Preparation and properties of an acid-resistant preformed particle gel for conformance control

In order to solve the problem of poor acid-resistant of preformed particle gel (PPG) as conformance control material in reservoirs with supercritical CO2 flooding, acrylamide (AM), N,N'-methylene bisacrylamide (MBA) and dimethyldiallylammonium chloride (DMDAAC) were used to prepare an acid-resistant preformed particle gel (AR-PPG) by radical polymerization method. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to analyze the structural property of AR-PPG. The swelling capability, viscoelasticity and shear resistance of AR-PPG in acid environment have been studied. The conformance control system with good dispersion stability was selected and its plugging behavior was studied. The results showed that the swelling ratio of AR-PPG in acid environment was 1.41. Compared with conventional PPG, AR-PPG displayed better swelling capability, shearing resistance and viscoelastic properties in acidic environment. In addition, the conformance control system with good dispersion was 1000 mg/L AR-PPG dispersed in 1000 mg/L cationic polyacrylamide (CPAM) solution. The plugging rate of this conformance control system could be 70.8% in the low permeability micro-fracture core after supercritical CO2 flooding. This work can provide an alternative material for plugging and conformance control in oilfields of supercritical CO2 flooding.

Automated summary

In this study, an acid-resistant preformed particle gel (AR-PPG) was prepared using acrylamide, N,N'-methylene bisacrylamide, and dimethyldiallylammonium chloride through radical polymerization. The AR-PPG exhibited improved swelling, shearing resistance, and viscoelastic properties in acidic environments compared to conventional PPG. Furthermore, a conformance control system composed of AR-PPG dispersed in cationic polyacrylamide solution showed good dispersion stability and achieved a plugging rate of 70.8% in low permeability cores after supercritical CO2 flooding, providing a potential alternative material for plugging and conformance control in oilfields.