Subsea Pendulum Arrestor Drag Sheet for BOP Landing
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Solution Overview
Problem
The final stage of landing a blowout preventer (BOP) stack assembly onto a wellhead is delayed due to lateral and radial movements, causing non-productive time and financial implications, as existing compensation systems do not effectively dampen the pendulum effect of the BOP swinging on a riser.
Innovation Solution
An apparatus and method that utilize a sheet of arrestor material with a drive mechanism to create a drag force by moving the material between different surface area positions, actuated by a torque tool of a remote operated vehicle (ROV) or autonomous underwater vehicle (AUV), with sensors like accelerometers to control the drag force and reduce pendulum motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a BOP stack assembly is lowered vertically suspended on a riser, then the assembly can be transported to the wellhead location, but the assembly swings in pendulum fashion causing lateral and radial movements that delay alignment and connection
Solution Approach 1:
The patent converts the harmful pendulum motion into a beneficial damping effect by deploying an arrestor bag that creates hydrodynamic drag. The swinging motion itself forces the bag to expand and interact with water, transforming the problematic kinetic energy into useful drag force that rapidly reduces oscillations and enables faster alignment.
2Stability of the object's composition
If existing compensation systems are used to provide vertical stability, then the BOP assembly maintains vertical positioning, but lateral and radial movements persist causing significant delays
Solution Approach 1:
The arrestor bag serves as an intermediary element between the BOP assembly and the surrounding water. It mediates the interaction by creating controlled hydrodynamic drag that dampens lateral and radial movements without interfering with the vertical stability provided by existing compensation systems, thereby enabling easier alignment.
3Object-affected harmful factors
If the arrestor material is deployed to create drag force, then pendulum motion is reduced, but the system requires a drive mechanism and control system
Solution Approach 1:
The arrestor bag system is designed to be self-activating through the pendulum motion itself. As the BOP assembly swings, the inertial forces automatically expand the bag and engage the hydrodynamic drag effect, eliminating the need for external drive mechanisms or complex control systems. The system serves itself by using the harmful motion to activate its own damping function.
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 solution significantly reduces the time required to align mating components during landing operations, can be easily retrofitted to existing subsea equipment, and does not require sophisticated control schemes, thereby minimizing delays and costs.
Implementation Method 1
create a drag force on the piece of subsea equipment by moving a sheet of arrestor material between a first position and a second position
Data Source
AI summary
An apparatus for, and method of, reducing a pendulum motion of a piece of subsea equipment during a landing operation includes a frame assembly arranged for connection to the piece of subsea equipment; a sheet of arrestor material disposed within a perimeter of the frame assembly, and a drive mechanism arranged to move the sheet of arrestor material between a first position and a second position, each position providing a different amount of surface area than the other to create a different drag force on the equipment.