Deflector Device for Keelhauling Rigid Risers
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Solution Overview
Problem
Current methods for attaching rigid risers to FPSOs using keelhauling operations face physical limitations due to clearance requirements, particularly with double-layer Lower Riser Balconies, which restrict the use of both rigid and flexible risers without major modifications to the FPSO structure.
Innovation Solution
A pull-in system and method utilizing a deflector device for the main pull-in cable and a Support Tube on a double-layer balcony, allowing centralization of the pull-in cable with the Support Tube orientation, minimizing sliding contact, and enabling the use of both rigid and flexible risers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If support tubes are installed in the internal layer of the LRB to enable keelhauling operations, then rigid riser pull-in becomes viable, but flexible riser connections are excluded due to occupation of I-Tube positions
Solution Approach 1:
The LRB is divided into two distinct layers: the internal layer for rigid riser support tubes and the external layer for flexible riser I-Tubes. This segmentation allows both riser types to be supported simultaneously without interference, resolving the contradiction between enabling rigid riser pull-in and maintaining flexible riser connection capability.
Solution Approach 2:
The solution transitions from a single-layer configuration to a double-layer configuration on the LRB. By utilizing the vertical dimension (internal vs. external layers), the system accommodates both rigid and flexible riser connection requirements that cannot be satisfied in a single layer, thus resolving the adaptability issue.
2Ease of operation
If the pull-in cable is aligned with the support tube orientation, then centralized cable control is achieved, but clearance requirements for maneuvering the riser through the receptacle are compromised
Solution Approach 1:
A deflector device is introduced as an intermediary component between the pull-in cable and the support tube. The deflector redirects the pull-in cable away from direct alignment with the support tube, creating necessary clearance for the riser to maneuver through the receptacle while still enabling centralized cable control through the deflector's positioning mechanism.
3Object-affected harmful factors
If major modifications are made to the FPSO structure to meet clearance conditions, then proper clearance for riser installation is achieved, but operation time and costs increase significantly
Solution Approach 1:
The support tubes and deflector devices are pre-installed on the LRB before the actual riser pull-in operation. This preliminary configuration ensures that all clearance requirements are already satisfied, eliminating the need for time-consuming structural modifications during the operation and reducing overall operation time.
4Object-affected harmful factors
If the pull-in cable is not aligned with the support tube, then clearance for maneuvering is maintained, but additional interference and operational complexity arise
Solution Approach 1:
The deflector device serves as a controlled intermediary that manages the cable's path relative to the support tube. It maintains necessary clearance to prevent interference while providing a predictable, controlled geometry that simplifies operational procedures compared to uncontrolled misalignment. The deflector's position and angle can be precisely controlled to optimize the cable path.
Data Source
AI summary
The present invention pertains to the technical field of oil and gas; more specifically to the field of risers and flow line connections to offshore structures, and describes a pull-in cable deflector system in keelhauling of rigid risers comprising: a deflector assembly including a deflector device housed in a structural block, a sliding structure, at least two rails. The deflector device installed in the structural block is moved through a sliding structure on rails installed forward of the URB to the different pull-in or pull-out positions in keelhauling of rigid risers. The structural block is slidably mounted on a base frame by means of a system of sliding supports to perform a first adjustment of the transverse distance from the deflector device to the URB. The deflector device is then rotated around the vertical line depending on the azimuth of the support tube. A second adjustment of the transverse distance of the deflector device is performed during the pull-in operation.