Zhongbin Ye

Synthesis and evaluation of novel water-soluble copolymers based on acrylamide and modular β-cyclodextrin

Mono-6-(allyl amino)-β-cyclodextrin (N-β-CD) and mono-2-O-(allyl oxygen radicals-2-hydroxyl propyl)-β-cyclodextrin (O-β-CD) were copolymerized with acrylamide (AM), acrylic acid (AA), and 1-llyl-3-oil acyloxyimidazole-1-ammonion bramide (AOAB) initiated by redox initiation system in an aqueous medium. The AM/AA/AOAB/N-β-CD and AM/AA/AOAB/O-β-CD were prepared by adjusting the reactive conditions, such as initiator concentration, pH, temperature, and monomer ratios. The obtained copolymers were characterized by means of infrared (IR) spectroscopy, (1)H NMR spectroscopy, scanning electron microscope (SEM), rotational rheometer, intrinsic viscosity, salt resistance, core flood test, etc. The temperature-tolerance, shear-tolerance, salt-resistance and thickening function of these copolymers are improved remarkably compared with partially hydrolyzed polyacrylamide (HPAM). About 18.3% and 12.5% oil recovery could be enhanced by 2000mg/L AM/AA/AOAB/N-β-CD and AM/AA/AOAB/O-β-CD comparing with water-flooding. In addition, the result of X-ray diffractometry (XRD) test showed that the solutions of obtained copolymers could remarkably reduce the crystalline interspace of sodium montmorillonite (from 18.9Å to 15.3Å).

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.

A novel micro-nano structure profile control agent: graphene oxide dispersion

Graphite oxide sheet, now referred to as graphene oxide (GO), is the product of chemical exfoliation of graphite and has been known for more than a century. A GO sheet is characterized by two abruptly different length scales; the apparent thickness of the functionalized carbon sheet is approximately 1 nm, but the lateral dimensions can range from a few nanometers to micrometers. In this paper, an improved method for the preparation of graphene oxide within a mild condition is described. We have found that cancelling the high-temperature stage and prolonging the reaction time of mid-temperature can improve the efficiency of oxidation process. We utilized FTIR, XRD, Ultraviolet-visible, TGA, Raman spectrum, and XPS measurements to characterize the successfully synthesized GO. SEM images were employed to reveal the interior microstructure of as-prepared GO dispersion. We also wondrously found that the GO dispersion could be used as profile control agent in the oilfield water-flooding. Flooding experiments showed that the GO dispersion has an ability to adjust water injection profile, reduce permeability ratio, and improve conformance factor. So the GO dispersion would have potential applications in oilfield exploitation.

Effect of sodium dodecyl benzene sulfonate to the displacement performance of hyperbranched polymer

Experimental studies were conducted to realize displacement performance effect of anionic surfactant sodium dodecyl benzene sulfonate (SDBS) on hyperbranched poly(AM/AA/AMPS/GA), which was successfully synthesized via free radical polymerization using modified dendritic functional monomer (GA), acrylamide (AM), acrylate (AA), and 2-acrylamido-2-methyl propane sulfonic acid (AMPS). Compared with individual polymer, SP (surfactant polymer) binary systems showed lower apparent viscosity, interfacial tension, and hydrodynamic radius as the result of the electrostatic repulsion between the tail end of hydrophilic polymer branched chain and the head of the surfactant. It was found from abundant static adsorption and dynamic retention tests that the values of static adsorption and dynamics retention of SDBS which is mixed with hyperbranched polymer decrease due to the competitive interaction. However, unlike this phenomenon, SDBS would heighten the dynamic retention value of poly(AM/AA/AMPS/GA), resulting in addition of residual resistance factor. Oil displacement experiment indicated that SP solutions have greater capability of enhance oil recovery than individual polymer under same conditions.

Preparation and properties of hyperbranched polymer containing functionalized Nano-SiO2 for low-moderate permeability reservoirs

A novel water-soluble hyperbranched polymer (AA/AM/SMNS) consisting of functionalized Nano-SiO2 as the core was synthesized by free-radical polymerization for low-moderate permeability reservoirs. The AA/AM/SMNS was carefully characterized by spectroscopic and electronic technologies. It was found that the microscopic structures of AA/AM/SMNS was denser and more regular in comparison to the linear polymer HPAM. The hydrodynamic radius of AA/AM/SMNS was 197 nm, less than the HPAM radius of 244 nm with similar molecular weight, so that the AA/AM/SMNS had a good matching relationship with pore throat in midpermeability reservoirs (100–500 mD). Besides, the introduction of Nano-SiO2 endowed the AA/AM/SMNS remarkable thermal stability, shear resistance and viscoelasticity. Based on core flooding experiments, the AA/AM/SMNS could build high resistance factor and residual resistance factor in the corresponding porous medium. Furthermore, the sheared AA/AM/SMNS solution of 1500 mg L–1 performed excellent oil recovery of 15.47% in the 300 mD porous medium, which suggested the hyperbranched polymer based on modified Nano-SiO2 have a valuable prospect for enhancing oil recovery in low-moderate permeability reservoirs.

Interaction between Aqueous Solutions of Hydrophobically Associating Polyacrylamide and Dodecyl Dimethyl Betaine

The interaction between hydrophobically associating polyacrylamide (HAPAM) and dodecyl dimethyl betaine (BS-12) is studied through surface tension, interfacial tension (IFT), apparent viscosity, aggregation behavior, and microscopic morphologies. Results show that surface and interface properties of BS-12 are largely affected by HAPAM. BS-12 critical micelle concentrations are increased with the increment of polymer concentrations. Abilities of reduced air-water surface tension and oil-water interfacial tension are dropped. The oil-water interfacial tension to reach minimum time is increased. HAPAM can form network structures in the aqueous solution. Mixed micelles are formed by the interaction between BS-12 micelles and hydrophobic groups of HAPAM in aqueous solution and self-assembly behavior of HAPAM is affected. With the increment of surfactant concentrations, the apparent viscosity, apparent weight average molecular weights (), root mean square radius of gyration (), and hydrodynamic radius of HAPAM increase first and then decline. Moreover, microscopic morphologies of the mixed system are formed from relatively loose network structures to dense network structures and then become looser network structures and the part of network structures fracture.

The Wettability Alteration Behavior of Cationic Gemini Surfactants on Oil-aged Mica Mineral Surfaces

Abstract The wettability of oil reservoir rock will affect the oil recovery efficiency by reducing the capillary force. A Gemini cationic surfactant containing double dodecyl chains and two quaternary ammonium headgroups was synthetized and used as a new wetting alteration agent. This paper focuses on the wettability alteration of Gemini cationic surfactants on oil-aged mica mineral surface. The results of contact angle data show that Gemini cationic surfactant have great wettability to alter oil-aged mica surfaces to mid-wetting even weakly water-wet. The adsorption morphology by atomic force microscopy shows that the degree of wettability alteration is mainly dependent on the coverage areas of surfactant molecules. Gemini surfactant formed monolayer on oil-aged mica surface and the monolayer has the trend to from a compact film with increasing concentration. Compared with the single chain surfactant, Gemini surfactant has stronger ability to alter oil-aged surfaces. Considering the flooding experiment in lab results, this Gemini surfactant might be a good choice to be used in chemical flooding.

A Novel Nanodrag Reducer for Low Permeability Reservoir Water Flooding

Chemical modification of graphene oxide GO by grafting hydrophobic chains on the surface has drawn much attention nowadays in the academic world, and it was suggested that modified GO could lead to new functionalized materials with specific structure and different properties. In this paper, modified GO M-GO were synthesized by chemically grafting alkylamines with varying chain lengths on the graphene oxide surface. Successful grafting of alkylamines was confirmed using Fourier transform infrared FTIR spectra, X-ray diffraction XRD, thermogravimetric analysis TGA, scanning electron microscope SEM, and Raman spectroscopy measurements. In addition, we investigated the properties of M-GO as nanodrag reducer in low permeability reservoir water flooding. Water contact angle CA measurements revealed that the hydrophobic nature of GO depended on the chain length of the grafted alkylamines. And flooding experiments showed that the hexadecylamine- and octadecylamine-modified GO had an ability to reduce water injection pressure and improve water-phase permeability of the low permeability reservoirs during water flooding. So the M-GO would have potential applications in oilfield exploitation.