Assessment of combined scale/corrosion inhibitors - A combined jar test/bubble cell

The formation of calcium carbonate scale and the occurrence of CO corrosion are both widespread phenomena observed within pipework during oil and gas production. The most common form of treatment for both processes is the application of chemical inhibition through corrosion and/or scale inhibitors. Surface scaling of pipework rarely occurs in environments where no corrosion exists, yet techniques used to develop and assess the performance of scale inhibitors tend to focus on assessing and reducing solely bulk/surface scaling, without affording consideration towards corrosion, whilst corrosion inhibitors are frequently evaluated in non-scaling environments. Furthermore, both chemicals tend to be evaluated independently meaning that any potential antagonistic effects between the chemicals can go unrecognised. This paper addresses this very issue by presenting a unique setup and methodology to enable the occurrence of scale and corrosion to be monitored simultaneously in a CO-saturated environment in the presence and absence of combined scale and corrosion inhibitors. The test cell focuses on evaluating four key parameters which are quantified either throughout the duration of the test, or from the implementation of post-test surface analysis techniques. The multiple assessment of (i) bulk scale precipitation, (ii) surface scaling, (iii) general corrosion and (iv) localised corrosion permits a full assessment of the chemical blends propensity to mitigate both scaling and corrosion. Non-inhibited tests were initially conducted at 60 °C to form a baseline for comparison. Four combined scale/corrosion inhibitors were subsequently used at low concentrations in order to understand their mechanisms and highlight any competitive effect which existed in reducing either scale or corrosion. The results demonstrate that the methodology implemented is effective at assessing the efficiency of combined inhibitors in reducing both corrosion and scale in environments where both processes occur simultaneously. The limitations of conducting solely bulk scaling or corrosion tests in non-scaling environments are discussed relative to the results obtained in this work. The results of each individual inhibitor are discussed and markedly different behaviour is observed according to the concentration administered, as well as the particular blend of chemicals applied

Analyse du phénomène d'entartrage et de son inhibition (effet des ions majeurs présents dans les eaux du sud algérien)

Les eaux du Sahara algérien présentent des températures élevées (plus de 70C) et sont fortement chargées en sels, notamment en carbonates et en sulfates, avec une dureté dépassant 100F. Le tartre formé naturellement dans les conduites d eaux de la ville d Ouargla, dans cette région, a été analysé par ICP-AES, MEB/SED, DRX et spectroscopie Raman. Il est composé essentiellement de carbonate de calcium qui cristallise sous la forme allotropique aragonite. Dans cette thèse, nous nous intéressons, à la fois, à la précipitation du CaCO3 dans une eau calcocarboniquement pure (CCP), ainsi qu à l influence de plusieurs ions étrangers. L effet des ions majeurs présents dans les eaux du sud algérien est ainsi examiné, avec un intérêt particulier pour les ions sulfates. La formation accélérée du tartre est induite par voie électrochimique et l influence des paramètres tels que le pH, l hydrodynamique, la température, le potentiel de polarisation ont été étudiés. La cinétique d entartrage est suivie par chronoampérométrie et par la spectroscopie d impédance électrochimique. Ces mesures sont complétées par la caractérisation des dépôts formés par les mêmes méthodes d analyse citées auparavant : MEB/SED, DRX et spectroscopie Raman. L inhibition de l entartrage est aussi étudiée par l analyse de l effet croisé de la température et de la concentration en inhibiteur. L'efficacité de cinq inhibiteurs issus de trois grandes familles : polyphosphates, polyphosphonates et acides polycarboxyliques a été déterminée. L'analyse chimique élémentaire de ces composés a été réalisée par ICP-AES, en montrant en particulier que ces substances tartrifuges ne contiennent pas de métaux lourds en quantités significatives.Sahara Algerian waters present high temperatures and are strongly concentrated in salts, particularly carbonates and sulfates, with a hardness exceeding 100F. Calcareous deposits naturally formed in this region, were analyzed using ICP-AES, SEM/EDS, XRD and Raman spectroscopy. It consists essentially of calcium carbonate in aragonite allotropic form. Electrochemically accelerated scaling is also analyzed. The effect of the present major ions in South Algerian waters is examined with a particular interest for the sulphates ions. The influence of parameters such as pH, hydrodynamics, temperature and polarization potential was studied. The kinetics of scaling is followed by chronoamperometry and by electrochemical impedance. These measurements are followed by the characterization of deposits by the same techniques cited before: SEM/EDS, XRD and Raman spectroscopy. Scaling inhibition was also studied by the analysis of the crossed effect of temperature and inhibitors concentration. The efficiency of five inhibitors from three big families: polyphosphates, polyphosphonates and polycarboxylic acids was determined. The elementary chemical analysis of these compounds was realized by ICP-AES. It shows that these tartrifuges substances do not contain heavy metals in significant quantities.CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

Efficiency of five scale inhibitors on calcium carbonate precipitation from hard water: Effect of temperature and concentration

International audienc

Characterization of natural scale deposits formed in southern Algeria groundwater. Effect of its major ions on calcium carbonate precipitation

International audienc