When produced and transported from the reservoir to processing facilities, fluids experience a drop in pressure. This will release dissolved gases that can cause the fluids to foam. Evolved gas is removed in a separator, but foaming can lead to liquid carry-over into the gas stream, disrupting gas processing. Stable foams may also upset separator level control.
Using gas-sparging rigs developed at KAT, foaming tendency is measured in terms of volume or height of the foam column and foam stability in terms of its collapse time.
Temperature and gas flow may be altered to suit field conditions. The rate of gas release can also be measured by monitoring the change of density with time. The performance of 'antifoam' chemicals can easily be examined by dosing the crude sample under test.
Crude oil is frequently produced with water that must be separated and removed to meet export specifications. The behaviour of emulsions, including stability and viscosity, are not only dependent on temperature, water-cut and composition but are also highly dependent on the severity and duration of mixing
At KAT, emulsions are prepared under prescribed mixing regimes, with either a laboratory blender or homogeniser, to simulate anticipated production conditions [i.e., representative of low turbulent flow to high shear ESP pumps]. Measurement of percentage water drop-out over time along with visual inspection of the separated water quality, emulsion pad, and droplet size and distribution by microscopy are used to assess subsequent water separation.
The apparent viscosity of a stable emulsion formed from a waxy oil can be several orders of magnitude higher than the dry oil at water cuts approaching the inversion point. Depending on the stability of the emulsions, Viscosity vs. Temperature profiles at several shear rates [ranging from 1 to 200 s-1] or controlled-shear flow curves [up to a maximum 1000s-1] at a range of discrete temperatures can be performed at KAT to characterise the potential impact on the flow performance of a system.