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Choke Valve for Oil and Gas Drilling Industry

Choke Valve for Oil and Gas Drilling Industry

The oil and gas choke valve is the core component of the well control device used in the choke manifold in the oil and gas industry. Its function is to maintain a certain casing pressure by opening and closing the well bottom when implementing the oil and gas well pressure control technology. The pressure change is stable within a certain narrow range.


Most of the throttle components of the oil and gas choke valve adopt a needle valve structure; some are cylindrical rubber, and the outer wall of the rubber tube is driven by gas and liquid to change the size of the inner hole. Others use two overlapping metal plates to rotate relative to each other. To change the size of the orifice. Although the structure of the oil and gas choke valve is different, the principle is to change the size of the fluid channel to make the resistance of the drilling fluid flow through the throttle element different, resulting in different wellhead back pressure. The smaller the through hole, the greater the resistance and the back pressure. The larger the through hole is, the smaller the resistance and the smaller the back pressure, so as to achieve the purpose of throttling.


The choke valve types in the throttle manifold are mainly divided into two categories, fixed choke and adjustable choke. Adjustable choke valve can be divided into needle choke valve, cylindrical choke valve, cage choke valve and orifice choke valve according to the structure of the disc. Its operation modes are manual, pneumatic, electric and hydraulic.


Ⅰ. Needle-shaped oil and gas choke valve


Needle-shaped oil and gas choke valves are used for choke manifolds, high pressure oil and gas wellhead devices, etc. There are two types of needle-shaped oil and gas choke valves, manual and hydraulic.


The needle-shaped oil and gas choke valve is mainly composed of flange, valve body, O-shaped sealing ring, packing box, gland, valve stem, handwheel, valve seat, bearing, pressure cap, valve needle, nut, key and so on. A pair of concealed choke head and valve seat reduce the damage caused by poultry speed fluid, a large nut on the top cover, convenient for maintenance, and the test port is convenient for installation of pressure measuring instruments. Needle-shaped oil and gas choke valves are widely used in wellhead systems, manifolds, testing and other purposes.


Ⅱ. Cylindrical oil and gas choke valve


The valve core of the cylindrical oil and gas choke valve is cylindrical and is solid carbide. The inner ring of the valve seat is inlaid with carbide. The contact end of the valve cover and the medium is welded with carbide to make it have good wear resistance and Corrosion resistance. A nylon wear-resistant bushing is embedded on the outlet channel of the valve to protect the valve body from abrasion.


Ⅲ. Hydraulic cylinder oil and gas choke valve


The tail of the valve cover of the hydraulic cylinder-shaped oil and gas choke valve is a hydraulic cylinder and a piston. The piston is driven by the hydraulic oil to drive the valve stem, and then the spool is driven forward and backward, so that the flow passage area between the spool and the valve seat is changed to the throttling Purpose. In order for the personnel operating the console to know the opening degree of the choke valve, a valve position transmitter is installed at the outer end of the liquid cylinder of the valve cover. The hydraulic cylinder oil and gas choke valve has the following characteristics


1. It has good corrosion resistance and erosion resistance.


2. The cylindrical valve core and the inner ring of the valve seat are made of hard alloy, and can be used upside down, which increases the service life.


3. Larger valve body cavity and cylindrical valve body structure. Compared with the usual needle-shaped oil and gas choke valve, it has a larger flow rate. It adopts the flow direction of side inlet and positive outlet, and the guide tube around the cylindrical valve plate is reduced. Vibration during throttling reduces noise.


4. The valve position transmitter can use the air pressure signal to convey the actual switch position of the oil and gas choke valve core to the console for display.


5. The operator can remotely control the opening and closing of the oil and gas choke valve through the console. When operating the manual cylindrical choke valve, turn the hand wheel clockwise, the opening degree becomes smaller and tends to close. Rotating the hand wheel counterclockwise, the opening degree becomes larger. Then, the opening of the choke valve can be displayed from the scale on the shield. When turning the hand wheel to the end of the stroke, it should not be too fast to avoid damaging the valve stem and limit cap.


The throttle valve can only be used to control pressure and flow, and must not be used as a cut-off function, that is, the valve core and the valve seat cannot be sealed.


Ⅳ. Cage-type oil and gas choke valve


The cage type oil and gas throttle valve uses a cage structure with holes to change the direction of the fluid, and uses the principle of fluid mechanics to make the fluid move along the center line of the cage to avoid damage and corrosion to the throttling element and reduce operating noise.


The cage type oil and gas throttle valve can provide a variable flow rate, and the throttle flow diameter has a larger adjustment range, but if the flow rate is required to be constant, the throttle valve can also provide a fixed flow rate at a certain position. This can meet the different traffic needs of users.


Both the inside of the caged oil and gas throttle valve core assembly and the throttle stem head are made of tungsten carbide, which is resistant to corrosion and impact, and has a long service life.


The oil and gas throttle valve is used to adjust the flow and pressure of the medium. The cut-off type throttle valve can be adjusted in a larger range and can also be adjusted, but the diameter is small, suitable for medium and small diameters, and the butterfly type throttle valve is suitable for large diameters. The throttle valve is not suitable for use as a cut-off valve. If the throttle valve is used for throttling for a long time, its sealing surface will inevitably be eroded, and the sealing performance cannot be guaranteed.

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