Some well operators define the acceptable leakage rates for the Christmas tree valve like UMV also known as Surface Safety Valve (SSV) to be 400cm3/min (23.4l/hr) for liquid or 0.43 m3/min (900scf/hr) for gas as recommended by the ISO10418/API14C & API14H standards. However, applying the standard’s acceptable gas leakage rate criterion (900scf/hr) to equation (1) gives an extremely high and unreasonable pressure rise (often over the design pressure rating) due to the extremely small isolated Christmas tree cavity volume (see Figure 1) available when in testing. This is verified in the equation (2) that finds the maximum allowable pressure rise (; for a typical Christmas tree inflow leak test data, with isolated Christmas tree cavity volume V = 0.28ft3, test duration t of 15 minutes, absolute temperature of gas T = 540 Rankine (27°C) and assuming a prefect gas of compressibility factor Z = 1;File Size: Page Count:
What are Christmas tree valves? Christmas tree valves are an integral part of oil and gas wells. They are implemented in both large and small wells alike and provide the access point for all fluids in and out of the wellhead. Below is a list of wells that implement Christmas tree valves but know these systems are more useful beyond this small range of applications.
Are Christmas tree valves safe for oil and gas wells? This means understanding what chemicals the Christmas tree will be exposed to and how it should respond to sedimentation, fluid forces, and fatigue stresses. Also ensure ample safety features, as hydrocarbon wells can quickly become explosive if handled incorrectly. Christmas tree valves are an integral part of oil and gas wells.
What is valve leakage rate? Valves are one of the main leakage sources in the pipeline system of the petrochemical industry, so it’s critical to the leakage of valves. Valve leakage rates are actually the valve sealing level, valve sealing performance is referred to as the valve sealing parts to prevent the ability of media leakage.
When to replace a leaky surface valve? If a liquid leakage rate > 400 cubic centimeters per minute or a gas leakage rate > 15 standard cubic feet per minute is observed, the valve must be removed, repaired and reinstalled or replaced. (2) Comply with the following testing requirements for surface valves: Annually, not to exceed 12 calendar months between tests.
What are Christmas tree valves?
How many valves does a Christmas tree have? 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).
What is a Christmas tree in a well? …valves, referred to as a Christmas tree, is installed at the top of the well. The valves regulate flow from the well and allow tools for subsurface work to be lowered through the tubing on a wire line.
What are the functions of a Christmas tree? A Christmas Tree often provides numerous functions including open or shut-in the well via wing valve, control and adjust the flow rate via the choke bean, place the well in safe conditions via master valves. Also, it includes additional functions such as chemical injection points,…
Are Christmas tree valves safe for oil and gas wells? This means understanding what chemicals the Christmas tree will be exposed to and how it should respond to sedimentation, fluid forces, and fatigue stresses. Also ensure ample safety features, as hydrocarbon wells can quickly become explosive if handled incorrectly. Christmas tree valves are an integral part of oil and gas wells.