(425j) High Pressure Calorimetry and Thermal Analysis Applied to Flow Assurance Related Topics

With the increasing number of deep offshore operations, the operators and the service companies have to solve more and more complex technical challenges related to flow assurance. In both gas transportation and oil exploration, gas hydrate formation can modify the flow characteristics and in some cases lead to blockages and catastrophic events. Thus it is important to prevent the formation of hydrates and ensure optimal operational conditions.

The usual way to determine the thermodynamic conditions of the formation of hydrates in drilling mud formulations is to use a PVT cell with visual observation and simultaneous temperature and pressure measurements. This technique requires heavy instrumentation and often cannot be used if solid particles are present in the formulation.

Another crucial topic for the flow assurance is related to the precipitation of paraffins contained in crude oils, which can occur in reservoirs, pipelines and process equipment resulting in a reduced production and/or a blocked line. To evaluate the possible wax precipitation of a given fluid, the wax appearance temperature (WAT) has to be determined. Most of the studies about WAT are carried out under atmospheric pressure. However, WAT determination under experimental conditions close to real operating ones (particularly under pressure) is a key point to predict the crude oils behavior.

High pressure calorimetry is another way to determine compositions, dissociation enthalpies and heat capacities of hydrates and to provide a detailed characterization of the crude oil in order to prevent the wax precipitation. Different examples of how this technique can be used to determine the thermodynamic properties and the kinetics of hydrate formation, as well as the WAT in crude oils under pressure will be presented.

The Differential Scanning Calorimetry technique (using microDSC 7 or microSC) enables study of samples at controlled high pressure up to 1000bar and temperatures between – 45°C and 120°C. For experiments at lower temperatures (-196 to 200°C) BT 2.15 can be used.