Oil Casing Application: Key Technology from Borewell to Oil and Gas Well

As an indispensable component of modern drilling engineering, oil casing pipe plays a key role in different types of drilling operations. This article will explore the technical characteristics, material selection and industry best practices of the three major application scenarios of borewell casing, borehole casing and well casing.

1) Borewell Casing Application

Borewell casing is a core component to ensure the structural integrity and water quality safety of water wells. It is mainly used in drinking water wells, irrigation wells and geothermal wells.

1. Material and specification characteristics
Common materials: low carbon steel J55/K55 grade, food grade epoxy resin coating
Diameter range: 4 inches to 16 inches
Wall thickness standard: 5-8mm
Surface treatment: hot-dip galvanizing, epoxy resin coating

Connection method: API short thread coupling (STC) or welding connection

2. Special application scenario solutions
Geothermal wells: In groundwater containing corrosive ions, the use of 13Cr stainless steel casing can significantly extend the service life.
Seawater intrusion area: FRP composite casing (chloride ion corrosion resistance)

A project in Rajasthan, India shows that the service life of water well casing made of 13Cr material in high-iron groundwater reaches 22 years, which is three times that of ordinary carbon steel casing.

3. Technological innovation
The new FRP composite casing performs well in seawater intrusion areas. Its chloride ion corrosion resistance is 5-8 times higher than that of traditional steel, while its weight is reduced by 40%, which greatly reduces the difficulty of installation and transportation costs.

2) Borehole Casing Application

Borehole casing mainly serves professional fields such as geological exploration, scientific drilling and mine support, facing more complex geological conditions. Casings must meet special working conditions:

1. Extreme working conditions response plan
Core drilling: use thin-walled (3-5mm) high-strength casing with diamond drill bits
Coalbed methane wells: use expandable casing technology, radial expansion rate can reach 15-20%
Scientific drilling: use special casing with coring window design

2. Technical parameter comparison

Drilling type:
Geological exploration: high torsion resistance design. 
Mine shaft: enhanced impact resistance.
Ground source heat pump: low thermal conductivity.

3. Intelligent monitoring technology
The latest developed intelligent borehole casing has a built-in high-precision strain sensor, which can monitor the stress state of the casing in real time, with a measurement accuracy of ±0.1%FS, providing data support for engineering safety.

3) Well Casing Application

The Well casing system is the "skeleton" of oil and gas wells, and its technological development represents the highest level in the casing field.

1. Completion hierarchical architecture
Conduit: resist shallow scour
Surface casing: prevent wellhead collapse
Technical casing: isolate complex formations
Production casing: ensure long-term production, high pressure and high temperature resistance

2. Application of cutting-edge materials
Sulfur-resistant casing: C110/T95 grade, certified by NACE MR0175
Composite casing: carbon fiber reinforced pipe body, 40% lighter
Duplex steel casing: 22Cr/25Cr, used in highly corrosive environments

3. Digital technology integration
Typical case of deepwater wells:
A deepwater project in the Gulf of Mexico uses 9-5/8" 125ksi casing with metal sealing buckles to successfully resist 58MPa formation pressure at a water depth of 2,300 meters. The project also deployed a fiber optic monitoring system to achieve real-time monitoring of the casing status.

Industry development trends:

1. Environmental protection direction
Research and development of degradable magnesium alloy casing materials
Application of low-carbon smelting process

2. Intelligent development
Self-sensing casing system
AI-driven integrity management system

3. Ultra-deep well technology
10,000-meter ultra-deep well casing (V170 steel grade)
Temperature resistance exceeds 350℃

Through comparative analysis, it can be seen that although the three types of casing have different application scenarios, they jointly promote the development of casing technology towards high strength, corrosion resistance and intelligence.

Read more: Types of Drilling Casing Pipe or Specifications and Dimensions of Drilling Casing