Casing Annulus Seal System for Reverse Circulation Cementing
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Solution Overview
Problem
Existing well head equipment does not effectively seal the casing-by-casing annulus to allow for the application of positive pressure, limiting the use of reverse circulation cementing operations and requiring significant hot work for installation.
Innovation Solution
A seal system comprising an anchor, head, plug, and additional components that securely fasten to the outer and inner casings to create a sealed annulus for fluid communication, allowing for positive pressure application without requiring extensive hot work.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If typical blow out preventor and well head equipment are used to seal the annulus, then the annulus can be sealed, but significant hot work is required to install BOP flanges or wellhead equipment to the surface casing
Solution Approach 1:
The seal system is divided into separate components: a seal assembly that attaches to the surface casing, a head assembly with fluid communication opening, and a plug assembly. These segmented components can be installed independently without requiring extensive hot work, resolving the contradiction between reliable sealing and installation ease
Solution Approach 2:
The patent introduces a intermediary seal assembly that connects between the surface casing and the head assembly, providing the sealing function without requiring direct attachment of heavy BOP equipment to the surface casing. This intermediary component reduces the hot work requirement while maintaining sealing reliability
2Reliability
If typical blow out preventor and well head equipment are used to seal the annulus, then the annulus can be sealed, but access to the annulus is limited for performing reverse circulation cementing operations
Solution Approach 1:
The head assembly is designed with a fluid communication opening that serves multiple functions: maintaining annulus seal integrity while simultaneously providing access for cementing operations. This multi-functional design resolves the contradiction between reliable sealing and operational access
Solution Approach 2:
The plug assembly can be positioned and removed dynamically to allow cementing operations through the fluid communication opening, then repositioned to maintain the seal. This dynamic capability enables both sealing and access requirements to be met at different operational stages
3Reliability
If typical blow out preventor and well head equipment are used, then the annulus can be sealed, but the surface casing must be fitted to accept the wellhead equipment
Solution Approach 1:
The seal assembly is designed with adjustable parameters including different sizes and attachment configurations that can adapt to various surface casing specifications. This parameter variability allows the system to work with different casing types without requiring the casing to be pre-fitted for specific wellhead equipment
Data Source
AI summary
A method for sealing an annulus defined between an outer casing and an inner casing, the method having steps as follows: fastening a lock ring to an anchor base, wherein the lock ring comprises a threaded fastener of the lock ring to the head; positioning the lock ring and anchor base about the outer casing; fastening a limit clamp to an exterior surface of the outer casing; repositioning the lock ring and anchor base so that the anchor base is in contact with the limit clamp; fastening a head to the lock ring; providing an opening for fluid communication with the annulus through the head; positioning a plug about the inner casing and in contact with the inner casing and the head; positioning a seal fitting clamp about the inner casing and in contact with the plug; positioning a bull cap about the inner casing and in contact with the seal fitting clamp; and fastening the bull cap to the head.