API 5CT Oil Well Casing: Robust Structural Integrity for Demanding Reservoirs
Engineered to Stabilize Boreholes & Withstand Extreme Downhole Stresses
API 5CT-compliant oil well casing pipes line boreholes to prevent collapse, isolate formations, and ensure safe hydrocarbon extraction. Available in 4½”–36″ OD (114.3–914 mm) with wall thicknesses from 0.205″–0.635″ (5.21–16.13 mm), these ERW/seamless tubes handle pressures up to 20,000 psi (API TR 5C3) and temperatures from -30°F to 450°F.
Key Specifications & Certifications
- Standards: API 5CT, ISO 11960, NACE MR0175 (sour service).
- Process Types:
Seamless (SMLS) ERW Superior collapse resistance Cost-effective for shallow wells Max OD: 26″ Max OD: 36″ - Grades: J55 (55 ksi yield) to Q125 (125 ksi yield).
- Threads: STC, LTC, BTC (API 5B compliant).
Casing Types & Applications
1. Conductor Casing
- OD: 18″–36″ | Grade: J55/K55.
- Function: Protects shallow formations, supports wellhead.
- Installation: Driven/hammered into surface soil.
2. Surface Casing
- OD: 13⅜” (common) | Grade: N80/L80.
- Pressure Rating: 5,000–10,000 psi.
- Role: Isolates freshwater zones, anchors BOP systems.
3. Intermediate Casing
- OD: 13⅜”–16″ | Grade: L80-13Cr/C95.
- Use Case: Mitigates lost circulation in salt/coal seams.
4. Production Casing
- OD: 4½”–9⅝” | Grade: P110/Q125.
- Performance: Resists H₂S/CO₂ corrosion in HPHT reservoirs.
5. Production Liner
- OD: 2⅜”–7″ | Material: L80-9Cr/T95.
- Advantage: Pre-perforated designs cut completion time by 40%.
Material Grades & Chemical Composition
| Grade | Yield Strength (ksi) | Key Additives | H₂S Tolerance |
|---|---|---|---|
| J55 | 55 | 0.25% Mn, 0.015% S | Not Rated |
| L80-13Cr | 80 | 13% Cr, 1% Mo | ≤15 ppm |
| P110 | 110 | 0.20% C, 0.008% P | ≤5 ppm |
Compliance:
- Sulfur (S): ≤0.015% | Phosphorus (P): ≤0.025%.
- Chromium (Cr): 12–14% in sour-service grades (ISO 15156).
Dimensional Tolerances & Testing
- OD Accuracy: ±0.5% | WT Consistency: ±10%.
- Hydrostatic Testing: 1.5x working pressure (API 5C5).
- NDT: Ultrasonic (ASTM E317) + Magnetic Particle (ASTM E1444).
Competitive Advantages
- Lead Time: 20–35 days (MOQ 50 tons).
- Customization: Pre-cut threads, anti-galling coatings.
- Warranty: 10-year integrity guarantee for P110/Q125 grades.
Applications by Industry
- Onshore Oil:
- Shale Gas: J55 surface casing for 8,000-ft vertical wells.
- Salt Domes: L80-13Cr intermediate casing with STC threads.
- Offshore:
- Q125 production casing for 25,000-psi subsea wells.
- CCUS:
- C95 liners for CO₂ injection integrity.
Performance Comparison
| Casing Type | Max Temp (°F) | Collapse Pressure (psi) | Cost per ft |
|---|---|---|---|
| J55 ERW | 250 | 3,500 | $18–25 |
| L80-13Cr SMLS | 450 | 12,000 | $55–70 |
| P110 Seamless | 400 | 18,000 | $80–110 |
Logical Connectors:
- Contrast: While ERW is economical, seamless offers 3x collapse resistance.
- Example: For instance, 13⅜” surface casing anchors BOP stacks.
- Cause-Effect: Tighter chemistry control reduces sulfide cracking by 30%.
Packing And Delivery
