Corrosion Evaluation of Tungsten Alloy Electroplated Downhole Tubular Materials

Abstract

With prolonged oilfield development and the shift toward enhanced oil recovery techniques, downhole corrosion has become increasingly severe in wells. As a more cost-effective corrosion control technology, tungsten alloy electroplating technology (TAET) has attracted more and more attentions, which can form a dense corrosion product film on the surface of metal materials and prevent the corrosive medium from penetrating into the base-body. This study conducted laboratory experiments simulating various downhole corrosive conditions to comparatively analyze the surface morphology evolution and corrosion rate differentials of tungsten alloy plated tubular (TAPT) materials with other materials, systematically evaluating the plating's protective efficacy and environmental adaptability. Three groups of lab tests were conducted respectively and results showed that corrosion rate of the TAPT material is about 1% of the 13Cr material under the test conditions, which is even about 1‰ of the 3Cr material under the same test conditions. The TAPT material also exhibits excellent corrosion resistance under both the strong acid environment and the high chloride ion environment, with corrosion rates much lower than that of unplated carbon steels (CSs). Taking actual downhole environment conditions in the GCY oilfield as an example, it was found that the corrosion rate of the TAPT material (0.0363 mm/a) is also lower than that of the unplated S13Cr material (0.0453 mm/a), which is quite far lower than that of the unplated N80 CS material (2.6998 mm/a). Comprehensive corrosion evaluations indicate that TAET presents a novel cost-effective solution for addressing corrosion protection challenges in downhole tubular materials within oil and gas fields.