Marine Sensor Cable Exterior Coil Mounting
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Solution Overview
Problem
Existing marine electromagnetic survey systems face challenges in reducing induction noise caused by sensor movement, as the magnetic field sensors within the receiver cables are susceptible to deformation during survey operations, leading to inaccurate measurements of spatial distribution of electrical properties in rock formations.
Innovation Solution
The implementation of magnetic field sensors disposed along the receiver cable with specific coil configurations, such as saddle coils and orthogonal coils, that are less susceptible to cable deformation, allowing for improved detection of induced voltages and strain measurements, thereby reducing noise from sensor movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic field sensors are placed inside the receiver cable structure, then the sensors are protected from external damage, but the sensors become susceptible to cable deformation during survey operations
Solution Approach 1:
The magnetic field sensors are extracted from the interior of the receiver cable and mounted on the exterior surface. This allows the sensors to remain protected by the cable structure while avoiding the deformation issues that occur when sensors are embedded within the cable. The sensors are positioned to measure the magnetic field at the cable surface without being subjected to the internal stresses and deformations of the cable construction.
2Ease of operation
If the receiver cable is made flexible for towing operations, then the cable can be deployed and retrieved, but the cable deformation causes sensor movement and measurement errors
Solution Approach 1:
The solution applies local quality by creating a specific deformation-resistant zone at the cable surface where the sensors are mounted. While the cable remains flexible overall for towing operations, the sensor mounting structure and immediate surrounding area are designed to minimize local deformation. This allows the cable to be deployed and retrieved while maintaining measurement precision in the critical sensor region.
3Loss of information
If sensors are positioned to measure magnetic field variations along the cable length, then spatial distribution data can be obtained, but cable bending and twisting cause additional noise in the measurements
Solution Approach 1:
An intermediary deformation compensation mechanism is introduced between the cable structure and the sensors. This compensation system detects cable deformation and applies corrective adjustments to the sensor readings, effectively separating the true magnetic field variations from the noise caused by cable bending and twisting. This allows spatial distribution information to be accurately recovered despite cable movement.
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 configuration enhances the accuracy of electromagnetic survey data by minimizing noise from cable movement, enabling better detection of induced voltages and strain, thus improving the spatial distribution analysis of electrical properties in rock formations.
Implementation Method 1
measuring a parameter related to an amount of current passed through an electromagnetic transmitter to induce an electromagnetic field in subsurface formations. A magnetic field proximate the electromagnetic receiver is measured.
Implementation Method 2
The Earth magnetic field induced voltage noise at each receiver is proportional to the rate of change of magnetic flux, which is proportional to the product of the Earth's magnetic field H(t) and the component of the receiver cable velocity vector that is perpendicular to the Earth's magnetic field.
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
A marine electromagnetic sensor cable includes a first jacket covering an exterior of the cable. At least one wire loop is disposed on the exterior of the first jacket. The wire loop is shaped to have a magnetic dipole moment along a selected direction. A contact ring is disposed inside the first jacket to make electrical connection between the at least one wire loop and an associated signal processing circuit disposed inside the first jacket.