Pulsed Neutron Logging Tool Layout for Combined Porosity and Spectroscopy
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Solution Overview
Problem
Combining neutron porosity and spectroscopy measurements in a single integrated pulsed neutron logging tool is challenging due to space constraints and physics conflicts, resource inefficiencies, and interference between different measurement types, particularly in logging while drilling applications.
Innovation Solution
A dual-purpose pulsed neutron logging tool with a scintillator detector and a pulsed neutron generator that allows for simultaneous detection of neutron-induced and natural gamma rays, optimizing detector placement and using shielding to minimize interference, enabling simultaneous spectroscopy and porosity measurements during a single downhole logging trip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate neutron porosity and spectroscopy tools are used, then measurement accuracy is improved, but device complexity and rig time increase
Solution Approach 1:
The patent combines separate neutron porosity and spectroscopy measurement tools into a single integrated pulsed neutron logging tool. This merging allows both measurement types to be performed simultaneously during one downhole trip, reducing device complexity and rig time while maintaining measurement accuracy through optimized detector placement and shielding design.
Solution Approach 2:
The integrated tool performs multiple functions - both neutron porosity measurement and spectroscopy measurement - using a single pulsed neutron generator and shared detection system. This multi-functionality eliminates the need for separate dedicated tools, reducing overall device complexity while preserving the measurement capabilities of each individual tool type.
2Measurement precision
If separate neutron porosity and spectroscopy tools are used, then measurement accuracy is improved, but loss of time increases
Solution Approach 1:
By merging neutron porosity and spectroscopy measurements into a single integrated tool, both measurement types can be performed simultaneously during one downhole trip. This eliminates the time required to run separate tools independently, significantly reducing total rig time while maintaining the measurement accuracy of each technique.
Solution Approach 2:
The integrated tool enables continuous simultaneous operation of both neutron porosity and spectroscopy measurements during a single logging run. This continuous dual-function operation maximizes productivity by eliminating idle time between separate measurement passes and ensuring both data sets are collected during the same formation traversal.
3Difficulty of detecting and measuring
If detectors are placed close to the pulsed neutron generator, then detection efficiency is improved, but interference between measurement types increases
Solution Approach 1:
The patent applies different local qualities to different parts of the detection system by placing specific detectors at optimized distances from the pulsed neutron generator. Thermal neutron detectors are positioned closer to maximize thermal neutron detection efficiency, while gamma ray detectors are positioned at optimized distances to balance gamma ray detection efficiency with minimization of neutron-induced interference. This spatial differentiation of detector placement optimizes both detection efficiency and interference reduction for each measurement type.
Solution Approach 2:
The patent introduces shielding materials as intermediary elements between the pulsed neutron generator and the detectors. These shielding components selectively attenuate neutron flux and gamma ray backgrounds, reducing interference between measurement types while allowing the detectors to remain positioned at optimal distances for detection efficiency. The shielding acts as a mediator that filters harmful radiation while preserving the useful signal.
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 reduces the complexity of bottom-hole assemblies and saves rig time by allowing for comprehensive formation analysis in a single run, enhancing data quality and efficiency in both wireline and logging while drilling operations.
Implementation Method 1
a scintillator detector and a pulsed neutron generator that allows for simultaneous detection of neutron-induced and natural gamma rays
Implementation Method 2
transmit neutrons into a formation for either logging while drilling (LWD) or wireline logging measurements
Data Source
AI summary
A system and a method for a pulsed neutron logging tool. The pulsed neutron logging tool may include a pulsed neutron generator for generating one or more neutrons, one or more gamma ray scintillator detectors disposed in a detection area, a shielding block that separates the pulsed neutron generator from the one or more gamma ray scintillator detectors, and a shielding layer. The pulsed neutron logging tool may further comprise an information handling system communicatively connected at least in part to the pulsed neutron logging tool. The information handling system is configured to create a gamma ray spectrum from the one or more gamma rays detected by the one or more gamma ray scintillator detectors, remove a background from the gamma ray spectrum to form a peaks-only spectrum, and compare one or more peaks-only elemental standards to the peaks-only spectrum to determine an elemental weight and yield.