EM Receiver Impedance Characterization for Conductive Liner Attenuation
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Solution Overview
Problem
The performance of magnetic field receivers in wellbore casing is compromised by electrically conductive casings, leading to attenuated measurements and difficulties in determining the attenuation factor, which results in errors in hydrocarbon reservoir characterization.
Innovation Solution
Determining the impedances of an electromagnetic (EM) receiver at multiple frequencies to characterize the properties of an electrically conductive liner, such as conductivity, magnetic permeability, and thickness, allowing for the calculation of the attenuation factor and subsequent correction of measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic field receivers are positioned within a wellbore casing to measure formation resistivity, then formation resistivity measurements can be obtained, but the electrically conductive casing attenuates the magnetic field signal making it undetectable by standard receivers
Solution Approach 1:
The patent measures the impedance of the receiver at multiple frequencies to characterize the liner properties (conductivity, permeability, thickness). The harmful attenuation effect is converted into useful information by using the same conductive liner that causes attenuation as the object of measurement to determine its properties, which then enables correction of the formation resistivity measurements.
Solution Approach 2:
The patent changes the operating frequency parameter of the EM receiver to measure impedance at multiple frequencies. By measuring at different frequencies, the system can characterize the liner properties and determine the attenuation factor, transforming a single-frequency measurement into a multi-frequency analysis that resolves the attenuation problem.
2Device complexity
If standard EM receivers are used in cased wellbores, then device complexity is minimized, but measurement precision deteriorates due to signal attenuation and inability to determine attenuation factor
Solution Approach 1:
The EM receiver performs dual functionality: it both measures the formation resistivity and characterizes the liner properties by measuring its own impedance at multiple frequencies. The receiver uses itself as the measurement object to determine liner conductivity, permeability, and thickness, eliminating the need for separate characterization equipment.
3Adaptability or versatility
If variations in conductivity, permeability, and thickness along the casing are present, then real-world conditions are accurately represented, but determining the attenuation factor at any selected point becomes difficult
Solution Approach 1:
The patent divides the continuous liner into discrete segments or zones along the wellbore. By measuring impedance at multiple frequencies at each location, the system characterizes liner properties for each segment independently, allowing the attenuation factor to be determined at selected points despite overall variations along the casing length.
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 enables accurate characterization of the liner properties, improving the sensitivity and accuracy of EM measurements by accounting for variations in conductivity, permeability, and thickness, thereby reducing measurement errors and enhancing the determination of hydrocarbon reservoir properties.
Implementation Method 1
One technique to measure formation resistivity involves the use of electromagnetic induction using transmitters of low frequency magnetic fields which induce electrical currents in the formation. These currents in turn produce secondary magnetic fields which are measured in an adjacent wellbore (or at some distance away in the same wellbore) by a magnetic field receiver.
Data Source
AI summary
Impedances of an electromagnetic (EM) coil positioned in a well lined with an electrically conductive liner are determined. The impedances correspond to plural frequencies of operation of the EM coil. Based on the impedances of the EM coil corresponding to the plural frequencies, an attenuation factor associated with the electrically conductive liner is determined.