Microscale evaluation of natural anti-agglomeration behavior of oils via gas hydrate interparticle cohesive force measurements

Abstract

Gas hydrate formation in flowlines presents one of the major threats to flow assurance. Exploitation of a non-plugging oil, which contains hydrate anti-agglomerant (AA) properties is an attractive hydrate management strategy. Hence, it is important to evaluate an oil for its potential as a non-plugging oil, considering its significant economic savings, since the properties to prevent hydrate plugging already exist in the oil without additional cost. In this work, a High-Pressure Micromechanical Force (HP-MMF) apparatus was used to quantify the cohesive forces between hydrate particles to provide insight into the natural anti-agglomeration tendencies of oils. Investigation was conducted using seven oils (A – G). Based on the significant reductions ranging from 81 to 99.8% to the cohesive force observed for oils A – E, these oils were categorized as potential non-plugging oils. The cohesive force reductions are attributed to the presence of natural surfactants in these oils that take the role as AAs. Increase in water content in the presence of non-plugging oils led to higher cohesive force, which weakened the non-plugging oil’s performance in preventing hydrate agglomeration, but can be overcome by salt. Oils F and G showed no significant reductions to the hydrate cohesive force, therefore are classified as plugging oils. These results show that the microscale evaluation in the HP-MMF can be applied to identify natural anti-agglomeration behavior of different oils, providing important insights to optimize hydrate flow assurance strategy in the field.