Evaluation of the Effect of Surface Finish on Calcium Carbonate Scaling Under High Pressure
Name: ANTONIO CARLOS BARBOSA ZANCANELLA
Publication date: 09/07/2025
Examining board:
Name |
Role |
|---|---|
| SILVIO LUIZ DE MELLO JUNQUEIRA | Examinador Externo |
Pages
Summary: The formation of calcium carbonate scale causes significant losses in deepwater oil production and is influenced by factors such as pressure, temperature, pH, solution chemistry, and surface finish. The surface plays a critical role by interacting with the fluid and serving as a substrate for crystal anchoring; however, the literature presents conflicting results regarding its effect on scaling, along with experimental limitations due to tests conducted under low pressure and static conditions. The release of CO from the solution is also a relevant thermodynamic factor, promoting precipitation and intensifying the problem. This study evaluates the influence of surface finish on scale formation under more realistic operational conditions, using high pressure and CO injection. AISI 304 stainless steel was chosen as the base material due to its chemical stability and widespread industrial use. Surfaces prepared by metallographic polishing, machining, sandblasting, and laser texturing were analyzed, covering a broad range of finishes. In addition, coatings of Cerakote H225, synthetic enamel, and polyurethane were tested with the aim of mitigating scaling. Surface characterization was performed using 3D optical profilometry; linear scratch testing was used to assess calcium carbonate adhesion, and Raman spectroscopy was employed to evaluate the formed polymorph. Beyond the traditional analysis found in the literature using average surface parameters (, , and ), a complementary evaluation using fractal dimension analysis was adopted to accurately quantify the complexity of the surfaces and correlate it with the scale mass. Results from uncoated samples indicate that surfaces with higher fractal dimension exhibit greater scale accumulation and higher adhesion force, demonstrating that fractal dimension is an effective estimator of a surface's scaling potential. Calcite was the predominant calcium carbonate polymorph observed in the tests. Among the coated surfaces, Cerakote H225 stood out by reducing scaling by 85.5% compared to sandblasted AISI 304 stainless steel. These findings are essential for optimizing material and surface treatment selection in deepwater oil production, improving operational efficiency, and reducing costs.
Keywords: Mineral scaling; calcium carbonate; surface finish; carbon dioxide injection; high pressure.
