Subsea Wellhead Support Structure Seabed Installation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Subsea wellhead assemblies face risks of bending or breaking due to excessive forces transferred to the conductor casing, especially in hard soil conditions where traditional anchoring methods are ineffective, leading to potential structural failure and soil washout.
Innovation Solution
A method and assembly design that includes a wellhead support structure connected to the wellhead housing, fixed onto the seabed using a settable material to create a rigid connection, allowing bending moments to be transferred to the seabed, thereby reducing the load on the conductor casing and preventing structural failure, while also addressing soil washout issues by ensuring a stable interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wellhead support structure is provided to transfer forces from the Christmas tree, BOP and riser to the seabed, then the risk of conductor casing bending or breaking is reduced, but the complexity of the installation increases
Solution Approach 1:
The system is divided into distinct components: the wellhead support structure and the conductor casing. The support structure is designed as a separate entity that can be independently installed and positioned on the seabed, while the conductor casing is installed separately in the wellbore. This segmentation allows each component to be optimized for its specific function and simplifies the overall installation process by enabling independent handling of each element.
Solution Approach 2:
The wellhead support structure is installed and positioned on the seabed before the conductor casing is set in the wellbore. This preliminary action ensures that the support structure is in place to receive and transfer loads from the wellhead equipment, and it allows for proper positioning and alignment before the conductor casing is cemented and locked in place.
2Strength
If the wellhead support structure is fixed directly onto the seabed, then the connection strength is improved, but soil washout occurs in hard soil conditions
Solution Approach 1:
A settable material is introduced as an intermediary substance between the wellhead support structure and the seabed. This material is pumped into the gap in a fluid state, allowing it to flow into and around the soil particles without causing washout. Once in position, the material sets to form a rigid connection that transfers loads effectively while preserving the integrity of the hard soil formation.
Solution Approach 2:
The settable material undergoes a parameter change from a fluid state during installation to a solid state during operation. In its fluid state, the material can be pumped into the gap without disturbing the hard soil. After setting, it transforms into a rigid connection that provides the necessary structural strength to transfer bending moments and other loads from the wellhead equipment to the seabed.
3Ease of manufacture
If a gap is left between the wellhead support structure and the seabed to allow settable material insertion, then the ease of manufacture is improved, but the connection rigidity may be compromised
Solution Approach 1:
The settable material undergoes a parameter change from a fluid state during installation to a solid state during operation. The gap is maintained during installation to allow the material to be pumped in, but once the material sets, it transforms into a rigid connection that provides the necessary structural stability and rigidity to transfer loads effectively.
Solution Approach 2:
The settable material acts as an intermediary that fills the gap between the wellhead support structure and the seabed. This material provides a bonding interface that maintains the structural integrity and rigidity of the connection while allowing for the practical consideration of material insertion during installation.
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 solution effectively transfers bending moments to the seabed, reducing the risk of conductor casing damage and soil washout, providing a stable and reliable connection even in hard soil conditions, ensuring the integrity of the wellhead assembly and minimizing operational risks.
Implementation Method 1
putting the settable material into the gap when in a non-solid state and allowing it to solidify to provide a rigid connection between the waterbed and the underside of the wellhead support structure
Data Source
AI summary
A wellhead assembly and a method of installing a wellhead assembly. The method includes providing a well casing; providing a wellhead support structure; locating and fixing the well casing in a hole in the waterbed, wherein when the well casing is located and fixed in the hole the wellhead support structure is located a distance above the waterbed so as to leave a gap between the surface of the waterbed and the underside of the wellhead support structure; and fixing the wellhead support structure onto the surface of a waterbed with a settable material by putting the settable material into the gap when in a non-solid state to provide a rigid connection between the waterbed and the underside of the wellhead support structure. The assembly is arranged so that bending moments applied to the wellhead assembly can be at least partially transferred to the waterbed via the wellhead support structure.