Subsea Protective Cap Assembly Composite Sealing

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Solution Overview

Problem

Subsea wellhead assemblies are susceptible to damage and corrosion during temporary abandonment of hydrocarbon wells due to exposure to seawater, leading to issues with sealing and connection integrity, and existing protective cap assemblies are heavy and costly to install, with potential for corrosion inhibitor fluid to drain and compromise the seal.

Innovation Solution

A protective cap assembly designed for subsea equipment mandrels or hubs, featuring a primary seal, secondary seal, primary inlet check valve, and locking assemblies, which maintains a sealing relationship and allows for corrosion inhibitor injection to prevent corrosion and deposit formation, constructed to be lightweight for ROV installation and capable of containing internal pressures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protective cap assembly is installed to prevent corrosion and damage to subsea equipment during temporary abandonment, then the sealing integrity and protection against seawater exposure is improved, but the weight and installation cost increase due to traditional heavy construction materials

Engineering Contradiction:

Improvesealing integrityVSAvoidprotective cap assembly weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The protective cap assembly is constructed using composite materials that change the physical parameters of the structure, reducing density and weight while maintaining structural integrity and sealing capability. This allows the cap to be lightweight enough for ROV installation while still providing reliable corrosion protection during temporary well abandonment.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The protective cap assembly utilizes composite material construction combining multiple materials with complementary properties to achieve both lightweight characteristics and durable sealing performance. The composite structure provides corrosion resistance, mechanical strength, and weight reduction simultaneously, resolving the contradiction between protection reliability and installation feasibility.

Inventive Principle:

Principle #40Composite materials

2Productivity

If a protective cap assembly is designed to be lightweight for ROV installation, then installation cost and time are reduced, but the ability to contain internal pressures and maintain sealing integrity may be compromised

Engineering Contradiction:

Improveinstallation efficiencyVSAvoidinternal pressure containment

Core Design Contradiction:

ProductivityVSStress or pressure

Solution Approach 1:

The composite material construction changes the mechanical parameters of the protective cap, providing high strength-to-weight ratio that enables both lightweight design for ROV installation and adequate pressure containment capability. The material properties are selected to withstand internal pressures from corrosion inhibitor fluid while maintaining structural integrity.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If corrosion inhibitor fluid is injected into the protective cap assembly, then corrosion protection is improved, but the fluid may drain and compromise the sealing integrity

Engineering Contradiction:

Improvecorrosion protectionVSAvoidcorrosion inhibitor fluid retention

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The protective cap assembly incorporates a drain prevention mechanism that acts in advance to prevent corrosion inhibitor fluid from draining. This preliminary protective action maintains fluid retention within the cap assembly, ensuring continuous corrosion protection of the subsea equipment during temporary abandonment without compromising sealing integrity.

Inventive Principle:

Principle #9Preliminary anti-action

4Reliability

If traditional protective cap assemblies are installed using drilling rig, then installation reliability is improved, but installation cost and time consumption increase significantly

Engineering Contradiction:

Improveinstallation reliabilityVSAvoiddrilling rig time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The protective cap assembly is designed with counterbalancing features including integration with the wellhead structure and buoyancy considerations that enable safe handling and installation by ROV. The design compensates for the reduced installation platform capability, allowing reliable installation by lighter ROV equipment rather than requiring heavy drilling rig resources.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Data Source

PatentUS10907433B2Protective cap assembly for subsea equipment

Publication Date: 2021.02.02 THOMAS SEAN P

AI summary

A protective cap assembly for a subsea equipment mandrel or hub, including a protective cap body with a top plate and a cylindrical sidewall. The protective cap body may further include a primary inlet port, a first annular groove, a secondary inlet port, a second annular groove, and one or more secondary outlet ports. A primary seal may be disposed in the first annular groove to sealingly engage the mandrel or hub, and a secondary seal may be disposed in the second annular groove to sealingly engage the mandrel or hub. The protective cap assembly may further define at least in part primary and secondary chambers configured to fluidly communicate, and the secondary chamber configured to fluidly communicate directly or indirectly with the external subsea environment.