CO₂气窜时机预测对CO₂气窜预防与提高采收率具有重要意义,目前的研究很少涉及气窜时机的定量表征。根据目标区块油藏参数,应用数值模拟手段分析了原油黏度、储层渗透率、注气速度、注采井距等因素对CO₂驱前缘移动规律的影响,建立了考虑多因素影响的气窜时间及气窜时波及系数表征公式,并通过与矿场实际对比,验证了公式的准确性。研究表明：在定压生产条件下,原油黏度越大,波及系数减小。当原油黏度大于3 mPa·s,见气时间增加幅度减缓;储层渗透率变大时,渗流阻力变小,驱替前缘移动速度加快,油井突破时间越早;当注气速度增加,前缘移动速度加快,见气时间提前,当注气速度为2 500 m³/d时,波及系数最小;当注采井距增大时,气体前缘移动速度减慢,油井见气时间延长,当注采井距大于240 m时,继续增大井距,波及系数提高幅度较小。

CO₂ gas channeling time prediction is of great significance for CO₂ gas channeling prevention and enhanced oil recovery. Current studies rarely involve quantitative characterization of the gas channeling time. According to the parameters of the target block reservoir, the crude oil viscosity, reservoir permeability, gas injection rate and injection-production well spacing and other factors impact on the moving rule of the CO₂ drive front is analyzed by the numerical simulation method, then the characterization formula of gas flow time and gas flow influence coefficient considering multiple factors is established, and the accuracy of the formula is verified by comparing with the field practice. The results show that under the condition of constant pressure production, the sweep efficiency decreases with the increase of crude oil viscosity. When the crude oil viscosity is greater than 3 mPa·s, the increase of gas emergence time slows down. When the reservoir permeability increases, the seepage resistance decreases, the displacement front moves faster, and the oil well breaks out earlier. When the gas injection velocity increases, the leading edge movement speed increases and the gas appearance time advances. When the gas injection velocity is 2 500 m³/d, the sweep efficiency is the minimum. When the injection-production well spacing increases, the moving speed of gas front slows down, and the gas emergence time of oil well prolongs. When the injection-production well spacing is larger than 250 m, the well spacing continues to increase, and the sweep efficiency increases slightly.