| Thermal recovery by steam injection is an effective EOR method for heavy oil reservoir. But in the process of steam injection, "steam overlying" and "steam channeling" will cause adverse consequences of steam loss and sweep efficiency decrease, influencing the recovery effect. Unfavorable mobility ratio is one of the essential reasons causing steam overlying and channeling. It is an efficient way to promote the sweep efficiency of steam flooding through mobility ratio controlling. In order to improve the mobility ratio in steam injection process, the following work was carried out in this dissertation.Firstly, high-temperature foaming agents were prepared and evaluated in laboratory. First of all, anionic surfactant AGS-8 and PMP-1 were prepared. Next, the static and dynamic experimental evaluations were carried out to compare the properties of foaming agents AGS-8, PMP-1, F240B, SuntechⅣ, ATS, AOS2024 and LD-Foam. The results showed that in terms of temperature resistance, foam volume, foam half-life, salt tolerance, oil resistance, the agents of F240B, AGS-8 and PMP-1 have the best performance. F240B, AGS-8 and PMP-1 can generate large resistance factors, which decrease a little as temperature increasing, indicating that F240B, AGS-8 and PMP-1 can achieve good effect in steam mobility control. When flooded by 0.5pv, the displacement efficiencies of F240B, AGS-8 and PMP-1 are 65.3%,58.9% and 51.6% respectively. Finally, the sensitivity factors of steam mobility control by foam were studied. The results showed that for low concentration of foaming agent, the resistance factor of foam increased rapidly as the concentration increase, while for the foaming solution with concentration over 0.5%, the increasing tendency of resistance factor becomes weaker. The mobility control ability of foam decreased dramatically as the oil saturation increases to above 15%. The resistant factor increased as the increase of permeability, and after the permeability was higher than 8μm2, the resistant factor remained basically unchanged. The resistant factor was high as the gas-liquid ratio is in the range of 0.5～1.5.Secondly, chemical agent for controlling the mobility of steam condensation water was selected and evaluated. At First, in view of the characteristic of temperature change at the temperature front during the process of steam injection, the method to control mobility of water phase by chemical agent with special properties was put forward. The principle is to decrease the permeability of the condensation water through partially blocking the water flow channel by the temporary and selective crystallization of special chemical agent. Next, the mechnism of water phase mobility control by chemical agent was analyzed theoretically, the possibility of chemical agent to reach the steam front was demonstrated, and the influences of chemical agent on mobility ratio and displacement efficiency of steam flooding were analyzed. Then, according to the quality demand of mobility control agent, MCA was selected to be used as the agent to control the mobility of water phase in the process of steam flooding. Finally, laboratory simulated experiments on condensation water mobility control were carried out. The results showed that, when the core was saturated by MCA with a saturation of 1%pv, the permeability of the core was decreased to about 20% of the initial value; with the MCA was gradually dissolved and swept out of the core, the saturation decreased and the permeability recovered gradually, the permeability can return to above 93% of the initial value, showing that the permeability reduction caused by the crystallization of MCA is temporary and invertible. When displaced by about 2pv, the average efficiency of the displacements without addition of MCA was 53.24%, while the average efficiency of MCA added displacements was 61.25%, the application of MCA can increase the efficiency of the linear displacement experiments with a value about 8% of the OOIP averagely.Thirdly, catalysis system for heavy oil in-situ upgrading was prepared and evaluated. First of all, the possibility and reinforcement of viscosity reduction by aquathermolysis of Liaohe heavy oil were investigated. The results showed that after aquathermolysis for 24 hours at 240℃, the viscosity reduced 7.26%, and the content of saturated hydrocarbon and aromatic hydrocarbon increased, while the content of resin and asphaltene decreased a little; oil sands can increase the viscosity reduction of the reacted heavy oil about 1 time; 0.3% ferrous sulphate together with oil sands can decrease the heavy oil viscosity by 55.02%, and after the aquathermolysis under the action of tetralin and oil sands, the viscosity reduction of heavy oil can increase about 40%, showing the Liaohe heavy oil can occur aquathermolysis, and the catalyst and hydrogen donor can reinforce the viscosity reduction by aquathermolysis. Next, the main agent of in-situ upgrading catalysis system was developed with nickel and cobalt contained minerals. The performance evaluation showed that the thermal stability of the developed catalyst is good, it is compatible with formation water, and has coordination with reservoir minerals; methylbenzene or mixed benzene was selected as the hydrogen donor for the catalytic aquathermolysis; sulfonic acid anionic surfactant was selected as the auxiliary agent to gain further improvement on the in-sity viscosity reduction. The formula of catalysis system developed is 0.2% cobalt/nickel oleate mixture,1.0% mehtylbenzene,0.3% mahogany sulfonate. Finally, the results of laboratory evaluation on the catalysis system developed showed that after aquathermolysis with the action of catalysis system, the quality of heavy oil is upgraded, the content of saturated hydrocarbon and aromatic hydrocarbon increased, while the content of resin and asphaltene decreased obviously, the content of carbon in heavy oil decreased, while the content of hydrogen increased, and the content of sulphur decreased markedly, the viscosity decreased inconvertibly with a viscosity reduction ratio of about 90%, as a result, the mobility of the heavy oil was improved.At last, the implementation program for field application of mobility control agents was preliminary designed. More work should be done in the future to optimize the injection volume, injection time and injection pattern and so on.
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