Well Logging Acoustic Tool Wave Cancellation for Formation Signal Separation
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Solution Overview
Problem
Existing well logging tools face challenges in effectively separating tool waves from formation waves due to interference, which compromises the integrity of the logging tool and depth range, and existing filtering methods are inadequate when formation wave slowness is close to tool wave slowness.
Innovation Solution
The method involves actively reducing tool waves using a transmitter approach, where auxiliary transmitters emit inverse-phase acoustic waves to cancel out the tool wave, and a receiver approach, where waveform data from auxiliary receivers is used to estimate and remove the tool wave, ensuring the tool wave propagating factor differs from the formation wave.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If slotted sleeves and grooved collars are added to sonically isolate the transmitter and receiver, then tool wave reduction is achieved, but tool strength is compromised
Solution Approach 1:
The patent replaces passive mechanical isolation structures (slotted sleeves, grooved collars) with active electronic signal processing. The system uses sensors to detect tool waves and applies adaptive filtering algorithms to subtract these waves from the received signal, eliminating the need for mechanical modifications that would compromise tool strength.
Solution Approach 2:
The patent introduces an intermediary signal processing system between the transmitter and receiver. This intermediary system includes adaptive filters and wavefield separation algorithms that actively cancel tool waves through destructive interference of sound waves or digital signal subtraction, allowing full-strength tool construction while achieving wave isolation.
2Object-affected harmful factors
If array filtering is applied to separate tool waves from formation waves, then tool wave reduction is achieved, but filtering effectiveness is insufficient when formation wave slowness is close to tool wave slowness
Solution Approach 1:
The patent employs dynamic adaptive filtering where filter parameters are continuously adjusted based on real-time signal characteristics. The system uses reference signals from additional sensors to adaptively tune filter coefficients, allowing the filter to dynamically track and separate tool waves from formation waves even when their slowness values are similar, maintaining high measurement precision under varying conditions.
Solution Approach 2:
The patent implements feedback mechanisms where the output signal is continuously monitored and fed back to adjust filter parameters. This closed-loop system uses the detected formation wave characteristics to optimize the separation process, ensuring that when formation wave slowness approaches tool wave slowness, the filter automatically adapts to maintain effective separation and measurement accuracy.
3Object-affected harmful factors
If passive attenuation components are added to the logging tool, then tool wave reduction is achieved, but device complexity increases
Solution Approach 1:
The patent replaces complex passive mechanical attenuation structures with compact electronic signal processing systems. Instead of adding multiple physical isolation components, the invention uses digital signal processors and adaptive filtering algorithms that can be implemented in existing tool electronics, significantly reducing structural complexity while achieving equivalent or superior tool wave reduction.
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 effectively suppresses tool waves by up to -20 dB, maintaining the strength and depth range of the logging tool while accurately determining formation properties for hydrocarbon presence and cement integrity.
Implementation Method 1
auxiliary transmitters positioned along the longitudinal axis of the logging tool transmit an acoustic wave that causes the tool wave excited by the primary transmitter to be reduced
Data Source
AI summary
Enclosed herein are a method and system for reduction of a tool wave excited by a transmitter of the well logging tool. In one embodiment, a method comprises transmitting, by a primary transmitter, a primary acoustic wave into a geologic formation which excites a tool wave and a formation wave in the geologic formation, wherein the logging tool comprises a tool wave propagating factor which is different from a formation wave propagating factor; receiving, by one or more receivers, the formation wave and the tool wave; propagating waveform data associated with the received tool wave and formation wave based on a distance between the auxiliary receiver and a primary receiver; and reducing the tool wave in waveform data associated with the formation wave and the tool wave received by a primary receiver of the one or more receivers based on the propagated waveform data.