H. Ding, J. Geng, A. Imqam, B. Bai
Missouri University of Science and Technology,
Keywords: enhanced oil recovery, conformance control, gel treatment, nanogel
Summary:The heterogeneity of reservoir is always responsible for problems such as low oil recovery and excessive water production because of the trend of injection fluids to go through higher permeability zone. Hydrogel has been used in petroleum industry by plugging high permeability zone to solve the conformance problem. However, hydrogels are usually in macron to millimeter size and cannot penetrate into deep formation. This work investigated the flow behavior in porous media, which included plugging, oil recovery improvement and injectivity, of polyacrylamide based nanogel, which is widely used in petroleum industry. The polyacrylamide nanogel used in this work is polymerized by acrylamide and N,N’-methylenebisacrylamide via suspension polymerization. Three factors were studied in this work: 1) crosslinking density of nanogel; 2) permeability of porous media; 3) ionic strength of nanogel dispersion. Among nanogels synthesized by four different crosslinker concentrations, results showed that particles would have a bigger size with lower crosslinker concentration. Meantime, within a same permeability range of core samples, there were higher plugging efficiency and oil recovery improvement with lower crosslinker concentration. Nanogel treatment had a less plugging efficiency in lower permeability rocks, which could be caused by the high injection pressure in lower permeability porous media. However, the oil recovery was higher in low permeability rocks.