Surface casing
1、Used to seal the upper unstable loose, collapse-prone and leaky formations and water layers.
2、Installation of wellhead device to control well blowout.
3、Support part of the weight of technical casing and oil layer casing.

The depth of the surface casing down depends on the specific situation, usually a few dozen meters to a few hundred meters or deeper (30 to 1500m). The cement return height outside the tubing is usually returned to the surface. When drilling high-pressure gas wells, if the upper rock layer is loose and broken, the surface casing needs to be lowered to prevent the high-pressure gas from escaping the surface. If the surface casing needs to be deeper and the first drilling time is longer, a layer of conduit should be considered before placing the surface casing. Its function is to seal the surface, prevent the collapse of the wellhead and form a drilling fluid circulation channel for a long drilling period. The conduit is generally lowered to a depth of 20-30 meters, with the cement outside the conduit returned to the surface. The conduit is usually made of spiral or straight seam pipe.

Technical Casing
1、It is used to seal complex formations where drilling fluid is difficult to control, severe leakage layers, and oil, gas and water formations where the pressure difference is significant, etc., to prevent the well diameter from expanding.
2、In directional wells with large well slope, technical casing is lowered in the slope-making section to facilitate the safe drilling of directional wells.
3, for the installation of well control equipment, blowout prevention, leak prevention and suspension of the tail pipe to provide the conditions, the formation casing also has a protective role.

Technical casing does not have to be lowered, but can be controlled by using high quality drilling fluids, accelerating drilling speed, strengthening drilling and other measures to control the complexities of the well, and strive not to lower or less technical casing. The depth of the technical casing is determined by the complex formation to be sealed. The cement return height should reach more than 100 meters of the formation to be sealed, and for high-pressure gas wells, the cement is often returned to the surface in order to better prevent gas leakage.

Oil Formation Casing
It is used to seal off the target layer from other layers; to seal off oil, gas and water layers with different pressures, and to establish an oil and gas channel in the well to ensure long-term production.
The depth of the formation casing depends on the depth of the target formation and the completion method. For high pressure wells, the cement slurry should be returned to the ground to reinforce the casing and enhance the sealing of the casing wireline so that it can withstand the larger shut-in pressure.

Petroleum casing emerged not only for oil extraction but also as a pipeline for transporting raw materials. In order to strengthen the quality of petroleum casing, every link in the production process is particularly important, especially the temperature control during the period, which must be mastered in strict accordance with the regulations. Usually, the petroleum casing is quenched by sub-temperature quenching method instead of the ordinary quenching method, because the ordinary quenching method adopted will allow a large amount of residual stress inside the workpiece, thus expanding the brittleness, and the subsequent processing is not so convenient. The sub-temperature quenching is to prevent the brittleness of the oil casing from affecting the subsequent process. The main operation method is to first select the heating temperature for sub-temperature quenching, usually between 740-810°C, and the heating time is usually about 15 minutes. After quenching and then tempering, the heating time of tempering is fifty minutes, and the temperature should be selected to 630°C. Of course, each type of steel has its own heating temperature and time during heat treatment, and as long as the performance of the workpiece can be improved and enhanced, then the purpose of heat treatment will be achieved.

Heat treatment is the most important process in the processing of oil casing, the performance and quality of the finished product can meet most of the results of heat treatment, so the manufacturers of heat treatment process requirements are very strict, do not dare to have a trace of slack. Sometimes can also be quenched by means of low-temperature quenching, low-temperature quenching can effectively remove the residual stress of the oil casing, not only to reduce the degree of deformation of the workpiece after quenching, but also to process the oil casing into a more suitable raw material for the later process. Therefore, the current achievements of petroleum casing and heat treatment are inseparable. Since the heat treatment process, regardless of the impact toughness, destruction resistance or tensile strength of petroleum casing, there has been a great improvement.

Different types of casing used in the oil recovery process: surface oil casing – protects the drilling well from contamination by shallow water and gas formations, – supports the wellhead equipment and maintains the weight of other layers of the casing. Technical casing – separates the pressure in the different layers to allow proper flow of drilling fluid levels and to protect the production casing. – To allow for the installation of anti-fracture devices, leak prevention devices and tail pipes in the drilled well. Oil Formation Casing – To move oil and gas out of the reservoir below the surface. – Used to protect drilling wells by layering the drilling mud. Oil casing is typically produced with an outside diameter of 114.3 mm to 508 mm.
Protects the drilling well from contamination by shallow water and gas formations, – Supports the wellhead equipment and maintains the weight of other layers of the casing.
Technical oil casing – separates pressures at different levels to allow proper flow of drilling fluid amounts and to protect production casing. – To allow for the installation of anti-fracture devices, leak prevention devices and tail pipes in the drilled well.
Oil Formation Casing – To move oil and gas out of the reservoir below the surface. – Used to protect drilling wells by layering the drilling mud. Oil casing is produced with an outside diameter usually from 114.3 mm to 508 mm.
Types and packaging of oil casing are divided into two types according to SY/T6194-96 “Oil Casing”: short threaded casing and its coupling and long threaded casing and its coupling.

Oil casing is a steel pipe used to support the well wall of oil and gas wells to ensure that the drilling process is carried out and that the entire well operates normally after completion. Several layers of casing are used in each well according to different drilling depths and geological conditions. The casing is cemented after the well is drilled, and unlike tubing and drill pipe, it is not reusable and is a one-time consumable material. Therefore, the consumption of casing accounts for more than 70 percent of all oil well tubing. Casing can be divided into: conduit, surface casing, technical casing and oil layer casing according to usage. There are two types of welded pipe according to the specified wall thickness: ordinary oil casing and thickened oil casing.

Different types of casing used in the oil extraction process: surface petroleum casing protects the drilling well from contamination by shallow water and shallow gas formations, supports the wellhead equipment and maintains the weight of other layers of the casing. Technical oil casing separates the pressure in the different layers to allow proper flow of drilling fluid amounts and to protect the production casing. Enables installation of anti-storm fracture devices, leak prevention devices and tail pipes in drilled wells. Oil Formation Oil casing to move oil and gas out of the reservoir below the surface. It is used to protect the drilling well by layering the drilling mud. Oil casing is typically manufactured with an outside diameter of 114.3 mm to 508 mm.

J55 oil casing is a necessary pipe for drilling oil and gas and needs to have good performance in use. Petroleum casing in different temperature sections selected different temperature control, heating needs to be produced in accordance with a certain temperature, 27MnCrV steel AC1 = 736 ℃, AC3 = 810 ℃, tempering after quenching selected temperature 630 ℃, tempering heating holding time of 50 min. sub-temperature quenching heating temperature is selected between 740-810 ℃. Sub-temperature quenching selected heating temperature 780 ℃, quenching heating holding time 15min; as sub-temperature quenching in the α + γ two-phase zone heating, quenching in the retention of part of the undissolved ferrite state, while maintaining the temperature, toughness can be improved.

Oil casing is a steel pipe used to support the well wall of oil and gas wells to ensure the drilling process is carried out and the normal operation of the whole well after completion. Several layers of casing are used in each well depending on the drilling depth and geology. The casing is cemented after the well is drilled, and unlike tubing and drill pipe, it is not reusable and is a one-time consumable material. Therefore, the consumption of casing accounts for more than 70 percent of all oil well tubing. Casing can be classified according to usage: conduit, surface casing, technical casing and oil casing.

Oil casing is the lifeline for maintaining the operation of oil wells. Due to different geological conditions, the downhole stress state is complex, and the combined effects of tensile, compressive, bending and torsional stresses act on the tubular body, which places high demands on the quality of the casing itself. Once the casing itself is damaged for some reason, it may lead to production reduction of the whole well or even scrapping. According to the strength of the steel itself, casing can be divided into different steel grades, i.e. J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc. Different well conditions and depths require different steel grades. In corrosive environments, the casing itself is required to have corrosion resistance. In places with complex geological conditions, the casing is also required to have anti-crushing properties and anti-microbial erosion.

Oil special pipe is mainly used for oil and gas well drilling and oil and gas transmission. It includes oil drilling pipe, oil casing and oil pumping pipe. Oil drill pipe is mainly used to connect drill collar and drill bit and transmit drilling power. Oil casing is mainly used to support the well wall during the drilling process and after completion to ensure the drilling process and the normal operation of the whole well after completion. The pumping tubing is mainly used to transport oil and gas from the bottom of the well to the surface.

Defects between the length of the L C and the vanishing point of the thread are allowed to extend no deeper than the cone of the thread base diameter or no greater than 12.5% of the specified wall thickness (whichever is greater), but no corrosion products are allowed on the thread surface. Grinding and dressing are permitted to eliminate defects, but grinding and filing are not permitted to eliminate pits. The outer chamfer (65°) is guaranteed to be complete around the 360° circumference of the pipe end, with the chamfer diameter such that the thread root disappears on the chamfered surface rather than on the pipe end, and without a sharp edge. The outer chamfer should be 65° to 70°; the inner chamfer should be 360° full circle and 40° to 50°, and if there is any unchamfered part, the chamfer should be hand filed.

Oil casing is a large diameter pipe that holds the wall or borehole of oil and gas wells in place. The casing is inserted into the borehole and fixed with cement to prevent the borehole from separating the rock formation and collapsing, and to ensure the circulation of drilling mud to facilitate drilling and extraction. Steel grade of oil casing: H40, J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc. Casing end processing forms: short round thread, long round thread, partial trapezoidal thread, special buckle, etc. It is mainly used for oil well drilling to support the well wall during the drilling process and after the completion of the well to ensure the normal operation of the whole well after the drilling process and completion of the well.

The oil industry is an industry that uses a large amount of oil tubing, and oil tubing plays a very important role in the oil industry: the amount of oil tubing used is large and costly, and the potential to save money and reduce costs is huge. The consumption of oil tubing can be projected by the amount of feet drilled each year. According to the specific situation in China, roughly 62kg of oil well pipe is needed for every 1m drilled, including 48kg of casing and 10kg of tubing. a blind groove of the same size as the cut is corroded on the inner wall of the pipe. Drill pipe 3kg, drill collar 0.5kg; 2 the mechanical and environmental behavior of oil pipe has an important impact on the oil industry to adopt advanced technology and increase production and efficiency; 3 oil pipe failure loss is huge, reliability and oil life is significant to the oil industry. [(OD – wall thickness)wall thickness]0.02466=kg/m (weight per meter).

The steel grade used varies by well condition and depth. In corrosive environments, the casing itself is required to have anti-corrosion properties, and API seamless steel pipe is also required to have anti-crushing properties in places with complex geological conditions. The pumping pipe mainly transports oil and gas from the bottom of oil wells to the surface. Threaded connection forms: short round threaded casing (STC); long round threaded casing (LTC) bias trapezoidal threaded casing (BTC); straight connected casing (XC) non-thickened tubing (NU); externally thickened tubing (EU); integral joint tubing (IJ).

API 5CT oil casing,API 5L oil pipeline pipe standard,API 5CT oil casing,API 5L oil pipeline pipe standard,oil casing is made of seamless steel pipe,electric welded steel pipe and hot rolled steel pipe by CNC turning wire. The joint adopts the international advanced pure manganese high-temperature phosphating process, with strong phosphate film bonding, uniform and dense crystallization, high hardness, corrosion resistance and anti-buckling ability. ASTM steel pipe can be divided into different steel grades according to the strength of the steel itself, namely J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc.

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