Experimental Investigation of PVT Properties of Foamy Oil

ABSTRACT

Investigating the properties of live heavy oil, as the pressure is dropped from the original reservoir pressure to ambient pressure, can aid in interpreting and simulating the response of heavy oil reservoirs undergoing primary production. Foamy oil has a distinctly different and more complex behavior compared to conventional oil as the reservoir pressure depletes and the gas leaves solution within the oil. Solution gas separates much more slowly from the oil, thus conventional PVT measurements are not trivial to perform. In this paper, we present novel experiments that utilize x-ray CT scanning and low field NMR techniques. These non-destructive tomographic methods are capable of providing unique in-situ measurements of how oil properties change as pressure depletes in a PVT cell. Experiments were initially performed at a slow rate, as in conventional PVT tests, allowing equilibrium to be reached at each pressure step. These results are compared to non-equilibrium tests, whereby pressure declines linearly with time, as in core flood experiments. The findings presented in this work lead to interesting insights into the unique nature of foamy oil, and valuable data for predicting foamy oil properties.

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