Technology Research In Heavy Oil Exploitation By Gas Injection

As the oil and gas exploration and development further in depth, the proportion of the reserve hard to develop increases. The steam injection pressure is difficult to realize and the heat loss is far more when exploit the deep heavy oil .So thermal recovery methods doesn't adapt to these reservoirs. Gas injection is an important way of tertiary oil recovery, in the first place, at a certain pressure, injection gas can dissolve in the heavy oil through numerous contacts with it, and can reduce viscosity effectively; in the second place, in regard to buried deeply, thin oil reservoir, gas injection is more cost-effective than thermal recovery. Therefore, the study of gas injection to increase heavy oil recovery has great practical and economic significance.In the research of this paper, according to the investigation in the technology of gas injection development over the world, the mechanism and the influence factors of heavy oil reservoir development by gas injection have been studied. Studied the influence law of reservoir characteristic parameters(oil saturation, formation porosity, reservoir depth, permeability, reservoir thickness) and injection/production technologic parameters(periodic gas injection quantity, daily liquid rate, soak time, bottom-hole pressure, injection rate, gas injection pressure) on the development of heavy oil reservoir(nitrogen huff and puff, hydrocarbon gas huff and puff, carbon dioxide huff and puff)by using reservoir numerical simulation method. Optimize periodic gas injection quantity, daily liquid rate, soak time, bottom-hole pressure, injection rate, gas injection pressure by using orthogonal design method based on periodic oil production. Design the optimization scheme of heavy oil development by gas injection. Finally, through the analysis of nitrogen huff and puff, hydrocarbon gas huff and puff, carbon dioxide huff and puff, select the best method of heavy oil reservoir by gas injection.