Preparation and evaluation of a novel in-situ self-propping fracturing fluid system

Due to the contradiction between the size, sedimentation of proppants and the complex fracture network created by low-viscosity fluids, fractures of various sizes are difficult to be effectively supported through traditional hydraulic fracturing technology, thus the in-situ self-propping fracturing fluid (ISSPFF) technology came into being. This technology only injects liquid into the wellbore to create fractures, autogenous proppants (APs) are then formed in the reservoir in situ with the increased temperature, which greatly improves the efficiency of reservoir stimulation. Herein, styrene is first selected as the polymerization reaction monomer for the synthesis of a novel ISSPFF system and the corresponding APs. Owing to the reduced interfacial energy, a stable water/oil dispersion system of the ISSPFF is formed, further confirmed by the molecular dynamics simulation. By optimizing component concentrations, the synthesized APs exhibit remarkable properties of uniform particle size, enhanced compressive strength, high conductivity, and long-term stability, better than those of the quartz sand. On this basis, the solidification behavior of the ISSPFF system with formation fluids, core column, crustal stress, and narrow fractures is thoroughly explored. The ISSPFF system can effectively open and support the microfractures with the average permeability and Kirschner permeability increased by 18 times and 42 times, respectively, revealing its great potential in improving the conductivity of microfractures. As a result, the developed ISSPFF system is highly expected to be applied in hydraulic fracturing for unconventional reservoir stimulation.