| Abstract | Despite the high efficiency of polymer flooding as a chemical enhanced oil recovery (CEOR) technique, the low thermal stability and poor salt resistance of widely applied partially hydrolyzed polyacrylamide (HPAM) limited the application of this technique in oil reservoirs at harsh reservoir conditions of high–temperature and high–salinity (HTHS). These inadequacies of HPAM, result in the urge for environmentally friendly polymer with good viscosifying properties and a substantial effect on mobility ratio at HTHS reservoir condition.
This research has introduced an assessment for the valorisation of a high acid value waste vegetable oil (WVO) into novel environmentally benign, thermo-responsive amphoteric nanocomposite for enhanced oil recovery (EOR) application at HTHS reservoir conditions. Two green reaction routes have been proposed to synthesize a novel oleic phenoxypropyl acrylate (OPA) thermosensitive monomer from high acid value WVO using different catalytic processes involve homogenous and heterogenous catalysts. A novel green copper-silica oxide/reduced graphene oxide (CuO-SiO2/RGO) multifunctional heterogeneous nanocatalyst derived from pomegranate peel extract has been synthesized and assessed for the direct conversion of high acid value WVO into OPA thermosensitive monomer via a single-step reaction. The prepared catalyst has been characterized using Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX). Response surface methodology (RSM) via Box-Behnken Design (BBD) has been utilized to derive the optimum OPA monomer yield at minimum reaction conditions for each reaction route, where the influence of the process variables and their interactions on the OPA yield has been evaluated. The reactive acryloyl double bond in the synthesized OPA monomer has been copolymerized with acrylamide (AM), acrylacyloxyethyltrimethyl ammonium chloride (DAC) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) in presence of dimethylphenylvinylsilane via free radical emulsion polymerization for the synthesis of a novel thermo-responsive amphoteric green polymer functionalized silica nanocomposite (AGPC) for EOR application at HTHS conditions. RSM based on central composite design (CCD) has been utilized to tailor-make the feed composition of the synthesized AGPC nanocomposite.
Further, the synthesized AGPC has been extensively characterized by different techniques. The results indicated that the optimal conditions of OPA monomer synthesis using 4- (dimethylamino)pyridine (DMAP) homogenous catalyst have been developed at 2- hydroxy-3-phenoxypropyl acrylate to methyl ester (HPA:FAME) molar ratio of 7.8:1, reaction temperature of 45 ºC, catalyst loading of 1.72 % (w/w) in 5.8 hours reaction time for 92.6 % OPA yield. However, for OPA monomer synthesis using CuO-SiO2/RGO nanocatalyst the optimal conditions have been developed at hydroxy-3-phenoxypropyl acrylate to WVO (HPA:WVO) molar ratio of 7.8:1, catalyst loading of 2.5 % (w/w) and reaction temperature of 94 ºC in 9.5 hours for 95.6 % OPA yield. The synthesized nanocomposite solution exhibited a pouncing thermo-thickening behaviour and superior viscosifying properties even at ultra-low polymer concentration of 400 ppm as the temperature increased from 25 to 100 ºC, with increasing salinity from 10,000 to 230,000 mg.L-1TDS as well as salt-free solutions. The nanocomposite solutions exhibit high resistance factor (Rf) and residual resistance factor (Rrf) values of 11.61 and 7.88, respectively at a low polymer concentration of 1000 ppm which proves its ability to improve the sweeping efficiency. Flooding experiments demonstrated that oil recovery factor reached 15.4 %, 22.6 % and 25 % using low nanocomposite concentrations of 400 ppm, 600 ppm and 1000 ppm, respectively evaluated under hostile conditions of 100 ºC and a salinity about 230,000 mg.L-1TDS. Therefore, this research offers a new direction for the synthesis of a novel green, high molecular weight thermo-responsive nanocomposite for EOR application at extreme harsh reservoir conditions via WVO valorisation. |
|---|