Influence of Boronizing on Steel Performance under Erosion-Abrasion-Corrosion Conditions Simulating Downhole Oil Production

Abstract

Downhole heavy oil production and oil sand processing are associated with severe damage and failures of production equipment components, e.g., production tubing and pumping systems, due to erosion-corrosion resulting in processing losses, production downtime, high maintenance and replacement cost. Protective coatings (layers) on the production components mostly fabricated from low-alloy steels can be applied to minimize these problems. In the present work, the performance of hard boronized coating on carbon steel obtained through the thermal diffusion process and consisted of two iron boride layers (FeB and Fe2B) was studied in synergistic erosion-abrasion-corrosion conditions simulating oil production environment in comparison with bare steel. Special wear testing equipment was designed and fabricated. In this testing, the inner surface of tubular sections was subjected to high velocity erosive flows of water-oil slurries containing silica sand and salts combined with rotating and oscillating motions of steel pony rods. Structural examination of the studied materials’ surfaces and their profilometry after wear testing were conducted. The iron boride coating demonstrated significantly higher performance in abrasion and erosion-abrasion-corrosion conditions compared to bare carbon steel due to its high hardness, high chemical inertness, dual-layer architecture and diffusion-induced bonding with the substrate. The boronized steel tubing and casing with inner surface protection can be effectively employed in the most critical operation conditions.