How to extend the service life of kelly bar and ensure drilling quality?

Wear and tear of kelly bar

During the drilling process, the kelly bar will be subject to friction and impact from materials such as soil and rocks, which can cause wear, depression, deformation, and other problems on the surface of the drill pipe. Wear not only affects the service life of kelly bar, but also affects the quality and safety of drilling.

The wear of kelly bar mainly comes from the following aspects:

Abrasive wear: This is the phenomenon of surface abrasion and material detachment caused by external hard particles or micro peaks on the hard surface during the relative motion of the friction pair's dual surface. The surface characteristics of the drill string are scratches, tears, longitudinal tensile marks, local peeling, and cracks. The mechanism of abrasive wear is micro cutting, with multiple plastic deformations leading to fracture and micro fracture.

Adhesive wear: The wear phenomenon caused by the transfer of materials from one surface to another or the detachment of materials from the surface due to adhesion when two pairs of surfaces in a friction pair slide relative to each other. Due to the small actual contact area between the dual surfaces of the friction pair, the contact point stress is high. The dual surface of the friction pair is in this high temperature and high stress state, and the surface of the rod ruptures, causing adhesion of the contact micro peaks, which are then sheared off during sliding.

Fatigue wear: This is the most common type of drill pipe failure. There are three basic types of fatigue wear: low angle erosion, high angle erosion, and microcracks and micro cutting.

In addition, when the drill pipe reaches the critical speed, it may vibrate, leading to bending and excessive wear. Therefore, when using kelly bar, it is necessary to pay attention to the operating methods and avoid improper behaviors such as lifting and pulling stuck kelly bar, in order to reduce the wear of kelly bar. Meanwhile, it is necessary to promptly repair or replace worn kelly bar.

Protection of kelly bar

The protection of kelly bar is mainly to prevent them from being damaged or worn during operation, thereby affecting drilling quality and safety.

The following are some common drill pipe protection measures:

Using casing or casing: During the drilling process, using casing or casing can effectively prevent the drill pipe from being rubbed and impacted by soil, rocks, and other substances, thereby reducing the wear of the drill pipe.

Coating wear-resistant materials: Coating wear-resistant materials such as hard alloys, ceramics, etc. on the surface of kelly bar can effectively increase their wear resistance and impact resistance, thereby extending their service life.

Adopting advanced drill bit design and manufacturing technology: By adopting advanced drill bit design and manufacturing technology, more wear-resistant and impact resistant drill bits can be manufactured, thereby reducing the wear of drill rods.

Reasonable selection of drilling parameters: Reasonable selection of drilling parameters, such as drilling pressure, rotation speed, etc., can reduce the wear and vibration of kelly bar, thereby extending their service life.

Regular inspection and maintenance: Regularly inspect the quality and safety of kelly bar, and replace damaged kelly bar in a timely manner; Regularly clean and lubricate kelly bar to prevent corrosion and jamming; Reasonably store kelly bar to avoid mechanical damage and environmental factors.

Here are some suggestions for drill pipe maintenance and upkeep:

Regular inspection: Regularly inspect the appearance quality, size, and performance of kelly bar, including their curvature, thread wear, and pipe corrosion. If damage or severe wear is found, it should be replaced in a timely manner.

Rust prevention treatment: During storage and use, anti rust paint or butter should be regularly applied to prevent kelly bar from rusting. Especially after working in humid or acid-base environments, attention should be paid to rust prevention treatment.

Cleaning and maintenance: After each use, the soil, oil stains, and rock debris on the drill pipe should be promptly removed, and washed clean with water. At the same time, keep the drill pipe dry to prevent moisture and rainwater from entering, in order to avoid rusting and reduce performance.

Regular lubrication: During the drilling process, the drill pipe should be lubricated regularly to reduce friction and wear. Especially at the connection parts and threads, lubrication and maintenance should be paid more attention to.

Anti corrosion treatment: For kelly bar working in acidic and alkaline environments, anti-corrosion treatment is required. For example, kelly bar made of acid and alkali resistant materials or coated with anti-corrosion coatings can be used.

Storage and handling: During the storage and handling process, kelly bar should be avoided from being hit, squeezed, and twisted to prevent damage and deformation. Meanwhile, it is important to avoid prolonged exposure to sunlight and humid environments.

Regular inspection: kelly bar should be inspected regularly to identify potential defects and issues. If cracks, deformations, or other problems are found on the drill pipe, it should be repaired or replaced in a timely manner.

Maintenance records: A maintenance record of kelly bar should be established to record each inspection, repair, and replacement, in order to facilitate management and tracking of the use of kelly bar.