Classification and Function of Petroleum Casing Pipe
The casing is a steel pipe that supports the walls of oil and gas wells. Each well will use several layers of casing according to different drilling depths and geological conditions. Cement is used to cement the casing after it goes down the well. It is different from tubing and drill pipe and cannot be reused. It is a disposable material. Therefore, the casing consumption accounts for more than 70% of all oil well pipes. The casing pipe can be divided into: casing, surface casing, technical casing and oil layer casing according to the usage.
1. Guide bush
It is mainly used for drilling in oceans and deserts to separate seawater and sand to ensure smooth drilling.
2. Surface casing
It is mainly used for the first drilling, drilling the soft ground layer to the bedrock, in order to seal this part of the formation from collapse, it needs to be sealed with surface casing.
3. Technical casing
Technical casing is used in the drilling of complex formations. When it encounters complex parts such as collapse layer, oil layer, gas layer, water layer, loss layer and salt-gypsum layer, it needs to be sealed with technical casing, otherwise drilling will be impossible. get on. Some wells are deep and complex, and the down-hole depth is several kilometers. This deep well requires several layers of technical casing. Its mechanical properties and sealing performance requirements are very high, and the steel grade used is also high.
4. Oil layer casing
When the drilling reaches the target layer (oil and gas-bearing horizon), the oil and gas layer and the upper exposed stratum are all sealed with an oil layer casing. Inside the oil layer casing is the oil layer. Reservoir casing has the deepest down-hole depth in various casings, and its mechanical and sealing performance requirements are also the highest.