Synthesis and application of nonionic polyacrylamide with controlled molecular weight for fracturing in low permeability oil reservoirs

Nonionic polyacrylamide (NPAM) with controlled molecular weight was successfully synthesized as a gel fracturing fluid by aqueous solution polymerization. The effects of the monomer concentration, initiator concentration, reaction time, feeding temperature and reaction temperature on the molecular weight were systematically investigated through single‐factor and orthogonal experiments. The NPAM molecular weight can be controlled by adjusting these factors. The decisive factor is the acrylamide concentration, whereas the initiator concentration and feeding temperature are secondary factors. These synthetic NPAMs can be crosslinked with zirconium acetate to produce a gel fracturing fluid for use in low permeability oil reservoirs. Gel fracturing fluids based on synthetic NPAMs have high shear resistance, low filtration performance, easy gel breaking performance, good proppant carrying capability and low core damage capability. By adjusting the NPAM or crosslinker concentrations, the gel fracturing fluid can be adapted for use in low permeability oil reservoirs for a wide temperature range (60–120°C). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41637.