Dual String Tubing Hanger Assembly with Nested Auxiliary Line
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Solution Overview
Problem
Current dual string well configurations with coil tubing face operational difficulties and high costs due to handling challenges, interference during installation, and the need for extensive well maintenance, which includes risk of oil spills and blowouts during service operations.
Innovation Solution
A dual string tubing hanger assembly that includes an insert with a non-concentric auxiliary line hanging profile and an adaptor with a production string tubing hanger bowl, allowing for separate and secure hanging of production and auxiliary tubing strings within a well casing, enabling independent servicing of the production string without disturbing the auxiliary line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If coil tubing is used as auxiliary tubing string, then fluid circulation effectiveness is improved, but handling difficulty and installation complexity increase
Solution Approach 1:
The patent implements nesting by placing the auxiliary coil tubing inside the production tubing string, with both strings suspended from the same hanger assembly. The hanger body contains separate retention mechanisms for both tubing strings, allowing the auxiliary string to be nested within the production string's operational space while maintaining independent functionality and fluid circulation capability.
Solution Approach 2:
The hanger assembly is segmented into distinct functional components: a hanger body with separate retention mechanisms for production tubing and auxiliary tubing, a well control BOP valve integrated into the assembly, and independent hanging profiles. This segmentation allows each component to be optimized independently while working together as an integrated system.
2Adaptability or versatility
If existing dual string hangers are used, then both tubing strings can be hung, but service operations require removing both strings simultaneously increasing time and cost
Solution Approach 1:
The hanger assembly uses separate retention mechanisms within the hanger body for production tubing and auxiliary tubing. This segmentation enables independent removal and installation of each tubing string through separate operational access points, allowing service operations on one string without disturbing the other.
Solution Approach 2:
The hanger assembly incorporates dynamic operational capability where the production tubing can be independently removed and reinstalled through the hanger body while the auxiliary tubing remains suspended. This dynamic design allows flexible service operations without requiring simultaneous handling of both strings.
3Reliability
If kill fluids are used for well control during installation or removal, then well pressure is controlled, but gas circulation may lift kill fluid causing oil spill or blowout
Solution Approach 1:
The patent introduces a well control BOP (blowout preventor) valve as an intermediary device integrated into the hanger assembly. This BOP valve provides mechanical well control capability that replaces or supplements kill fluid methods, allowing precise pressure control during installation and service operations without relying on fluid columns that could be displaced by gas circulation.
Solution Approach 2:
The patent replaces the fluid-based well control method (kill fluids) with a mechanical well control system (BOP valve integrated into the hanger assembly). This mechanical substitution eliminates the hazard of kill fluid displacement by gas while maintaining effective well pressure control during operations.
4Strength
If production tubing is landed in the heel of the well, then wear distribution is improved, but auxiliary tubing installation becomes more difficult
Solution Approach 1:
The hanger assembly enables both production tubing and auxiliary tubing to be nested and suspended from the same installation point at the wellhead. This nested configuration allows the production tubing to extend to the heel for wear distribution while the auxiliary tubing is simultaneously installed through the same hanger mechanism, eliminating the conflict between landing position and installation difficulty.
Data Source
AI summary
The dual string hanger assembly includes an insert and an adaptor. The insert is installed within the inner diameter of the tubing head and the adaptor is coupled over the top of the tubing head. The insert therefore becomes sealed within the interior space between the tubing head and the adaptor. In use, the production string is supported in a tubing hanger profile built into the adaptor above the existing tubing head. The auxiliary line is supported in a second, smaller diameter hanger profile that is on the insert, which is installed within the tubing head. The assembly may include a hanging apparatus, such as slips, to secure the auxiliary line in the hanger profile of the insert.