Abstract

The phase behavior and physical properties of heavy oil have been considered of great importance during cold production process. In this study, constant composition expansion and compression (CCEC) tests were performed to measure and evaluate the live oil expansion and compression under various temperatures and pressures conditions through a PVT apparatus. The live oil viscosity and density were also obtained from the the experiments. CCEC tests were conducted using the recombined live oil (with specified gas-oil ratio) in the PVT cell without mixing by utilizing three different constant volume change rates (i.e. "Fast Rate", 1.5 cc/min; "Moderate Rate", 0.015 cc/min; and "Slow Rate", 0.0003 cc/min) at 75°C and 15°C. During the expansion period, the total volume was monitored continuously until it reaches the cell maximum. Following the expansion process, the oil and gas were compressed back to the initial pressure following the same rates as the expansion stage. The P-V diagram has been plotted according to the PVT data, therefore pseudo-bubblepoint pressure was able to be determined based on the slope change of the P-V curve. It is found that pseudo-bubblepoint pressure determined at 75°C is higher than that of 15°C. For different volume expansion rates, a faster rate results in a lower determined pseudo-bubblepoint pressure, indicating a strong foamy oil behavior. On the other hand, however, the volume compression rate did not significantly affect the tendency of total volume reduction curve regarding the PVT experiments. The results obtained from the current study will facilitate industry to make better design for heavy oil reservoir development.

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