Offshore Anchoring via Dynamic Positioning and Seabed Assemblies
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Solution Overview
Problem
Current methods for temporarily anchoring offshore vessels/mobile offshore drilling units (MODUs) are inefficient and costly, requiring significant energy and generating emissions due to the reliance on anchor handling vessels.
Innovation Solution
The method involves laying out a plurality of anchoring assemblies at the sea floor, each comprising a connection unit, an anchor line, and a sea floor anchor. The MODU is then brought to the site and dynamically positioned to connect with each anchoring assembly via a drilling unit anchor line, which is subsequently tensioned to secure the MODU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anchor handling vessels are used to lay out and retrieve anchoring assemblies, then the anchoring operation can be completed, but energy consumption and emissions increase significantly
Solution Approach 1:
The MODU uses its own dynamic positioning system and onboard winches to perform anchoring operations, eliminating the need for external anchor handling vessels. The system serves itself by positioning the vessel dynamically and handling the anchor lines independently, thereby reducing energy consumption and emissions associated with additional support vessels.
Solution Approach 2:
The patent extracts the anchor handling function from external support vessels and transfers it to the MODU itself. By removing the dependency on anchor handling vessels for laying out and retrieving anchoring assemblies, the system eliminates the energy consumption and emissions generated by these additional vessels while maintaining reliable anchoring operations.
2Reliability
If anchor handling vessels are used to assist in hooking up anchoring assemblies, then connection reliability is improved, but operational costs and energy consumption increase
Solution Approach 1:
The MODU performs the connection operation using its own dynamic positioning system and onboard equipment. The vessel dynamically positions itself above each connection unit and uses its winches to lower and connect the anchor lines, eliminating the need for anchor handling vessels and associated operational costs while maintaining connection reliability through precise self-positioning.
Solution Approach 2:
The patent employs dynamic positioning technology to enable the MODU to move precisely to positions vertically above each connection unit. This dynamic capability allows the vessel to perform connection operations independently without external assistance, reducing operational costs while ensuring reliable connections through real-time position control.
3Productivity
If multiple anchor handling vessels are deployed for anchoring operations, then the anchoring process can be completed thoroughly, but emissions and environmental impact increase
Solution Approach 1:
The MODU independently performs all anchoring operations including laying out, connecting, and retrieving anchor lines using its own dynamic positioning system and onboard winches. This self-sufficient approach eliminates the need for multiple anchor handling vessels, thereby completing the anchoring process thoroughly while significantly reducing emissions and environmental impact.
Solution Approach 2:
The anchoring assemblies are laid out on the seabed in advance using a simplified process that does not require complex vessel coordination. The connection units are pre-positioned at the seabed, and the MODU simply needs to dynamically position itself and connect the anchor lines, enabling thorough anchoring completion with minimal environmental impact from a single vessel.
4Reliability
If traditional anchoring methods are used with anchor handling vessels, then the MODU can be secured at the site, but the operation requires considerable energy and time
Solution Approach 1:
The patent uses dynamic positioning technology to enable rapid and precise movement of the MODU to positions vertically above each connection unit. This dynamic positioning capability significantly reduces the time required for the anchoring operation compared to traditional methods, while the reliable securing is achieved through precise positioning and secure connection of anchor lines to the seabed-mounted connection units.
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 approach reduces the need for anchor handling vessels, decreases energy consumption and emissions, and enhances operational efficiency by allowing for more precise positioning and reduced weather dependency.
Implementation Method 1
a dynamic positioning system at the mobile offshore drilling unit is operated to move the mobile offshore drilling unit to a position substantially vertically above the respective connection unit
Implementation Method 2
Each drilling unit anchor line is tensioned from the mobile offshore drilling unit so as to anchor the mobile offshore drilling unit at the offshore drilling site via the plurality of anchoring assemblies
Data Source
AI summary
A method of temporarily anchoring a mobile offshore drilling unit (MODU) at an offshore drilling site includes laying out anchoring assemblies at a sea floor. Each anchoring assembly has a connection unit adjacent to the drilling site, an anchor line extending away therefrom, and a sea floor anchor. The MODU is brought to the drilling site. Successively, for each connection unit, a dynamic positioning system at the MODU is operated to move the MODU to a position substantially vertically above the connection unit, a drilling unit anchor line having a connection member is lowered from the MODU to engage the connection unit, and the drilling unit anchor line is connected with the respective anchoring assembly via the connection unit and the connection member. Each drilling unit anchor line is tensioned from the MODU to anchor the MODU at the drilling site via the plurality of anchoring assemblies.