| The reservoir rock in the North ? East area is a set of clastic rocks deposited in the Cretaceous continental lake basin.The rock is mainly composed of feldspar quartz sand,the rock is mainly fine sand,the compaction degree of the oil layer is poor,the oil layer is thicker,and it belongs to the high porosity,high permeability and medium high viscosity reservoir.At present,the study area has entered a highly high water cut period.In order to improve the utilization of residual oil in the study area,this paper studies the influence of displacement speed,speed raising time,permeability gradation,injection production direction,stew well and profile control on oil displacement efficiency by long core physical simulation experiments,and studies the high water cut period with the development characteristics.The mechanism of water flooding.Based on the basic geological characteristics of the North ? East area,the similarity principle is used to deduce the similarity criterion of water drive oil,and the parameters of the reservoir physical property and the experimental model are converted.4 groups of long core experiments are designed to simulate the effect of water flooding in the homogeneous reservoir,and 4 groups of parallel long core experiments are designed to simulate the effect of water flooding in heterogeneous reservoirs.The results of single long rock core water flooding experiment show that when the comprehensive moisture content is 98%,the effect of increasing speed is better than that of accumulative water content increasing by 98%.When the comprehensive moisture content is 98%,increasing the speed and improving the displacement efficiency is more than 15%.The experimental results of water flooding in parallel long rock heart show that the effect of speed increase when the single layer water content is 98%is better than that when the total water content of the three layer is 98%.Speed increase can improve the total oil displacement efficiency,but it will also increase the difference of oil displacement efficiency between high and low permeable layers,resulting in a large number of remaining oil in the middle and low permeable reservoirs.When the comprehensive moisture content is 98%,profile control is conducted to reduce the effect of interlayer interference on the medium and low permeability layers,improve the utilization of remaining oil and improve the oil displacement efficiency.When the comprehensive water content is 98%,changing the direction of injection production and stewing well is difficult to improve the oil displacement efficiency.When the speed up to 8ml/min is adjusted,the flow,pressure and oil displacement efficiency of the low permeability layer increase rapidly in a short time,but the phenomenon of oil and water emulsification appears at the same time,which increases the difficulty of extracting oil and water in the measurement experiment.The analysis of water drive characteristic curve shows that the suitable water drive characteristic curve of the core with different pore and permeability structure is different before and after the speed increase,and the water drive characteristic curve which is in accordance with the actual production data can predict the recoverable reserves accurately.Speed up,profile control and well completion make the characteristic curve of water drive lower,which shows that these measures can improve the effect of water flooding.Changing the direction of injection and production has no effect on the shape change of water drive characteristic curve,which shows that this measure is difficult to improve the effect of water flooding.Through the experimental study of the long core water flooding experiment and the reservoir engineering method,the water drive characteristic curves of different stages are studied.The main mechanism of the oil displacement efficiency of the North ? East area at the high water cut stage is to expand the volume,reduce interlayer interference and reset the oil and water channel. |
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