Study On Oscillatory Injection In Middle And Late Development Of Steam Flooding In Heavy Oil Reservoir

Steam flooding is a widely used EOR technology in the development of heavy oil reservoirs.When steam flooding develops into the middle and late stage,the number of steam channeling wells increases,and the contradiction between injection and production increases,and the output of wells decreases rapidly.If we continue to use conventional continuous steam injection mode for heavy oil development,we will further aggravate the degree of steam channeling.Therefore,it is of great significance to study the development technology and mechanism of post injection steam in the development of heavy oil reservoirs.This paper is based on the development of steam flooding in the Qi 40 heavy oil reservoir of Liaohe Oilfield,and on this basis,the mechanism of improving the recovery of heavy oil by intermittent steam flooding is carried out through the reservoir numerical simulation method.The concept model is established to study the mechanism of intermittent steam flooding to improve the recovery of heavy oil,to determine the key mechanism of intermittent steam flooding to improve the steam specific volume,to promote the redistribution of oil and water and to reduce the gas channeling to improve the recovery rate of intermittent steam flooding.According to the change law of the volume of steam cavity and the temperature field during the stop injection,it is determined that the volume of the 30 d steam cavity decreases less than 5%,and the formation temperature is only 8 c.On this basis,the injection / stopping time ratio is studied.By comparing 4 different schemes,considering the actual production in the field,it is determined that steam injection 30 d is the best injection / stop time ratio for stopping 30 d.According to the actual production dynamics of the 4 typical wells in the 40 western regions,the fine geological modeling and the numerical simulation history fitting are used to carry out numerical simulation research on the selected well group.Through the comparison of regular continuous steam injection,alternately intermittent injection of steam,alternately intermittent injection of steam as well as the overall alternating intermittent injection of steam,the results show that the use of alternate intermittent injection of steam can reduce the steam channeling to a certain extent,and can improve the recovery of heavy oil.