氮气泡沫驱注入参数优化试验研究

为提高高温高矿化度中渗油藏注水开发后期的油藏原油采收率,研究优选了发泡剂浓度、气液比、注入量、注入方式、设备注入性和泡沫的封窜能力等工艺参数。实验结果表明:最佳气液比为2:1;最佳发泡剂浓度为0.5%;在气液比为2:1和发泡剂浓度0.5%的条件下,氮气泡沫注入量由0.11 PV增加到0.54 PV,采收率由20.6%增大到68.6%;水段塞与氮气泡沫段塞体积比为1:2～1:3时,最终采收率较高;在2.0 mL/min范围内,注入速度的变化对提高原油采收率的影响不明显。试注试验表明:注气设备额定压力在35 MPa以上可以满足试验区注入要求;水气交替注氮气易发生气窜;泡沫具有明显的封堵气窜和调剖作用。

Laboratory research on optimization of injection parameters for nitrogen foam flooding

In order to enhance oil recovery of medium porosity reserviors in post waterflooding of oilfield with high temperature and salinity,the process parameters of foaming agent concentration,gas-liquid ration,injection volume,injection mode,equipment injectivity and channeling blocking ability of foam were optimized in experiments.The experimental results show that the best gas-liquid ration and foaming agent concentration is respectively 2:1 and 0.5%.In optimum condition the oil recovery ratio increaced from 20.6%to 68.6%with the N₂ foam injection volume increasing from 0.11 PV to 0.54 PV.The oil recovery ratio reach maximum when the injetion volume ratio of water and N₂ foam slug is in the range of 1:2～1: 3.The variation of injection rate which is in the scope of 0～2.0 ml/min has no obvious effect on oil recovery ratio.The field injection test indicated that the injection equiments are able to met the requiment of field test if the its rated pressure is more than 35 MPa.Gas chan- neling will easily occur when using water and N₂ gas alternate injection.Foam has obvious effect on channeling blocking and Profile modification.