Capacitive Tri-Axial Electric Field Sensors for Borehole Measurements
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Solution Overview
Problem
Current electric field sensors in borehole environments are unreliable due to sensitivity to environmental conditions and require maintenance, limiting their ability to measure tri-axial electric fields at low frequencies, which hampers the development of effective electromagnetic instrumentation for reservoir characterization and monitoring.
Innovation Solution
The use of capacitive electrode technology coupled with miniaturized magnetic field sensors allows for reliable tri-axial electric field measurements in boreholes, independent of local environmental conditions, enabling extended depth of investigation and reduced maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If magnetic coils are used for electromagnetic measurements in boreholes, then the technology can detect induced magnetic fields, but it cannot measure electric field components in three dimensions at low frequency
Solution Approach 1:
The patent combines capacitive electric field sensors and magnetic field sensors into a single integrated measurement system. The capacitive sensor array measures electric field components while the magnetic sensor measures magnetic field components, allowing simultaneous tri-axial electric and magnetic field measurements in the borehole environment.
Solution Approach 2:
The patent replaces the traditional magnetic coil-based electromagnetic induction system with a capacitive sensor system. The capacitive sensors directly measure electric field components through capacitance changes, substituting the indirect magnetic induction method with a direct electric field measurement approach that works effectively at low frequencies.
2Measurement precision
If conventional electric field sensors are installed in boreholes, then measurements can be taken, but they are very sensitive to environmental conditions and require careful maintenance
Solution Approach 1:
The patent employs a capacitive sensor array where each sensor element has localized measurement capability. The capacitive structure allows each sensor to independently measure electric field components at its specific location, providing spatially distributed measurements that are less susceptible to environmental variations compared to conventional sensors.
Solution Approach 2:
The patent changes the operating principle from magnetic induction to capacitive measurement. By measuring changes in capacitance rather than induced magnetic fields, the system achieves measurements that are less sensitive to environmental conditions such as fluid composition, temperature, and pressure, thereby improving reliability.
3Measurement precision
If capacitive electrodes are used for high frequency measurements, then they can measure wellbore resistivity, but they are limited to a small zone in the vicinity of the borehole
Solution Approach 1:
The patent extends the measurement capability from a localized zone to a three-dimensional volume around the borehole. By using an array of capacitive sensors oriented in multiple directions (tri-axial configuration), the system measures electric field components in all three spatial dimensions, enabling characterization of the broader reservoir environment.
Solution Approach 2:
The patent divides the measurement system into multiple discrete capacitive sensor elements arranged in an array. Each sensor element measures local electric field components, and the combined data from all elements provides comprehensive information about the electromagnetic field distribution in the surrounding reservoir volume.
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 solution enhances the sensitivity to fluid composition changes in reservoirs, enabling more accurate characterization and monitoring of oil and gas production, with capacitive electrodes providing stable and reliable measurements across varying conditions without chemical reactions or electrolytes.
Implementation Method 1
The present invention relates to tri-axial field sensors for low frequency electromagnetic fields... capacitive electrode technology... measuring the electromagnetic field... capacitive measurements have been made in a borehole environment
Implementation Method 2
These devices are designed to detect and measure the induced magnetic field generated by an electromagnetic source operating in the frequency or in the time domain
Data Source
AI summary
A method and apparatus is provided for collecting reservoir data. The method includes providing one or more electromagnetic sources for generating an electromagnetic field in a reservoir and providing one or more electromagnetic sensors equipped with capacitive electrodes. The electromagnetic source is located separately from the electromagnetic sensor. The electromagnetic sensor may either be located within a well or at the surface, is capable of measuring the electromagnetic field in three dimensions, and may be isolated from the well fluids. The data collected by the electromagnetic sensors can be used to create a model of the oil reservoir, including the water saturation.