Annular Insert with Axial Slots for Wellhead Lockdown

Solution Overview

Problem

Existing wellhead assemblies face challenges in achieving sufficient lockdown force and efficient fluid flow management due to material strength limitations of the wellhead housing and casing hanger, which restricts lockdown capacity and increases installation costs.

Innovation Solution

An annular insert with axial slots and a lock ring system is introduced, providing a higher strength material than the wellhead housing to enhance lockdown force and fluid flow paths, allowing for increased lockdown capacity and reduced installation costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a wellhead housing and casing hanger are made from materials with sufficient strength to achieve high lockdown force, then the lockdown capacity is improved, but the material cost and installation cost increase

Engineering Contradiction:

Improvelockdown forceVSAvoidinstallation cost

Core Design Contradiction:

ForceVSEase of manufacture

Solution Approach 1:

The wellhead assembly is segmented into distinct components with different material properties: the wellhead housing and casing hanger use cost-effective materials, while a separate annular insert made from high-strength material (such as Inconel) is inserted into the housing. This segmentation allows the expensive high-strength material to be used only where maximum strength is required (at the lockdown interface), rather than throughout the entire assembly, thereby reducing overall material and installation costs while maintaining high lockdown capacity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention applies local quality by concentrating the high-strength material property specifically at the lockdown interface where maximum force transmission is needed. The annular insert provides localized high-strength support at the critical interface between the wellhead housing and casing hanger, while other parts of the assembly use standard materials. This localized application of high-strength material optimizes the force transmission capability exactly where required without unnecessarily increasing costs throughout the entire assembly.

Inventive Principle:

Principle #3Local quality

2Strength

If the wellhead housing material strength is increased to improve lockdown capacity, then the lockdown force is improved, but the machining cost and operational flexibility deteriorate

Engineering Contradiction:

Improvelockdown capacityVSAvoidmachining cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The wellhead assembly is segmented into distinct components with different material properties: the wellhead housing and casing hanger use cost-effective materials, while a separate annular insert made from high-strength material (such as Inconel) is inserted into the housing. This segmentation allows the expensive high-strength material to be used only where maximum strength is required (at the lockdown interface), rather than throughout the entire assembly, thereby reducing overall material and installation costs while maintaining high lockdown capacity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention effectively creates a composite structure by combining the wellhead housing (made from standard material) with the annular insert (made from high-strength material). This composite approach allows the assembly to achieve the mechanical properties of high-strength materials at the critical interface while using more economical materials for the bulk of the structure, thereby optimizing both strength and manufacturability.

Inventive Principle:

Principle #40Composite materials

3Ease of operation

If axial flow paths are provided through the casing hanger, then fluid flow management is improved, but the structural integrity and lockdown force are reduced

Engineering Contradiction:

Improvefluid flow managementVSAvoidlockdown force

Core Design Contradiction:

Ease of operationVSForce

Solution Approach 1:

The annular insert acts as an intermediary component that bridges the wellhead housing and casing hanger. It provides a dedicated flow path through its own structure (independent of the casing hanger) while maintaining the structural integrity of both the housing and hanger. This intermediary structure allows fluid flow to occur through the insert rather than through the casing hanger itself, preserving the lockdown capability of the hanger while still achieving efficient fluid management.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10174574B2Insert for use with wellhead housing having flow-by path

Publication Date: 2019.01.08 VETCO GRAY LLC

AI summary

A wellhead assembly having an insert that is disposed between a wellhead housing and casing hanger. Axial slots through the insert define a flow path between the wellhead housing and casing hanger. The insert is made from a higher strength material and supports a load exerted between the casing hanger and wellhead housing. The insert is a ring like member, and the slots can more easily be machined in the insert than in the wellhead housing.