Towed EM Streamer for Passive Magnetotelluric Data Acquisition
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Solution Overview
Problem
Traditional magnetotelluric (MT) surveys in marine environments require costly and time-consuming deployment of water-bottom sensing equipment, limiting their flexibility and efficiency compared to towed streamer surveys.
Innovation Solution
A towed electromagnetic (EM) streamer system that collects passive EM field data, either alone or in combination with active EM surveys, allowing for the acquisition of MT data without the need for water-bottom equipment, thereby reducing time and cost by utilizing active EM survey equipment for MT surveys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If water-bottom sensing equipment is used for MT surveys, then measurement precision is improved, but loss of time and operational efficiency deteriorate due to manual deployment and retrieval requirements
Solution Approach 1:
The patent replaces the mechanical deployment and retrieval system with a towed streamer system that is pulled through the water by a vessel. The streamer contains sensors that continuously collect MT data as it moves, eliminating the need for manual placement and recovery of water-bottom equipment while maintaining measurement quality through controlled towing operations.
Solution Approach 2:
The invention transitions from a static water-bottom sensor array to a dynamic towed streamer system. The streamer moves continuously through the survey area, allowing data collection across multiple locations without repeated deployment cycles. This dynamic approach maintains measurement precision while dramatically reducing the time lost to setup and teardown operations.
2Area of stationary object
If water-bottom equipment is deployed for MT surveys, then survey coverage is improved, but device complexity and operational effort increase due to manual handling requirements
Solution Approach 1:
The towed streamer system serves multiple functions simultaneously: it acts as both the sensor platform and the deployment mechanism. The streamer can be towed along various survey lines to cover different areas, and the same equipment configuration can be reused for multiple survey regions, reducing overall operational complexity while expanding coverage capability.
Solution Approach 2:
The streamer is divided into multiple segments with distributed sensors along its length. This segmentation allows the system to cover a wide area as it is towed, with each segment contributing to the overall survey coverage. The modular structure simplifies handling and deployment compared to a single large water-bottom array.
3Measurement precision
If traditional MT survey methods are used, then subsurface investigation capability is improved, but productivity deteriorates due to time-consuming equipment deployment
Solution Approach 1:
The towed streamer enables continuous data collection as it moves through the survey area. Unlike traditional methods that require stopping for deployment and retrieval, the streamer continuously gathers MT data throughout the towing operation, maintaining productive action throughout the entire survey process and significantly increasing the acquisition rate of subsurface information.
Solution Approach 2:
The streamer is prepared and deployed in advance as a single unit before the survey begins. This preliminary preparation eliminates the need for repeated setup operations during the survey, allowing the main data collection phase to proceed at high speed with minimal interruptions, thereby improving overall productivity while maintaining investigation capability.
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
Enables efficient and cost-effective acquisition of long-period passive EM field data, enabling deeper subsurface investigation with reduced operational time and effort, while maintaining acceptable survey resolution.
Implementation Method 1
One particular survey technique involves detection of passive EM fields, for example, by measuring the variation in the natural geomagnetic and/or geoelectric fields of the Earth, and using this information to generate inferences regarding sub-surface geology in the region in which the passive EM fields are measured. This type of survey may also be referred to as a magnetotelluric (MT) survey.
Implementation Method 2
A towed electromagnetic (EM) streamer system that collects passive EM field data
Data Source
AI summary
Techniques are disclosed for generating a time series representation of passive electromagnetic (EM) fields via towed streamer measurements without dependence on water-bottom measurement equipment. Such techniques may include storing records of respective time series measurements of passive EM fields measured by individual receivers as the individual receivers pass over a first measurement point, where the respective time series measurements correspond to respective measurement intervals, and where the respective time series measurements are synchronized with respect to a reference clock. The records of the respective time series measurements may be combined to generate a time series representation of passive EM fields observed at the first measurement point over a combination of the respective measurement intervals. The time series representation of passive EM fields observed at the first measurement point may, in turn, be used to identify one or more characteristics of subsurface structure.