Introduction Of Oil Casing

Introduction of Oil Casing


Oil casing is the important equipment in oil drilling, its main equipment include drill pipe, drill collar and small diameter drilling with steel pipe, tube and casing, etc. Domestic casing is made of geological drilling steel by hot rolling process or cold drawing process, the steel grade adopts DZ to present, commonly used casing steel grade DZ40, DZ55, DZ753.


1. Application

The oil casing 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.

2. Type

According to SY/T6194-96, the oil casing pipe can be divided into short thread casing with coupling and long thread casing with coupling.

3. Specifications and appearance quality

According to the stipulation of SY/T6194-96, the casing with uncertain feet in length, the range of 8 to 13m. The casing no less than 6m can be provided, but its amount shall not exceed 20% of the total.

(2) The internal and external surfaces of the casing shall not 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) The 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.

4.The physical properties test

(1) According to provisions of SY/T6194-96. For flattening test (GB246-97), tensile test (GB228-87), the hydraulic pressure test.

(2) According to APISPEC5CT1988 stipulation, hydrostatic test, flattening test, sulfide stress corrosion cracking test, hardness test, tensile test, transverse impact test, determination of grain size should be have.

5.Chemical composition inspection

(1)According to provisions of SY/T6194-96, the same grade of steel should be taken for the casing and coupling. Sulfur content<0.045%, phosphorus content < 0.045%.

(2)According to the provisions of the GB222-84, chemical analysis should be have according to the provisions of the relevant part of the GB223.

(3)The American petroleum institute 1988 version 1 stipulate that the chemical analysis should be have according to the latest version ASTME59 sample preparation, chemical analysis according to the latest version ASTME350.


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 with protection ring in order to protect the threads.

7. The main import and export situation

(1)oil casing main import countries include Germany, Japan, Romania, the Czech republic, Italy, Britain, Austria, Switzerland, the United States, Argentina, Singapore. Import standards with reference to the American petroleum institute standard API5A5AX5AC. Grade of steel is H-40, J-55, N-80, P-110, C-75, C-95, etc. Specifications are mainly 139.77.72R-2, 177.89.19R-2, 244.58.94R-2, 244.510.03R-2, 244.511.05R-2, etc.

(2)There are three kinds of API specified length: R-1: 4.88 ~ 7.62m, R-2: 7.62 ~ 10.36m, R-3: 10.36m or longer.

(3)Part of the imported goods are marked with LTC - filament buckle casing.

(4)Except a small number of the imported casing fromJapanin accordance with the standard of Japanese manufacturer, other all use API standards, and steel grade is NC-55E, NC-80E, NC-L80, NC-80HE and so on.