Casing Wear Estimation Using Adjusted Survey Points
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Solution Overview
Problem
Existing models for identifying and predicting casing wear in oilfield operations are inadequate, particularly for deviated well configurations, leading to potential casing integrity failures and associated economic and environmental losses.
Innovation Solution
A system and method for estimating casing string wear volume by accounting for the variance between the paths of the borehole and the casing string, using a combination of logging while drilling (LWD) systems, wireline logging tools, and software that determines the casing trajectory and side forces to calculate wear based on survey points, stiffness, and drilling parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing models are used to predict casing wear, then the prediction process is simple, but the accuracy of wear prediction is inadequate for deviated well configurations
Solution Approach 1:
The model segments the borehole-casing system into distinct trajectory components (borehole survey points, casing string positions, intermediate points) and calculates wear at each segment independently. This allows accurate prediction for deviated wells by treating each section with appropriate geometric relationships rather than applying a single simplified model to the entire wellbore.
Solution Approach 2:
The invention transitions from traditional 2D cross-sectional wear models to a 3D spatial model that incorporates the full borehole trajectory and casing string configuration. By adding the dimensional aspect of wellbore curvature and deviation angles, the model accurately captures wear patterns in deviated configurations that previous models missed.
2Measurement precision
If the variance between borehole and casing string paths is accounted for, then wear estimation accuracy improves, but the computational complexity increases
Solution Approach 1:
The model performs preliminary calculations of borehole-casing trajectory alignment and identifies high-risk wear zones before conducting detailed wear computations. By pre-processing the geometric relationships and flagging critical sections, the system reduces overall computational complexity while maintaining accuracy in the most important areas.
Solution Approach 2:
The invention applies different levels of computational detail to different wellbore sections based on their risk profiles. High-curvature deviated sections receive full 3D trajectory analysis, while straight sections use simplified models. This localized approach maintains high accuracy where needed while reducing overall computational burden.
3Measurement precision
If more detailed survey points are collected to improve wear prediction, then the accuracy of wear identification improves, but the time and resources required for data collection increase
Solution Approach 1:
The model uses a selective survey point strategy, collecting detailed measurements at critical locations (high deviation angles, tight curvature zones, previous wear locations) while using interpolated data for less critical sections. This partial action approach achieves sufficient accuracy for wear prediction without requiring exhaustive surveying of the entire wellbore.
Solution Approach 2:
The invention introduces computational interpolation and trajectory modeling as intermediaries between sparse survey points. Rather than requiring dense physical measurements throughout the wellbore, the system uses mathematical models to estimate conditions between measured points, reducing field data collection requirements while maintaining prediction accuracy.
Data Source
AI summary
Disclosed embodiments include a method for estimating casing wear including the operations of: obtaining locations of survey points along a borehole, said survey point locations representing a borehole trajectory; casing at least a portion of the borehole with a casing string; deriving locations of adjusted survey points that represent a casing trajectory along said portion of the borehole, the casing trajectory being different from the borehole trajectory; estimating, as a function of position along said casing string, a side force of a drill string against the casing string; computing, as a function of position along the casing string, casing wear based at least in part on the side force; and generating a notification of any positions where casing wear exceeds a threshold.