生物多糖在高温高盐油藏聚合物驱可行性探索

探索了定优胶在高温、高盐油藏聚合物驱的可行性，采用黄原胶、魔芋胶作为对比，对其流变性、流度控制及提高采收率能力进行考察。稳态流变性及流度控制能力研究显示，三者增稠能力及在多孔介质中流度控制能力强弱顺序为：定优胶>黄原胶>魔芋胶。与另两种生物多糖相比较，定优胶有更好的耐温、耐盐特性及在高温中良好的长期稳定性。结合石英砂润湿性改性及原液、产出液流体力学半径变化情况，分析了3种多糖建立阻力的主要机理，对于魔芋胶、黄原胶、定优胶，机械捕集作用对多孔介质动态滞留量的贡献率分别为45.90%、60.78%、81.83%，定优胶较大的流体力学半径更易被多孔介质捕集，降低高渗多孔介质水相渗透率能力更强，且室内驱油实验中，定优胶提高采收率高达24.31%，明显优于黄原胶(17.02%)及魔芋胶(8.19%)，是一种很有前景的提高高温、高盐油藏稠油采收率的驱油剂。

Feasibility Study of Polymer Flooding in High-temperature and High-salinity Reservoirs by Using Biopolysaccharides

The feasibility of polymer flooding in high-temperature and high-salinity reservoir by using diutan gum was explored. Xanthan gum and konjac gum were used as comparison to investigate the rheological property, the capability of mobility control and EOR (enhanced oil recovery). The results of steady-state rheological property and mobility control show that the order of the capability of thickening and mobility control in porous media are as follows: diutan gum > xanthan gum > konjac gum. Compared with the other two biopolysaccharides, diutan gum has better temperature- and salinity-tolerance characteristics and good long-term stability in high-temperature environment. Based on the wettability modification of quartz sand surface (modified into oil wet) and the changes of hydrodynamics radius of the injected and produced fluids, the main mechanism of establishing resistance of three biopolysaccharides was analyzed. For konjac gum, xanthan gum and diutan gum, the contribution rate of mechanical trapping to the dynamic retention of porous media was 45.90%, 60.78% and 81.83%, respectively. The larger hydrodynamics radius of the diutan gum makes it easier to be trapped by porous media, and the ability to reduce the water phase permeability in porous media is stronger. Additionally, in the laboratory oil displacement experiment, the EOR of diutan gum is up to 24.31% OOIP (original oil in place), which is significantly higher than xanthan gum (17.02% OOIP) and konjac gum (8.19% OOIP). It is expected to be a promising oil displacement agent for enhanced heavy oil recovery in high-temperature and high-salinity reservoirs.