Buckled Pipe Contact Force Analysis in Wellbores
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Solution Overview
Problem
Existing methods for determining the moments and forces of concentric pipes in a wellbore fail to accurately account for the contact forces and displacements when the tubing buckles and contacts the casing, leading to inaccurate displacement solutions and neglecting the requirement that contact forces between the pipes and the wellbore must be positive.
Innovation Solution
A method and system using a computer processor to determine the bending moment and shear force of tubing and casing by analyzing external pipe displacement, contact forces between the pipes, and contact with the wellbore, ensuring that contact forces are greater than or equal to zero, and using displacement solutions that minimize potential energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the pipes are assumed to remain concentric and do not touch each other, then the analysis is simplified, but the displacement solution becomes inaccurate and does not satisfy contact force requirements
Solution Approach 1:
The patent transitions from a static concentric assumption to a dynamic analysis where the internal pipe can buckle and contact the external pipe. The system allows the configuration to change from concentric to contacted states based on buckling behavior, making the analysis adaptive rather than fixed.
Solution Approach 2:
The patent changes the fundamental parameter of pipe configuration from always concentric to potentially contacted. By introducing contact conditions and solving for contact forces, the model transforms the geometric parameters to reflect actual buckling behavior where pipes may touch and transfer loads.
2Device complexity
If the external casing is assumed to be rigid, then the analysis is simplified, but the displacement and contact force calculations become inaccurate
Solution Approach 1:
The patent changes the mechanical property parameter of the external casing from rigid to elastic. This allows the casing to deform under contact loads from the buckling internal pipe, providing more accurate displacement and contact force calculations while capturing the realistic behavior of elastic casing material.
3Device complexity
If contact forces are not explicitly constrained to be positive, then the mathematical solution is easier to obtain, but the physical reality of non-penetration is violated
Solution Approach 1:
The patent applies preliminary constraints to prevent unphysical solutions by requiring contact forces to be non-negative. This anti-action prevents the mathematical solution from producing negative contact forces that would imply pipe penetration, ensuring the solution respects the physical non-penetration condition before finalizing results.
Solution Approach 2:
The patent incorporates feedback by checking whether calculated contact forces satisfy the non-negative constraint. If the initial solution produces negative contact forces, the model adjusts the displacement field and re-calculates until contact forces are physically valid, creating an iterative feedback loop that ensures physical realism.
Data Source
AI summary
Systems and methods for determining the bending moment and shear force of tubing and casing when the tubing buckles and contacts the casing.