化学合成的聚合物聚丙烯酰胺(HPAM)在常规油藏中取得了优异的驱油效果,但其在极端油藏环境下的驱油能力较差。开发适用于极端储层条件的生物聚合物驱油剂,三种生物聚合物的粘度变化和流变特性,Diutan口香糖,黄原胶,和scleroglucan,在极端储层条件下进行了研究(高盐,高温,强酸,和碱),以及温度的影响,矿化,pH值,等因素对其粘度和长期稳定性进行了分析比较。结果表明,三种生物聚合物在90°C及以下的温度下具有最佳的增粘能力。三种生物聚合物的粘度为80.94mPa·s,11.57mPa·s,和59.83mPa·s,分别,当浓度为1500mg/L,盐度为220g/L时。在250s-1的剪切速率下,100°C〜140°C,硬葡聚糖具有最好的粘度。在140°C时,溶液粘度为19.74mPa·s,保留率可达118.27%。长期稳定性研究结果表明,矿化水平为220mg/L的硬葡聚糖在40天内的溶液粘度为89.54%,而杜坦胶可以稳定10天,粘度保持在90mPa·s。这三种生物聚合物都是高度耐酸和耐碱的,在pH3~10范围内粘度变化小于15%。流变学测试表明,迪优坦胶独特的双螺旋结构和硬葡聚糖的刚性三螺旋结构使它们具有比黄原胶更好的粘弹性。因此,这两种生物聚合物,Diutan口香糖,和scleroglucan,具有极端油藏驱油应用的潜力。建议在高达90°C的储层中使用diutan胶进行驱油,在100°C至140°C的储层中使用硬葡聚糖进行驱油。
The chemically synthesized polymer polyacrylamide (HPAM) has achieved excellent oil displacement in conventional reservoirs, but its oil displacement is poor in extreme reservoir environments. To develop a biopolymer oil flooding agent suitable for extreme reservoir conditions, the viscosity changes and rheological properties of three biopolymers, diutan gum, xanthan gum, and scleroglucan, were studied under extreme reservoir conditions (high salt, high temperature, strong acid, and alkali), and the effects of temperature, mineralization, pH, and other factors on their viscosities and long-term stability were analyzed and compared. The results show that the three biopolymers had the best viscosity-increasing ability at temperatures of 90 °C and below. The viscosity of the three biopolymers was 80.94 mPa·s, 11.57 mPa·s, and 59.83 mPa·s, respectively, when the concentration was 1500 mg/L and the salinity 220 g/L. At the shear rate of 250 s-1, 100 °C~140 °C, scleroglucan had the best viscosification. At 140 °C, the solution viscosity was 19.74 mPa·s, and the retention rate could reach 118.27%. The results of the long-term stability study showed that the solution viscosity of scleroglucan with a mineralization level of 220 mg/L was 89.54% viscosity retention in 40 days, and the diutan gum could be stabilized for 10 days, with the viscosity maintained at 90 mPa·s. All three biopolymers were highly acid- and alkali-resistant, with viscosity variations of less than 15% in the pH3~10 range. Rheological tests showed that the unique double-helix structure of diutan gum and the rigid triple-helix structure of scleroglucan caused them to have better viscoelastic properties than xanthan gum. Therefore, these two biopolymers, diutan gum, and scleroglucan, have the potential for extreme reservoir oil displacement applications. It is recommended to use diutan gum for oil displacement in reservoirs up to 90 °C and scleroglucan for oil displacement in reservoirs between 100 °C and 140 °C.