Asymmetric Drill Pipe Structure for Horizontal Well Bending
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Solution Overview
Problem
Drill pipes used in horizontal drilling operations face excessive bending and frictional issues due to compressive loads, leading to potential damage and inefficiencies, as traditional designs lack sufficient stiffness without increasing weight or altering external dimensions.
Innovation Solution
The design incorporates a tubular body with mechanical asymmetry, featuring helically twisted grooves and lands that maintain constant weight while increasing stiffness, reducing bending and frictional forces by altering the moment of inertia along different axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If drill pipe wall thickness is increased to reduce bending under compressive load, then stiffness is improved, but weight increases causing excessive friction in horizontal wells
Solution Approach 1:
The drill pipe incorporates an asymmetric cross-sectional profile with a flattened side and a rounded side, creating different moments of inertia about different axes. The flattened side has a smaller moment of inertia while the rounded side has a larger moment of inertia, allowing the pipe to be more resistant to bending in the direction of the flattened side without increasing overall weight. This asymmetric geometry enables the pipe to maintain stiffness under compressive loads while minimizing weight and associated friction in horizontal well applications.
2Force
If additional mass is added to drill pipe to overcome frictional forces in horizontal wells, then weight on bit is improved, but sliding friction and rotational torque requirements increase exponentially
Solution Approach 1:
The asymmetric cross-sectional profile with flattened and rounded sides creates directional stiffness that reduces the drill pipe's tendency to bend under its own weight in horizontal sections. By orienting the flattened side appropriately, the pipe maintains better contact with the wellbore wall in a controlled manner, reducing unpredictable bending and midsection rubbing. This decreases both sliding friction and rotational torque requirements while still delivering adequate weight on bit.
3Reliability
If drill pipe is made stiffer to prevent bending and midsection contact with wellbore, then reliability is improved, but weight increases adding to frictional problems
Solution Approach 1:
The asymmetric cross-sectional design with flattened and rounded sides provides enhanced stiffness in the direction of the flattened side without proportionally increasing weight. This directional stiffness prevention reduces the likelihood of excessive bending and midsection contact with the wellbore, improving reliability and damage prevention while maintaining weight efficiency for horizontal well applications.
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 design enhances the drill pipe's stiffness and resistance to bending and friction, reducing the risk of damage and improving drilling efficiency in horizontal wells without adding unnecessary weight or altering the external dimensions.
Implementation Method 1
increasing stiffness, reducing bending and frictional forces by altering the moment of inertia along different axes
Data Source
AI summary
A drill pipe has a tubular body with a first end, a second end, an outer wall and an inner wall. A first connection end is connected to the first end of the tubular body and a second connection end is connected with the second end of the tubular body. The first connection end and the second connection end have an inner wall and an outer wall, the outer wall is substantially cylindrical in shape and the inner wall defines a central cavity. The first connection end and the second connection end are sized to allow for mating with a corresponding drill pipe. The outer wall of the tubular body is substantially cylindrical in shape. The inner wall of the tubular body defines a central cavity that is in fluid communication with the central cavity of the first connection end and the second connection end. The inner wall has at least one land and at least one groove. The at least one groove has at least one twist along the length of the tubular body.