Wellbore Lining Correction Factors via Sensor Array
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Solution Overview
Problem
Conventional electromagnetic induction survey techniques fail to accurately correct for the effects of inhomogeneous electrically conductive lining structures in wellbores, leading to errors in resistivity measurements due to variations in conductivity, permeability, thickness, and diameter along the casing, which complicates the determination of attenuation factors and affects the accuracy of hydrocarbon reservoir characterization.
Innovation Solution
A method and system utilizing an array of sensors, including a transmitter and multiple receivers, deployed in a wellbore with a conductive lining structure, measure magnetic fields and compute correction factors to account for the lining structure's effects, allowing for precise determination of lining structure correction factors and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electromagnetic induction survey techniques are used, then the measurement process is simple, but the measurement precision deteriorates due to uncorrected lining structure effects
Solution Approach 1:
The patent divides the measurement system into multiple sensor elements (transmitters and receivers) distributed along the wellbore. Each sensor measures local magnetic field effects, and the individual measurements are combined to determine overall attenuation factors. This segmentation allows accurate characterization of inhomogeneous lining structures by capturing local variations in conductivity, permeability, thickness, and diameter.
Solution Approach 2:
The sensor array is designed to perform multiple functions: transmitting magnetic fields, receiving magnetic fields, and measuring attenuation effects. The same physical sensors can operate in different modes (transmitter or receiver) depending on the measurement configuration, reducing the need for separate specialized equipment while maintaining measurement precision.
2Measurement precision
If a single attenuation factor is used for the entire casing, then the device complexity is low, but the measurement precision deteriorates due to inhomogeneous lining properties
Solution Approach 1:
The patent determines attenuation factors for different portions or segments of the casing rather than using a single uniform factor. Each sensor pair measures the magnetic field attenuation at its specific location, capturing local variations in lining structure properties. This allows the system to account for inhomogeneities in conductivity, permeability, thickness, and diameter along the wellbore length.
Solution Approach 2:
The patent transitions from a one-dimensional uniform attenuation model to a multi-dimensional approach by distributing sensors along the length of the wellbore. This spatial distribution adds the dimension of position to the attenuation measurement, enabling the system to capture how attenuation varies along the longitudinal axis of the casing.
3Measurement precision
If multiple sensors are deployed to measure magnetic fields at different positions, then the measurement precision improves, but the use of energy increases due to multiple transmitter activations
Solution Approach 1:
The patent activates transmitters periodically or sequentially rather than simultaneously. Each transmitter is activated in turn to measure the magnetic field at its position, and the measurements are combined to determine attenuation factors. This periodic activation reduces the total energy consumption compared to simultaneous activation of all transmitters while still achieving comprehensive spatial sampling.
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
The solution enables accurate correction for the effects of inhomogeneous lining structures, enhancing the accuracy of resistivity measurements and hydrocarbon reservoir characterization by accounting for the varying properties of the casing, thereby reducing measurement errors and improving the efficiency of hydrocarbon reservoir management.
Implementation Method 1
One technique to measure formation resistivity involves the use of electromagnetic induction using transmitters of low frequency magnetic fields that induce electrical currents in the formation. The induced currents in turn produce secondary magnetic fields that are measured in an adjacent wellbore (or at some distance away in the same wellbore) by a magnetic field receiver.
Implementation Method 2
Specifically, the measurable magnetic field induces a current that flows concentrically about the receiver coil and tends to reduce the magnetic field within the casing. The magnetic permeability of the casing also acts to distort the magnetic field and influences the behavior of the currents.
Data Source
AI summary
To determine effect on a magnetic field caused by a lining structure in a wellbore, an array may be deployed into the wellbore lined with the lining structure. The array comprises a plurality of sensors including sensor A configured to operate as a transmitter, sensor B configured to operate as either a transmitter or a receiver, and sensor C configured to operate as a receiver. The array measures magnetic fields using sensor B as a receiver and sensor C in response to activation of sensor B as a transmitter and sensor A. A plurality of lining structure correction factors can be calculated based on the measured magnetic fields, based on the reciprocity of the sensors.