Preventing Scale Formation Using Modified Surfaces

A  major challenge face by the oil and gas industry is the minimisation of scale formation within installations; new regulations are requiring conventional inhibitors to be replaced by green chemistries and anti-scaling surfaces. This paper focuses on the ability of different surfaces to reduce or modify calcium carbonate scale formation with the final objective being to understand what constitutes a surface that minimises the potential for scaling.

Two brines and seven different surfaces have been tested (stainless steel, stainless steel pre-treated with PPCA, PTFE-, DLC-, ceramic- and polymer- coated stainless steels and an isotropic superfinished stainless steel surface). In addition, a set of surfaces were eroded using a suspension of sand in a jet impingement apparatus.  The surfaces were first characterized by contact angle, roughness measurements and EDX. Calcium carbonate growth, under flow conditions, has been assessed for each of the surfaces by studying the amount of scale and the morphology of the crystals using SEM. From the results a systematic ranking of the surfaces resistance to scaling has been established together with an improved description of the scale deposition process.