Eco-friendly sodium alginate for drag reduction in hydraulic fracturing: Experimental and FFT-based dynamic analysis

Hydraulic fracturing is necessary for petroleum engineering, yet synthetic drag-reducing polymers often introduce environmental hazards. In this work we use sodium alginate, a seaweed-originated biopolymer, to address these concerns. Experiments conducted in a smooth microtube show that the eco-friendly additive can reduce the friction to 15 %, and application of the scaling law suggests a drag reduction up to 37 % in a large pipeline. Fast Fourier transform of a newly defined dimensionless pressure drop reveals a spectrum for sodium alginate that is simpler than that of the pure solvent, confirming suppression of turbulent fluctuations through the polymer-turbulence interaction. A ten-minute degradation test indicates that the initial drag reduction of 15 % declines only to 13 %, demonstrating a good anti-shear ability in the drag-reducing flow. Dynamic-light-scattering profiles confirm that chain scission is only partial, underscoring the polymer's structural robustness under the turbulent flow. Last, we use thermodynamic and kinetic, supported by dynamic-light-scattering data, to provide a mechanism of drag reduction by polymers: the structure of sodium alginate resists the high shear rates encountered in turbulent flow, preserving its drag-reducing efficiency. These combined environmental and economic advantages indicate sodium alginate as a promising green additive for hydraulic-fracturing operations, especially under stringent ecological regulations.