Experimental study on the temperature effects of foamy oil flow in porous media

The foamy oil flow phenomena occur in the primary production period of heavy oil during the solution gas derive have been considered as the key factor that leading to unusual high recovery efficiency. Temperature, as a critical fundamental property, will largely affect foamy oil behavior. The temperature effect on foamy oil behavior has not yet been fully understood. There are controversial opinions upon the effect of temperature which requires further verification. Therefore, it is important to study the influence of temperature on foamy oil flow. In this study, the sand-pack pressure depletion tests under different temperatures are conducted to investigate the temperature effect on foamy oil behavior. The experimental study suggests the negative effect of temperature on the foamy oil flow. As the temperature increases from 20 °C to 50 °C, the foamy oil behavior is weakened due to the oil viscosity reduction. Lower oil viscosity causes less gas being trapped by the oil phase and increases the gas phase mobility. Consequently, the oil recovery factor reduces form 19.35% to 6.96% and both the gas recovery factor as well as cumulative gas-oil ratio increase. In addition, the second foamy oil flow region is observed during the experimental study, where foamy oil flow appears second time during the late stage of production after oil–gas two phase flow region. Gas is continuously released from the oil phase at the two-phase flow region and causes an increase of oil viscosity. As a result, the oil recovery is enhanced at the late stage of production.