Universal Neutron Pulsing for Single-Trip Sigma and CO Logging
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Solution Overview
Problem
Current logging techniques require multiple trips of a pulsed neutron logging tool to perform different pulsing schemes for various measurements, which is inefficient and time-consuming, especially in logging while drilling (LWD) operations.
Innovation Solution
A universal pulsing scheme for a pulsed neutron logging tool that allows multiple types of measurements to be taken simultaneously, combining Sigma and CO pulsing schemes, optimizing neutron burst widths, and adjusting parameters for real-time data quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple pulsing schemes are used for different measurements, then measurement variety is improved, but logging time and trips are increased
Solution Approach 1:
The patent implements a universal pulsing scheme that enables a single logging tool to perform multiple measurement types (Sigma, CO, and other neutron-based measurements) through different pulsing modes. This multi-functional approach allows the tool to gather diverse formation evaluation data without requiring multiple separate logging trips, directly resolving the contradiction between measurement variety and logging time.
Solution Approach 2:
The patent employs periodic pulsing schemes with varying duty cycles and pulse widths to enable different measurement types. By systematically alternating between Sigma pulsing mode, CO pulsing mode, and other measurement modes within a single logging trip, the system achieves multiple measurements efficiently, reducing total logging time while maintaining measurement diversity.
2Measurement precision
If multiple logging trips are performed, then measurement completeness is improved, but tool wear and operational efficiency are worsened
Solution Approach 1:
The universal pulsing scheme consolidates multiple measurement capabilities into a single logging tool configuration. The tool can perform Sigma measurements, CO measurements, and other neutron-based evaluations during one continuous logging trip, eliminating the need for multiple trips and thereby reducing tool wear while maintaining measurement completeness.
Solution Approach 2:
The patent merges previously separate measurement operations into a single integrated logging trip. By combining Sigma pulsing, CO pulsing, and other measurement modes in one operational sequence, the system achieves complete formation evaluation data without requiring multiple separate trips, thus improving operational efficiency and reducing tool wear.
3Quantity of substance
If neutron burst width is increased, then neutron flux is improved, but measurement resolution is worsened
Solution Approach 1:
The patent dynamically adjusts the neutron burst width and duty cycle based on the specific measurement mode being performed. During Sigma measurements, one pulsing configuration is used, while during CO measurements, a different pulsing configuration is applied. This dynamic adaptation allows optimization of neutron flux for each measurement type while maintaining appropriate temporal resolution, resolving the contradiction between neutron flux and measurement resolution.
Solution Approach 2:
The system changes key pulsing parameters (burst width, duty cycle, pulse repetition frequency) depending on the measurement objective. By adjusting these parameters appropriately for each measurement mode, the system achieves sufficient neutron flux for statistical accuracy while maintaining the temporal resolution needed for precise formation evaluation, thus resolving the flux-resolution trade-off.
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 efficient, high-quality data acquisition in a single logging trip, reducing rig time and tool wear, and improving tool performance and efficiency in both LWD and wireline operations.
Implementation Method 1
The pulsed neutron tool may comprise a pulsed neutron generator (PNG) that may operate and function to transmit neutrons into a formation for either logging while drilling (LWD) or wireline logging measurements
Data Source
AI summary
A method and system for creating a pulsing scheme. The method may include selecting a pulsing scheme for downhole measurements using a pulsed neutron logging tool and selecting a neutron burst width for the pulsing scheme based at least in part on a neutron tube utilized by the pulsed neutron logging tool during the downhole measurements. The method may further include selecting a carbon-oxygen ratio (CO) neutron burst train for the pulsing scheme to be utilized by the neutron tube, selecting a Sigma decay time for the pulsing scheme, and performing one or more measurements with the pulsed neutron logging tool using the pulsing scheme. The system may include a pulsed neutron logging tool. The pulsed neutron logging tool may include a neutron tube disposed in a pulsed neutron generator, one or more gamma ray scintillator detectors, and one or more thermal neutron detectors.