甜菜碱类变黏分流酸的流变性及变黏机制

根据黏弹性表面活性剂(VES)理论,研制一种性能优良的甜菜碱类变黏分流酸,分析其胶束结构特点和变黏性能,考察剪切速率对油酸酰胺丙基甜菜碱质量分数、pH值和不同温度下变黏分流酸流变性的影响,探讨pH值对胶束结构的影响,得出变黏分流酸的变黏机制.结果表明:油酸酰胺丙基甜菜碱在10 %HCl中为球型胶束,在5% HCl中为球型棒型过渡类型和棒状胶束,在2% HCl中为蠕虫状胶束;变黏分流酸随着酸液质量分数降低表观黏度逐渐增加,当油酸酰胺丙基甜菜碱质量分数大于临界胶束浓度(w_cmc)时,变黏分流酸增黏后具有剪切稀释的黏弹流体特点;变黏分流酸在酸化过程中压力有先上升后下降的趋势,发生液流转向进入中低渗层,对储层无伤害.

Rheological property and viscosity variation mechanism of variable viscosity diverting acid based on betaine

Based on visco elastic surfactant theory, a new variable viscosity diverting acid (VVDC) with good performance was developed, and its micelle structure characteristics and viscosity variation property were analyzed. The influence of shear rate on the concentration of oleic amide propyl betaine, pH and rheological property of VVDC for different temperature was studied. The influence of the pH on micelle structure was discussed, and the viscosity variation mechanism of VVDC was obtained. The results show that the micelle structures of VVDC in the HCl of 10%, 5%, 2% (mass fraction) are globular, rod and the transitional form between globular and rod, and wormlike respectively. The apparent viscosity of VVDC increases with the acid concentration decreasing, and it has the dilution shearing feature when the oleic amide propyl betaine concentration is higher than the critical micelle concentration. During the acidizing process, the pressure of VVDC is reduced after increasing. And the flow of acid turned into the low-medium permeability reservoir, which does no harm to the reservoir.