Multi-Frequency Induction Logging for Multi-Casing Well Evaluation
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Solution Overview
Problem
Conventional electromagnetic field testing methods primarily focus on determining individual pipe thicknesses and corrosion, lacking effective techniques for evaluating multi-casing wells, which results in the loss of critical information about casing count and sizes, impacting the assessment and management of oil and gas assets.
Innovation Solution
Employing a multi-frequency, non-collocated induction measurement approach using an EM inspection tool with a transmitter and multiple non-collocated receivers to obtain multi-spacing measurements, allowing for the determination of casing count and size by analyzing electromagnetic field distributions in different zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional EM field testing is used to determine individual pipe thicknesses, then casing thickness and corrosion can be measured, but the number and sizes of nested casings cannot be determined
Solution Approach 1:
The patent segments the EM field measurement into multiple frequency components and multiple receiver positions (non-collocated receivers at different spacings). This segmentation allows the system to resolve multiple casings by assigning different frequencies to different casings, enabling both thickness measurement and casing count/size determination simultaneously
Solution Approach 2:
The patent adds the frequency dimension to the traditional single-frequency EM measurement. By using multi-frequency measurements with non-collocated receivers, the system transforms a one-dimensional thickness measurement problem into a multi-dimensional problem that can resolve both casing properties and casing count/size information
2Device complexity
If single-frequency EM measurements are used, then the measurement system is simple, but multi-casing evaluation is not possible
Solution Approach 1:
The patent makes the EM measurement system universal by enabling it to perform multiple functions: determining individual casing thicknesses, identifying the number of nested casings, and measuring casing sizes. The multi-frequency, non-collocated receiver configuration allows a single system to handle both single-casing and multi-casing evaluation scenarios
Solution Approach 2:
The patent introduces dynamic frequency selection and adaptive receiver positioning. The system can dynamically adjust which frequencies to use and which receivers to activate based on the specific well configuration, allowing versatile multi-casing evaluation while maintaining manageable system complexity through intelligent control
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 accurate determination of the number and size of nested casings in multi-casing wells, restoring critical information for effective asset management and performance assessment.
Implementation Method 1
A transmitter of the field-testing probe induces an EM field that interacts with the casing
Implementation Method 2
The EM field may vary depending on thickness and/or corrosion in the casing
Implementation Method 3
Receivers may detect these variations in the EM field
Data Source
AI summary
Techniques and apparatus for evaluating sensor placement and frequency selection for an electromagnetic inspection tool, and determining casing count and casing sizes in a multi-casing well are described. The electromagnetic inspection tool includes a transmitter and multiple receivers configured to operate at one or more frequencies. Each receiver is located at a different spacing from the transmitter. At least one of a casing count for a well or a respective size of each casing in the well is determined using multi-frequency, non-collocated induction measurements obtained via the electromagnetic inspection tool. The size of an innermost casing may be determined based on slope(s) of high frequency response(s) at spacings in a direct coupling zone of an electromagnetic field distribution. Each size of an outer casing(s) may be determined based in part on null frequency locations within the frequency domain responses at spacings in the transition zone of the electromagnetic field distribution.