Study On Rational Production Pressure Of Multi-layer Combined Production In Western Oilfield Of Daqing Central District

As a key technology of secondary oil recovery,water flooding plays an important role in oilfield development strategy in the early stage.However,with the ongoing of water flooding development,especially at later stage of high water cut,more and more problems are exposed.As strong reservoir heterogeneity of the west of Daqing central,and big difference of oil/water viscosity,it cause some layers have poor water absorption capacity.In addition,it cause many wells early water breakthrough,and even serious water channeling.Serious interlayer interference cause inefficient invalid water cycle is serious,the effects of water flooding development is seriously affected and the economic cost is increased.Aiming at this problem,through the statistics of permeability distribution in the western part of Daqing central area,several laboratory simulation experiments were designed.By measuring water content,recovery rate,shunt rate and other parameters,the effects of injection-production pressure difference,permeability ratio and pressure lifting law on interlayer interference were studied.According to the analysis,there is a reasonable injection and production pressure difference to maximize the overall recovery rate in multi-pipe parallel water flooding experiment.Under the experimental conditions in this paper,the reasonable injection and production pressure difference is 0.1MPa;The greater the permeability level difference is,the stronger the interference degree of the high-permeability interval to the low-permeability interval is,and the lower the overall recovery rate is when the economic limit is reached;In addition,based on the comprehensive recovery rate,the degree of interference of the core with same permeability ratio but different permeability level is similar when they produce together;What's more,when multi-layer produced together,the interference form at the production end is that the fluid flow from the high-permeability zone to the low-permeability zone,and the lower the core permeability level,the slower the interflow velocity,the greater the core permeability ratio,the faster the interflow velocity;The effect of water flooding with gradual pressure lifting is better than that of direct pressure lifting,but the effect of water flooding with early pressure lifting is poor.In the late stage of high water cut,in order to reduce the inter-layer interference,it is suggested to reclassify the strata,profile control or water plugging for the high permeability layer,but it is not recommended to increase the injection pressure to increase the water flooding recovery.