Drill pipe (https://www.eastern-steels.com/products/drill-pipe.html), as a core drilling tool in well operations, inevitably faces various severe challenges. During drilling, it must withstand the continuous action of alternating stresses such as torque, tension, compression, bending, and impact. Simultaneously, its inner bore must resist the intense scouring and corrosion of high-pressure drilling mud. These working conditions are undoubtedly extremely complex and demanding, leading to numerous problems in practical applications. Below, we will comprehensively review and summarize these problems.

Drill Pipe Sequencing
1. Causes
The main causes are the interaction between the drill pipe and the drilling tools, and the wear of the drill pipe's inner bore by impurities in the drilling mud. These factors cause the drill pipe to easily experience sequencing under torque and tensile stress, thus affecting the smooth progress of drilling operations.
Poor quality or impurities in the thread grease.
Single parameter of the drill pipe thread (https://www.eastern-steels.com/newsdetail/how-many-types-of-drill-pipe-threads-are-there.html) does not meet the standard.
Insufficient alignment accuracy during connection.
Insufficient torque during threading, leading to secondary uncoupling.

2. Failure Characteristics
Damage appears on the thread surface, making uncoupling difficult.

3. Preventive Measures
Ensure the use of high-quality threadlocker grease.
Strictly control the machining accuracy of the threads.
Use a standard-compliant hydraulic threadlocker and ensure appropriate threading torque.

Severe Drill Pipe Joint Wear
1. Causes
High formation hardness causes severe friction between the drill pipe and the wellbore during drilling, leading to wear.

2. Failure Characteristics
Significant wear was observed in the drill pipe below a certain well section, accompanied by uneven wear.

3. Preventive Measures
Adjust drilling parameters appropriately and reduce drill pipe rotation speed to mitigate wear.
Use high-hardness wear-resistant tape, such as tungsten carbide wear-resistant tape, and ensure timely repair by welding.
Strictly control well inclination and use a reasonable drill string configuration to reduce uneven wear.

Female Connector Thread Expansion
1. Causes
Insufficient threading torque may lead to stuck pipe on the surface, or excessive torque may cause secondary threading downhole, resulting in female thread expansion and damage to the male connector threads.

The connector strength not meeting standard requirements is also a significant cause of female connector thread expansion.

2. Failure Characteristics
Occasionally, difficulty in uncoupling may occur during single-well operations.

3. Prevention Measures:
Strictly control the threading torque.
Use qualified thread grease.
Prevent the effects of excessive torque.

Drill Pipe Female Connector Frictional Thermal Cracking
1. Causes
In the build-up section of directional or horizontal wells, due to the dogleg effect, the drill pipe female connector is subjected to lateral forces and rubs against the hard well wall. This friction generates a large amount of heat instantaneously, causing the steel temperature to rise rapidly to the phase transformation temperature (above 850 degrees Celsius).
When the drill pipe female connector leaves the well wall and comes into contact with the mud, a hardened structure forms on its surface. Under tensile stress, these hardened structures cause micro-cracks to form on the outer surface. Over time, these cracks propagate, eventually leading to puncture.

2. Failure Characteristics
Obvious wear marks appear on the surface of the drill pipe female joint. Magnetic particle testing reveals a large number of micro-cracks.

3. Preventive Measures
Ensure proper control of wellbore quality.
Use low drilling speeds to reduce wear.
Weld the joint to reinforce the raised portion of the wear-resistant zone.

Puncture or Fracture at the Thread Root of the Male Joint
1. Causes
During drill pipe connection (https://www.eastern-steels.com/newsdetail/connection-method-of-drill-pipe.html), if the threading torque does not meet the standard, fatigue cracks may develop at the large end of the thread during use. As the crack propagates, the wall thickness is penetrated, leading to puncture. If not detected and addressed promptly, these cracks may even cause fracture.

Furthermore, substandard thread parameters or insufficient material strength are also significant causes of puncture or fracture.

2. Failure Characteristics
Batch failures occur, with microcracks detected by magnetic particle testing.

3. Preventive Measures
Strictly control the threading torque to ensure it remains within the appropriate range.
Use high-quality thread lubricant to ensure smooth and durable threaded connections.
Strengthen quality control during thread processing and raw material inspection to improve overall quality.

Disappearance of Thickened Transition Zone Leads to Penetration of Female Thread End
1. Causes
Uneven wellbore quality, such as localized doglegs, causes sustained stress at these concentrated areas, leading to fatigue problems.
Missing or poorly formed thickened transition zones, typically manifesting as wrinkles, also negatively impact the overall structure.

2. Failure Characteristics
Similar problems occur in multiple wells, primarily concentrated in a specific well section.

3. Preventive Measures
Ensure wellbore quality and reduce the impact of doglegs.
Improve the quality of post-threading molding.

Perforation of the Male Thread End at the Disappearance of the Thickened Transition Zone
1. Causes
Complex formation conditions and drill skipping during drilling cause stress to concentrate at a specific point, leading to fatigue failure.
Inappropriate drill string assembly fails to effectively distribute stress or adapt to formation changes.
Poor transition zone formation quality fails to effectively buffer stress concentration, resulting in perforation of the male thread end.

2. Failure Characteristics
Significantly occurs on several drill pipes near the drill collar, accompanied by failure of other drilling tools.

3. Prevention Measures
Reduce drill skipping by adjusting drilling parameters.
Properly plan the drill string assembly and use heavy weight drill pipe (https://www.eastern-steels.com/newsdetail/what-is-heavy-weight-drill-pipe.html) for transition to reduce pipe corrosion fatigue.

Drill Pipe Corrosion Fatigue
1. Causes
Presence of corrosive media in the well or improper mud mix ratio.

2. Failure Characteristics
Deep corrosion pits appear on the internal or external walls of the drill pipe. These failure sites are disordered, and the cracks propagate rapidly, easily leading to fracture.

3. Preventive Measures
Apply a coating to the inner wall of the drill pipe to enhance its corrosion resistance.
Strictly control the pH value of the drilling mud to prevent corrosion of the drill pipe.

Drill Pipe Body Breaks
1. Causes
During downhole accidents, excessive pulling of the drill string can cause the load to exceed the tensile strength of the drill pipe.
The mechanical properties of the drill pipe itself do not meet the established standards, and there are potential defects or weak points.

2. Failure Characteristics
A single drill pipe fractures, and the fracture surface exhibits a significant reduction in diameter.

3. Preventive Measures:
Avoid overloading.
Ensure that the drill pipe used is of qualified quality.

Risk of Corrosion Fracture Due to Hydrogen Sulfide
1. Causes
First, the presence of H2S gas in the well; second, the lack of effective H2S suppression measures; third, the possible use of high-strength drill pipe.

2. Failure Characteristics
Even under low load, fracture may occur, with a flat fracture surface and no obvious fatigue crack initiation observed.

3. Prevention Measures
Use drill pipe materials with sulfur resistance.
Effectively implement H2S suppression technologies.

Read more:
Drill Pipe Weight Chart and Calculation: https://www.eastern-steels.com/newsdetail/drill-pipe-weight-chart-and-calculation.html
or
Is Drill Pipe Weldable?: https://www.eastern-steels.com/newsdetail/is-drill-pipe-weldable.html