Borehole Logging Signal Deconvolution for High Count Rate Resolution
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Solution Overview
Problem
Existing borehole logging techniques face limitations in signal-to-noise ratio and energy resolution due to high-pass filters, leading to increased measurement time and reduced logging speed, especially at higher count rates, which hampers the detection of subsurface rock content in oil well logging.
Innovation Solution
A method that involves collecting and processing detector output data to resolve individual signals by determining their form, temporal position, and energy, using calibration processes and mathematical models to improve data characterization and reduce dwell time, thereby enhancing logging speed and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-pass filters are used to shorten pulse length and increase throughput, then logging speed is improved, but signal-to-noise ratio and energy resolution deteriorate
Solution Approach 1:
The patent changes the fundamental parameter of signal processing from linear filtering to non-linear deconvolution algorithms. This allows the system to maintain both high throughput and high energy resolution by mathematically separating overlapping pulses without the need for high-pass filtering, thus resolving the contradiction between logging speed and energy resolution.
Solution Approach 2:
The patent replaces the mechanical/electronic high-pass filter system with a digital signal processing system using deconvolution algorithms. This substitution eliminates the need for trade-offs between filter cutoff frequency and resolution, allowing simultaneous optimization of both logging speed and energy resolution through computational methods.
2Productivity
If count rate is increased to improve productivity, then logging speed is improved, but pile-up events increase and measurement accuracy deteriorates
Solution Approach 1:
The patent converts the harmful effect of pulse pile-up into a beneficial challenge for the deconvolution algorithm. By using non-linear deconvolution, the system can actually extract more information from piled-up pulses than from isolated pulses, turning the high count rate problem into an opportunity for enhanced measurement capability.
Solution Approach 2:
The patent enables continuous processing of high-rate pulse streams without the interruptions caused by pile-up rejection. The deconvolution algorithm continuously extracts signal information from the entire pulse train, maintaining useful action throughout the measurement period rather than discarding portions of the data stream.
3Productivity
If dwell time is reduced to increase logging speed, then productivity is improved, but data collection time for accurate measurement decreases
Solution Approach 1:
The patent performs preliminary signal separation and characterization during the dwell time period, preparing the data for rapid analysis. By pre-processing the pulse signals through deconvolution, the system extracts maximum information content before the dwell time expires, enabling accurate measurements even with reduced collection time.
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 significantly reduces dwell time and increases logging tool speed, maintaining high data throughput even at high count rates, allowing for more accurate and efficient characterization of subsurface content, such as elemental concentrations in oil well logging.
Implementation Method 1
detecting radiation emitted by the material
Data Source
AI summary
A method and apparatus for borehole logging, the method comprising collecting detector output data from a radiation detector of a borehole logging tool, and resolving individual signals in the detector output data by (i) determining a signal form of signals present in the data, (ii) making parameter estimates of one or more parameters of the signals, wherein the one or more parameters comprise at least a signal temporal position, and (iii) determining the energy of each of the signals from at least the signal form and the parameter estimates. The logging tool is shorter, logging tool speed is greater, dwell time is shorter and/or resolution is improved.