Study On Tube Flow Characteristics Of Heavy Oil Under Water - Based Foam

With the exploitation of conventional crude oil, the positon and function of heavy oil is increasingly important.Some drag-reduction methods for the heavy oil flow are generally used to wholly treat the oil, and they have different shortages, including high energy consumption, a large amount requirement of light oil or diluent, and large treatment volume. Under the inspiration of microbubble drag reduction theory, the flow properties of heavy oil flow under the lubricant action of aqueous foam is simulated, which provides a new way for the drag reduction of heavy oil pipe transportion and gives a certain theoretical guidance for field practice.Focusing on the heavy oil pipe flow characteristics under the action of aqueous foam, the basic properties of Tahe heavy oil THCO1and201simethicone were tested and analyzed, and then one kind of simethicone was selected as the simulation oil for heavy oil transportation experiment. After the evaluation of the performance of different qualities of foam, one kind of foam was used in lubricating drag reduction experiment. The indoor experiment method of foam-lubricating drag reduction was built, and then the drag reduction efficiencies of simethicone-aquoues foam flow in pipe with different inclination angles (both upward transportation) were studied experimentally. Through the analysis of simethicone-aquoues foam flow patterns and pressure drop results, the theoretical models of simethicone-aquoues foam flow pressure drop in pipe with different inclination angles were built, and compared with the experimental values. With the use of ANSYS FLUENT14.5software, the influences of aqueous foam/simethicone flow ratio, pipe inclination angle, and foam quality on the drag reduction efficiencies were simulated numerically, which helps to achieve further understanging of the flow conditions of lubricating drag reduction.The results showed that:At20℃,2#simethicone can been used as the simulation oil for heavy oil-aquoues foam lubricaton drage reduction experiment. Foam2(quality is0.5, wet foam) prepared from aquous foam system-2seclected for the mentioned above lubrication experiment. In horizontal pipe, the flow pattern changes are almost all stratified flow with top foam layer and bottom simethicone layer, but there exsits foam drainage at the bottom pipe wall. When the flow rate ratio is between0.2and0.8, the drag reduction efficiency is relatively high. The change law of flow patern in inclined pipe is similar with that in horizontal pipe. When the foam/simethicone flow ratio exceeds0.3, it has little relationship with the drag reduction efficiencies (all over50%), and the biggest efficiency is73%. In vertical pipe, when the foam/simethicone flow ratio reaches0.22(Qo=8.33L/min), there exists a significant drag reduction efficicency (more than50%), and when the ratio reaches0.50(Qo=8.33L/min), a complete foam annulus is nearly formed, which leads to a high drag reduction efficiency (more than60%).With the increasing of simethicone flow rate, the above foam/simethicone flow ratio and corresponding drag reduction efficiency both increase slighty. A stable silicon oil-foam center annulus flow is more easily formed in vertical pipe than in horizontal pipe. For horizontal pipe, the relative errors between the calculated values based on simethicone-foam flow pressure drop theoretical model and experimental values are generally higher than300%, but these can be reduced to less than10%while the oil flow friction item of the model is multiplied by a modified coefficient β of0.4019. For inclined pipe, the pressure drop theortical model is more applicable for the situations that foam/silicon oil ratio of is between0.2and0.8, the error for pipe with30°inclination and60°inclination angle is respectively±30%and±20%. For vertical pipe, when foam lubricating layer isolation is formed between pipe and simethicone, the errors between the calculated values and experimental values are±40%. Known from the numerical simulation results, when the aqueous foam/simethicone flow ratio is between0.2and0.5, the drag reduction efficiencies are all very high for pipes with different inclination angles. The foam lubricating drag reduction effect in vertical pipe is better than in horizontal and inclined pipe. The drag reduction efficiency increases with the decrease of foam quality obvouisly.