The Classification and Function of the API Steel Pipe

The time of issue:2014-1-28 11:59:58       Author:

The API steel pipe is also called the casting pipe. It is one of the welded steel pipes that are used for oil. The API steel pipe includes oil casting pipe, drill pipe, box coupling as well as short spar.

The API steel pipe is a kind of welded steel pipe that supports the wall of a well of the oil as well as the gas. Each well needs to use different layers of API steel pipe according to different well drilling depth and geological condition. After descending the API steel pipe, it is needed to use cement to fix the wall. And the API steel pipe is different from oil tube and drilling stem, so it cannot be reused, belonging to once consumable material. Thus, the consumption of the API steel pipe occupies at least 70% of the whole oil well pipe. The API steel pipe can be divided into conduit, surface casting, protection string as well as production string according to the service condition.

The conduit is mainly utilized on drilling well in ocean and desert. Its function is to separate water from sand to make sure the successful well drilling. The surface casting is mainly used for drilling for the first time. Drill the soft ground of the earth's surface to bed rock. In order to seal and separate this earth layer to prevent it from slumping, it is needed to use the surface casting to seal. In addition, the depth of the down tube depends on the depth of the loose earth layer. And the inside pressure as well as the outside pressure it bears is not so large, so it is general to use steel grade of K55 and N80 API steel pipe.

The protection string is used in the middle of drilling complex earth layer. When meet with collapse layer, oil layer, air layer, water layer, weak later, evaporate bed as well as other complex parts, it is all needed to place the protection strings to seal and fix, or the well drilling cannot be carried out. Some wells have deep and complex stratum, and has thousands of meters of the depth of descending the well. These wells need to descend several layers API steel pipes. Because their high requirements of the mechanical properties as well as the sealing property, it is needed to descend API steel pipe made of steel with high grade.

When drilling to the target layer or the horizon has oil as well as gas, it is required to uses production string to seal hydrocarbon zone as well as the upper bare layer. The inside of the production layer is oil layer. Among all kinds of steel pipes, the production layer has the deepest depth of descending the well, so it requires higher mechanical property as well as the sealing property.

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