Rotating Flow Head Segmented Bearing Assembly for RCD Maintenance
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Solution Overview
Problem
Rotating control devices (RCDs) installed in deep water offshore applications face challenges such as limited accessibility for repair, high operational costs due to specialized manufacturing for specific marine riser systems, and increased non-productive time (NPT) due to premature bearing failures, which require shutting down well operations for maintenance and repair.
Innovation Solution
A rotating flow head (RFH) design with a housing and radially extensible locking elements allows for easy installation and removal of the bearing assembly, enabling quick access and maintenance on a rig platform, and utilizing a running tool with shear pin assemblies and spring-biased dogs for secure retrieval and installation of components, maintaining a full internal diameter bore for tool passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RCD is manufactured specifically for the particular riser being used and is secured and stationary below the tensioning ring, then the RCD is immune from movement such as heave and rotational movements, but the RCD cannot be used for any other application and becomes a component of an individual marine riser system
Solution Approach 1:
The RCD is divided into two main segments: a stationary housing that remains attached to the riser, and a replaceable bearing assembly that can be removed and replaced. This segmentation allows the housing to provide stable mounting while the modular bearing assembly can be reused across different applications.
Solution Approach 2:
The bearing assembly is designed as a universal component that can be used across multiple RCD units and applications. By making the bearing assembly interchangeable and标准化的, it can serve multiple purposes and be reused in different marine riser systems, increasing adaptability while maintaining the stability of the installed RCD.
2Reliability
If the RCD is installed below the tensioning ring in deep water offshore applications, then the RCD is submerged and not subjected to movement from ocean tides and currents, but limited access to the RCD makes repair and maintenance difficult
Solution Approach 1:
The RCD is segmented into a stationary housing and a replaceable bearing assembly. This allows the critical bearing component to be independently accessed and replaced without requiring complete removal of the entire RCD from the riser, significantly improving ease of repair while maintaining the stable submerged installation.
Solution Approach 2:
The bearing assembly is extracted as a separate, removable component from the RCD housing. This extraction allows maintenance personnel to access and replace the bearing assembly through the riser without needing to retrieve the entire RCD, making repairs feasible even in deep water offshore installations.
3Device complexity
If the RCD is installed below the tensioning ring, then there is limited risk of tensioning cables becoming entangled with return flow lines, but premature bearing failures require shutting down well operations for maintenance
Solution Approach 1:
By segmenting the RCD into a stationary housing and a replaceable bearing assembly, maintenance can be performed by replacing only the bearing component through the riser. This significantly reduces the non-productive time required for maintenance compared to complete RCD replacement, while the submerged installation below the tensioning ring continues to minimize cable entanglement risks.
Solution Approach 2:
The bearing assembly is designed to be easily removed, replaced, and recovered as a separate component. When bearings fail, the bearing assembly can be quickly extracted and replaced without shutting down well operations, and the removed bearing assembly can be recovered for shore-based repair or disposal, minimizing loss of time.
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 minimizes non-productive time, reduces operational risks, and allows for easier repair and maintenance of RCDs, enhancing operational efficiency and reducing the risk of component loss during maintenance.
Implementation Method 1
spring-biased dogs for secure retrieval and installation of components
Implementation Method 2
shear pin assemblies
Data Source
AI summary
A rotating flow head (RFH) has a housing having an internal bore with diameter substantially equal to that of a riser and at least one flow port proximate one longitudinal end thereof. First and second arrays of radially extensible and retractable locking elements are disposed circumferentially around the RFH housing. The RFH has a bearing assembly (BA) housing having an exterior diameter selected to fit within the internal bore of the RFH housing so as to provide an annular space therein. The BA housing engages one of the arrays of locking elements when extended. A mandrel is rotatably, sealingly supported within the BA housing. Another end of the BA housing and the other array of locking elements provide longitudinal force on the BA housing when the other array is extended. A seal element disposed in the annular space is energized by the longitudinal force applied to the BA housing.