Casing Integrity Prediction Using Directional EM Corrosion Data
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Solution Overview
Problem
Existing electromagnetic (EM) corrosion logging tools provide only circumferential average readings of metal thickness loss, making it challenging to accurately interpret and analyze corrosion data for downhole casing integrity, as average metal loss values do not account for directional losses or varying casing sizes, leading to uncertainty in identifying casing failures.
Innovation Solution
A computer-implemented method that processes raw EM corrosion data to calculate corrosion parameters such as Average Remaining Barrier, Corrosion Rate, and Expected Life, generates probability distribution curves, and assigns hotspots to corrosion severity classes based on these parameters, enabling a risk-based corrosion logging frequency model for predicting casing leaks and forecasting well completion life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If circumferential average readings are used to measure metal thickness loss, then the measurement process is simplified, but the measurement precision deteriorates due to inability to detect directional losses
Solution Approach 1:
The patent segments the circumferential measurement into multiple directional sectors (e.g., 0-45°, 45-90°, etc.) around the casing. Instead of providing a single average reading, the EM tool now provides separate metal thickness loss measurements for each sector, enabling detection of localized corrosion patterns while maintaining operational simplicity through automated data collection.
Solution Approach 2:
The patent transitions from a single-dimensional average measurement to a multi-dimensional measurement approach by adding angular/directional information. The corrosion data is now represented in both radial (thickness loss) and angular (directional position) dimensions, creating a two-dimensional corrosion map that significantly improves detection precision.
2Device complexity
If average metal loss values are used without directional information, then data analysis is simplified, but the reliability of casing failure identification deteriorates due to wide range of possibilities
Solution Approach 1:
The patent applies local quality analysis by examining corrosion characteristics in specific directional sectors rather than treating the entire circumference uniformly. Each sector's corrosion data is analyzed independently to identify localized damage patterns, allowing reliable distinction between uniform wear (less critical) and localized pitting (more critical), thereby improving failure identification reliability.
Solution Approach 2:
The patent adds the angular dimension to the corrosion data analysis, transforming single-value average measurements into multi-value directional measurements. This dimensional enhancement allows the system to differentiate between various failure modes (e.g., uniform corrosion vs. localized pitting) based on the distribution pattern across different sectors, significantly improving reliability.
3Ease of operation
If circumferential average readings are provided, then the EM tool operation is simplified, but the ability to predict casing leaks deteriorates due to uncertainty in metal loss distribution
Solution Approach 1:
The patent segments the corrosion measurement into multiple directional sectors, providing separate metal thickness loss values for each sector. This segmentation enables the prediction model to identify critical locations where corrosion has progressed most severely, improving leak prediction accuracy while the automated sector-based measurement maintains operational simplicity.
Solution Approach 2:
The patent incorporates angular positioning information as an additional dimension in the corrosion data structure. By mapping metal thickness loss values to specific angular positions around the casing, the system can identify asymmetric corrosion patterns and predict leak locations more accurately, while the EM tool continues to operate automatically without complex manual procedures.
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 converts qualitative EM corrosion data into quantitative assessments, providing a robust methodology for predicting casing leaks and ensuring safe, practical monitoring of downhole casing integrity by accounting for directional losses and varying casing sizes, thus reducing uncertainty in casing failure identification.
Implementation Method 1
electromagnetic (EM) corrosion logging tools to collect raw EM corrosion data associated with casing hotspots
Data Source
AI summary
The present disclosure describes methods and systems, including computer-implemented methods, computer program products, and computer systems, for predicting casing leaks. One computer-implemented method includes obtaining raw electromagnetic (EM) corrosion data for a hotspot, wherein the raw EM corrosion data includes a metal thickness loss value for the hotspot; determining a corrosion parameter based on the raw EM corrosion data; generating a probability distribution curve for the corrosion parameter; generating a corrosion severity classification matrix based on the probability distribution curve, wherein the corrosion severity classification matrix includes a plurality of corrosion severity classes and cutoff values for each of the plurality of corrosion severity classes; and assigning the hotspot into one of the plurality of corrosion severity classes based on the corrosion severity classification matrix and the corrosion parameter of the hotspot.