Marine Electromagnetic Survey Electrode Degradation Detection

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Solution Overview

Problem

Marine electromagnetic survey systems face challenges in identifying degrading electrodes while in use, leading to decreased accuracy and operational life due to seawater interactions and biological contaminations, requiring inefficient and costly retrieval and replacement.

Innovation Solution

A method and system to detect degrading electrodes in real-time by measuring voltage changes and noise levels across electrodes, allowing for in-situ identification and replacement without surfacing, using a shunt resistor and processor to calculate resistance and noise levels, and potentially electrochemically restoring Ag-AgCl electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If electrodes are deployed in seawater for marine electromagnetic surveying, then the survey system can collect electromagnetic data from subterranean formations, but the electrodes degrade due to seawater interactions and biological contaminations

Engineering Contradiction:
Improvesurvey data collection capabilityVSAvoidelectrode performance stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system performs preliminary identification of degrading electrodes through resistance measurements and noise level analysis before they completely fail. By continuously monitoring electrode conditions during deployment, the system can detect degradation trends and identify problematic electrodes while still operational, allowing for proactive replacement rather than waiting for complete failure.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms by measuring resistance values and noise levels from each electrode and comparing them against threshold criteria. This feedback loop enables real-time monitoring of electrode health, allowing the system to identify degrading electrodes based on measured parameters that indicate seawater interaction and biological contamination effects.

Inventive Principle:
Principle #23Feedback

2Ease of repair

If electrodes are individually tested above the surface to identify degrading ones, then degraded electrodes can be replaced, but the process requires significant time, effort, and expense

Engineering Contradiction:
Improveelectrode replacement capabilityVSAvoidelectrode retrieval and replacement time
Core Design Contradiction:
Ease of repairVSLoss of time

Solution Approach 1:

The patent replaces manual mechanical testing and retrieval processes with automated electrical measurements. Instead of physically retrieving and manually testing each electrode above water, the system uses electrical resistance measurements and noise level analysis conducted while electrodes remain deployed in the seabed, substituting mechanical retrieval with electronic identification.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system enables self-service by allowing electrodes to be identified and flagged for replacement based on their own measured electrical characteristics. The monitoring system automatically detects which electrodes are degrading through resistance and noise analysis, eliminating the need for external manual inspection and retrieval operations.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If electrodes are monitored continuously during deployment, then degrading electrodes can be identified in real-time, but the system complexity increases

Engineering Contradiction:
Improveelectrode degradation detection accuracyVSAvoidmonitoring system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The monitoring system is segmented into simple, modular measurement functions: resistance measurement circuitry and noise level detection circuitry. Each electrode is monitored through basic electrical measurements that can be processed independently, allowing the complex task of electrode monitoring to be divided into simple, repeatable measurement steps that reduce overall system complexity.

Inventive Principle:
Principle #1Segmentation

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 identification and replacement of degrading electrodes, reducing downtime, effort, and expense, while maintaining survey system performance and safety by pinpointing single degrading electrodes among many, and potentially restoring electrode functionality through electrochemical means.

Implementation Method 1

measuring a voltage between the pair of electrodes and determining a total resistance for the marine electromagnetic survey system based on the measured voltage

Methodology Applied
Scientific EffectOhm's Law: Ohm's Law

Implementation Method 2

determining a noise level for the marine electromagnetic survey system based on the measured voltage and the determined total resistance

Methodology Applied
Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentEP3136131B1Identification of degrading electrodes in a marine electromagnetic survey system
Publication Date: 2021.06.02 PGS GEOPHYSICAL AS
  • EP3136131B1 patent drawingFigure 1
  • EP3136131B1 patent drawingFigure 2
  • EP3136131B1 patent drawingFigure 3

AI summary

A system and method is provided for identifying degrading electrodes (12) in a marine electromagnetic survey system (1). A system may comprise a sensor array (18) operable for use in a marine electromagnetic survey system (1), wherein the sensor array comprises a plurality of electrodes (12). The system may comprise a shunt resistor (42) connected to the electrodes (12) and a processor operable to vary a resistance of the shunt resistor in the presence of a voltage across the electrodes. A method for identifying degrading electrodes may comprise measuring an electric field in a body of water with a pair of electrodes, wherein a shunt resistor is connected between the pair of electrodes. The method may comprise varying a resistance of the shunt resistor. The method may comprise measuring a voltage across the shunt resistor while varying the resistance of the shunt resistor to obtain measured voltages for different shunt resistor values. The method may comprise comparing the measured voltages of the different shunt resistor values to calculate resistance of the pair of electrodes.