Flexible Sleeve Absorbs Side Loads in Rotating Control Device
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Solution Overview
Problem
Conventional rotating control devices (RCDs) in drilling operations face rapid bearing failure due to misalignment and side loading, which existing solutions like misalignment limiters and ball joints do not adequately address, leading to insufficient reduction of intermittent wobble loads on the bearings.
Innovation Solution
A flexible sleeve assembly is integrated between the RCD mandrel and the stripper element, allowing for translational and rotational movements to absorb side loads and reduce high load variations, thereby extending bearing life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid stripper element is used to seal against the drill pipe, then sealing effectiveness is improved, but side loads and misalignment-induced stress on bearings increase
Solution Approach 1:
A flexible sleeve made of elastomeric material is positioned between the stripper element and the RCD mandrel. This flexible sleeve can deform to accommodate misalignment between the drill pipe and RCD housing, absorbing side motion and reducing the transmission of lateral loads to the bearings while maintaining the sealing function of the stripper element.
Solution Approach 2:
The introduction of the flexible sleeve changes the mechanical parameters of the connection between the stripper element and the mandrel. It transforms the rigid connection into a compliant one, allowing for translational and rotational movements that accommodate misalignment without compromising the sealing effectiveness or overloading the bearings.
2Duration of action of stationary object
If misalignment limiters or ball joints are used to reduce side loading, then bearing life is improved, but the reduction of intermittent wobble loads is insufficient
Solution Approach 1:
The flexible elastomeric sleeve provides continuous compliance rather than the discrete adjustment of misalignment limiters or ball joints. This allows for smooth absorption of intermittent wobble loads and misalignment forces, providing more effective protection to the bearings against variable loading conditions.
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
The flexible sleeve effectively absorbs side motion and load variations, leading to increased bearing performance and extended life by providing the necessary degrees of freedom to mitigate misalignment-induced stress on the RCD bearings.
Implementation Method 1
a flexible sleeve which is more flexible than the stripper element... The flexible sleeve effectively absorbs side motion and load variations... allowing for translational and rotational movements to absorb side loads
Data Source
AI summary
A rotating control device (RCD) for use in pressurized drilling operations. The RCD having a non-rotating RCD housing enclosing an elongate passage, a tubular RCD mandrel extending along the elongate passage of the RCD housing, wherein the RCD mandrel has a longitudinal axis and is configured in use to rotate relative to the RCD housing about the longitudinal axis, and a stripper element which is mounted on an end of the RCD mandrel and which is configured to seal against and rotate with a tubular drill pipe extending along the elongate passage of the RCD housing, wherein the stripper element is secured to the end of the RCD mandrel by a flexible sleeve which is more flexible than the stripper element.