Research On Steam Huff And Puff Efficiency Improvement Of Gas-assisted Horizontal Wells In Heavy Oil Reservoirs In Jinxie 102

With the increase of huff and puff rounds in heavy oil reservoirs,the formation pressure decreases,and the production of horizontal wells in heavy oil reservoirs gradually decreases.Therefore,how to improve the productivity of horizontal wells in heavy oil reservoirs has become an important issue.In order to improve the productivity,it is necessary to optimize the gas-assisted steam injection parameters for horizontal wells.In this thesis,the heat transfer model of multi-component thermal fluid in vertical wellbore is established first.The calculation results show that when 7 t/h of water vapor contains 2000 Nm~3/h of nitrogen or carbon dioxide,the quality of the bottom-hole steam at a depth of 900 meters can be increased by more than 0.1.Considering the fluid outflow in the horizontal well,a multi-component thermal fluid variable mass flow model is established.The effects of different pipe structures and heterogeneity on the horizontal well were calculated.When the steam is injected into the sliding sleeve,the amount of steam absorbed at the heel end is larger;when the steam is injected at the toe,the amount of steam absorbed at the toe end is larger;when the steam is injected into the heel,the steam intake profile along the way is the most balanced but the steam quality is much lower than the former two.The specific effect of heterogeneity on the steam intake profile along the well is that the steam intake in the high-permeability part increases significantly.When auxiliary gas is added,the steam profile along the well becomes more uniform as the steam injection pressure increases.With the increase of steam quality,steam injection speed and auxiliary gas volume,the steam volume at the heel end will increase.Combined with the actual situation of the Jinxie 102,the distribution of remaining oil around the horizontal well at the end of the fitting is analyzed.And by the steam injection-production characteristic curve,it is predicted that when the steam huff and puff limit oil-gas ratio is 0.25,the oilfield limit production is 15.72×10~4t,and the steam huff and puff ultimate oil recovery rate is 22.077%.The simulation of adding auxiliary gas to the horizontal well in the Jinxie 102shows that the auxiliary effect of carbon dioxide is much better than nitrogen.When the flue gas is add,the synergistic effect of nitrogen and carbon dioxide appears in the wells near the edge water as the volume fraction of carbon dioxide increases.Comparing the optimal scheme with the scheme without auxiliary gas,when auxiliary gas is add,except for the wells whose edge water has broken through,the oil increase of other horizontal wells is all above 200 m~3,and the oil-steam ratio is improved above 0.1.