Oil casing knowledge - casing classification

The casing is a large diameter pipe that acts as a wall or well for oil and gas oil wells. The casing is inserted into the wellbore and fixed with cement to prevent the wellbore from separating the formation and the wellbore from collapsing, and to ensure that the drilling mud circulates for drilling. Different types of casing used in oil extraction: 
　　surface oil casing
　　- protects the well from contamination by shallow water and shallow gas layers, 
　　- supports wellhead equipment and maintains the other layers of the casing. 
　　Technical oil casing 
　　- Separate pressures at different levels to allow normal circulation of the drilling fluid and protect the production casing. 
　　- to install anti-burst devices, leak-proof devices and tailpipes in the well. 
　　Oil layer oil casing 
　　- Exports oil and natural gas from the subsurface storage layer. 
　　- Used to protect the well and stratify the drilling mud. 
　　When producing oil casings, the outer diameter is usually 114.3 mm to 508 mm.