Oil casing is the important equipment in oil drilling, its main equipment include drill pipe, tube and casing, drill collar and small diameter drilling with steel tube and so on.Domestic casing with geological drilling steel after hot rolling and cold drawing, steel grade with "geological" (DZ) said that the commonly used casing steel grade DZ40, DZ55, DZ753 kinds.
Used in oil well drilling is mainly used in the drilling process and after the completion of borehole wall support, to ensure that the drilling process and after completion of the normal operation of the oil Wells.
Oil casing pipe type and packing according to SY/T6194-96 "petroleum casing" points short thread casing and coupling and long thread casing and coupling of two kinds.According to the provisions of the SY/T6194-96 domestic casing should with steel wire or steel strapping.Show part of each casing and coupling thread shall be screwed on protection ring in order to protect the threads.
Specifications and appearance quality
1) according to provisions of SY/T6194-96 domestic casing, casing uncertain feet in length, the range of 8 to 13 m.But not less than 6 m casing can be provided, the amount shall not exceed 20%.
2) the internal and external surfaces of the casing shall have folded, hairline, delamination, crack, rolling and scarring.These defects shall be completely removed, remove depth shall not exceed 12.5% of the nominal wall thickness.
3) coupling surface must not have folded, hairline, delamination, crack, rolling defects such as folding, scarring.
4) casing and coupling thread surface should be smooth, there is no burr, tear and enough to make the thread tied to interrupt impact strength and other defects.
Chemical composition inspection
1) according to provisions of SY/T6194-96.The same grade of steel casing and coupling.Sulfur content < 0.045%, phosphorus content < 0.045%.
2) according to the provisions of GB/T222-84 sample for chemical analysis.According to the relevant part of the GB223 rules for chemical analysis.
3) the American petroleum institute ARISPEC5CT1988 version 1.Chemical analysis according to the latest version ASTME59 sample preparation, according to the latest version ASTME350 for chemical analysis.
Physical properties test
1) according to provisions of SY/T6194-96.For flattening test (GB246-97) tension test (GB228-87) and the hydraulic pressure test.
2) according to the American petroleum institute APISPEC5CT1988 version 1 year for hydrostatic test, flattening test, sulfide stress corrosion cracking test, hardness test (ASTME18 or E10 the latest version of the provisions), tensile test, transverse impact test (ASTMA370, ASTME23 and the latest version of the provisions of related standards), determination of grain size (ASTME112 latest version or other methods).
According to the provisions of the SY/T6194-96 domestic casing should with steel wire or steel strapping.Show part of each casing and coupling thread shall be screwed on protection ring in order to protect the threads.
APISPEC5CT1988 year by the American petroleum institute standard version 1, casing steel grade points H - 40 and 55, N, K, J - 55-80, C - 75, L - 75, C - 90, C - 95, P - 110, a total of 10 Q - 125.
Casing thread and the collar should be brought to supply, or supply any pipe end according to the following form:
Flat end, round collar thread without a collar or belt, buttress thread coupling with or without collar, direct type screw thread, the special end processing, sealing ring structure.
Oil special pipe use and category
Oil special pipe is mainly used in oil and gas well drilling and oil and gas transmission.It includes petroleum drill pipe, oil casing, tubing.Oil drill pipe is mainly used to connect the drill collar and bit and drilling.Oil casing pipe is mainly used in the drilling process and after the completion of borehole wall support, to ensure that the drilling process and after completion of the normal operation of the oil Wells.Main pipe will be well at the bottom of the oil and gas transmission to the ground.
Oil casing is to maintain the lifeblood of any oil Wells.Due to different geological conditions, underground stress state is complex, tension, pressure, bending, torsion stress combination on the pipe body, which put forward higher requirements about the quality of the casing itself.Once the casing damage due to some reason itself, may lead to the whole production of the well, or even scrapped.
According to the strength of the steel itself casing can be divided into different steel grade, namely the J55, K55, N80, L80, C90, T95, P110 and Q125, V150, etc.Different well conditions, hole depth, the grade of steel are also different.In corrosive environment also requires casing itself has corrosion resistance.In the complicated geological conditions where also calls for casing collapse resistance.
Strong heat treatment process
27 MNCRV is producing TP110T steel grade oil pipeline of new steel grade, the regular production TP110T steel grade oil pipeline steel is 29 crmo44 and 26 crmo4.Relative to the latter two, 27 MNCRV contains less Mo element, can greatly reduce the production cost.But the austenitizing quenching process of the normal production of 27 MNCRV obvious after high temperature tempering brittleness, the impact toughness is low and unstable.
Solve such problems are usually adopts two methods: one is to use rapid cooling method to avoid high temperature after tempering brittleness, obtain toughness., the second is the temperature quenching method through the steel grade of incomplete austenitizing to effectively improve the harmful elements and impurities, improve the toughness.The first method, relatively strict with heat treatment equipment, you need to add additional cost.
27 MNCRV steel AC1 = 736 ℃, AC3 = 810 ℃, the temperature quenching heating temperature when choosing between 740-810 ℃.The selected temperature quenching heating temperature 780 ℃, quenching heating heat preservation time of 15 min.After quenching tempering temperature 630 ℃, tempering heat holding time 50 min.Because in the alpha + gamma two-phase area temperature quenching heating, in keep some dissolved ferrite quenching under state, while maintaining high strength, toughness was improved.
Low temperature quenching was lower than those of conventional temperature at the same time, reduced the quenching stress, thereby reducing the quenching deformation, so that to ensure the smooth operation of heat treatment production, and car silk for subsequent processing provides a good raw material.
At present this technology has been to used in tianjin steel pipe factory, quality assurance data show that after heat treatment of steel tube in 820-860 mpa, yield strength Rt0.6 Rm in 910-940 mpa tensile strength, impact toughness Akv between 65-85 - j, anti-damage performance of 100% qualified.Data show that 27 MNCRV steel pipe is quite high quality high grade oil casing, on the other hand also shows that the temperature quenching process is to avoid high temperature brittleness in the production of steel products of a kind of very good method.
Oil casing is a kind of large diameter pipes, have fixed the role of oil and gas oil casing or hole.Casing is inserted into the hole and fixed with cement, in order to prevent the borehole and separated strata borehole collapse, and ensure the drilling mud circulating flow, so that the drilling.Used in the process of oil exploration of the different types of casing, drilling, surface oil casing - protection to avoid polluted by shallow layer and shallow gas, - to support the wellhead equipment and keep the other layer weight of the casing.Technology of oil casing - dividing different levels of pressure, so that the normal circulation and protect the production casing drilling fluid lines.- in order to install the blowout drilling device, blowout preventer and tail pipe.Reservoir oil casing, oil and natural gas derived from the storage layer under the surface of the earth.- protects the drilling, drilling mud layer.Oil casing production, usually is 114.3 mm to 508 mm diameter.