API 5CT is a standard for casing and tubing formulated by the American Petroleum Institute (API). There are many types of casing buckles under this standard, and different buckles have different characteristics to meet different oil production needs. The following is a detailed introduction for you:
Round thread buckle type
1.Short round thread casing (STC)
Introduction: Short round thread casing is a common buckle type with short threads, relatively simple processing and low cost. It has a fast connection speed and can improve operating efficiency.
Application scenario: It is suitable for general oil and gas wells. It is widely used in shallow wells, relatively non-harsh pressure and temperature conditions. For example, for some shallow oil production wells, STC buckle casing can meet the basic sealing and connection requirements 5.
2.Long round thread casing (LTC)
Introduction: The thread length of long round thread casing is longer than that of short round thread casing, and the sealing performance is relatively good. Its thread bearing capacity is also strong and can withstand certain tension and pressure.
Application scenarios: Suitable for oil and gas wells with moderate depth, slightly higher pressure and temperature. In some medium-depth oil and gas wells, LTC buckle-type casing can provide more reliable connection and sealing performance5.
3.Trapezoidal thread buckle type (BTC)
Introduction
The thread tooth profile of the trapezoidal thread casing is trapezoidal and asymmetrical. This buckle type has relatively high sealing performance and connection strength, and can withstand large axial tension, pressure and torque.
Application scenarios
Commonly used in deep wells, high-pressure wells, high-temperature wells and oil and gas wells containing corrosive media. In some deep-sea oil wells or high-temperature and high-pressure oil and gas production environments, BTC buckle-type casing can ensure the reliability and sealing of casing connection and prevent oil and gas leakage
4.Direct-connection casing (XC)
Introduction
Direct-connection casing has no coupling and is directly connected through the threads at both ends of the pipe, which reduces the outer diameter change caused by the coupling and increases the diameter of the casing. It has high connection strength and good sealing performance.
Application scenarios
Applicable to wells with high requirements for casing inner diameter, such as oil wells and gas wells that require large-diameter downhole operations. In some wells that require large-scale fracturing operations or require the insertion of larger-sized tools, XC buckle-type casing can provide a larger inner diameter space5.
5.Special buckle type
Introduction
In addition to the common buckle types mentioned above, there are some special buckle types, such as New Vam, fox, etc. These buckle types usually have better sealing performance, corrosion resistance and fatigue resistance.
Application scenarios
Used in oil wells and gas wells with some special working conditions, such as high-sulfur gas wells, horizontal wells, large-displacement wells, etc. In these complex mining environments, special buckle-type casing can better meet engineering needs and ensure the safety and efficiency of mining operations.
