Performance Evaluation Of Composite Hot Foam System After Polymer Flooding

According to the principle of rocket's engine, the technology of Composite hot foam flooding is proposed. It is that combustion of diesel oil in the combustion chamber produces high temperature and high pressure flue gas, which mixes with the aqueous solution of foaming agent to form Composite hot foam flooding system in order to enhance oil recovery. The system has not only the advantage of foam flooding and thermal flooding, but also playing some roles of carbon dioxide and nitrogen flooding. Therefore, it is a new method of tertiary recovery.Firstly, this paper investigated into foam flooding technical development at home and abroad and analyzed the Composite hot foam flooding mechanism.Secondly, using hot flue gas as foaming gas, the foamability of a variety of surfactant was tested through air current method. Using foam composite index, the foamability was evaluated. Consequently, foaming agent HY-3 which has high temperature resistant was selected. At the same time, gas-liquid ratio, concentration of foaming agent, water salinity, foam stabilizer, pressure, temperature and other factors were researched how to effect system properties, and adsorption of foaming agent in porous media was measured.Thirdly, hot flue gas was chosen as foaming gas and surfactant HY-3 was chosen as foaming agent. Through simulating the actual formation temperature and pressure conditions, using high pressure thermal foam displacement devices, high pressure Composite hot foam seepage experiments were performed in order to study the effect of core permeability, gas-liquid ratio, heterogeneity and injection rate on seepage capacity of the Composite hot foam in porous media.Fourthly, under the high-pressure conditions, polymer and sodium carboxymethyl cellulose were chosen as foam stabilizer and Composite hot foam flooding experiments were carried out. In the experiments, size and composition of foam slug, injection rate, core permeability, temperature and other factors how to affect the Composite hot foam system displacement effect was studied.Finally, numerical simulation was carried out. In accordance with the actual injection-production well groups, mathematical model and geological model were established. And then using the model, history matching of water cut and degree of reserve recovery were also performed for the purpose of optimization of the Composite hot foam flooding program.The research shows that the surfactant HY-3 has better foaming effects, which has strong foaming performance and high temperature resistance. Seepage flow experiments show that the higher permeability is, the bigger resistance coefficient is, and the better sealing characteristic of foam is. Under the same permeability, sealing characteristic of foam in heterogeneous cores is better than that in homogeneous cores. And the greater gas-liquid ratio is, the bigger foam flow resistance is. When gas-liquid ratio reaches 1:1, stable foam can be formed. Furthermore, the higher injection rate is, the stronger foam is, and the better sealing characteristic of foam is.Composite hot foam system has good flooding effect, and along with the foam slug and core permeability increasing, displacement differential pressure and foam flooding recovery increases; injection rate has little effect on the Composite hot foam flooding recovery. When injection rate increases from 0.35mL/min to 1.00mL/min, foam flooding recovery increased by only 1.7%. After polymer flooding, Composite hot foam flooding recovery increased with the temperature increasing. When reservoir temperature is 70℃, Composite hot foam recovery reaches 11.39%; when reservoir temperature is 90℃, Composite hot foam recovery reaches 12.84%; in the temperature of 120℃,Composite hot foam recovery reaches 16.29% after the polymer flooding. Three-tube parallel experimental results show that after foam was injected, flooding and diversion effect has been improved obviously in medium and low-permeability cores, which indicates that Composite hot foam system plays a good role of profile control.Therefore, the research indicated that the Composite hot foam flooding was a new tertiary recovery technology, which could increase oil recovery effectively after polymer flooding.