Sustainable Removal of Re-Occurring Scale & Corrosion Products by Textural Analyses Using Petrographic Thin-Sections: A New Cross-Disciplinary Application of a Traditional Geological Technique

Abstract

Abstract Corrosion and scale products are frequently encountered in the oil & gas industry and often are main concerns regarding flow assurance. They form due to chemical conditions that are in most cases not within the operational specifications. The same chemical conditions are quite often also responsible for corrosion failures. Removal of scale and corrosion products is often a time-consuming process including a significant proportion of human work in areas with high HSSE-risks; e.g. cleaning of tanks. Furthermore, the interruption of production processes is generally accompanied by financial losses. Scale and corrosion products form due to environmental conditions that are often outside the normal operating conditions (Burns, 2016). Therefore, identifying those conditions can be very challenging and if the reason(s) for scale/corrosion product formation are not discovered they are likely to occur again. The detailed analyses of the texture as well as mineralogical-chemical composition of scale and corrosion products and fluids present can provide valuable information on formation conditions. This information can be crucial to identify reasons for scale precipitation or corrosion thus providing involved experts with the knowledge to prevent recurring issues with both. However, our own experience has shown that analytical programs of scale & corrosion products are often not designed to answer the most important question why they have formed are missing. This can result in reoccurring formation of scale & corrosion products and repeated cost-intensive removal. Three crucial points have been identified strongly influencing the quality of scale & corrosion product analyses and interpretation. These points are: Sampling Analytical methods used Interpretation of results In course of the described case studies, a work-flow has been used that aims to ensure to avoid any failures in the identified crucial points. This work-flow will be discussed based on the experiences from the case studies with special emphasize on description of sampling, application of individual analytical methods including utilization of petrographic thin-sections and integrated interpretation of the results together with the customer.