Study On The Optimization Of Oil Repellent And Well-operated Methods In The Second-class Oil-driven And Cloth Wells In The South Six Districts Of Daqing Oilfield

The development of the main reservoirs in the Daqing Oilfield is relatively long and the production decline trend is obvious.In order to ensure the trend of high production and stable production in the Daqing Oilfield,the development of the oilfield has gradually shifted from a type I reservoir to a type II or III reservoir with rich reserves but poor geological conditions.In recent years,trials of polymer flooding and weak-alkaline / strong-alkali ternary complex flooding field tests conducted in the Daqing Oilfield have achieved good results.However,the sedimentary development characteristics of each block are very different,and a unified layer combination and flooding scheme technology have not yet been formed.This paper optimizes the flooding method and well deployment method for the tertiary oil recovery in the second-type reservoir in the sixth area of Saltunan,and gives a clear layer combination scheme and flooding scheme.Through detailed description and research of the block's structural characteristics,reservoir deposition characteristics,reservoir development characteristics,reservoir heterogeneity,and barrier development,etc.We initially determined the research and development targets of the second-level oil layers in the South Sixth District.And it was recognized that the second-level oil layers in the South Sixth Zone were mainly flooded with sand,and the proportion of effective utilization was high.Under the comparison of the effects of other polymer flooding and ternary flooding blocks,combined with laboratory experiments,the composite flooding system suitable for the second-stage oil reservoirs in the South Sixth District was selected as a weak alkaline ternary,and a surfactant suitable for the development of the oil reservoir was identified.Under the comprehensive analysis and evaluation the development of the different layers,the development of the interval,the control degree of the ternary flooding well pattern,the reserve potential,the mining span,and the current exploitation of the water flooding wells of the weak-alkali ternary composite flooding system combination of the second-type oil reservoirs.The first mining interval is Sa II1-4 + Sa II 7-12 reservoir.According to the comprehensive analysis and evaluation of the ternary flooding control degree of different well spacings,utilization of well conditions,investment in new drilling costs,the proportion of the same well site,and the effect of improving recovery efficiency,the well layout plan was finally determined to be a 125 m five-point area well pattern.After determining the flooding system and well deployment plan,numericalsimulation was used to optimize the ternary system injection scheme,and the optimization scheme was determined as the stepwise concentration reduction injection method.The injection parameters of each plug of the ternary compound flooding were given.The actual production situation on the site shows that the well layout of the well pattern of 125 m area can establish a good pressure driving system in the second-type reservoir,the block injection pressure has steadily increased,and the profile has been effectively improved.From the perspective of production effects,the weakly alkaline ternary compound flooding system and designed injection scheme for the second-stage oil reservoirs in the South Sixth District are suitable for a well pattern of 125 m in area,and have achieved a good effect of increasing oil precipitation.The maximum water cut is 11.4 percentage points.Long period of low water content,balanced advancement of chemical agents.Up to now,the enhanced recovery factor is 3 percentage points higher than the digital simulation forecast,which indicates that the weak alkaline ternary system is suitable for the development of the second-class reservoirs in the South Sixth District.