Wellhead Equipment and Christmas Tree Assembly
The system is designed to safely manage high pressures, control flow rates, and allow maintenance and intervention operations throughout the life of the well.
General system overview
The assembly is divided into three main sections:
Section A
The wellhead base and casing support section
Section C
The tubing head and transition section
Section D
The Christmas tree production control section
Each section has a specific role and must be installed in the correct sequence to ensure safety and operational efficiency.
Section A Wellhead base and casing system
This is the lowest part of the assembly and is installed directly on top of the well casing. It provides structural integrity and pressure containment.
Main components include:
Casing head
Supports the surface casing and provides the foundation for the wellhead system.
Casing Spool
Allows additional casing strings to be suspended and sealed while providing side outlets for pressure monitoring and cementing operations.
Casing Hanger
Suspends the casing string inside the casing head or spool .
Secondary seal
Prevents pressure leakage between casing strings.
Lock screws
Secure the casing hangers in place and prevent movement under pressure.
Base Plate
Provides mechanical stability for the entire wellhead structure.
Importance of Section A
This section carries the mechanical load of the casing strings and isolates formation pressures, ensuring long term well integrity.
Section C Tubing head and Tubing Suspension
This section forms the interface between the wellhead and the Christmas tree and is responsible for suspending the production tubing.
Main components include:
Tubing Head
Supports the tubing hanger and provides pressure control between the casing and tubing.
Tubing hanger
Suspends the production tubing and seals the annular space between tubing and casing.
Tubing head adapter
Connects the tubing head to the Christmas tree.
Instrument flange
Allows installation of pressure gauges and monitoring instruments.
Valves
Used for pressure control, testing, and well monitoring
Importance of Section C
This section ensures proper suspension of the production tubing and safe isolation of annular pressures.
Section D Christmas tree assembly
The Christmas tree is the uppermost part of the system and provides full control of well production and intervention operations.
Main components include:
Lower master valve
The primary safety valve used to shut in the well in emergency situations.
Upper master valve
Used during normal operations to control production
Wing valves
Control the direction of flow. One wing is used for production.
