2023-05-11 00:00:00
How to select a casing head? This article takes you to understand the structure and function of the casing head!
How to select a casing head? This article takes you to understand the structure and function of the casing head!
The casing head is installed at the upper end of the surface casing string, which is used to suspend each layer of casing outside the surface casing and seal the annular space of the casing as a wellhead device component.
Type of casing head
Common types of casing heads include single-layer casing heads, double-layer casing heads, and three-layer casing heads.
1. Single stage of casing head
2. Double stage of casing head
3. Three stage of casing head
The function of the casing head
1. Suspend some or all of the weight of each layer of casing except for the surface casing through a hanger;
2. Forming a pressure seal between the inner and outer casing columns;
3. Connect wellhead devices such as blowout preventers;
4. Provide an outlet to release any pressure that may accumulate between two complete casing strings;
5. In emergency situations, fluid such as well killing fluid or fire extinguishing agent can be pumped into the well through the side hole of the casing head;
Structural characteristics and sealing principle of casing head
The casing head mainly consists of the bottom casing head, casing hanger, casing head spool, and valve.
The sealing of the casing head consists of the casing head body, BT type rubber sealing ring, casing hanger, dovetail type rubber sealing ring, top thread V-shaped sealing ring, and sealing washer.
The casing hanger seat is suspended on the steps of the casing head body. Due to the hanging weight of the shell, the contact between metal and metal creates a rigid passive seal. The casing hanger and casing are sealed with threads.
The casing head spool has a BT seal that matches the outer diameter of the casing hanger (or casing outer diameter) and corresponding grease injection pressure testing holes. When using, high-pressure sealing grease must be injected from the grease injection valve in order to make the BT seal effective.
If the seal leaks oil, seal grease should be injected separately from the grease injection valve and the pressure test valve to ensure that the seal continues to function.
The grease injection pressure shall not exceed the rated working pressure of the flange; When sealing the casing, the rated allowable collapse pressure of the casing should not be exceeded.
The pressure test hole is used for the external sealing test of the casing hanger.
There is a screw on the flange that is used to lock the wear-resistant sleeve (protecting the sealing surface) and lock the sleeve hanger behind the sleeve hanger.
If there is air leakage at the top thread, the pressure cap can be tightened to ensure effective sealing. The flanges on both sides of the casing head intersect, with one end connected to a flat valve (or blind flange) and the other end connected to a flat valve, threaded flange, joint, globe valve, and pressure gauge. The annular pressure between each layer of the two casings can be observed through the pressure gauge.
2023-05-11 00:00:00
How to select a casing head? This article takes you to understand the structure and function of the casing head!
How to select a casing head? This article takes you to understand the structure and function of the casing head!
The casing head is installed at the upper end of the surface casing string, which is used to suspend each layer of casing outside the surface casing and seal the annular space of the casing as a wellhead device component.
Type of casing head
Common types of casing heads include single-layer casing heads, double-layer casing heads, and three-layer casing heads.
1. Single stage of casing head
2. Double stage of casing head
3. Three stage of casing head
The function of the casing head
1. Suspend some or all of the weight of each layer of casing except for the surface casing through a hanger;
2. Forming a pressure seal between the inner and outer casing columns;
3. Connect wellhead devices such as blowout preventers;
4. Provide an outlet to release any pressure that may accumulate between two complete casing strings;
5. In emergency situations, fluid such as well killing fluid or fire extinguishing agent can be pumped into the well through the side hole of the casing head;
Structural characteristics and sealing principle of casing head
The casing head mainly consists of the bottom casing head, casing hanger, casing head spool, and valve.
The sealing of the casing head consists of the casing head body, BT type rubber sealing ring, casing hanger, dovetail type rubber sealing ring, top thread V-shaped sealing ring, and sealing washer.
The casing hanger seat is suspended on the steps of the casing head body. Due to the hanging weight of the shell, the contact between metal and metal creates a rigid passive seal. The casing hanger and casing are sealed with threads.
The casing head spool has a BT seal that matches the outer diameter of the casing hanger (or casing outer diameter) and corresponding grease injection pressure testing holes. When using, high-pressure sealing grease must be injected from the grease injection valve in order to make the BT seal effective.
If the seal leaks oil, seal grease should be injected separately from the grease injection valve and the pressure test valve to ensure that the seal continues to function.
The grease injection pressure shall not exceed the rated working pressure of the flange; When sealing the casing, the rated allowable collapse pressure of the casing should not be exceeded.
The pressure test hole is used for the external sealing test of the casing hanger.
There is a screw on the flange that is used to lock the wear-resistant sleeve (protecting the sealing surface) and lock the sleeve hanger behind the sleeve hanger.
If there is air leakage at the top thread, the pressure cap can be tightened to ensure effective sealing. The flanges on both sides of the casing head intersect, with one end connected to a flat valve (or blind flange) and the other end connected to a flat valve, threaded flange, joint, globe valve, and pressure gauge. The annular pressure between each layer of the two casings can be observed through the pressure gauge.
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Jiangsu Subo Petrochemical Machinery Co., Ltd
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