Ethanol based foamed asphalt as potential alternative for low emission asphalt technology

Foamed asphalt typically relies on water as a foaming agent because water becomes gaseous at elevated temperatures, generating numerous tiny bubbles in the asphalt and causing spontaneous foaming. In this study, ethanol was used as a potential alternative to water as a foaming agent. Ethanol is expected to be a physical blowing agent in the same manner as water, except it requires less energy to foam due to its 78 ℃ boiling point. This study compares the performance of water and ethanol as foaming agents through the measurements of rotational viscosity, the reduction in temperature during foaming, and volatile loss. The ethanol-foamed asphalt binders were prepared at 80 ~C and 100 ~C, while the water-foamed asphalt binders were prepared at 100 ~C and 120 ~＇C. Additionally, the rolling thin film oven （RTFO） was used to generate short-term aging of the foamed asphalt binders. A rotational viscometer was used to determine the viscosity of the asphalt binders at 80 ~C, 100 ~C, 120 ~C, 140 ~C, and 160 ~C. Overall, ethanol can function in the same manner as water but requires less energy to foam. It is proven based on the smaller drop in temperature of the asphalt binder foamed using ethanol compared with that prepared with water. This is due to the lower latent heat capacity of ethanol, which requires less energy to vaporize compared with water. Through the rotational viscometer test, ethanol performs better in lowering the viscosity of asphalt binders, which is essential in allowing produc- tion processes at low temperatures, as well as a better workability and aggregate coating. Ethanol can be expelled from the foamed asphalt binders at a higher rate due to its lower boiling point and latent heat.

Numerical simulation of foam diversion acidizing in heterogeneous reservoirs

Foam diversion acidizing can effectively solve the problem of acid distribution with severe heterogeneity between and within layers.Based on the foam diversion principle,the gas trap theory,and volume conservation principle,the foam slug diversion acidizing model was established and solved considering the change of bottomhole temperature and deviation factor of foam.The simulation results show that the change of temperature has a great influence on the diversion effect at the initial stage of injection,but a small influence at the middle and late stage.The effect of temperature on the highly permeable layer is greater than that of temperature on the low permeability layer.The deviation factor of foam is mainly controlled by temperature at the initial stage,and by pressure at the middle and late stage,and the whole process shows a downward trend,which has little influence on the diversion effect.The quasi-skin factor of gas trap is the most important parameter that influences the effect of foam diversion.The water saturation of the low permeability layer rises faster than that of the high permeability layer,and the effect of diversion is obvious.The research results have a strong guiding significance for foam diversion acidizing.