The ' main + auxiliary ' synergistic strategy for constructing binary polyacrylamide-based ultra-high temperature fracturing fluid

In this work, based on theory and experiment the fracturing fluid additives are developed, including thickener, crosslinker, pH regulator and temperature stabilizer. The effect of additives on the performance of fracturing fluid was investigated with the temperature and shear resistance as the evaluation index. A synergistic strategy for constructing ultra-high temperature fracturing fluid was obtained. The main content of this strategy is ' main + auxiliary ', the correct choice of the main agent combined with an auxiliary agent to form a temperature-resistant fracturing fluid system. The main agent is thickener and crosslinker, pH regulator and temperature stabilizer are auxiliary agents. Two ultra-high temperature fracturing fluid systems are obtained by the strategy, which meets the requirements of temperature and shear resistance at 200 °C, 100 s−1 and 240 °C, 100 s−1, respectively. More importantly, the temperature resistance mechanism of fracturing fluid is analyzed at the micro and macro levels, based on chemical reaction, rheology, and microstructure information. This study is helpful for us to understand the selection and function of fracturing fluid additives. The developed fracturing fluid is expected to be used in the fracturing stimulation of unconventional reservoirs.