EM Receiver Array Noise Suppression via Beamforming
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Solution Overview
Problem
Electromagnetic (EM) receivers used in subterranean surveys face noise interference due to tow cable vibrations, leading to inaccurate measurements when deployed in water environments.
Innovation Solution
The solution involves arranging EM receivers with reduced spacings and using adaptive beamforming techniques, as well as designing the tow cable with mechanical characteristics such as dampening materials and controlled tension to minimize noise, including using a slim cable with a high resonant frequency and adding mass to reduce vibration-induced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If EM receivers are arranged with reduced spacing to enable adaptive beamforming, then noise suppression capability is improved, but the complexity of data processing increases
Solution Approach 1:
The patent applies preliminary action by pre-arranging EM receivers at specific reduced spacings before deployment to enable adaptive beamforming. The receivers are positioned in advance with optimized spacing to capture noise signals that can be subsequently processed using beamforming algorithms, allowing noise suppression to be achieved through predetermined geometric configuration combined with signal processing.
2Measurement precision
If tow cable is designed with dampening materials and increased mass to reduce vibrations, then measurement accuracy is improved, but the cable weight increases
Solution Approach 1:
The patent applies composite materials by incorporating dampening materials into the tow cable structure. The cable is designed as a composite construction that combines structural elements with vibration-dampening layers or materials, allowing the cable to maintain its mechanical strength while reducing vibrations that would otherwise interfere with EM measurements. This composite approach enables improved measurement accuracy without simply adding mass, but rather by integrating functional materials that actively reduce harmful vibrations.
3Object-affected harmful factors
If EM receivers are placed closer together, then noise suppression through beamforming is improved, but the coverage area per receiver decreases
Solution Approach 1:
The patent applies dimensionality change by transitioning from conventional sparse receiver spacing to a dense array configuration where receivers are placed closer together in multiple dimensions. This creates a two-dimensional or three-dimensional array structure that enables adaptive beamforming capabilities. The reduced spacing allows the system to form directional beams and suppress noise from specific directions, effectively adding spatial dimensionality to the measurement approach and improving noise suppression while maintaining comprehensive survey coverage through coordinated processing of multiple closely-spaced receivers.
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 noise, enhancing the accuracy of EM measurements by isolating electrical wires from cable vibrations and optimizing cable design to keep noise outside the frequency range of interest.
Implementation Method 1
designing the tow cable with mechanical characteristics such as dampening materials and controlled tension to minimize noise
Implementation Method 2
using a slim cable with a high resonant frequency and adding mass to reduce vibration-induced noise
Data Source
AI summary
To survey a subterranean structure, for acquiring an electromagnetic (EM) measurement signal across EM receivers having a target axial spacing, a group of more than two EM receivers in an interval defined by the target axial spacing along a sensor cable is provided. The spacing between successive ones of at least some EM receivers in the group is less than the target axial spacing. EM measurements are acquired using the EM receivers in the group.