Nano-Ceramic Coatings- A Means of Enhancing Bit Life and Reducing Drill String Trips

摘要

Drilling bit is the main tool which performs the task of grinding and cutting through the formation. This causes cracking, spallation and delamination of the drilling bit and it needs to be replaced periodically depending upon the formation conditions. This replacement of the bit requires tripping the drill string and running it in again which causes loss of time. Also, a new bit has to be installed which causes monetary loss. Coating the bit with Nano-Ceramic coatings can help reduce the wear and tear significantly. Another promising fact is that these coatings don’t allow the metal substrate below to be affected. So, the worn out bit can be recoated with a fresh layer of Nano-Ceramic coatings and be reused. This paper shall go through the Nano-Ceramic crystalline structure, coating processes, testing mechanical properties (Young’s Modulus, Bond strength, Tensile strength) of the coatings and the comparison of mechanical properties of conventional and Nanostructured coatings. An application of this technology will be to use it for bits to drill highly abrasive formations like those formed by igneous rocks. The Nano-Ceramic coatings are made from an Al2O3-TiO2 Nano-Ceramic powder. This is applied on the bit surface via plasma coating method. The powder is partially melted to form grains of varying sizes. This lack of homogeneity is a major factor in enhancement of mechanical properties which will be explained further in the paper. There is a marked reduction in propagation of cracks as seen under SEM photographs. There is doubling of Bond strength as compared to conventional coatings.The toughness is about 2-4 times that of a conventional coating. This shall be further illustrated in the paper with help of graphs and images. This technology could lead to huge savings for operators as tripping frequency would be reduced. The replaceability of the bit also ensures savings for the operating company.