Drill pipe is one of the most important tools in oil drilling operations. Its core function is to connect the drilling rig's surface equipment and downhole drilling tools (such as the drill bit), transmit torque and drilling fluid, and withstand complex loads. Therefore, almost all rotary drilling operations are inseparable from drill pipe. Drill pipe has a wide range of applications in oil exploration and development. The following is a detailed summary of its application range:

1. Conventional Oilfield Drilling

Basic Application: Oil drill pipe is suitable for most conventional oilfield drilling operations, transmitting torque and conveying drilling fluid to deepen the wellbore.

Material Selection: Steel drill pipe is commonly used in conventional oilfield drilling. This type of drill pipe is made of seamless steel and offers high strength and rigidity.

2. Complex Geological Conditions

Deep Well Operations: In deep well operations where frequent addition and removal of drill pipe is required, auger drill pipe offers significant advantages. Auger drill pipe is connected together using threaded connections for ease of operation.

High-Temperature and High-Pressure Environments: Oil drill pipe is also suitable for drilling operations under complex conditions such as ultra-high pressure and high temperature. For example, special steel grades (such as BNKC95S) are used to handle the challenging environments of sulfur-bearing oil wells.

3. Special Drilling Operations

Horizontal and Curved Wells: Wireline drill pipe is more suitable for horizontal and curved well operations. Wireline drill pipe is constructed from multiple strands of steel wire, making it lightweight and highly adaptable.

Geological Exploration: Needle valve drill pipe, with a needle valve at the bottom connector, can control gas pressure and flow at the bottom of the well and is suitable for exploratory wells and geological exploration.

4. Drill Pipe Assembly Applications

Drill String Components: Oil drill pipe is a key component of the drill string and is typically used with the drill bit, drill collar, stabilizer, specialized connectors, and kelly.

Connection Order: During drilling, the drill pipe connection order is typically one kelly (1 piece) + n drill pipes (n pieces, determined by the well depth) + weighted drill pipe (n pieces, determined by the drill string assembly design).

5. Scientific Research and Underground Construction

Scientific Research: The working principle of drill pipe is also crucial in scientific research. Using drill pipe to penetrate the ground, samples and data can be obtained, significantly aiding research in fields such as geology and climatology.

Underground Construction: In urban infrastructure construction, the use of drill pipes can avoid ground damage and enable more precise layout of underground facilities, such as underground pipelines and tunnels.

Drill pipe is classified by its function and position in the drill string:

1. Kelly pipe: Located at the top of the drill string, it directly interfaces with the drill rig's rotary table, transmitting surface rotation and torque to the entire drill string. Suitable for all drilling operations requiring drill string rotation.

2. Conventional drill pipe: Consists of the main body of the drill string and is the most numerous. Suitable for transmitting torque, conveying drilling fluid, and extending well depth.

3. Weighted drill pipe: With a wall thickness 2-3 times thicker than conventional drill pipe, it is heavier and more rigid. Typically placed in the middle of the drill string (between the drill pipe and the drill collar), it serves as a transition point, effectively reducing fatigue damage in the drill string and providing some weight-on-bit. It is particularly suitable for directional, horizontal, and deep wells.

4. Drill collar: With the thickest wall and heaviest weight, it provides weight-on-bit and maintains stability in the lower drill string. Although not called "drill pipe," it is a key component of the drill string. Suitable for all drilling operations requiring weight-on-bit at the drill bit.