Oil Casing is a critical component in the Oil and Gas extraction process. The production technology of oil casing encompasses several essential steps and considerations. Let’s explore them in detail.
To start with, the selection of high-quality raw Materials is of utmost importance. For instance, special Steel alloys are cHosen that possess the required strength and durability to withstand the demanding conditions within the oil and gas reservoir. These alloys may include chromium, nickel, or manganese, enhancing the casing’s resistance to corrosion and mechanical stress.
The manufacturing process commences with sh APIng the steel into the desired form. This could involve techniques such as rolling, forging, or extrusion. A prime example is the use of precision rolling to achieve the exact Diameter and Wall thickness of the casing, ensuring a snug fit within the wellbore.
Following the forming process, the casing undergoes heat treatment to enhance its mechanical properties. Annealing, quenching, and tempering are commonly employed to increase the strength and toughness of the material. An instance of this would be subjecting the casing to a specific temperature range and cooling rate to obtain the desired hardness and ductility.
To guarantee the integrity of the casing, rigorous quality control measures are implemented. Non-destructive testing methods, such as X-rays or ultrasound, are employed to detect any potential flaws or defects. A case in point would be using ultrasound waves to identify internal cracks or inhomogeneities that could compromise the casing’s performance.
Corrosion resistance is a paramount concern. To address this, the casing is often coated or treated with anti-corrosion agents. An example could be applying a zinc coating or using specialized coatings that provide an additional layer of protection against the corrosive effects of the oil, gas, and surrounding environment.
| Chemical Composition, Mass Fraction (%) | ||||||||||||||
| grade | C | Mn | Mo | Cr | Ni | Cu | P | S | Si | |||||
| Type | min | max | min | max | min | max | min | max | max | max | max | max | max | |
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| H40 | — | — | — | — | — | — | — | — | — | — | — | — | 0.03 | — |
| J55 | — | — | — | — | — | — | — | — | — | — | — | — | 0.03 | — |
| K55 | — | — | — | — | — | — | — | — | — | — | — | — | 0.03 | — |
| N80 | 1 | — | — | — | — | — | — | — | — | — | — | 0.03 | 0.03 | — |
| N80 | Q | — | — | — | — | — | — | — | — | — | — | 0.03 | 0.03 | — |
| R95 | — | — | 0.45 c | — | 1.9 | — | — | — | — | — | — | 0.03 | 0.03 | 0.45 |
| l80 | 1 | — | 0.43 a | — | 1.9 | — | — | — | — | 0.25 | 0.35 | 0.03 | 0.03 | 0.45 |
| L80 | 9Cr | — | 0.15 | 0.3 | 0.6 | 0.9 | 1.1 | 8 | 10 | 0.5 | 0.25 | 0.02 | 0.03 | 1 |
| L80 | 13Cr | 0.15 | 0.22 | 0.25 | 1 | — | — | 12 | 14 | 0.5 | 0.25 | 0.02 | 0.03 | 1 |
| C90 | 1 | — | 0.35 | — | 1.2 | 0.25 b | 0.85 | — | 1.5 | 0.99 | — | 0.02 | 0.03 | — |
| T95 | 1 | — | 0.35 | — | 1.2 | 0.25 b | 0.85 | 0.4 | 1.5 | 0.99 | — | 0.02 | 0.03 | — |
| C110 | — | — | 0.35 | — | 1.2 | 0.25 | 1 | 0.4 | 1.5 | 0.99 | — | 0.02 | 0.03 | — |
| P110 | e | — | — | — | — | — | — | — | — | — | — | 0.030 e | 0.030 e | — |
| Q125 | 1 | — | 0.35 | 1.35 | — | 0.85 | — | 1.5 | 0.99 | — | 0.02 | 0.01 | — | |
| NOTE Elements shown shall be reported in product analysis. | ||||||||||||||
| a The carbon content for L80 may be increased up to 0.50 % maximum if the product is oil-quenched or polymer-quenched. | ||||||||||||||
| b The molybdenum content for Grade C90 Type 1 has no minimum tolerance if the wall thickness is less than 17.78 mm. | ||||||||||||||
| c The carbon content for R95 may be increased up to 0.55 % maximum if the product is oil-quenched. | ||||||||||||||
| d The molybdenum content for T95 Type 1 may be decreased to 0.15 % minimum if the wall thickness is less than 17.78 mm. | ||||||||||||||
| e For EW Grade P110, the phosphorus content shall be 0.020 % maximum and the sulfur content 0.010 % maximum. | ||||||||||||||
| Tensile and Hardness Requirements | |||||||||
| Grade | Yield Strength MPa | Tensile Strength | Hardness a,c | Specified Wall Thickness | Allowable Hardness Variation b | ||||
| Type | Total Elongation Under Load | min MPa | max | ||||||
| min | max | HRC | HBW | mm | HRC | ||||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| H40 | — | 0.5 | 276 | 552 | 414 | — | — | — | — |
| J55 | — | 0.5 | 379 | 552 | 517 | — | — | — | — |
| K55 | — | 0.5 | 379 | 552 | 655 | — | — | — | — |
| N80 | 1 | 0.5 | 552 | 758 | 689 | — | — | — | — |
| N80 | Q | 0.5 | 552 | 758 | 689 | — | — | — | — |
| R95 | — | 0.5 | 655 | 758 | 724 | — | — | — | — |
| L80 L80 | 1 | 0.5 | 552 | 655 | 655 | 23 | 241 | — | — |
| L80 | 9Cr 13Cr | 0.5 | 552 | 655 | 655 | 23 | 241 | — | — |
| 0.5 | 552 | 655 | 655 | 23 | 241 | — | — | ||
| C90 | 1 | 0.5 | 621 | 724 | 689 | 25.4 | 255 | £12.70 | 3 |
| 12.71 to 19.04 | 4 | ||||||||
| 19.05 to 25.39 | 5 | ||||||||
| ³ 25.40 | 6 | ||||||||
| T95 | 1 | 0.5 | 655 | 758 | 724 | 25.4 | 255 | £12.70 | 3 |
| 12.71 to 19.04 | 4 | ||||||||
| 19.05 to 25.39 | 5 | ||||||||
| ³ 25.40 | 6 | ||||||||
| C110 | — | 0.7 | 758 | 828 | 793 | 30 | 286 | £12.70 | 3 |
| 12.71 to 19.04 | 4 | ||||||||
| 19.05 to 25.39 | 5 | ||||||||
| ³ 25.40 | 6 | ||||||||
| P110 | — | 0.6 | 758 | 965 | 862 | — | — | — | — |
| Q125 | 1 | 0.65 | 862 | 1034 | 931 | b | — | £12.70 | 3 |
| 12.71 to 19.04 19.05 | 4 | ||||||||
| 5 | |||||||||
| a In case of dispute, laboratory Rockwell C hardness testing shall be used as the referee method. | |||||||||
| b No hardness limits are specified, but the maximum variation is restricted as a manufacturing control in accordance with 7.8 and 7.9. | |||||||||
| c For through-wall hardness tests of Grades L80 (all types), C90, T95 and C110, the requirements stated in HRC scale are for maximum mean hardness number. | |||||||||
In summary, the production technology of oil casing entails a meticulous blend of superior materials, precise manufacturing processes, and stringent quality control. By adhering to these measures, we can produce dependable and high-performing oil casings, ensuring the safety and efficacy of oil and gas extraction operations.
