Impact Of Surface Conditions On Calcium Carbonate (Caco3) Scaling Kinetics In A Once-Through Capillary Flow Rig

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Product Number: 51321-16562-SG

Author: Kabir Raheem/ Thibaut Charpentier/ Olujide Sanni/ Anne Neville

Publication Date: 2021

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Mineral scale formation is one of the most common deleterious challenges in oil and gas production, restricting the steady flow of fluids. It poses major safety & operational issues and results in significant costs due to loss of production and remediation when not properly managed. Recent studies have shown that scaling processes on the surface are not necessarily a result of precipitation of crystals in the bulk solution and that they do not often share the same trends with regards to crystal growth kinetics and inhibition. Most of the past studies on scale deposition have focused on the static bulk data, some attention has been paid to surface conditions and hydrodynamic parameters. However, there is still no reconciliation between bulk precipitation and surface deposition. This study investigates the kinetics of CaCO3 fouling by assessing the interplay between surface feature/condition and scale growth during heterogeneous nucleation processes, to better understand what characteristics of a surface promotes or reduces the likelihood of scale formation. To study the effect of surface “history” on fouling kinetics, scaling tests were performed on pre-scaled samples using brines of two saturation ratios (SR) at a flow rate of 10ml/min up to a previously determined induction time. Surface wettability effects were investigated by the application of silane on stainless steel to increase hydrophobicity, at three SR values and flow rates ranging from 10-30 ml/min at 70⁰C. CaCO3 surface scaling kinetics was assessed from differential pressure change in a novel capillary flow rig designed to study heterogeneous scale formation under hydrodynamic conditions by keeping SR constant and ensuring that there is no bulk precipitate in the solution. The results show a non-water wet surface having improved scale performance by delaying the onset of nucleation and reducing the amount of surface fouling, while pre-scaled surfaces enable faster scale growth in comparison to non-seeded surfaces.

Keywords: CaCO3, surface precipitation, heterogeneous nucleation, kinetics, pre-scale, capillary cell, dynamic tube, wettability, flow rate