热响应复合凝胶转向剂的合成及性能研究

Synthesis and Performance Evaluation of Thermo-responsive Composite Gel Diverting Agent

为提高无机凝胶的强度、避免在无机凝胶中加入聚合物后出现沉淀和析出的现象,采用低成本聚合硫酸铝铁、尿素、丙烯酰胺、引发剂过硫酸铵及交联剂N,N-亚甲基双丙烯酰胺合成了热响应复合凝胶转向剂,利用红外光谱、扫描电镜对其微观结构进行了表征,研究了复合凝胶转向剂的耐温性和耐冲刷性。研究结果表明,热响应复合凝胶转向剂适宜的合成条件为(以质量分数计):2.0%数3.0%丙烯酰胺、1.5%数2.5%聚合硫酸铝铁、0.4%数0.8%尿素、0.03%数0.05%过硫酸铵、0.02%数0.04%N,N-亚甲基双丙烯酰胺,成胶温度50数90℃。该转向剂成胶时间可控(5数36 h),凝胶强度大(>3×10~4m Pa·s),克服了普通无机凝胶成胶快的缺陷;同时该转向剂具有良好的注入性及深部运移性能,成胶前溶液的表观黏度<10 m Pa·s,可以实现大剂量注入并深部放置;复合凝胶的热稳定性良好,在90℃下老化120 d后的黏度保留率为87.4%;复合凝胶的封堵与耐冲刷能力好于普通无机凝胶及有机凝胶,其对岩心的封堵率大于98%,满足现场调驱施工的要求。

In order to improve the strengthen of inorganic gel and avoid precipitation and separation after adding polymer into inorganic gel,a thermo-responsive composite gel diverting agent was synthesized using low-cost polymerized aluminum ferric sulfate,urea,acryl amide,initiator ammonium peroxydisulfate and cross-linking agent N,N-methylene-bis-acrylamide. The microstructure and distribution state of diverting agent were characterized by using infrared spectrometer and scanning electron microscope. The temperature resistance and washing resistance of composite gel diverting agent were studied. The results showed that the suitable synthesis condition of thermo-responsive composite gel diverting agent was obtained as follows：2.0%—3.0% acryl amide,1.5%—2.5% polymerized aluminum ferric sulfate,0.4%—0.8% urea,0.03%—0.05% ammonium peroxydisulfate,0.02%—0.04% N,N-methylene-bis-acrylamide,50—90℃ gelling temperature. The gelation time of this diverting agent ranged from 5 to 36 hrs and the gel strength was higher than 3 × 104 m Pa·s. It overcame the deficiency of gelling quickly of common inorganic gel.Because of the low initial viscosity（10 m Pa·s）,the diverting agent had favorable injectivity and migration property which achieved objectives of large dose injection and in-depth plugging. The composite gel had good thermal stability with 87.4%viscosity retention rate after aging 120 days at 90℃. The plugging ratio of composite gel was above 98%,and its sealing property and washing resistance were obviously stronger than that of common inorganic gel and organic gel. The thermo-responsive composite gel diverting agent could meet the requirement of profile controlling and flooding in oilfield.