Passive Electromagnetic Formation Surveillance Using Solar Wind Signals
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Solution Overview
Problem
Monitoring hydrocarbon-bearing formations over long periods is challenging due to changes in fluid distributions and the durability of instrumentation, making repeatable measurements problematic, especially when saline water displaces oil, causing significant resistivity contrasts.
Innovation Solution
Utilizing naturally-occurring electromagnetic signals generated by the interaction of solar wind with the Earth's magnetosphere, measured by sensors positioned adjacent and within boreholes, to determine electromagnetic changes over time, which are processed to generate a computational model of the hydrocarbon-bearing formation, reducing the need for maintenance and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active-source electromagnetic surveys are used to monitor fluid changes in hydrocarbon-bearing formations, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The system utilizes naturally-occurring electromagnetic signals from the Earth's magnetosphere and solar wind interactions as passive sources, eliminating the need for active electromagnetic sources. Sensors deployed in boreholes continuously monitor these natural signals and their changes over time, allowing the formation itself to provide the measurement signals without external intervention or complex survey equipment
Solution Approach 2:
The invention extracts and utilizes the naturally-occurring electromagnetic signals that already exist in the environment, separating the measurement function from the need for active sources. By taking out the active-source requirement and relying on passive natural signals, the system achieves fluid monitoring capability with significantly reduced device complexity and operational cost
2Measurement precision
If repeated electromagnetic measurements are taken over long periods to track fluid displacement, then measurement precision is improved, but reliability deteriorates due to instrumentation durability issues and changing formation conditions
Solution Approach 1:
The system enables continuous, long-term monitoring of electromagnetic signals from the formation without interruption. Sensors remain deployed in boreholes for extended periods, continuously recording natural electromagnetic signals and their temporal changes, providing uninterrupted data for tracking fluid displacement processes over weeks, months, or years
Solution Approach 2:
By using passive natural electromagnetic signals as the measurement source, the system eliminates wear and durability issues associated with active electromagnetic sources and complex survey equipment. The natural signals require no maintenance, and the passive sensing approach allows instruments to operate reliably for extended periods without degradation from repeated active emissions or complex operational cycles
3Measurement precision
If saline water displacement of oil is monitored using traditional methods, then measurement precision is improved, but loss of time increases due to frequent re-deployment of instrumentation
Solution Approach 1:
Sensors are permanently installed in boreholes before production activities begin, positioned to continuously monitor electromagnetic signals from the formation. This preliminary deployment eliminates the need for repeated installation, calibration, and re-deployment of measurement equipment throughout the monitoring period, capturing all fluid displacement events as they occur
Solution Approach 2:
The permanent sensor deployment enables uninterrupted, continuous monitoring of electromagnetic signal changes throughout the entire fluid displacement process. Unlike traditional methods requiring periodic re-deployment, this system maintains constant surveillance of formation conditions, capturing resistivity changes as saline water displaces oil without any interruption or time loss for equipment reinstallation
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 allows for continuous, inexpensive monitoring of fluid changes in hydrocarbon-bearing formations, providing reliable and stable impedance estimates over a broad frequency range, enhancing the detection of fluid saturation variations and reducing the need for active-source surveys.
Implementation Method 1
Naturally-occurring, electromagnetic signals generated by interaction of solar wind with earth's magnetosphere adjacent a borehole are measured by an electromagnetic sensor positioned adjacent the borehole in the hydrocarbon-bearing formation
Implementation Method 2
Either the electromagnetic sensor or the borehole sensor includes a capacitive electric field sensor
Data Source
AI summary
Naturally-occurring, electromagnetic signals generated by interaction of solar wind with earth's magnetosphere adjacent a borehole are measured by an electromagnetic sensor positioned adjacent the borehole in the hydrocarbon-bearing formation. Electromagnetic signals generated within the borehole are measured over a period of time by a borehole sensor positioned within the borehole. The electromagnetic signals change over the period of time due to variations in fluid distributions within the hydrocarbon-bearing formation. Electromagnetic changes to the electromagnetic signals generated within the borehole and to the passive, naturally-occurring electromagnetic signals over the period of time are determined by one or more processors. A computational model of the hydrocarbon-bearing formation is generated based in part on the electromagnetic changes.