing direct field signal coupling errors.
Implementation Method 1
a first transceiver antenna to transmit a common signal into a formation and to receive a first corresponding nuclear magnetic resonance (NMR) signal from a first volume of the formation
Implementation Method 2
a second transceiver antenna to receive a resistivity signal as a version of the common signal transformed by the formation
Data Source
AI summary
In some embodiments, an apparatus, system, and method may operate to transmit, using a first transceiver antenna, a common signal into a geological formation, and to receive in response to the transmitting, at the first transceiver antenna, a first corresponding nuclear magnetic resonance (NMR) signal from a first volume of the formation. Additional activity may include receiving, in response to the transmitting, at a second transceiver antenna spaced apart from the first transceiver antenna, the common signal transformed by the formation into a received resistivity signal, as well as transmitting, using the second transceiver antenna, a second corresponding NMR signal into a second volume of the formation different from the first volume of the formation. Additional apparatus, systems, and methods are disclosed.