Numerical Simulation Of Carbon Dioxide Throughput In Horizontal Wells Of Shallow Heavy Oil Reservoirs

Heavy oil occupies very important position in the world oil resources. As the main resource, it distributes in the land and sea broadly, and the heavy oil in the land takes about one in fifth of the total crude oil, therefore was started to exploit earlier by people. There are many methods to exploit it, the important three are stream injection, gas push and cyclic gas injection. Although the first one is used mostly in the heavy oil exploitation, formation energy and pressure decrease quickly, even more it will lead emulsification near well bore, reduce permeability around it, in the end, decrease the oil production. Owe to CO2huff and puff can complement energy in some degree, let formation pressure keeps in a certain level or goes down slowly, and more, CO2is acid gas, it can dissolve in the water to form acid solution, it also has the effect of demulsification and acidizing blocking removal, then increase the permeability. For that, CO2huff and puff becomes the new main exploitation method recently.As for heavy oil reservoir, especially the thin heavy oil reservoir with bottom water, there is aneffective method that uses horizontal well to raise production. Comppare with vertical well, horizontal well has Horizontal well has larger connection area between well bore and reservoir, can improve drainage area, and prevent or slow down coning in bottom water and so on, all these provide favorable production condition for the heavy oil reservoir with low transmissibility to increase production. Using horizontal well to CO2huff and puff will improve the small effect area and radius and low injectability of vertical well. Therefore the exploitation of thin bottom water heavy oil, Using horizontal well to CO2huff and puff has huge potential.This paper bases on the mechanism of CO2huff and puff, uses numerical simulation theory and technology, build conception model, gains the superiority of horizontal well CO2huff and puff, and researches the effect of main governing factor(inject speed, the volume, shut time, exploit speed and the interval in two cyclic) and reservoir sensibility(reservoir thickness, reservoir pressure, reservoir permeability, reservoir porosity, reservoir saturation and horizontal well length), at last compares with the practical production well, get the most reasonable conclusion, such as the best oil thickness is about10to12meters, the best oil saturation before CO2huff and puff is50percents, the bigeer of the porosity and the longer of the horizontal well is the better of the effect and the best cycle of real reservoir is two. all of these provide the basis that can be referred for the exploitation of thin bottom water heavy oil reservoir.