超临界二氧化碳增稠剂的制备与驱油效果评价

Preparation and Oil Displacement Effect Evaluation of Supercritical Carbon Dioxide Thickener

付虹 宋考平 刘明熹 孟恩 丁伟 袁天 张宇

FU Hong SONG Kaoping LIU Mingxi MENG En DINGWei YUAN Tian ZHANG Yu

二氧化碳（CO2）驱是三次采油基础上进一步开发高含水老油田、提高采收率的有效方法。针对CO2与原油 黏度差较大引起的气窜问题，制备了可用于驱油的超临界二氧化碳（scCO2）增稠剂。对增稠剂的制备条件进行 了优选，评价了增稠剂的溶解性、增稠性能和驱油效果。结果表明，引发剂用量对产物的分子量分布影响最大； 最优合成条件为：72 ℃下，马来酸酐、苯乙烯、醋酸乙烯酯的物质的量比为4∶1∶1，单体加量为22%，引发剂加量 为0.16 g，此时聚合产物的分子量分布为1.12，产率为85%。增稠剂在scCO2中的饱和溶解度为2.30%，最小混相 压力为7.77 MPa；加量为0.2%的增稠剂在15 MPa、50 ℃下可大幅提高scCO2的黏度，比同条件下的scCO2增黏 19.7 倍；升温至110 ℃，增稠剂-scCO2体系的黏度保留率为45.26%。模拟地层环境（15 MPa），引入0.2%的增稠剂 可有效改善scCO2驱的驱油效果，渗透率越高提采效果越显著。对同一岩心，加入增稠剂的scCO2驱可在水驱后 提高采出程度约10百分点。

Carbon dioxide（CO2）flooding is an effective mean to further develop old oilfields with high water cut and improve oil recovery based on tertiary oil recovery. Aiming at the gas channeling problem caused by the large viscosity difference between CO2 and crude oil，a supercritical carbon dioxide thickener（P）that could be applied to oil flooding was prepared. The preparation conditions of thickener were optimized，and then the solubility，thickening performance and oil displacement effect of thickener were evaluated. The results showed that the amount of initiator had the greatest influence on the molecular weight distribution of the product. The optimum synthesis condition was obtained as follows：72 ℃，4∶1∶1 the molar ratio of reactive monomer（maleic anhydride，styrene，vinyl acetate），22% the dosage of monomer，and 0.16 g the dosage of initiator. Under the condition，the molecular weight distribution of product was 1.12，meanwhile，the yield was 85% . The saturation solubility of thickener in supercritical carbon dioxide was 2.30%. The minimum miscible pressure was 7.77 MPa. The thickener with a dosage of 0.2% increased the viscosity of supercritical carbon dioxide by 19.7 times at 15 MPa and 50 ℃. When the temperature raised to 110 ℃， the viscosity retention rate was 45.26% . Under a simulated formation environment（15 MPa），adding 0.2% thickener could effectively improve the oil displacement effect of supercritical carbon dioxide flooding. Furthermore，the higher the permeability， the more significant the extraction effect was. In the same core，the total recovery degree of supercritical carbon dioxide flooding with thickener was more than ten percentage points higher than that after water flooding.

10.19346/j.cnki.1000-4092.2023.02.019