Drill Tube

1. Definition of Drill Tube

Drill tube is one of the key equipments for drilling operations in oil, gas, geological exploration and mineral exploitation, and is an important part of Drill String. It is made of high-strength alloy steel, hollow tubular structure, mainly used for transmitting drilling pressure and torque, and at the same time, conveying drilling fluid (mud) to the drill bit, in order to cool, lubricate the drill bit and carry rock chips back to the ground.

Drill tube usually consists of a tube Body and a Tool Joint welded together, with the joints specially hardened to increase wear resistance. Depending on the application and strength, drill tube can be divided into various types, such as conventional drill tube, Heavy Weight Drill tube (HWDP) and so on, in order to adapt to the needs of drilling at different depths.

2. Material of drilling tube:

①High-strength alloy steel

This is the most widely used drilling tube material, with high hardness, high strength, good compatibility and other advantages, can adapt to high temperature, high pressure, strong acid, strong alkali and other special environments.

② Carbon steel

Carbon steel is also one of the common drilling tube materials, usually used to make seamless steel tube, its standard number is GB/T 9808-2008.

③Stainless steel

Stainless steel drilling tubes have good corrosion resistance and are suitable for drilling operations in some special environments. 

④Titanium alloy

Titanium alloy drilling tubes are characterized by light weight and high strength, and are suitable for scenarios with high weight requirements.

⑤ Polymer

Drill tubes made of polymer are usually used in specific environments, such as those requiring corrosion resistance or insulating properties.

⑥ 42MnMo7

which was commonly used in the past to manufacture DZ60 grade geological drilling tubes to meet the needs of geological drilling.

The choice of these materials depends on the specific drilling environment, technical requirements and cost considerations.

3. Scope of application of drill tube:

①Oil and gas drilling

In oil and gas exploration and exploitation, the drill tube is used to connect the drilling rig and the drill bit, transfer the rotary power and drilling pressure, so that the drill bit can break the rock layer and drill to the target depth.

②Geological Exploration

In geological survey and mineral exploration (e.g. coal, metal ore), drill tubes are used to obtain samples of underground rock formations and analyze the geological structure and distribution of mineral resources.

③Hydrological Drilling

In water wells, geothermal wells and other projects, drill tubes are used for drilling aquifers, obtaining groundwater or geothermal energy development.

④Deep sea and polar drilling

In offshore drilling platforms or polar exploration, drill tubes need to have higher corrosion resistance and low temperature resistance to adapt to harsh environments.

⑤Scientific drilling

Drill tubes are used to collect deep or extraterrestrial geological samples in scientific research projects, such as continental scientific drilling (e.g. China's “Songke No.2 Well”), lunar or Mars exploration, and so on.

4. Advantages of drill tube:

①High strength and durability

Drill tube is made of high-quality alloy steel with high tensile, compressive and torsional strength, which can withstand the great stress of deep well operation.

②Good sealing

The joints are connected by precision threads to ensure that the drilling fluid will not leak under high pressure and improve drilling efficiency.

③Strong adaptability

The material, wall thickness and joint design can be adjusted to meet the needs of different geological conditions and drilling depths.

④Improve drilling efficiency

Reasonable use of drill tube can reduce faults in the drilling process, increase drilling speed and reduce operating costs.

5. Disadvantages of drill tube:

①Heavy weight and high transportation cost

Drill tube is usually long (single length of about 9-12 meters), and made of high-strength steel, transportation and handling require special equipment, increasing operating costs.

②Susceptible to wear and corrosion

During the drilling process, the drilling tube rubs against the well wall, and the joint part is easy to wear out; at the same time, the chemicals in the drilling fluid may cause corrosion, affecting the service life.

③High maintenance requirements

Drill tube needs regular inspection (e.g. ultrasonic flaw detection, magnetic particle inspection, etc.) to prevent fatigue cracks or fracture accidents, and the maintenance cost is high.

④Limitations of deep well operation

In ultra-deep wells (e.g., more than 8,000 meters) or high temperature and high pressure environments, the drilling tube may face problems such as degradation of material properties, flexural deformation, etc., which requires the use of special materials or optimized design.

6. Summary of drilling tube:

As a core component of drilling operation, drilling tube plays an irreplaceable role in petroleum, geology, hydrology and other fields. Despite the disadvantages of high weight and easy to wear, its performance and life span are still improving through material improvement, optimized design and regular maintenance. 

In the future, with the application of new materials (e.g. composite materials) and intelligent monitoring technology, drill tube will further improve drilling efficiency and adapt to more complex exploration needs.