Understanding the Factors Influencing the Formation and Control of Calcium Naphthenate Solids and Stabilised Emulsions Using a Novel Laboratory Flow Rig

摘要

The formation of calcium naphthenate solids and stabilised emulsions continues to be a major flow assurance issue. The ability to replicate the conditions under which naphthenates form in the laboratory has, until recently, been an unresolved challenge. Recent work by the authors has resulted in improved test methodologies, utilising a novel flow rig. The rig enables the study of the formation and control of naphthenate solids and stabilised emulsions under fieldrepresentative conditions, and allows the prediction and control of their occurrence in the varying production conditions that may be experienced over a field's lifetime. This paper describes the use of the flow rig to test a number of crude systems, some of which have known calcium naphthenate problems, and some of which are known to have no calcium naphthenate issues. The results from the flow rig have been compared with field observations and show excellent correlation. Data is then presented which more directly assess the influence of a number of variables, such as water-cut, brine composition, bicarbonate level, and pH, on emulsion stability and naphthenate formation than has previously been possible under conventional laboratory test methodology. This work therefore extends our understanding of “practical” naphthenate formation.