Effects of synthesis parameters on the performance of crosslinked Co-polymers with clays for conformance control

Conformance control or water shut-off is a technique used to improve oil recovery. During conformance control, polymers block high permeability water areas and redistribute water drive toward unswept oil zones. In this study, co-polymers (denoted ATP-PGV/AM-co-AMPS) were synthesized using acrylamide (AM) and 2-acrylamide-2-methylpropane sulfonic acid (AMPS) as the monomers, polyethylene glycol (PEG)-200 and methylenebisacrylamide (MBA) as the crosslinkers, attapulgite (ATP) and bentonite (PGV) as the clay types, and ammonium persulfate (APS) as the initiator, in addition to paraffin oil and surfactants. Samples were synthesized using inverse emulsion polymerization with different concentrations of monomers, crosslinkers, and clays, and they were characterized using Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). FTIR spectra of the samples confirmed the existence of sulfonate and hydroxyl groups, which are important for polymer swelling. SEM-EDX images indicated that the morphology and elemental composition were different before and after swelling, confirming the occurrence of swelling. Moreover, samples were placed in sodium chloride solution (20,000 ppm) for 7 days to evaluate swelling at both room temperature and 90 °C. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to determine the thermal characteristics of the microparticles. Finally, rheological measurements were used to assess the deformation and rheological behavior of the hydrogels. The results showed that after 1 day, good swelling without loss of mechanical strength was achieved with the composite synthesized using 10% AM, 15% AMPS, 6% PGV, and 10% ATP.