Acoustic Density Logging Without Radioactive Sources
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Solution Overview
Problem
The use of radioactive sources for density logging in hydrocarbon reservoirs poses health risks to workers, regulatory challenges, and logistical difficulties due to radiation exposure and the need for extensive safety procedures, as well as supply constraints and high costs associated with these sources.
Innovation Solution
Acoustic logging techniques that measure formation density using compressional and shear wave velocities, eliminating the need for radioactive sources by integrating a fluid cell with an acoustic logging tool to calculate formation density based on acoustic impedance and wave propagation velocities, enabling real-time density logging in both wireline and logging-while-drilling environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radioactive sources are used for density logging, then density measurement capability is achieved, but health risks to workers and regulatory burdens increase
Solution Approach 1:
The patent removes the radioactive source from the logging tool, extracting the harmful element while retaining the density measurement capability through alternative acoustic methods using compressional and shear wave velocities
Solution Approach 2:
The patent replaces the radioactive gamma ray source with an acoustic system that uses mechanical wave propagation (compressional and shear waves) through the formation to determine density, eliminating radiation while maintaining measurement functionality
2Measurement precision
If radioactive sources are used for density logging, then density logs can be obtained, but regulatory compliance costs and safety procedure requirements increase
Solution Approach 1:
The patent extracts the radioactive source from the system, thereby eliminating the need for regulatory compliance with nuclear regulations (10 CFR Parts 20, 32, and 150) and associated safety procedures while maintaining density measurement capability through acoustic methods
3Measurement precision
If radioactive sources are used for density logging, then density measurement is possible, but supply constraints and material costs increase
Solution Approach 1:
The patent removes the radioactive source from the density logging tool, eliminating dependence on scarce and expensive radioactive materials (Cesium-137, Americium-241) while achieving density measurement through alternative acoustic wave propagation methods
Solution Approach 2:
The patent replaces expensive, long-lived radioactive sources with acoustic transducers that have no material scarcity issues and do not require special handling or disposal procedures, effectively using inexpensive, non-radioactive alternatives
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 provides precise density logs without radioactive sources, reducing health risks and regulatory burdens, and offers improved accuracy, especially in rugose boreholes, while eliminating the need for costly and scarce radioactive materials.
Implementation Method 1
measuring propagation velocities of compressional and shear waves through the formation
Implementation Method 2
measuring propagation velocities of compressional and shear waves through the formation
Implementation Method 3
a fluid cell integrated with the acoustic logging tool measures acoustic wave propagation velocity and acoustic impedance of the borehole fluid
Data Source
Figure 1~2
Figure 3~5
Figure 6
AI summary
Formation density is calculated from acoustic logging measurements. This technique does not require a radioactive source and in fact it may offer better precision particularly in rugose boreholes. In at least some embodiments, the technique exploits an observed relationship between a transmission coefficient T(p b , V c ,p m V m ) and a breakdown resistance µB(p b , V c ,V s ) to enable determination of the formation density pb from measurements of the formation's compressional wave velocity V c , the formation's shear wave velocity Vs, and the borehole fluid's acoustic impedance p m V m . The desired measurements can be acquired by attaching or integrating a fluid cell with an acoustic logging tool that measures acoustic wave propagation velocities. Real-time density logs can be obtained from both wireline and logging- while-drilling implementations.