Oil Casing

Oil casing is a type of pipe used to support the wellbore of oil and gas wells, ensuring the normal operation of the entire well during drilling and after completion. Each well requires several layers of casing depending on the drilling depth and geological conditions. After the casing is inserted into the well, cement cementing should be used. Unlike oil pipes and drill rods, it cannot be reused and is a disposable consumable material. So, the consumption of casing accounts for over 70% of all oil well pipes.

Casing can be divided into: conduit, surface casing, technical casing, and reservoir casing according to their usage.

Surface oil casing: with the largest diameter, shallowest depth (usually several hundred meters), and the lowest steel grade (such as H40, J55). Protect the drilling well from contamination by shallow water and gas layers, support wellhead equipment, and maintain the weight of other layers of the casing.

Technical oil casing: Medium diameter, deep down (up to several kilometers). Medium grade steel (such as K55, N80) is used to separate the pressure at different levels, in order to facilitate the normal flow of drilling fluid and protect the production casing. Anti burst devices, leak prevention devices, and tail pipes are installed inside the drilling well.

Oil reservoir casing: with the largest diameter and deepest depth (up to several kilometers). The highest steel grade (such as P110, Q125) exports oil and natural gas from underground reservoirs. Used to protect drilling by layering drilling mud. During the production of oil casing, the outer diameter is usually between 114.3 millimeters and 508 millimeters.

Petroleum specific pipes are mainly used for drilling oil and gas wells and transporting oil and gas. It includes oil drill pipes, oil casing, and oil extraction pipes. Petroleum drill pipes are mainly used to connect drill collars and drill bits and transmit drilling power. Oil casing is mainly used to support the wellbore during drilling and after completion, to ensure the normal operation of the entire oil well during the drilling process and after completion. The oil extraction pipe mainly transports the oil and gas from the bottom of the oil well to the surface.

Oil casing is a large-diameter pipe that serves to secure the walls or boreholes of oil and gas wells. A casing is inserted into a wellbore and fixed with cement to help separate rock formations and prevent wellbore collapse, while ensuring the circulation of drilling mud for easy drilling and mining.

Steel grades for oil casing: H40, J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc. Processing forms of casing end: short round thread, long round thread, trapezoidal thread, special buckle, etc. Used for oil well drilling, it is mainly used to support the wellbore during the drilling process and after completion, to ensure the normal operation of the entire oil well during the drilling process and after completion.

The English expressions for different threads inside oil casing are:

Short Thread: CSG (Casing Short Thread), also known as STC

Long Thread: LCSG (Casing Long Thread), also known as LTC

Partial trapezoidal thread: BCSG (Buttress Casing Thread), also known as BTC