In Perm, experts shared tips on how to save costs when replacing oil and gas equipment.

In the production of deep well rod pumps for mineral extraction, coatings made from various grades of NiCrBSi (nickel-chromium-boron-silicon) are widely used. These coatings are applied through gas-flame spraying. Despite their high wear resistance, such surfaces are prone to failure. Nearly 38 percent of malfunctions are linked to stress corrosion cracking of the material. Researchers at PNIPU have identified the primary causes of this issue and developed recommendations to enhance the durability of the equipment and maintain economic benefits.

2024-10-31 10:00:24https://naked-science.ru/article/column/neftegazovogo-oborudovani

The article has been published in the journal "Black Metals." The research was conducted as part of the strategic academic leadership program "Priority 2030."

Components that enable the operation of deep pumps are referred to as plungers. These are hollow pistons that move within a cylinder. When moving upward, fluid is drawn from the well, and when moving downward, it is pushed into the lifting pipes. Traditionally, nickel alloy with a coating composition of NiCrBSi, as stipulated by domestic and international standards, is chosen for such parts. Its production involves gas flame spraying followed by melting. The material exhibits high wear and corrosion resistance, but due to its composition and manufacturing method, it becomes porous and may contain unmelted particles, making it more susceptible to wear.

The plunger operates in a highly aggressive environment with chlorides and hydrogen sulfide, and it also undergoes degradation due to repeated stress impacts. These factors mutually reinforce each other, causing greater damage.

Researchers from Perm Polytechnic University examined the surfaces of the components after operation. A microscope and a solid-state microstructure fragment analyzer were used for the study. It was found that the oil-containing medium has a significant concentration of hydrogen sulfide (over 10 percent) and iron chlorides. Their presence is explained by the treatment of wells with hydrochloric acid to dissolve sulfides that clog the channels and cavities of the equipment.

“We believe that during operation in environments containing hydrogen sulfide and chlorides, the plunger coating is simultaneously subjected to stress corrosion cracking and contact fatigue. The cracks are oriented almost perpendicularly, leading to fragmentation and peeling of the coating. To mitigate the impact of these factors, it is necessary to adjust the content of chromium carbides and borides in the coating by reducing the carbon and boron in the initial powder,” comments Yuri Simonov, head of the Department of "Metallurgy, Thermal and Laser Treatment of Metals" at PNIU, Doctor of Technical Sciences.

“The potential reduction in costs from preventing even one instance of equipment failure can exceed 150,000 rubles, so a slight decrease in equipment failures due to corrosion cracking would have a positive impact on the industry. Investments in the development of new resilient materials will pay off through increased reliability and reduced maintenance costs, thereby enhancing extraction efficiency,” explains Stanislav Moltsen, a graduate student at the Department of "Metallurgy, Thermal and Laser Treatment of Metals" at PNIU and Quality Director at ELKAM-Neftemash JSC.

Researchers at Perm Polytechnic University propose to reduce repair and replacement costs for oil pumps by adjusting the content of chromium carbides and borides in the coatings for pump components to enhance their resistance to corrosion and mechanical loads.