ABSTRACT

Following our preceding papers on the theoretical underpinnings and laboratory development of the micelle detection method, this paper will describe a variety of case studies where it has been applied to systems to investigate the field-relevant functional dose of corrosion inhibitor. The relationship between the critical micelle concentration (CMC) of surfactant-based corrosion inhibitors and inhibitory efficacy has been recognized since the early 1980's. By coupling these academic findings with recent advances in analytical hardware and chemical markers which provide the ability to detect micelles rapidly within oilfield brines, useful information can be accessed in field conditions related to the physical action of the inhibitor rather than a chemical residual. The absence of micelles can be used to diagnose an under-dosed system in situ or the enumeration of present micelles can be used to fine-tune the inhibitor concentration for balancing inhibitor activity and oil-water separation.

Case studies will be presented which demonstrate the use of the technology for 1) simulating field fluids (both production and water injection) over an inhibitor concentration range as an initial estimate for field dosage, in combination with other screening tools, 2) exploring the effect of different crude oils on inhibitor micelles, 3) the effect of solids within a fluid system on the availability of injected inhibitor, 4) field analysis of a MEG reclamation system to monitor rapid accumulation of surfactant CI components, 5) measurement of production brines in different fields for the presence of corrosion inhibitor micelles. The most prominent finding across these studies was the significant impact that changes in field conditions can have on available inhibitor and how such changes are often unpredictable or very difficult to simulate in lab conditions. The need for timely field data was emphasized from the results of field analysis.

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