Development and field application of a drag-reducing agent for the hydraulic fracturing of shale gas

When the shear stress borne by the molecular chains of drag reducing agent polymers increases to a force sufficient for breaking, the viscosity will reduce and impact the drag reduction rate and sand-carrying performance, directly determining the success or failure of execution of hydraulic fracturing and impacting the effective after hydraulic fracturing, aiming at the problem of poor shear stability of ordinary synthetic polymers, in order to change the molecular structure to obtain polymers with stronger shear resistance. By developing a method for synthesizing a star-shaped polymer, this study determined the core functional groups within dendritic polymer initiators and a synthesis method for initiating the polymerization of monomers, such as acrylamide. In addition, we completed the synthesis of a dendritic polymer initiator and a star-shaped polymer with an optimized initiator type and concentration and determined that PAMAM-TX (polyamidoamine-thioxanthone) as the initiator had a concentration of 0.09% with a monomer concentration of 20%, of which the AMPS (2-Acrylamido-2-methylpropane sulfonic acid) monomer was 3–5 mol. % and the concentration of the hydrophobic monomer DM-12 (methacry loyloxyethyldimethyldodecyl ammonium bromide) was 0.3–0.5 mol. %. For performance evaluation and field testing, the drag-reducing rate of star-shaped polymer is higher than 70%.