In petroleum and natural gas extraction, a Christmas tree, or "tree" (not "wellhead" as sometimes incorrectly referred to), is an assembly of. A design taken from their above-ground cousins, subsea trees are sometimes called xmas trees because the devices can resemble a tree with decorations. A Christmas Tree is an assembly of valves, spools, and fittings used for an oil well, gas well, water injection well, water disposal well, gas injection well, condensate well, and other types of wells. The primary function of a tree is to control the flow into or out of the well, usually oil or gas.
|Published:||16 January 2015|
|PDF File Size:||14.64 Mb|
|ePub File Size:||42.95 Mb|
Subsea trees can be vertical or horizontal based on how the master valves — the valves set on the flow path and capable of closing off production — are designed.
Surface Christmas Tree (Dry Tree) Basic Knowlege
Subsea trees have even less of a resemblance to a Christmas tree, but the name persists out of tradition. It is important to understand where these valves are located and what role they play in getting gas from the well bore to the customer.
The lower master valve will normally be manually xmas tree oil and gas, while the upper master valve is often hydraulically actuated. Hydraulic tree wing valves are usually built to be fail-safe closed, meaning they require active hydraulic pressure to stay open.
The right-hand valve is often called the flow wing valve or production wing valve, because it is in the flow path the hydrocarbons take to production facilities.
The left-hand valve is often called the kill wing valve. It is also use to control sand production in some cases. A choke restricts areas for production flow through a bean or an orifice inserted into a choke body.
Xmas tree oil and gas
Two types of chokes are 1 positive choke with interchangeable beans 2 adjustable choke which allows adjusting the choke size easily. Figure 7 — Choke Valve Swab Valve On a Christmas tree, a swab valve is the topmost valve providing vertical access to the well for well intervention operations conducted by xmas tree oil and gas, slickline, coiled tubing or a snubbing unit.
A pressure gauge is used to monitor the pressure of the well.
Figure 9 — Xmas tree oil and gas and Pressure Gauge Unitized Christmas Tree A unitized Christmas tree is an integrated Christmas tree which consists of a lower and upper master valve, and a swab valve in one body. A general SCT is normally used in shallower waters measuring up to 1, meters deep.
Other subsea trees include horizontal trees, mudline suspension trees, monobore trees and large bore trees. Wells being produced with rod pumps pump jacks, nodding donkeys, grasshopper pumps, and so on frequently do not utilize any tree owing the absence of a pressure-containment requirement.
A basic surface tree consists of xmas tree oil and gas or three manual valves usually gate valves because xmas tree oil and gas their flow characteristics, i.
A typical sophisticated surface tree will have at least four or five valves, normally arranged in a crucifix type pattern hence the endurance of the term "Christmas tree". The two lower valves are called the master valves upper and lower respectively.
How Do Subsea Trees Work? | Rigzone
Master valves are normally in the fully open position and are never opened or closed when the well is flowing except in an emergency to prevent erosion of the valve sealing surfaces. The lower master valve will normally be manually operated, while the upper master valve is often hydraulically actuated, allowing it to be used as xmas tree oil and gas means of remotely shutting in the well in the event of emergency.
An actuated wing valve is normally used to shut in the well when flowing, thus preserving the master valves for positive shut off for maintenance purposes. Hydraulic operated wing valves are usually built to be fail safe closed, meaning they require active hydraulic pressure to stay open.