Wellhead Isolation Sleeve for Fracturing String Retrieval
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing wellhead assembly processes require the installation and removal of a bridge plug and blowout preventer, as well as a bored out spool, to retrieve the fracturing string and hanger, which complicates the fracturing string retrieval process.
Innovation Solution
A wellhead assembly with an annular isolation sleeve and tubing head that allows the fracturing string hanger to pass through, eliminating the need for a bridge plug, blowout preventer, and bored out spool by providing a larger inner radius for the isolation sleeve and tubing head, enabling direct retrieval of the string hanger and fracturing string.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bridge plug and blowout preventer are installed to retrieve the fracturing string and hanger, then safety and pressure control are improved, but device complexity and operational time increase
Solution Approach 1:
The wellhead assembly is designed with a universal main bore that can accommodate both the fracturing string during operation and the retrieval operation afterward. The isolation sleeve and landing area create a multi-functional system that handles both installation and retrieval phases without requiring separate specialized equipment like bridge plugs or blowout preventers.
Solution Approach 2:
The invention extracts the retrieval function directly into the wellhead assembly structure itself. By incorporating the isolation sleeve and profiled landing area into the wellhead, the retrieval capability is built-in, eliminating the need to add external safety equipment (bridge plug, blowout preventer) just for retrieval operations.
2Ease of operation
If a bored out spool is used to allow full bore opening for retrieval, then ease of operation is improved, but device complexity and number of components increase
Solution Approach 1:
The main bore is designed as a universal passage that serves dual purposes: containing the fracturing string during operation and allowing its retrieval afterward. The isolation sleeve creates a clear pathway within the same bore, eliminating the need for a separate bored out spool component.
Solution Approach 2:
The invention merges the containment function and retrieval function into a single integrated wellhead assembly structure. The isolation sleeve and main bore work together as a unified system that provides both operational containment and retrieval capability, combining multiple functions into one structure rather than requiring separate components.
3Reliability
If additional components (bridge plug, blowout preventer) are installed for retrieval, then pressure control during retrieval is improved, but loss of time and operational efficiency worsen
Solution Approach 1:
The isolation sleeve and profiled landing area are installed as part of the initial wellhead assembly configuration before fracturing operations begin. This preliminary setup ensures that pressure control and retrieval capabilities are already in place, eliminating the need for time-consuming installation of bridge plugs or blowout preventers when retrieval is needed.
4Ease of operation
If the isolation sleeve inner radius is made greater than the fracturing string hanger outer radius, then ease of operation for retrieval is improved, but manufacturing precision requirements increase
Solution Approach 1:
The isolation sleeve is designed with a specific local geometric feature: an inner radius that is deliberately made greater than the outer radius of the fracturing string hanger. This localized dimensional relationship at the critical interface between the isolation sleeve and hanger provides the necessary clearance for retrieval operations while maintaining manufacturability.
Data Source
AI summary
A wellhead assembly includes a casing head, tubing head, and a production tree mounted on the tubing head. An isolation sleeve is set in a main bore of the wellhead assembly that extends across an interface between the casing and tubing heads so that a portion resides in each. The isolation sleeve is configured so that a fracturing string, and its associated hanger, can be retrieved through the isolation sleeve; which significantly reduces the time and steps required to conduct a fracturing operation in a well. Moreover, the present isolation sleeve can be used without changes to existing casing or tubing heads.