Study On The Development Methods Of Combination Huff-puff In Ultra-heavy Oil Reservoir

Viscosity reducer and carbon dioxide - assisted steam stimulation is one of the important ways to improve the recovery ratio of heavy oil. This paper mainly researches the application of viscosity reducer and carbon dioxide-assisted steam soak in Ultra-heavy Oil reservoir. The changes of parameters in heavy oil production have studied by numerical simulation and reservoir engineering to find the proper methods to develop heavy oil. The studies show that thermal ternary combination huff-puff is a effective way to improve recovery ratio of Ultra-heavy Oil reservoir and it is also a direct example of other similar Ultra-heavy oil reservoir.In development parameter change rule research, this paper mainly discuss the mechanism of cyclic steam stimulation, viscosity reducer and carbon dioxide to improve effect of steam stimulation and study the effect of steam injection intensity,the pressure of steam injection,steam injection rate, steam quality, viscosity reducer volume and carbon dioxide volume. Based on the Zheng 411 geological conditions and fluid parameters, the 3D simulation model was built. Based on the history matching, influential factors of thermal ternary combination huff-puff are studied, such as crude oil viscosity,oil effective thickness,vertical permeability and horizontal permeability ratio,stratigraphic rhythm and so on. Well spacing pattern,horizontal wells layer,the length of horizontal wells are optimized. The results show that the spacing pattern with horizontal wells is better than compound mode of horizontal well and vertical wells; the horizontal wells layer should be in the middle of layer 3; the optimal length of horizontal wells is 250m in terms of economic cost. Optimization of extraction parameters mainly include the optimization of viscosity reducer injection method,viscosity reducer injection volume,viscosity reducer injection timing,carbon dioxide injection method,carbon dioxide injection volume,carbon dioxide injection timing. When viscosity Reducer injection volume of the cycle is 60t, second, third, fourth, fifth cycles implantation; carbon dioxide injection volume of the cycle is 200t, third, fourth, fifth, sixth cycles be injected can get both higher recovery ratio also higher OSR. Frother injection method,frother injection volume and nitrogen gas injection volume are optimized. The results show that optimal frother injection method is plug; optimal frother injection volume is 40t; proper gas fluid ratio is 1:1. Compared to the normal steam soak, the cumulative oil of every cycle is certainly improved. Cycle production time is increased, enhance cumulative oil production of 6 cycles 1825t, enhance recovery 2.77%.