Non-crosslinked multiphase hybrid fracturing fluid with high temperature resistance of 300 °C

The introduction of nanomaterials usually enhances the stability and temperature resistance of materials, but whether the introduction of nanomaterials in polymer fracturing fluids will significantly enhance their temperature resistance needs to be investigated urgently. The objective of this study is to form a crosslinker-free fracturing fluid system by multiphase hybridization of modified montmorillonite with polymers, and to discuss its advantages over ordinary polymer fracturing fluids in order to achieve a breakthrough of polymer fracturing fluids in terms of temperature resistance. The successful modification of the montmorillonite and the successful synthesis of the temperature-resistant polymer were demonstrated by FT-IR detection. The microdistribution state and microstructure of the fracturing fluid were analyzed by combining SEM and TEM tests, and the mode and mechanism of action of the montmorillonite and the polymer were demonstrated. In other words, the montmorillonite is dispersed in the polymer in three structures, filling, intercalation, and lamellar peeling, to form a heterogeneous effect, which gives the fracturing fluid more excellent stability performance. At the same time, the thermogravimetric analysis of the multiphase hybridized fracturing fluid and the comparison of the experimental results of the unhybridized fracturing fluid clarify and confirm the temperature-resistant effect and the temperature-resistant mechanism of the multiphase hybridized fracturing fluid. After the performance evaluation, it is concluded that the multiphase hybridized fracturing fluid has excellent temperature and shear resistance, sand-carrying and gel-breaking performance. Temperature resistance for over 30 min after reaching the temperature of 300 °C, and the ambient temperature sand sedimentation rate was lower than 10 % for 120 min. The multiphase heterogeneous fracturing fluid can be completely broken within 5 h after adding a gel-breaking agent. Compared with the conventional modified and synthesised polymer fracturing fluids, the multiphase hybridized fracturing fluids studied in this paper have significantly improved the temperature resistance through nanoorganic multiphase hybridization, and the operation process is simple to realize the resistance to 300 °C ultrahigh temperature. The performance indexes meet the requirements of the industry and show great potential for application in fracturing and reforming of reservoirs in ultra-high temperature and 10,000-m deep wells.