Deepwater Riser Hang-Off Test Rig for Dynamic Coupling Validation
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Solution Overview
Problem
The existing marine deepwater drilling riser systems face challenges in hang-off modes, particularly in severe sea conditions like typhoons, where dynamic compression and extreme tension can lead to instability and potential riser fracture, and there is a need for accurate validation of theoretical dynamic models which is difficult due to the large size of the equipment.
Innovation Solution
A linkage test apparatus for deepwater drilling risers and hang-off systems, comprising a motion excitation system, a hang-off system with hydraulic actuators and sensors, and a riser system, designed to simulate dynamic coupling processes using a six-degree-of-freedom excitation platform and sensors for real-time monitoring and data collection, allowing for validation of theoretical models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full-scale laboratory test is conducted for risers and hang-off system, then model validation accuracy is improved, but test feasibility deteriorates due to huge size of equipment
Solution Approach 1:
The patent divides the full-scale riser and hang-off system into segmented models: a riser model with multiple joints and sections, and a hang-off system model with separate hydraulic cylinder actuator, spider, and counterweight components. This segmentation enables laboratory testing while preserving the dynamic characteristics of the full-scale system through proportional scaling relationships.
Solution Approach 2:
The patent creates scaled-down copy models that replicate the dynamic behavior of the full-scale system. The riser model uses proportional dimensions and materials to simulate full-scale flexural rigidity and mass distribution. The hang-off system model copies the mechanical relationships and dynamic coupling characteristics, allowing valid experimental verification without requiring full-scale equipment.
2Strength
If rigid connection is used between riser top and platform, then connection strength is improved, but riser stability deteriorates due to dynamic compression and extreme tension
Solution Approach 1:
The patent transitions from a static rigid connection model to a dynamic hang-off system model where the spider and hydraulic actuators can move relative to the platform. This dynamic configuration allows the system to adapt to wave-induced motions, reducing dynamic compression and extreme tension on the riser while maintaining connection integrity through controlled mechanical coupling.
Solution Approach 2:
The patent changes the connection parameters from fixed rigid constraints to variable mechanical couplings with degrees of freedom. The spider mechanism provides rotational and translational flexibility, while the hydraulic actuators adjust connection stiffness and positioning in real-time, optimizing both connection strength and riser stability under varying environmental loads.
3Stability of the object's composition
If soft hang-off mode with tensioner is used, then riser stability is improved by compensating heave motion, but operational complexity increases making it difficult to implement in severe sea conditions
Solution Approach 1:
The patent extracts and simplifies the tensioner function into a dedicated hydraulic cylinder actuator within the hang-off system model. This separate actuator specifically handles heave motion compensation, allowing the rest of the system to focus on other critical functions. The extraction clarifies the division of labor and reduces overall operational complexity by making the stabilization function modular and manageable.
Solution Approach 2:
The patent introduces the spider mechanism as an intermediary between the platform and riser, providing mechanical coupling with inherent flexibility. This intermediary absorbs and attenuates wave-induced motions before they reach the riser, reducing the burden on the hydraulic actuators and simplifying their control requirements while maintaining riser stability.
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 apparatus enables realistic simulation of dynamic responses, providing detailed experimental data for modifying theoretical models, ensuring safe operation of hang-off systems and allowing for various test conditions and configurations, thus addressing the instability and validation challenges.
Implementation Method 1
a two-position three-way electromagnetic reversing valve
Implementation Method 2
the hydraulic system includes a trip valve, a throttle valve, a two-position three-way electromagnetic reversing valve, an relief valve, a check valve, a hydraulic pump
Implementation Method 3
a six-degree-of-freedom excitation platform for simulating the motion of a marine drilling platform
Implementation Method 4
a displacement sensor and an acceleration sensor
Implementation Method 5
a strain gauge
Implementation Method 6
the riser system is mostly contained in the water environment for simulating an actual marine environment
Data Source
AI summary
The present invention relates to a linkage test apparatus for deepwater drilling riser and hang-off system. The linkage test apparatus includes a motion excitation system, a hang-off system and a riser system. The motion excitation system includes a six-degree-of-freedom excitation platform and sensors. The hang-off system includes a hydraulic cylinder actuating mechanism and a hydraulic system. The hydraulic cylinder in the hydraulic cylinder actuating mechanism is composed of an inner cylinder and an outer cylinder and it is fixed on the six-degree-of-freedom excitation platform by a spider. The inner cylinder of the hydraulic cylinder is hollow. A hang-off joint passes through the center of the inner cylinder, and a bottom of the hang-off joint is connected to the riser system via a rotating flange. The riser system is successively connected by multiple riser test joints, and the bottom is suspended with a lower marine riser package model.