Nanjun Lai

Synthesis and Evaluation of a Water-Soluble Hyperbranched Polymer as Enhanced Oil Recovery Chemical

A novel hyperbranched polymer was synthesized using acrylamide (AM), acrylic acid (AA), N-vinyl-2-pyrrolidone (NVP), and dendrite functional monomer as raw materials by redox initiation system in an aqueous medium. The hyperbranched polymer was characterized by infrared (IR) spectroscopy, 1H NMR spectroscopy, 13C NMR spectroscopy, elemental analysis, and scanning electron microscope (SEM). The viscosity retention rate of the hyperbranched polymer was 22.89% higher than that of the AM/AA copolymer (HPAM) at 95°C, and the viscosity retention rate was 8.17%, 12.49%, and 13.68% higher than that of HPAM in 18000 mg/L NaCl, 1800 mg/L CaCl2, and 1800 mg/L MgCl2·6H2O brine, respectively. The hyperbranched polymer exhibited higher apparent viscosity (25.2 mPa·s versus 8.1 mPa·s) under 500 s−1 shear rate at 80°C. Furthermore, the enhanced oil recovery (EOR) of 1500 mg/L hyperbranched polymer solutions was up to 23.51% by the core flooding test at 80°C.

Synthesis and Performance of an Acrylamide Copolymer Containing Nano-SiO2 as Enhanced Oil Recovery Chemical

A novel copolymer containing nano-SiO2 was synthesized by free radical polymerization using acrylamide (AM), acrylic acid (AA), and nano-SiO2 functional monomer (NSFM) as raw materials under mild conditions. The AM/AA/NSFM copolymer was characterized by infrared (IR) spectroscopy, 1H NMR spectroscopy, elemental analysis, and scanning electron microscope (SEM). It was found that the AM/AA/NSFM copolymer exhibited higher viscosity than the AM/AA copolymer at 500 s−1 shear rate (18.6 mPa·s versus 8.7 mPa·s). It was also found that AM/AA/NSFM could achieve up to 43.7% viscosity retention rate at 95°C. Mobility control results indicated that AM/AA/NSFM could establish much higher resistance factor (RF) and residual resistance factor (RRF) than AM/AA under the same conditions (RF: 16.52 versus 12.17, RRF: 3.63 versus 2.59). At last, the enhanced oil recovery (EOR) of AM/AA/NSFM was up to 20.10% by core flooding experiments at 65°C.

A water-soluble hyperbranched copolymer based on a dendritic structure for low-to-moderate permeability reservoirs

In this study, a modified dendritic functional monomer (named DA) consisting of 1,3-propanediamine as the initiated core was prepared and utilized to react with acrylamide (AM), acrylate (AA) and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) to synthesize a water-soluble hyperbranched copolymer (noted HPDA) for low-to-moderate permeability reservoirs through a redox free radical polymerization strategy. The copolymer was characterized by a series of experiments, including IR, 1H NMR, DLS and AFM. It was observed expectedly that the HPDA solution displayed a distinct topological structure in solution, resulting in a smaller mean diameter in comparison to the linear polymer. Furthermore, the rheology performances and anti-shearing properties of HPDA were investigated, which demonstrated that the introduced dendritic structure could endow the polymer with great viscosity retention and excellent elasticity in a relatively high frequency region. Based on the sand packed tube displacement experiment, a favorable matching relationship could be found between the size of the sheared HPDA and the pore throat as the permeability ranged from 500 to 100 mD. Moreover, compared with the linear polymer, AM/AA/AMPS, the sheared HPDA solution of 2000 mg L−1 could significantly increase the efficiency of oil recovery to 21.9% and 17.5% by controlling the displacing phase mobility and constructing an appreciable resistance factor and residual resistance factor in the 500 and 260 mD porous media.