Evaluation Of Low Efficiency Horizontal Well With Different CO₂ Huff And Puff Modes

The Z43 fault block K2t1 reservoir is a heavy oil reservoir with massive structural.Due to inadequate energy,water flooding and low displacement efficiency,more and more horizontal wells are in low production,low efficiency and high-water-bearing conditions.Aiming at the practical problems faced by JS oilfields during the current development process,after researching related literatures,the suitability evaluation block of the target reservoir is optimized.Meanwhile,this paper analyzes the mechanism,feasibility and best development way of CO2 huff and puff to enhance the recovery of heavy oil based on physical experiment simulation.In this paper,we completed the following conclusions and suggestions after completing the evaluation of reservoir facies characteristics,evaluation of reservoir gas injection characteristics,permeability evaluation of gas drive oil and analysis of CO2 huff and puff effect of single pipe and multi core long core.(1)Through a large number of literature research,we get the evaluation index standard and weight of CO2 huff and puff for horizontal wells in oil reservoirs,and use fuzzy mathematics to evaluate the suitability of target reservoirs.(2)By carrying out the experiment of liquid phase and the compatibility test of gas injection expansion,it can be concluded that oil and CO2 cannot be miscible in the proper pressure range.CO2 can compatibilizing effect of oil viscosity reduction.It can improve the flow rate of crude oil effectively and improve the efficiency of oil displacement.(3)Through the analysis of characteristics of seepage,the relative permeability curve of gas flooding oil,rock gas displacement efficiency is high.Immiscible flooding caused by gas injection gas channeling,gas injection after the break cannot be used to increase oil production by increasing the volume of gas injection scheme.By carrying out single and multi parallel long core experiment analysis of CO2 throughput,CO2 throughput for EOR,simulated horizontal flow analysis of reservoir heterogeneity on throughput effect,simulation of horizontal wells in different sections of different porosity and permeability of reservoir characteristics.(4)Through the establishment of single well mechanism model,CO2 huff and puff stimulation simulation is carried out.Compared with physical experiments,it is more conducive to analyze the influence of CO2 huff and puff on EOR and the mechanism of yield increase.Through the above experimental research,new ideas for the evaluation technology of low efficiency horizontal wells in different huff and puff ways are provided for JS oilfield,which provides a theoretical basis for the adjustment and development plan of Z43 fault block reservoirs in the later stage of development.