A small-diameter pipe run inside casing to transport crude oil/gas from the reservoir to the surface. It is retrievable for maintenance and handles downhole pressure, corrosion, and cyclic loading during production, injection, and well testing.
Casing
A large-diameter pipe cemented in the borehole to stabilize the wellbore, isolate formation fluids (preventing groundwater contamination), and support downhole tools. It is permanent and categorized by installation stage:
Conductor Casing: Shallow protection for surface formations.
Surface Casing: Isolates freshwater zones and supports BOP systems.
Intermediate Casing: Isolates high-pressure/abnormal-pressure zones, salt layers, or unstable shales.
Production Casing: Seals the reservoir and provides a barrier for tubing installation.
2. Key Specifications (API 5CT)
Item
Tubing
Casing
OD Range
1.900–4.500 in (48.26–114.3 mm)
4.500–20.000 in (114.3–508 mm)
Nominal Weight
1.90–13.50 lb/ft
9.50–169.00 lb/ft
Wall Thickness
4.83–9.52 mm
5.00–19.50 mm
Length Ranges
R1 (4.88–7.62 m), R2 (7.62–10.36 m), R3 (10.36–11.12 m)
Same as tubing
Steel Grades
J55, K55, N80, L80, T95, P110, C125
H40, J55, K55, N80, L80, P110, Q125, C125
Connections
API: NU, EU; Premium: VAM, Sentinel Prime
API: STC, LTC, BTC; Premium: VAM, Sentinel Prime
3. Material & Performance Advantages
Steel Grade Versatility: Standard API grades (J55–P110) for general wells; C125 for ultra-deep HPHT wells (≥7,000 m); Super 13Cr for sour (H₂S/CO₂) environments.
Seamless Manufacturing: Uniform structure for high collapse resistance, internal yield strength, and fatigue performance under cyclic stress.
Connection Options:
API Threads (NU, EU, STC, LTC, BTC): Cost-effective for standard applications.
Premium Threads: Enhanced sealing for HPHT, sour, or thermal recovery wells; reduces gas migration and improves torque transmission.
Corrosion Resistance: Anti-H₂S/CO₂ grades (e.g., N80Q, Super 13Cr) and proprietary heat treatments to mitigate sulfide stress cracking (SSC) and general corrosion.
4. Quality Assurance & Compliance
Full API 5CT certification, including chemical composition, mechanical property (tensile, yield, impact), and NDT (UT, MT, PT) testing.
Thread inspection per API 5B; separate thread processing qualification for premium connections (11th Edition requirement).
Traceability via heat number, grade, size, and manufacturing batch records.
5. Ordering & Customization
Standard: 1 kg per unit for small samples; bulk orders in 20-40 ft (6.10-12.19 m) joints.
Customization: Length, wall thickness, premium connections, and sour-service modifications available.
Delivery: 1–3 weeks for standard grades; 4–6 weeks for premium/customized products.
6. Business Value Proposition
Cost Efficiency: Optimized weight-to-strength ratios reduce material and transportation costs.
Reliability: API compliance and premium connections minimize downtime from leaks or failures.
Supply Chain Stability: In-house seamless rolling and heat treatment ensure on-time delivery.
