Pressure-Energized Wellhead Seal for High-Pressure Annulus Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional wellhead seals, particularly metal-to-metal seals, face challenges in maintaining a high-quality seal under high pressure conditions, as they often rely on mechanical expansion which may not be sufficient to ensure a reliable seal across varying pressure ranges.
Innovation Solution
A pressure-activated sealing arrangement featuring a flexible metal sealing lip that projects radially outward from the inner well casing, with a distal sealing surface that is urged towards the inner surface of the outer well casing by annulus pressure, enhancing sealing strength as pressure increases, and is designed to flex inwardly to create a metal-to-metal seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal-to-metal seals are energized by mechanical expansion, then the seal can be activated, but the sealing quality is insufficient under high pressure conditions
Solution Approach 1:
The seal element's activation method is changed from mechanical expansion to pressure-activated expansion. The seal remains inactive during installation and only expands when exposed to well pressure, changing the physical state parameter based on operating conditions. This resolves the contradiction by ensuring the seal is activated at the appropriate moment (when pressure is present) rather than during installation, providing reliable sealing under high pressure conditions.
Solution Approach 2:
The seal is pre-positioned in an inactive state during installation, and the activation action is delayed until pressure is applied. This preliminary positioning followed by conditional activation ensures the seal is ready but not yet engaged, allowing it to activate precisely when needed under pressure conditions.
2Reliability
If conventional seals are used, then the structure is simple, but the seal cannot maintain high quality under varying pressure ranges
Solution Approach 1:
The seal transitions from a static, pre-activated state to a dynamic, pressure-activated state. The seal element remains flexible and unexpanded during installation, then dynamically expands in response to applied pressure. This dynamic behavior allows the seal to adapt to varying pressure ranges, maintaining reliability across different operating conditions while keeping the overall structure relatively simple.
3Reliability
If the sealing lip projects radially outward, then the seal can be pressure-activated, but the initial radial position must be precisely controlled
Solution Approach 1:
The seal element uses the applied pressure itself to activate the sealing action. The pressure that is applied to the well also serves to expand the seal element into the sealing position, eliminating the need for separate activation mechanisms or precise pre-positioning. The system uses the operating pressure to automatically position the seal correctly, reducing manufacturing precision requirements.
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 provides a high-quality, pressure-energized metal-to-metal seal capable of withstanding higher pressures than conventional seals, ensuring a reliable and increased sealing strength across a wider range of pressure conditions.
Implementation Method 1
pressure within the annulus is arranged to urge the sealing surface towards the inner surface of the outer well casing
Implementation Method 2
a flexible metal sealing lip which projects radially outwardly and away from the central longitudinal axis of the inner well casing
Data Source
AI summary
A pressure energised seal for a wellhead, in particular, provides a seal of an annulus between an inner wellhead casing member and an outer wellhead casing member. The wellhead incorporates a clamping arrangement whereby the outer member is arranged to be deflected radially inwardly in order to grip and secure the inner member within the bore of the outer member. Also, a seal for use in such a clamping arrangement. In particular, the seal includes a sealing lip which locates within a groove provided in the outer clamping surface of the inner member. A seal is activated and created as the outer member is clamped inwardly since this causes the outer member to compress the inner member and to reduce the diameter of the inner member. Also, a well and a method of sealing an annulus in a well.