Application of N80 Oil Casing Pipe

N80 oil casing is an important equipment in oil drilling. Its main equipment also includes drill pipe, core pipe and casing, drill collar and steel pipe for small diameter drilling. The domestic casing is made of geological drilling steel by hot rolling or cold drawing. The steel number is indicated by "geological" (DZ). The commonly used types of casing steel are dz40, dz55 and dz753.


(1) the main importers of oil casings are: Germany, Japan, Romania, Czech Republic, Italy, Britain, Austria, Switzerland, the United States, Argentina and Singapore.
(2) API has three lengths: R-1 is 4.88-7.62m, R-2 is 7.62-10.36m, and R-3 is 10.36m or longer.
(3) some imported goods are marked with LTC, i.e. lamp screw sleeve.
(4) in addition to API standards, there are also a few Japanese factory standards imported from Japan.
(5) in the case of the claim, there are quality problems such as black buckle, thread damage, pipe bending, buckle fracture and thread tight distance tolerance, coupling J value difference, other appearance defects and casing cracking, low yield strength, etc.


Purpose: mainly used for oil well drilling, mainly used to support the well wall during and after drilling to ensure the normal operation of the whole well during and after drilling.
Type: the pipe type and packing of oil casing shall be in accordance with SY / t6194-96 "oil casing", short thread casing and its coupling, long thread casing and its coupling. According to SY / t6194-96, the domestic casing shall be bound with steel wire or steel belt. The exposed part of each bushing and connecting thread shall be tightened with a protective ring to protect the thread.
Specification: according to SY / t6194-96, the length of domestic casing is not fixed and the range is 8-13m. However, no less than 6m casing can be provided, and the quantity shall not exceed 20%.
Appearance: the inner and outer surfaces of the shell shall be free of folds, fine lines, separation, cracks, undulations and crusts. These defects shall be completely removed to a depth not exceeding 12.5% of the nominal wall thickness.
Quality requirements: the surface of casing and connecting thread shall be smooth and free of burr, tear and other defects sufficient to cause thread fracture and affect strength and tight joint.


Filler:
According to SY / t6194-96, the domestic casing shall be bound with steel wire or steel belt. The exposed part of each bushing and connecting thread shall be screwed onto the protection ring to protect the thread.
Chemical composition test:
(1) according to SY / t6194-96. The casing and its coupling are of the same steel type. Sulfur content < 0.045%, phosphorus content < 0.045%.
(2) carry out chemical analysis according to gb222-84. Carry out chemical analysis according to relevant provisions of gb223.
(3) first edition of American Petroleum Institute arispec5ct 1988. Perform chemical analysis according to the latest version of ASTM e59 and ASTM e350 analysis.


Casing calculation formula:
(outer diameter - wall thickness) * wall thickness * 0.02466 = kg / M (weight per meter)


Other:
According to the first edition of API Spec 5CT 1988, there are 10 kinds of casing steel grades: H-40, j-55, k-55, N-80, C-75, l-80, C-90, c-95, P-110, q-125.


The casing shall be provided with threads and joints or in any of the following pipe ends:
Flat end, circular thread without coupling or with coupling, trapezoidal local thread with or without coupling, straight thread, special end processing, sealing ring structure.