Research On Mechanism And Numerical Simulation Of Artificial Gas Cap Displacement Of Oil

The oil and water interface of the reservoir will rise obviously after the energy exploitation or water injection provided by the edge and bottom flooding.At this time,the productivity of the production wells in the lower profile of the reservoir increases rapidly,which affects the normal production of production wells.However,there are still a lot of remaining oil in the high part of the reservoir,and it is difficult to extract the "attic oil" by using the original mining method.The top gas injection can be used to form a secondary gas head at the top of the reservoir,and the residual oil is driven downward to effectively recover the remaining oil so as to improve the oil recovery.In this dissertation,the mechanism of top oil displacement by artificial gas is studied and the main mechanism is summarized.The regulation of the top edge of artificial gas is studied by using one-dimensional equation of gas drive.By using numerical simulation to study the influence of the concept of model formation dip and gas injection rate of artificial gas cap shape and oil displacement effect,morphological changes and influence factors of artificial gas cap Block B Well C oil displacement.The results of this paper are as follows:(1)A one-dimensional mathematical model of gas flooding has been established,and the law of the top edge motion of the artificial gas has been obtained by solving the problem.The greater the formation pressure,the greater the distance of the top edge of the artificial gas corresponding to the same gas saturation;the greater the gas injection rate,the faster the top edge of the artificial gas moves.(2)A conceptual geological model is established by means of numerical simulation,and the influence of formation dip angle and gas injection rate on the top displacement of artificial gas is obtained.Using artificial nitrogen injection gas driving oil,dip in 10 degrees or 10 degrees above can get good flooding effect,and dip the greater oil displacement effect;artificial gas cap shape increases with the increase of gas injection rate.(3)Through the numerical simulation study of Block B Well C,we obtained the maximum reasonable gas injection rate for Block B Well C block is 20000 m3/d.In the premise of gas injection under the increasing gas injection rate can increase the cumulative oil production and improve the recovery rate.It is suggested that the gas injection rate of Block B Well C shall be 15000 m3/d~20000 m3/d.It is suggested that wells should be shut for less than 3 months.