Explanation of Oil Casing Connections

In oil drilling operations, the connection type of drilling tools is a crucial and complex aspect. The connection type not only affects the usage of the tools but is also vital for the safety and efficiency of drilling operations. Understanding various connection types helps workers make correct decisions regarding material selection, preparation, and operational guidance. This article provides a detailed explanation of common oil pipe connections, including EU, NU, and New VAM, and briefly introduces drilling pipe connections.

Common Oil Pipe Connections

1. EU (External Upset) Connection
   • Characteristics: The EU connection is an external upset type of oil pipe joint that usually features an extra layer of thickness on the outside of the joint to enhance its strength and durability.
   • Markings: In the workshop, different markings for EU connections include:
     • EUE (External Upset End): External upset end.
     • EUP (External Upset Pin): External upset male connection.
     • EUB (External Upset Box): External upset female connection.
   • Differences: EU and NU connections might appear similar, but they can be easily distinguished by their overall characteristics. EU indicates an external upset, while NU does not have this feature. Additionally, EU typically has 8 threads per inch, whereas NU has 10 threads per inch.
2. NU (Non-Upset) Connection
   • Characteristics: The NU connection does not have the external upset design. The main difference from EU is the absence of the additional external thickness.
   • Markings: Commonly marked as NUE (Non-Upset End), indicating the end without external upset.
   • Differences: NU generally has 10 threads per inch, which is higher density compared to the 8 threads per inch in EU connections.
3. New VAM Connection
   • Characteristics: The New VAM connection features a cross-sectional shape that is essentially rectangular, with equal thread pitch spacing and minimal taper. It does not have an external upset design, which makes it distinct from EU and NU connections.
   • Appearance: New VAM threads are trapezoidal, making them easy to distinguish from other connection types.

Common Drilling Pipe Connections

1. REG (Regular) Connection
   • Characteristics: The REG connection conforms to API standards and is used for the standard threaded connection of drilling pipes. This type of connection was used to connect internally upset drilling pipes, ensuring the strength and stability of the pipe joints.
   • Thread Density: REG connections typically have 5 threads per inch and are used for larger pipe diameters (greater than 4-1/2”).
2. IF (Internal Flush) Connection
   • Characteristics: The IF connection also conforms to API standards and is typically used for drilling pipes with diameters less than 4-1/2”. The thread design is coarser compared to REG, and the texture is more pronounced.
   • Thread Density: IF connections generally have 4 threads per inch and are more common for pipes smaller than 4-1/2”.

Summary

Understanding and distinguishing different connection types is crucial for the smooth operation of drilling activities. Each connection type, such as EU, NU, and New VAM, has specific design features and application scenarios. In drilling pipes, the choice between REG and IF connections depends on the pipe diameter and operational requirements. Familiarity with these connection types and their markings helps workers make informed decisions, ensuring the efficiency and safety of drilling operations.