摘要
针对王窑加密区块裂缝性油藏封堵困难的问题，室内以甲醛和尿素为主剂，在55℃下合成了脲醛树脂堵剂，并考察了其性能。结果表明，脲醛树脂在注入水、煤油、10% HCl＋3% HF中的溶解率分别为1.54%、2.40%、14.30%，其水溶性、油溶性和酸溶性均较低，稳定性较好。随着温度的升高，脲醛树脂固化时间缩短，抗压强度迅速增大，55℃的固化时间为10 h、抗压强度为12.2 MPa。随着矿化度的增加，抗压强度降低，固化时间延长。当矿化度为50 g/L时，固化时间为12 h，抗压强度为4 MPa。脲醛树脂堵剂对裂缝性油藏的封堵效率高于95%，且突破压力大于24 MPa，封堵强度较高。应用“弱凝胶+脲醛树脂”体系在转注井王19-06井进行了现场施工，累计增油545.56 t，降水475.92 m3，有效期大于10个月，增油降水效果较好。
Abstract
According to the plugging difficulty in fractured reservoir of Wangyao infilled block, the urea-formaldehyde resin plugging agent with high strength was synthesized by formaldehyde and carbamide at 55℃, and its performance was studied. The results showed that the dissolution rate in injected water, paraffin and mixed acid (10% HCl＋3% HF) was 1.54%, 2.40% and 14.30%, respectively. Its hydrotrope, oil and acid soluble were all lower which indicated good stability. With increasing temperature, the curing time of urea-formaldehyde resin shortened, and its compressive resistance increased fast. The curing time was 10 h, and the compressive resistance was 12.2 MPa at 55℃. With increasing degree of mineralization, the compressive resistance decreased and the curing time extended. The curing time was 12 h, and the compressive resistance was 4 MPa when the degree of mineralization was 50 g/L. The plugging efficiency in fractured reservoir was higher than 95%, and the breakthrough pressure was more than 24 MPa which showed high plugging off intensity. The "weak gel and urea-formaldehyde resin" system was applied for field construction in converted injector well Wang19-06. Cumulative quantity of oil was 545.56 t, water cut decrease was 475.92 m3, and valid period was more than 10 months. The pilot effects of increasing oil production and decreasing water cut were good.
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