Drill String and Casing Buckling Prediction Through Adaptive FEA Segmentation
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Solution Overview
Problem
Conventional numerical methods face convergence issues in predicting buckling behavior of drill strings under severe load conditions, leading to instability and inaccurate predictions.
Innovation Solution
A method involving a first linear FEA followed by splitting the drill string into segments for non-linear FEA, with adaptive mesh refinement, to improve numerical stability and accuracy in predicting buckling behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional numerical methods are used to predict buckling behavior under severe load conditions, then the analysis can be performed with a complete drill string model, but the solution faces convergence issues and numerical instability
Solution Approach 1:
The drill string is divided into multiple segments along its length, with each segment analyzed separately using finite element analysis. This segmentation transforms the unstable global buckling problem into a series of stable local segment problems, eliminating convergence issues while maintaining prediction accuracy for buckling zones and post-buckling states
Solution Approach 2:
The method performs preliminary linear FEA on each segment to determine initial properties and identify possible buckling zones before conducting the final non-linear FEA. This preliminary analysis establishes stable baseline conditions that guide the subsequent buckling prediction, preventing numerical instability during the analysis process
2Measurement precision
If non-linear FEA is performed on the entire drill string to accurately predict buckling, then the prediction accuracy improves, but the computational complexity and time increase significantly
Solution Approach 1:
By dividing the drill string into segments and performing FEA on each segment individually rather than analyzing the entire drill string as one model, the computational complexity is dramatically reduced. Each segment analysis is computationally simpler and faster, while the collective segment results provide accurate buckling prediction for the complete drill string
Solution Approach 2:
The method applies non-linear FEA specifically to segments identified as possible buckling zones, while other segments use linear FEA. This localized application of computationally intensive non-linear analysis to only where needed maintains high prediction accuracy for buckling behavior while minimizing overall computation time
Data Source
AI summary
A method for predicting buckling behavior in a torque and drag analysis of a tubular string in a wellbore includes performing a first finite element analysis (FEA) on the tubular string. The method also includes determining one or more first properties of the tubular string based upon the first FEA. The method also includes identifying a possible buckling zone in the tubular string based upon the one or more first properties. The method also includes splitting the possible buckling zone into a plurality of segments. The method also includes performing a second FEA on one or more of the segments. The method also includes determining one or more second properties of the tubular string based upon the second FEA. The method also includes comparing the one or more first properties of first FEA to the one or more second properties of second FEA to identify incremental changes therebetween.