Xmas Trees

Xmas Trees

Primary flow control system for well once in production

Features and access requirements

•Outflow from well - production

•Inflow to well - injection or killing

•Vertical access to tubing - wire line, coiled tubing

 

Xmas Tree Components

•Pressure gauges (accessory)

– safety hazard / potential wrong pressure readings

•Gauge flange or tree cap

–provides seal for top of tree

•Lubricator valve

–isolate pressure, well access for intervention tools

•Flow tee

–used to direct flow, enable thru-tubing access

•Production wing valve

–used to isolate well for most routine operations

•Kill wing valve

–enables connection of pumping equipment

•Choke (accessory)

–controls rate of flow from well

•Master valves (main isolation valves)

–Upper Master Valve (operational valve), optional: hydraulic / pneumatic controlled
Surface Safety Valve

–Lower Master Valve (back-up valve)

  manually operated

 Categories of Xmas Tree

Flanged tree

•Several flanged components

– each connection is a potential leak path

•Much more common than monoblock design

•More flexible than monoblock design

•takes up more space (height)

Monoblock construction tree

•Single block construction

•Fewer possible leak paths

•Used in high pressure/leak sensitive locations

Monoblock Xmas Tree

Comprises inline or "Y" shaped block of single casting/forging

Valving arrangement

•Lower Master Valve (manual)

•Upper Master Valve (Surface Safety Valve)

•Y piece or side outlet flanges

–houses both production and kill wing valves

•Uppermost valve (manual swab valve)

 

  Multiple Completions

Cases where more than one completion string installed

•Each string independently suspended

•Must seal off tubing casing annulus

–either independently or collectively

•Independent control of fluid flow in each string

Xmas Tree Selection

produce a listing of the parameters of the anticipated process or operating envelope

- Classify the Well Type

  Water Well ( low or medium pressure, Rate )

  Oil Well (low, medium or high pressure, GOR, Rate )

  Gas Well ( low, medium or high pressure, WGR, Rate)

This will be the basis for the design and the selection of equipment type and rating

wellhead installation