Study On Carbon Dioxide Flood Control Technology And Its Effect Analysis In Fuyu Reservoir Of Daqing C District

Daqing CO₂ flooding test zone C,with the development of gas injection,gas channeling has been exposed in recent years,which leads to the ineffective circulation of CO₂ and the decrease of oil production.Therefore,a reasonable and effective gas channeling control technique is urgently needed to assist the development of CO₂ flooding test area.In this paper,the reasons and difficulties of gas channeling are analyzed according to the geological conditions of the target layer in the study area.A channel blocking agent has been developed and a field test of sealing channeling has been carried out.Daqing CO₂ flooding test zone C,tectonically located in the Songliao Basin,Fuyu reservoir sedimentary fluvial delta facies,lithology is relatively dense,sorting coefficient is3.7on average,median grain size 0.07-0.14 mm,the cement mud cementation.The permeability of the core block 50% is less than 0.1×10-3m²,the distribution of permeability dispersion,the anisotropy is more serious,leading to the formation of high mobility under the condition of supercritical CO₂ are more prone to fingering,resulting in ineffective circulation.Especially when the permeability is less than 1 × 10-3m²,the core water sensitivity is moderately strong,and the water injection development in the earlier stage has aggravated this phenomenon.Combined with investigation and research,it is confirmed that the foam type sealing system is most suitable for this kind of ultra-low permeable gas drive reservoir.Foam system has low viscosity,low interfacial tension meter can realize its effective injection,and in the formation of foam plugging gas does not plugging oil;at the same time in the play the role of the weak gel foam stabilizing selection,but also for optimizing the features of low porosity and low permeability blocks of low molecular weight products,viscosity system the base fluid is only 8-12mPa·s.The block belongs to the high temperature gradient reservoir,reservoir temperature more than 80℃,the temperature resistance of foam and gel,also made the corresponding adjustment and optimization,the gelation time is 3-7 days controllable;foam volume 550mL;foam half-life of 60 days or more.Considering the average oil production of single well 0.3t/day low production capacity,in the process to cancel the high cost of gas-liquid mixed injection process,formed consisting of foam,foam gel,antifreeze corrosion slug slug type sealing process,the cost is the gas-liquid injection process saves half.Field testing of 2 wells,construction costs have been reduced by half.After injection,the injection pressure increased by 4MPa;the injection profile was obviously improved;the original non gas absorption layer was effectively utilized;the daily oil output of the connected well was obviously increased and good results were achieved.