Adaptive Beamforming for Downhole Acoustic Imaging
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Solution Overview
Problem
Existing acoustic imaging technologies face challenges in effectively directing and focusing acoustic beams in harsh downhole environments, where high temperatures, pressures, and changing conditions complicate the measurement of earth formation characteristics and borehole conditions.
Innovation Solution
The implementation of an adaptive beamforming process using a phased array of acoustic transducers, where delays are calculated from reflection waveforms to focus acoustic energy on specific target locations, allowing for high-resolution imaging without being limited by the number of transducers and accommodating changes in the borehole environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional acoustic imaging methods are used in downhole environments, then the basic imaging function is maintained, but the resolution and beam directing capability deteriorate due to harsh conditions
Solution Approach 1:
The patent implements dynamic beamforming by continuously calculating travel times from reflected acoustic waves and adjusting beamforming delays in real-time. This allows the acoustic beam to be dynamically directed and focused on target locations despite changes in downhole conditions such as temperature, pressure, and borehole geometry, thereby maintaining both imaging resolution and beam directing capability
Solution Approach 2:
The system uses reflected acoustic waves as feedback to calculate travel times and determine optimal beamforming delays. By monitoring the reflected signals and continuously adjusting the beamforming parameters based on this feedback, the system maintains accurate beam direction and high imaging resolution even when downhole conditions change
2Measurement precision
If more transducers are added to improve imaging resolution, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
Each transducer in the array is designed to perform multiple functions: transmitting acoustic waves, receiving reflected waves, and participating in beamforming as either a transmitter or receiver depending on the operational mode. This multi-functionality allows the same transducer array to achieve high imaging resolution without requiring separate dedicated transmitter and receiver arrays, thereby reducing overall device complexity
3Adaptability or versatility
If fixed beamforming delays are used, then the device complexity is reduced, but the adaptability to changing downhole conditions deteriorates
Solution Approach 1:
The system automatically calculates travel times from reflected acoustic waves and determines the optimal beamforming delays without requiring external intervention or manual adjustment. The transducer array itself provides the feedback information needed to self-adjust the beamforming parameters, enabling the system to adapt to changing downhole conditions while keeping the control system relatively simple
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 enables high-resolution acoustic imaging of borehole fractures and formation characteristics, improving resolution and flexibility in directing acoustic beams, even in challenging downhole conditions, by calculating delays in real-time to maintain image quality and accuracy.
Implementation Method 1
transmitting an acoustic signal only by the transmitter; detecting an acoustic return signal by the transmitter and by the plurality of other transducers
Implementation Method 2
detecting an acoustic return signal; the estimating including measuring a travel time for each other transducer of the plurality of other transducers in the group of transducers
Implementation Method 3
calculating a beamforming delay associated with the transmitter and the plurality of other transducers based on the travel time, the beamforming delay configured to cause the group of transducers to generate an acoustic beam that is directed to the target location
Data Source
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AI summary
A method of performing acoustic imaging includes: selecting a target location, and selecting a group of transducers from a plurality of transducers to transmit an acoustic beam to be electronically directed to the target location; selecting a transmitter having an orientation toward a location proximate to the target location, and transmitting an acoustic signal only by the transmitter; detecting an acoustic return signal by the transmitter and by a plurality of other transducers in the group; estimating a travel time for each of the group of transducers, the estimating including measuring a travel time for each of the other transducers, and estimating a travel time for the transmitter based on the travel time for each of the other transducers; and calculating beamforming delays based on the travel time, the beamforming delay configured to cause the group of transducers to direct an acoustic beam to the target location.