Technical standards for oil casing
Common technical standards for oil casing include the following:
·API 5CT: American Petroleum Institute standard, widely used in the global oil industry, covering dimensions, materials, mechanical properties and test methods.
·ISO 11960: International Organization for Standardization standard for seamless and welded steel pipes for the oil and gas industry.
·GB/T 19830: Chinese national standard, regulating the manufacture and inspection of seamless and welded steel pipes for oil and gas exploitation.
1. Length range
Length category | Length range (m) | Application scenarios |
R-1 | 4.88 - 7.62 | Shallow well operations |
R-2 | 7.62 - 10.36 | Conventional depth wells |
R-3 | >10.36 | Deep wells, ultra-deep wells |
R-2 and R-3 length oil casing are more common and suitable for medium-deep wells and deep wells.
2.Oil casing steel grade
Grade | Yield strength (MPa) | Tensile strength (MPa) | Application Scenario |
J55 | 379 - 552 | 517 - 758 | Shallow wells or low-pressure wells |
K55 | 379 - 552 | 517 - 758 | Similar to J55, but more resilient |
N80 | 552 - 758 | 689 - 965 | Medium-deep wells, high-pressure resistant |
L80 | 552 - 758 | 689 - 965 | Acid gas wells, corrosion resistant |
P110 | 758 - 965 | 862 - 1034 | High-pressure deep wells, ultra-deep wells |
Different steel grades are selected according to well conditions to ensure that oil casing can work stably for a long time in complex downhole environments.
3 Thread type
Thread Type | Features |
STC | Short round thread, good sealing |
LTC | Long round thread, strong load-bearing capacity |
BTC | Partially trapezoidal thread, excellent sealing |
The selection of threads is crucial to ensure the connection strength of oil casing and prevent leakage and loose connection during downhole operations.
4. Mechanical properties
Grade | Yield strength (MPa) | Tensile strength (MPa) | Elongation (%) |
J55 | 379 - 552 | 517 - 758 | 15 |
N80 | 552 - 758 | 689 - 965 | 12 |
P110 | 758 - 965 | 862 - 1034 | 10 |
The technical standards of oil casing provide a reliable basis for ensuring its safety and life. When purchasing, oil companies need to select appropriate standards and steel grades according to well conditions to ensure the reliability and stability of oil casing during the mining process.
