Compensated Hoisting System for Offshore Drilling
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Solution Overview
Problem
Existing heave compensation systems for drilling platforms or vessels, especially passive top or crown mounted compensators, are costly and add significant mass, while active draw-works systems can fail due to mechanical or control system malfunctions, necessitating a more reliable and cost-effective solution for motion compensation during offshore drilling operations.
Innovation Solution
A hoisting system with a crown block, traveling block, and an intermediate sheave assembly connected via a compensation system using passive compensating cylinders, allowing vertical motion between the crown block and intermediate sheave assembly to isolate the traveling block from vessel motion, thereby providing both load capacity and speed adjustments based on connection configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive top or crown mounted compensators are used, then motion compensation is provided, but cost and added mass increase significantly
Solution Approach 1:
The hoisting system is divided into separate functional components: the crown block remains relatively simple and fixed, while the traveling block contains the compensation mechanism. This segmentation allows the compensation system to move with the load rather than being statically mounted on the crown block, reducing the mass that must be supported at the top of the derrick.
Solution Approach 2:
The patent introduces an intermediate compensation mechanism in the hoisting cable system that acts as a mediator between the crown block and traveling block. This intermediate system absorbs the vessel motion and transfers only the necessary lifting motion to the traveling block, reducing the mass requirements of the crown block while maintaining compensation effectiveness.
2Measurement precision
If active draw-works heave compensation systems are used, then precise motion compensation is achieved, but system reliability decreases due to potential mechanical or control system failures
Solution Approach 1:
The compensation system is designed to be self-regulating and passive, using the mechanical properties of the hoisting cable system and the motion of the vessel itself to provide compensation. The system automatically adjusts to vessel motion without requiring external power, control systems, or active intervention, thereby eliminating the failure points associated with active systems while maintaining precision.
Solution Approach 2:
The patent converts the dynamic motion of the floating vessel, which is normally a harmful disturbance, into a beneficial force that actively participates in the compensation process. By allowing the traveling block and compensation mechanism to move with the vessel motion, the system uses the vessel's own movement to counteract its effects on the drilling string, achieving reliable compensation without complex active control.
3Reliability
If top or crown mounted compensator systems are used, then motion compensation is provided, but device complexity and retrofit cost increase
Solution Approach 1:
The patent designs the hoisting system components to perform multiple functions: the existing crown block and traveling block structures are utilized for both traditional hoisting operations and heave compensation. The compensation mechanism is integrated into the existing cable system rather than being a separate additive system, reducing overall device complexity and making the system universally applicable to existing drilling rigs without requiring extensive retrofits.
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 system effectively compensates for vessel motion, enhancing drilling stability and efficiency by offering adjustable load capacity and travel speed, reducing the need for costly mass additions and minimizing the risk of system failures, while maintaining precision and safety during offshore operations.
Implementation Method 1
The compensation system comprises one or more compensating cylinders
Implementation Method 2
The hoisting system includes a crown block, a traveling block, and an intermediate sheave assembly
Implementation Method 3
The intermediate sheave assembly is moveable between and alternatively connectable to the crown and traveling blocks
Data Source
Figure 1
Figure 2A~2B
Figure 3A
AI summary
A hoisting system for a floating drilling platform or vessel is described. The hoisting system includes a smart block system that can be configured for either high speed or high load modes by moving the smart block between the crown block and traveling block. The smart block is also configurable for providing passive compensation.