| As the typical deep heavy oil reservoirs,Xiaowa oilfield has been at the later stage of multiple steam stimulation,and water content of crude oil is at ultra high level for a long time.The production and recovery efficiency are decreasing with reservoir pressure dropping.This situation leads to increasingly imbalance between supply and demand.Conventional production technology is unable to meet the development needs of the Xiaowa oilfield.Therefore,a new type of compound oil displacement agent is urgently needed to adapt to the oilfield with the specific crude oil properties to further improve the oil recovery.Based on the historical development data,this paper comprehensively introduced the geologic structure and exploitation status of Xiaowa oilfield.And the variations of some critical parameters,such as production,ratio of gas to oil and reservoir pressure were achieved.And the main problems faced by the deeply development at the present stage were summarized.Based on the oil-displacement mechanism of the alkali-surfactant-polymer flooding technology,the new displacement agent solution were prepared to determine the physical and chemical properties.The result shows that the solution is a kind of alkalescent liquid with a density close to water,it has good solubility,good compatibility and salt resistance with the formation water,and good thermal stability,and the viscosity of the original liquid decreases with the increase of temperature.Laboratory experiment on the interfacial tension of oil displacement agents with different concentration,viscosity reduction of crude oil and laboratory core flooding were respectively carried out.The results show that the interfacial tension decreases continuously with the contact of oil displacing agent and crude oil,the greater the concentration of oil displacement agent is,the lower the interfacial tension is;The oil displacement agent can effectively reduce the viscosity of the crude oil,under certain water content,the greater the concentration of the oil displacement agent is,the better the effect of viscosity reduction is;Emulsification and displacement performance of oil displacement agent are productive.Based on the indoor experimental results of oil displacement,the field test of composite flooding agent flooding was carried out by selecting 4 wells with different layers,different parts and different steam injection periods.The results of field test confirm that there is obvious optimized effect of the new agent on various operation indexes of production wells that the steam injection pressure is reduced to 10.6MPa from the 12.6MPa,the daily liquid of the oil well isincreased to 57.8m3 from 44.2m3,and the daily oil production is also increased to 10.6t from 9.4t,the input-output ratio comes up to 1:2.4 exceeding the target of 1:1.5,which is of great significance for improving oil displacement efficiency and realizing deeply development of Xiaowa oilfield. |
