蒸汽驱用耐高温堵剂性能研究

注蒸汽稠油开采过程中,高温蒸汽极易在油藏内大孔道和高渗透层形成窜流,导致吸汽剖面不均匀,蒸汽利用率和体积波及系数降低,注汽开发效果变差。提高蒸汽驱波及系数和稠油开采效率的最有效方法是调整蒸汽注入剖面和封堵水窜通道。聚合物耐温性能较差,高温下易降解,严重影响聚合物调整蒸汽注入剖面的效果。用硝基腐殖酸钠作为主剂,甲醛和间苯二酚作为交联剂,制得一种高温堵剂,并对其性能进行评价。结果表明:120℃下高温堵剂的最优配方为硝基腐殖酸钠9%+甲醛2.0%+间苯二酚1.5%,成胶时间为19h;最佳适用pH值为7～9;该堵剂耐盐性能良好,最高可耐NaCl和CaCl2浓度分别为40000mg/L和8000mg/L;该堵剂的初始黏度为10.3mPa.s,泵入性能良好,易于输送和注入;经硝化处理的腐殖酸钠可耐290℃以上的高温,完全满足控制蒸汽驱汽窜的温度要求;该堵剂对不同渗透率的岩心都有良好封堵效果,封堵率在95%以上,并具有堵大不堵小的特性。

Performance Study on High-temperature Resistant Plugging Agent Used for Steam Flooding

During the process of heavy oil recovery by steam injection,high-temperature steam is easy to form crossflow in big channel and high-permeability formations in oil reservoir.It will make development result worse because of uneven steam injection profile and decrease of steam efficiency and volumetric sweep efficiency.The most effective method for enhancing sweep efficiency of steam and recovery efficiency of heavy oil is steam injection profile control and water breakthrough channel plugging.Polymer is easy to be degraded at high temperature,which will influence the effect of steam injection profile control.A high-temperature resistant plugging agent is synthesized with nitro humic acid sodium as main plugging agent,formaldehyde and resorcinol as cross linking agent,and the property of it is evaluated.Results shows that the best formula of the high temperature resistant plugging agent at 120℃ is:9% nitro humic acid sodium+2.0% formaldehyde +1.5% resorcinol and the gelation time is 19 hours;the best applicable pH value is 7 to 9;the plugging agent has good salt tolerance for 40000mg/L NaCl and to 8000mg/L CaCl2 respectively;the initial viscosity of the plugging agent is 10.3mPa·s with good pumpability and injectivity;the humic acid sodium via nitrification processing is resistant to high temperature of up to 290℃ or more which fully meets the temperature requirement of controlling steam channeling for steam flooding;the plugging agent has great blocking effect for cores with different permeability,and its plugging ratio is above 95% with the property of plugging big rather than small.