Abrasion and erosion behavior of DLC-coated oil-well tubings in a heavy oil/sand environment

The sucker rod pump, an important machine in oil exploration and extraction, normally works in a heavy oil and sand environment in which severe abrasion and erosion occur, especially on oil-well tubings. To improve the service life, DLC coatings with different thicknesses are fabricated on the oil-well tubings and the mechanical, tribological, and anti-corrosion properties are investigated. The results show that the thickness can be compromised with adhesion due to the low stress induced by alternate implantation and deposition at the pulsed high-voltage bias. Compared to severe abrasion of the carbonitriding AISI 1045 oil-well tubing, the thick DLC coatings have good anti-abrasion properties in the heavy oil and sand environment. Moreover, excellent erosion resistance is observed from the DLC-coated samples as exemplified by the small corrosion current density and high corrosion potential. The tests conducted in both simulated and practical working conditions reveal that the service life of the oil-well tubing is significantly improved.