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Submersible pump outer cylinder anti-corrosion technology to solve the problem
Electric submersible pumps (ESPs) play a crucial role in ensuring long-term, stable oil production. However, ESP failures are a common issue in oilfield operations. According to field surveys, the failure rate of ESPs due to corrosion of the outer cylinder can range from 4% to as high as 83%, depending on the specific conditions of each oilfield. This wide variation highlights the critical need for improved protection against such failures.
Submersible pumps are typically installed at depths between 1,000 and 2,500 meters, where they are directly exposed to a mixture of crude oil, natural gas, water, and sand under high pressure—ranging from 12 to 25 MPa. The temperature in these environments can vary from 50°C to 150°C, creating harsh conditions that accelerate both chemical and electrochemical corrosion, as well as mechanical wear. Several factors contribute to this degradation:
First, the presence of corrosive elements like chloride ions (Clâ»), hydrogen sulfide (Hâ‚‚S), and carbon dioxide (COâ‚‚) in the produced fluid significantly increases the risk of corrosion. Hâ‚‚S is particularly damaging, as it can form a corrosive battery when in contact with the pump’s outer cylinder. In this scenario, the cylinder acts as the anode and corrodes rapidly. Additionally, if corrosion products and salts accumulate over time without being removed, the damage worsens. When the water content in the crude oil exceeds 80-90%, the corrosive nature of the fluid becomes even more severe.
Second, hydraulic impacts caused by the flow of fluids can lead to bubble formation and collapse on the pump’s surface, increasing the likelihood of corrosion and mechanical wear. Moreover, vibrations from the pump operation can cause fretting wear between the pump casing and the wellbore. Even minor vibrations in a corrosive environment can result in significant wear over time.
To address these challenges, two main approaches are commonly used. The first involves using advanced materials that can withstand the extreme downhole conditions. While effective, this method is expensive and not always practical for widespread implementation. The second approach focuses on surface treatments and coatings, which offer a more cost-effective solution. With advancements in material science and surface engineering, a variety of coatings have been developed to provide excellent corrosion and wear resistance.
One notable example is the anti-erosion technology developed by the New Materials Division of Beijing Anton Bull Engineering and Technology Co., Ltd. This technology uses AOC-240 alloy, a high-performance material, applied via thermal spraying to create a thin, durable coating (approximately 0.2 mm thick) on the outer surface of the electric submersible pump. The resulting coating exhibits exceptional properties, including outstanding corrosion resistance, strong adhesion to the substrate, excellent anti-fretting wear performance, good oil and water resistance, and effective anti-scaling capabilities. It also maintains high heat resistance and thermal conductivity, making it ideal for use in harsh downhole environments.
By applying this coating, the service life of electric submersible pumps has been dramatically extended—by up to ten times compared to conventional models. These coated pumps are now widely used in major oil fields such as Daqing, Bohai, and Liaohe, and have received positive feedback from operators due to their reliability and performance.