Synthesis and evaluation of acryloylated starch-g-poly (Acrylamide/Vinylmethacrylate/1-Vinyl-2-pyrrolidone) crosslinked terpolymer functionalized by dimethylphenylvinylsilane derivative as a novel polymer-flooding agent

Chemical and Physical Architecture of Macromolecular Gels for Fracturing Fluid Applications in the Oil and Gas Industry; Current Status, Challenges, and Prospects

Hydraulic fracturing is vital in recovering hydrocarbons from oil and gas reservoirs. It involves injecting a fluid under high pressure into reservoir rock. A significant part of fracturing fluids is the addition of polymers that become gels or gel-like under reservoir conditions. Polymers are employed as viscosifiers and friction reducers to provide proppants in fracturing fluids as a transport medium. There are numerous systems for fracturing fluids based on macromolecules. The employment of natural and man-made linear polymers, and also, to a lesser extent, synthetic hyperbranched polymers, as additives in fracturing fluids in the past one to two decades has shown great promise in enhancing the stability of fracturing fluids under various challenging reservoir conditions. Modern innovations demonstrate the importance of developing chemical structures and properties to improve performance. Key challenges include maintaining viscosity under reservoir conditions and achieving suitable shear-thinning behavior. The physical architecture of macromolecules and novel crosslinking processes are essential in addressing these issues. The effect of macromolecule interactions on reservoir conditions is very critical in regard to efficient fluid qualities and successful fracturing operations. In future, there is the potential for ongoing studies to produce specialized macromolecular solutions for increased efficiency and sustainability in oil and gas applications.

Assessment of modified chitosan composite in acidic reservoirs through pilot and field-scale simulation studies

Chemical flooding through biopolymers acquires higher attention, especially in acidic reservoirs. This research focuses on the application of biopolymers in chemical flooding for enhanced oil recovery in acidic reservoirs, with a particular emphasis on modified chitosan. The modification process involved combining chitosan with vinyl/silane monomers via emulsion polymerization, followed by an assessment of its rheological behavior under simulated reservoir conditions, including salinity, temperature, pressure, and medium pH. Laboratory-scale flooding experiments were carried out using both the original and modified chitosan at conditions of 2200 psi, 135,000 ppm salinity, and 196° temperature. The study evaluated the impact of pressure on the rheological properties of both chitosan forms, finding that the modified composite was better suited to acidic environments, showing enhanced resistance to pressure effects with a significant increase in viscosity and an 11% improvement in oil recovery over the 5% achieved with the unmodified chitosan. Advanced modeling and simulation techniques, particularly using the tNavigator Simulator on the Bahariya formations in the Western Desert, were employed to further understand the polymer solution dynamics in reservoir contexts and to predict key petroleum engineering metrics. The simulation results underscored the effectiveness of the chitosan composite in increasing oil recovery rates, with the composite outperforming both its native counterpart and traditional water flooding, achieving a recovery factor of 48%, compared to 39% and 37% for native chitosan and water flooding, thereby demonstrating the potential benefits of chitosan composites in enhancing oil recovery operations.

Experimental and Theoretical Investigation of Glycol-Based Hydrogels through Waterflooding Processes in Oil Reservoirs Using Molecular Dynamics and Dissipative Particle Dynamics Simulation

Enhanced oil processing aims to retrieve petroleum fluids from depleted reservoirs after traditional processing. Hydrogels and polymeric macromolecules are considered effective displacing agents in oil reservoirs. In the current work, the authors used hydrophilic hydrogels based on poly(ethylene glycol)/poly(propylene glycol) (PEG/PPG) surfmers for oil displacement processes. Statistical modeling of the rheological properties at 80 °C for the two hydrogels indicates that the viscosity-shearing profile obeys the power-law model. Also, shear stress scanning follows the Herschel-Bulkley and the Bingham plastic models. The two hydrogels exhibit an initial yield stress owing to the formation of a three-dimensional (3D) structure at zero shearings. Furthermore, PEG and PPG hydrogels can retain the viscosity after a shear rate of 64.68 S-1. On the scale of surface activity, the two hydrogels exhibit higher surface areas (A m) of 0.1088 and 0.1058 nm2 and lower surface excess concentrations (Γm) of 1.529 and 1.567 × 1010 mol/cm2, respectively. A molecular dynamics (MD) simulation was conducted to explore the Flory-Huggins chi parameter, the solubility parameter, and the cohesive energy density. The results indicate a negative magnitude of chi parameter (χ ij ) for water and salt, which indicates that the two hydrogels have a good tendency toward saline formation water in the underground petroleum reservoir. Furthermore, the dissipative particle dynamics (DPD) was performed on a mesoscale to investigate the interfacial tension, the radius of gyration, the concentration profile, and the radial distribution function. The increased radius of gyration (R g) confirms that the two hydrogels are more overextended and can align perpendicularly toward the water/oil boundary. Experimental displacement was operated on a linear sandpack model using different slug concentrations. The oil recovery factor, the water-cut, and the differential pressure data during the flooding process were estimated as a function of the injected pore volume. The obtained results show that the oil recovery factor reaches 72 and 88% in the cases of PEG and PPG hydrogels at 80 °C with concentrations of 1.0 and 1.5 g/L, which reveals that both hydrogels are effective enhanced oil recovery (EOR) agents for the depleted reservoirs. This study establishes a new route that employs MD and DPD simulation in the field of enhanced oil recovery and the petroleum industry.

The biopolymer produced by Rhizobium viscosum CECT 908 is a promising agent for application in microbial enhanced oil recovery

Polymer flooding is one of the most promising techniques used to increase the productivity of mature oil reservoirs. Polymers reduce the mobility ratio of the injected water relative to the crude oil, improving the displacement of the entrapped oil and consequently, increasing oil recovery. Biopolymers such as xanthan gum have emerged as environmentally friendly alternatives to the chemical polymers commonly employed by the oil industry. However, in order to seek more efficient biomolecules, alternative biopolymers must be studied. Here, the applicability of a biopolymer produced by Rhizobium viscosum CECT 908 in Microbial Enhanced Oil Recovery (MEOR) was evaluated. This biopolymer exhibited better rheological properties (including higher viscosity) when compared with xanthan gum. Its stability at high shear rates (up to 300 s^-1), temperatures (up to 80 °C) and salinities (up to 200 g/L of NaCl) was also demonstrated. The biopolymer exhibited better performance than xanthan gum in oil recovery assays performed with a heavy crude oil, achieving 25.7 ± 0.5% of additional recovery. Thus the R. viscosum CECT 908 biopolymer is a promising candidate for application in MEOR.

Synthesis of acryloylated starch-g-poly acrylates crosslinked polymer functionalized by emulsified vinyltrimethylsilane derivative as a novel EOR agent for severe polymer flooding strategy

Starch is a natural polysaccharide with reasonable biodegradable properties, which grafted with vinyl monomers through different initiators to be applied in enhanced oil recovery (EOR) techniques. Several authors stated about starch modification through copolymerization and grafting of different monomers, however, these derivatives have some drawbacks related to bacterial biodegradation, ionic and thermal aging under severe reservoir conditions. The present study reported the preparation of grafted acryloylated starch with acrylamide/acrylic acid monomers and vinyltrimethylsilane through initiation copolymerization with the aid of quaternary ammonium-based surfmer. The chemical analysis generated by various spectroscopic analysis comprising IR, NMR, meanwhile particles distribution estimated through DLS. The embedded silica through a polymer matrix photographed by TEM, SEM and EDX elementary analysis, and the thermal effect determined by thermal gravimetric analysis. The rheological analysis estimated relative to shear degradation, ionic strength, and thermal aging at imitated reservoir environment. Flooding runs performed on linear non-consolidated sandstone model at nearly practical field conditions, where the displaced oil by polymer effect was recorded through the volumetric collector. The flooding tests designate that the synthesized starch-g-copolymer is prospering for chemical flooding applications under severe reservoir conditions, and achieve a recovery factor of 46% S_or.