Surface Engineering Solutions for Scale Resistance

Scale formation on surfaces can normally be divided into two distinct processes: a “deposition process” which refers to the process of heterogeneous nucleation and growth at the asperities of the surface in the bulk solution and an “adhesion process” which refers to the sticking of pre-existing crystals, which have nucleated in the bulk solution, and which build up as a layer on the surface. The presented work represents an experimental study of scaling tests to assess the effect of hydrodynamic conditions in a complex scaling environment, supersaturated with sulphate/carbonate-dominated brine solutions, on the stainless steel substrate coated with a range of commercially-available coatings. Due to the complexity of the brine solutions, the formed scale deposits are the product of the coprecipitation process. The morphology of the scale deposits along with the chemical composition of the surface scale deposits in different conditions was analysed and characterised. In addition, the effect of the surface energy and surface roughness on both processes have been studied. The thesis provides data that will assist in the understanding of the controlling parameters in scale formation in different conditions, and also describes what characteristics of the surface can make it a good anti-scaling surface for inorganic scale; however, the results have shown that merely one parameter cannot assure a surface as a good antifouling surface. Since most of the surface scaling studies have been focused on laboratory experiments and very little data are available to demonstrate such results are relevant and can be scaled-up to field environment, the current study focuses on correlating the systematic laboratory results with field trials. The current study shows that if properly selected, surface engineering offers great promise as an approach to prevent mineral scale deposition in the piping system of oilfields