Well Control System Equipment

Wellhead Assembly

Wellhead Assembly, the key equipment in oil/gas production, consists of casing head, tubing head and X-mas tree, which are applicable for connection of casing string and tubing string, sealing the annular space between casing and tubing and controlling the pressure of the production wellhead and adjusting the flow rate of oil/gas wellhead as well as some special operations such as acid fracture, injection and test etc.

Part Ⅰ: Casing Head

The casing head, installed at the bottom of wellhead assembly connecting casings and various wellhead assemblies, is composed of a body, casing hanger and seal assembly. The casing head is used for supporting the weight of technical and production casing, sealing the annual space between the casing and providing a filtered connection for the installation of upper wellhead assemblies. These assemblies include a blowout preventer (BOP), tubing head and christmas tree. The surface casing is connected by a flange located below the casing head. The oil-string casing is connected by a screw thread inside of the casing head.

Specifications

Part Ⅱ:  Tubing Head

The tubing head is installed above the casing head and includes a tubing head spool and tubing hanger. The tubing hanger is used for hanging the internal tubing string and sealing the annular space between tubing and casing. This is used for conducting well flushing in direct circulation and reverse circulation, observing casing pressure, and for carrying out various tasks through the tubing and casing annular space.

Specifications

Part Ⅲ:  X-mas Tree

The X-mas tree is installed above the tubing head and is composed of a gate valve, choke valve, tee/cross, flange, X-mas tree cap, etc. This is used for controlling and regulating well production, directing oil or gas from wellhead to pipelines, and achieving down-hole installation and removal of tools and equipment.

Specifications:

• Working pressure: 2000 psi～20000 psi

• Nominal diameter: 7.1/16"～21.1/4"

• Working media: oil, gas, mud, H2S and CO2 gases

• Temperature rating: K-U (-75℉/-60℃～250℉/121℃)

• Material class: AA, BB, CC, DD, EE, FF and HH

• Specification level: PSL1～3G

• Performance level: PR1～2

• Structural type: integral-type and separated-type

• Installable (pneumatic) hydraulic safety valve

Christmas Tree

The christmas tree is wellhead equipment used to direct and control oil & gas from the well. This key piece of equipment for controlling the upper part of an oil & gas well and production adjustment and consists of a casing head, tubing head and oil (gas) tree ontology.

Gas production christmas trees and tubing heads are mainly used to produce and inject gas. While the relative density and gas column pressure is low, well head pressure is high and is prone to leakage. Sometimes natural gas may also contain corrosive media such as H2S and CO2. As a result, gas production christmas trees have more stringent requirements for both materials and sealing characteristics. To ensure a safe operating environment, two gate valves are used on the tubing and casing respectively. Some gate valves, which are used for high pressure and ultra-high pressure gas wells, are integrated valves manufactured from high quality forged steel.

Specifications:

• Working pressure: 2000 psi～20000 psi

• Nominal diameter: 2.1/16"～5.1/8"

• Working media: oil, gas, mud, H2S and CO2 gases

• Temperature rating: K-U (-75℉/-60℃～250℉/121℃)

• Material class: AA, BB, CC, DD, EE, FF and HH

• Specification level: PSL1～3G

• Performance level: PR1～2

• Structural type: integral-type and separated-type

• Installable (pneumatic) hydraulic safety valve

• It can be designed into general or integral structure as required.

• It can be classified into two kinds of the single-wing and the dual-wing.

• As required, matched choke may be positive choke or adjustable choke alternatively.