The Study On Improving Water-drive Effect Of Layer Well Pattern Adjustment For Extre-high Water Cut Oilfield

In the extre-high water cut development stage of A Oilfield,the remaining oil distribution is complex and diverse.There are differences in the well pattern form,and it is difficult to meet the requirements of greatly improving the development effect by adjusting the well pattern alone.Although a set of well pattern adjustment in the formation helps to improve the waterflooding effect to a certain extent,the remaining oil is locally enriched in different positions on the plane and in different rhythmic sections in the vertical direction,and the water consumption characteristics of the vertical multi-layered reservoirs are different.As a result,low utilization rate of injected water,unbalanced production of remaining oil,and further increase the difficulty of enhanced oil recovery.Based on the development status of A oilfield,this paper analyzes the mechanism and influencing factors of enhanced oil recovery,including injection-production direction,swept range,streamline distribution,differential pressure effect,and layer system interchange.Using similarity criteria,representative well patterns were extracted,and two sets of sand-filling models with superimposed upper and lower layer were made respectively.The displacement experiments of adjusting streamline line by well pattern adjustment and injection-production differential pressure adjustment were carried out.Analyzed the fluid production and recovery efficiency of different recovery wells,and the effect of water flooding by the interchange of the layer.The main research results obtained in this paper are as follows:(1)In the extre-high water cut stage,it is difficult to change the streamline distribution of injected water by other methods.However through the way of layer system interchange,the injected water streamline can be changed significantly to enhanced oil recovery..(2)After layer interchange well pattern adjustment water flooding and changeing injectionproduction differential pressure water flooding,through the comparison of recovery,the well pattern adjustment increased the recovery by 17.8% on average,and the injection-production differential pressure increased the recovery by 2.1% on average.Obviously,it can be seen that the effect of water flooding by adjusting the well pattern through the interchange of layers is far better than the method of increasing the injection-production differential pressure.(3)Comparing the recovery of the entire water flooding stage,the five-seven well pattern increased the recovery by 19.2% on average,and the row-shaped staggered well pattern increased the recovery by 16.1% on average.The water flooding effect of the five-seven well pattern represented by the A2 area is slightly better than the water flooding effect of the row-shaped staggered well pattern represented by the A1 area.(4)Comparing the actual production data and experimental data in the A oilfield,it is concluded that the adjustment of the interchange layer well pattern adjustment and the increase of the injection-production differential pressure have a significant effect on improving the water flooding effect.