Types and Uses of Oil Casing Commonly Used in Energy Projects

First, what is oil casing?

Oil casing is primarily used for drilling and transporting oil and gas in oil and gas wells. It includes drill pipe, casing, and sucker pipe. Drill pipe mainly connects the drill collar and drill bit and transmits drilling power. Casing mainly supports the wellbore during drilling and after completion to ensure the drilling process and the normal operation of the entire well. The suction pipe mainly transports oil and gas from the bottom of the well to the surface.

Oil casing is the lifeline for maintaining the operation of an oil well. Due to varying geological conditions, the downhole stress state is complex, with tensile, compressive, bending, and torsional stresses acting on the casing, which places high demands on the quality of the oil casing itself. If the oil casing is damaged for any reason, it may lead to reduced production of the entire well or even its abandonment.

Oil casing can be classified into different steel grades based on its inherent steel strength, such as J55, K55, N80, L80, C90, T95, P110, Q125, and V150. Different well conditions and depths require different steel grades. In corrosive environments, the oil casing itself must also possess corrosion resistance. In areas with complex geological conditions, the oil casing must also have resistance to crushing.

Second, types of oil casing.

Different types of oil casing are used in oil extraction: Surface casing protects the well from contamination by shallow water and gas layers, supports wellhead equipment, and maintains the weight of other layers. Technical casing separates the pressure of different layers to ensure the normal flow of drilling fluid and protect the production casing. It also facilitates the installation of anti-fracture devices, leak-proof devices, and tailpipes within the well. Formation casing extracts oil and natural gas from underground reservoirs. It is used to protect the well and stratify drilling mud. During production, the outer diameter of oil casing typically ranges from 114.3 mm to 508 mm. It protects the well from contamination by shallow water and gas layers, supports wellhead equipment, and maintains the weight of other layers within the oil casing. Technical oil casing separates the pressure of different layers to ensure proper flow of drilling fluid and protect the production oil casing. It also facilitates the installation of anti-fracture devices, leak-proof devices, and tailpipes within the well. Formation oil casing extracts oil and natural gas from underground reservoirs. It protects the well and separates drilling mud into layers. During production, the outer diameter of oil casing typically ranges from 114.3 mm to 508 mm. Oil casing types and packaging are classified according to SY/T6194-96 "Oil Casing" into short-threaded oil casing and its couplings, and long-threaded oil casing and its couplings.

Third, Applications of Oil Casing.

Oil casing is a large-diameter steel pipe used to fix the walls or borehole of oil and natural gas wells. Oil well casing is inserted into the wellbore and secured with cement to help isolate the wellbore from rock formations and prevent wellbore collapse, while also ensuring the circulation of drilling mud to facilitate drilling and production. Oil well casing steel grades include: H40, J55, K55, N80, L80, C90, T95, P110, Q125, and V150. Oil well casing end processing methods include: short round thread, long round thread, trapezoidal thread, and special threads. In oil well drilling, it is mainly used to support the wellbore during and after drilling to ensure the smooth operation of the drilling process and the normal functioning of the entire well after completion.

The petroleum industry is a major user of oil well casing, which plays a crucial role:

1. Oil well casing is used in large quantities and incurs high costs, indicating substantial potential for cost savings and reductions. The consumption of oil well casing can be estimated based on the annual drilling footage. Based on my country's specific conditions, approximately 62 kg of oil well tubing is required for every 1 meter of drilling, including 48 kg of oil casing and 10 kg of tubing. Drill pipe weighs 3 kg, and drill collars weigh 0.5 kg.

2. The mechanical and environmental behavior of oil casing has a significant impact on the adoption of advanced technologies and increased production efficiency in the petroleum industry.

3. Oil casing failure results in substantial losses; its safety, reliability, and service life are crucial to the petroleum industry.