Experimental Research On Thermal-CO₂-Chemical Flooding For Enhancing Heavy Oil Recovery

In recent years,the national development and consume a large amount of energy,causing the domestic energy supply,the tense situation for petroleum resources,heavy oil will become the present stage and in important energy to succeed,but the development of heavy oil has been a problem in the oil industry.The development of heavy oil has been from a single steam stimulation/steam drive to the displacement mode development more fluid technology,CO₂ and surfactants as additives is play an important role in the development of heavy oil.In view of the heavy oil development difficulties,the problem of recovery efficiency is not high,heavy oil in shengli oilfield is river as the research object,through the consult literature and indoor experiment methods,properties of heavy oil,emulsifier and development mode is studied.First,test the basic physical parameters including density,the composition of heavy oil,to heavy oil viscosity-temperature relationship and rheological properties were studied;Experiment study of crude oil,formation temperature?83 ??,the viscosity is close to 5000 mPa·s,colloid asphalt content of 45%,crude oil viscosity-temperature abnormal point temperature is 86.65 ?.Second,the sand filling tube as physical model,studies the percolation mechanism of heavy oil under the condition of low permeability;Use sand filling tube model of permeability is 200 ×10^-3?m²,get the start-up pressure gradient is 0.015 MPa/cm,when permeability increase 400 ×10^-3?m²,reduced to half of the original start-up pressure gradient,fracture model of start-up pressure gradient reduced to 1/5 of the original.Third,the optimization is suitable for this experiment with heavy oil emulsification viscosity agent;83 ? the best viscosity of heavy oil formula used in the experiment: 0.4% Na₂CO₃ + 1250 mg/L of BJN-1 + 1250 mg/L of H₂,at this point,the heavy oil viscosity reduction rate is 92.6%,water is 92.1% off.Fourth,using the sand pack,for a variety of displacement mode of thick oil mining effect,the injection parameters,recovery degree,the moisture content and other indexes determination,analysis to improve oil recovery mechanism;Way 1?steam drive + CO₂ + steam drive,emulsifier,steam flooding?ultimate recovery was 64.9%,7% higher than that of steam + CO₂ flooding,17% higher than that of steam drive alone;Way 2?steam drive + CO₂ + steam drive + emulsifier + CO₂ + steam drive?ultimate recovery is 71.6%,is about 6% higher than a way;Steam and CO₂ in the viscosity of heavy oil,emulsifier three media,improve liquidity and improve the swept volume have synergy.