Hydrogel swelling properties: comparison between conventional and nanocomposite hydrogels for water shutoff treatment

Abstract

One of the unique properties of hydrogels is the dramatically change in their volume and shape. In this research, conventional hydrogels (composed of sulfonated polyacrylamide and Cr(OAc) 3 as copolymer and crosslinker, respectively) were investigated versus nanocomposite (NC) hydrogels for the purpose of achieving suitable composition with ability of high amount of equilibrium swelling ratio and low amount of salt sensitivity factor (f). The results showed that high ratio of Cr(OAc) 3 /copolymer (>0.39) and high concentration of copolymer (>27 000 ppm) were suitable areas for conventional hydrogels because of minimum f factor with still low ability of gel swelling. However, the results of NC hydrogels with composition of copolymer concentrations of 23 750 to 30 000 ppm, Cr(OAc) 3 /copolymer ratio of 0.28 and nano Na-MMT concentrations of 500 to 800 ppm represented a significantly high amount of swelling and low amount of f factor. Coreflooding tests were applied to investigate the effect of polymer gel swelling in porous media for water shutoff treatment. The values of the residual resistance factor of water/oil for samples with high and low swelling ratio were 32.34 and 7.08, respectively, confirming the ability of the polymer gel with high swelling ratio in reducing the relative permeability of water/oil in porous media.

Synthesis, characterization and evaluation of polyacrylamide graft starch/clay nanocomposite hydrogel system for enhanced oil recovery

“…The residual resistance factor (F rr ) is a measure of permeability reduction and calculated using the following equations (Mohammadi et al 2015;Salehi et al 2014):…”

“…The water and oil viscosities are not changed in the whole process, thus l w1 = l w2 and l o1 = l o2 (Mohammadi et al 2015;Singh and Mahto 2016a).…”

“…To evaluate the effectiveness of gel in reducing water permeability in contrast with oil permeability, the ratio of residual resistance factor of water to oil was calculated using the following equation (Mohammadi et al 2015):…”

“…Introducing nanoclay into hydrogels to prepare nanocomposite hydrogels may be considered as a useful method to improve the properties of hydrogels. These improvements can include high moduli, increased thermal stability and mechanical strength as well as high extensibility and elasticity compared to the graft polymers Aalaie and Vasheghani-Farahani 2012;Moghadam et al 2012;Mohammadi et al 2015).…”

Influence of polymer structure on the gelation kinetics and gel strength of acrylamide‐based copolymers, bentonite and polyethylenimine systems for conformance control of oil reservoirs

“…The addition of lamellar clays to gelling formulations has been used to increase the thermal resistance, mechanical strength (elastic modulus), as well as to reduce the syneresis and the sensitivity to salinity of the formed (nano)composite hydrogels …”