Wellhead Seal Device for Rough Casing
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Solution Overview
Problem
Existing wellhead systems face challenges in achieving reliable high-pressure metal-to-metal seals with threaded unions, as they often rely on elastomeric seals and struggle to energize metal seals effectively due to limited force applied during threaded connections, which is a problem in the oil industry seeking quicker and cost-effective assembly and disassembly.
Innovation Solution
A wellhead seal device featuring an annular metal sealing sleeve with separate primary and secondary metal seals, where the secondary seals are energized from above using threaded seal energizing members, allowing for sufficient force to be applied to create a reliable metal seal to rough casing surfaces without damaging the seals during threaded connections between wellhead members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If threaded unions are used between wellhead members, then assembly and disassembly speed is improved, but reliable high-pressure metal-to-metal seals cannot be achieved due to insufficient force to energize the seal
Solution Approach 1:
The seal device is divided into separate functional components: a seal member with sealing surfaces, an energizing member with threading, and a retaining member. This segmentation allows the threaded energizing member to be independently tightened to apply sufficient force to the seal member without requiring flanged connections, thus achieving both quick assembly and reliable sealing.
Solution Approach 2:
The energizing member acts as an intermediary between the threaded connection and the seal member. It transfers the rotational force from the threaded union into linear compressive force on the seal member, enabling sufficient seal energization force to be applied while maintaining the simplicity of threaded connections.
2Reliability
If flanged connections are used between wellhead members, then reliable high-pressure metal-to-metal seals can be achieved, but construction cost and assembly time increase
Solution Approach 1:
The invention extracts the essential sealing function from the complex flanged connection system. By separating the seal member from the wellhead members and using an independent threaded energizing member, the solution eliminates the need for time-consuming flange alignment and bolt tightening while maintaining reliable sealing through direct metal-to-metal contact.
Solution Approach 2:
The seal member is pre-installed and positioned in the wellhead assembly before the threaded connection is made. This preliminary positioning allows the threaded energizing member to be tightened to apply immediate seal force, eliminating the need for post-assembly adjustments required by flanged connections.
3Reliability
If metal seals are used to rough casing surfaces, then high-pressure sealing is achieved, but sufficient force must be applied to energize the seal which is difficult with threaded connections
Solution Approach 1:
The energizing member serves as a mechanical intermediary that converts the rotational tightening force into linear compressive force applied directly to the seal member. This intermediate force transmission mechanism ensures sufficient seal energization force is applied to rough casing surfaces while maintaining the simplicity of threaded connections.
Solution Approach 2:
The invention changes the force application parameter from indirect (through flange bolts) to direct (through threaded energizing member). The threaded connection allows precise control of the compressive force parameter on the seal member, enabling sufficient energization force to be applied consistently to rough surfaces.
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 enables the formation of reliable internal and external metal seals to rough casing surfaces, allowing for quick assembly and disassembly of wellhead systems using threaded connections while maintaining high-pressure integrity, and can be used with both threaded and flanged connections.
Implementation Method 1
A plurality of threaded seal energizing members are provided, each being adapted to be threaded through the first vertical threaded ports to push downwardly on the first wedge ring such that the first metal seal ring is compressed radially inwardly to form an inner metal seal to the inner tubular member
Implementation Method 2
A first wedge ring is provided which is adapted to fit around the inner tubular member above the first metal seal ring and having an inner cam surface to engage the conical surface of the first metal seal ring within the inner sealing annulus
Data Source
AI summary
A wellhead seal device forms metal seals in an annular space between inner and outer tubular members such as a rough casing held within aligned casing and tubing heads. An annular metal sealing sleeve has a lower portion seated in the annular space, and an upper portion which forms an inner sealing annulus adjacent the outer wall of the inner tubular member. A metal seal ring and a wedge ring are located in the inner sealing annulus. A retaining ring is retained by the upper portion above the wedge ring. Threaded seal energizing members extend through the retaining ring to push downwardly on the wedge ring and compress the metal seal ring radially inwardly to form a metal seal to the inner tubular member and thus seal the inner sealing annulus. The lower portion of the annular metal sealing sleeve may seal to the casing head and to the casing.