Organic nanoparticles are small particles formed from aggregated molecules or polymers. They are valued because they are easy to synthesize and can be tailored into various aggregated morphologies.1,2
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Organic nanoparticles are frequently used in enhanced oil recovery (EOR). These materials reduce interfacial tension (IFT), improve wettability, and increase oil recovery. Their unique properties make them highly useful in EOR processes.1,2
Types of Organic Nanoparticles in Enhanced Oil Recovery
Organic nanoparticles used in EOR include:
- Carbon-based Nanoparticles
- Carbon Nanotubes (CNTs)
- Lipid-based Nanoparticles
- Polymer Nanoparticles
- Polymer-coated Nanoparticles
- Polymer-grafted Nanoparticles (PGNPs).2,3
Carbon-Based Nanoparticles
A black powder of spherical carbon nanoparticles with specific properties can be synthesized using the hydrothermal method. Surface modifications can be achieved by chemically bonding organic compounds or polymers to nanoparticle surfaces.2
The primary types of carbon nanoparticles include CNTs, graphite nanopowders, graphene nanoparticles, and fullerenes. These particles enhance flow properties and reduce IFT, thereby improving oil displacement efficiency. Although graphene nanoparticles exhibit exceptional properties, only a few studies have investigated their potential application in EOR.2,4
A study published in the Journal of Materials Research and Technology characterized sandstone core plugs infused with brine, crude oil, and carbon nanofluids or composites, including graphene, using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, and field emission scanning electron microscopy (FESEM).4
IFT measurements were conducted for oil/brine/carbon nanoparticles and graphene nanofluids. Results indicated that nanoparticles formed adsorption layers on sandstone surfaces, significantly altering IFT and wettability. IFT values for carbon nanofluid/oil, graphene nanofluid/oil, and brine/oil were measured at 41-44 mN/m, 9.8-11.4 mN/m, and 39-40 mN/m, respectively.4
Spectroscopic analysis showed that graphene exhibited higher adsorption on sandstone than regular carbon nanoparticles. The enhanced IFT reduction by graphene nanofluids was attributed to their combined hydrophobic and hydrophilic properties.4
Carbon Nanotubes
CNTs are composed of graphene sheets and are one hundred times stronger than steel. They conduct electricity and heat along their length but are nonconductive across the tube. The use of CNTs in carbonate samples has been shown to increase the oil recovery factor.2,3
Recent studies showed that CNT nanoparticles could increase oil viscosity, resulting in enhanced recovery rates through enhanced mobilization.2,3 For instance, a study published in The APPEA Journal evaluated the effectiveness of the CNT and date leaf carbon particle (DLCP) method in green surfactant alkyl polyglucoside (APG) for residual oil recovery within rock pores.5
Based on IFT measurements, two formulations of CNT, DLCP, and green surfactant mixtures were selected for core-flood tests to investigate their potential for green EOR. Results showed 45 % tertiary oil recovery and 89 % oil initially in place (OIIP) in one experiment. This composition also yielded additional oil after water flooding.5
Lipid-Based Nanoparticles
Lipid nanoparticles are generally spherical, with diameters ranging from 10 to 100 nanometers. They consist of a solid lipid matrix embedded with a soluble lipophilic molecule. Emulsifiers and surfactants are used to stabilize the outer layer of these nanoparticles, which are applied as surfactant carriers.3
Nanostructured lipid carriers can reduce IFT and improve oil recovery. For instance, a study published in Fuel examined the use of lipid nanostructures as surfactant nanocarriers for the EOR process.3,6 In this approach, nanocarriers composed of hydrophobic nanoparticles store and transport surfactant molecules through reservoir porous media, releasing the surfactant only at the water/oil interface due to the nanocarrier’s solubilization.6
The surfactant released at the interface lowers the IFT, improving the oil recovery factor to levels comparable to those of using only the surfactant solution. Researchers synthesized these nanoparticles using nano-emulsification techniques, employing nonylphenol ethoxylate as a surfactant and beeswax as the lipid matrix.6
The study also examined the effects of nanoparticle production processes, temperature, and salt concentration on nanoparticle efficiency in surfactant delivery at the water/oil interface. Findings indicated substantial potential for lipid nanoparticles as surfactant nanocarriers in EOR applications.6
Polymer Nanoparticles
Polymer nanoparticles can be either nanospheres or nanocapsules. Nanospheres have a matrix structure, whereas nanocapsules have a core-shell structure.
They are synthesized using methods such as microemulsion, salting-out, solvent evaporation, mini-emulsion, interfacial polymerization, dialysis, surfactant-free emulsion, and supercritical fluid technology.2,3
In EOR, polymer-based nanoparticles reduce IFT, adjust wettability, control the mobility ratio, and modify the viscosity of injected fluids to improve sweep efficiency in oil reservoirs.2,3
A study published in Fuel introduced a novel nano-fluid developed from a nanocomposite composed of a betaine-type zwitterionic surfactant and polymer nanoparticles for EOR under harsh reservoir conditions.7
The synthesized nanocomposite was characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), FTIR spectroscopy, and dynamic light scattering (DLS). The nanofluid displayed notable stability at high temperatures (80 °C) and high salinity (15 wt% simulated brine) for over 30 days.7
Additionally, the water/oil IFT of Bakken crude oil was reduced by 99.49 %, and the contact angle increased by 125.73 % compared to initial values, leading to significantly improved oil recovery.7
Polymer Enhanced Oil Recovery
Polymer-Coated Nanoparticles
Polymer-coated nanoparticles consist of a metal oxide core surrounded by a polymer layer. This polymer coating, often made of polyethylene glycol (PEG), minimizes adsorption and electrostatic interactions, making these particles suitable for extreme reservoir conditions, such as high salinity and temperature.2
In EOR, polymer-coated nanoparticles can be adapted for specific applications, such as improving mobility control, reducing IFT, increasing displacing agent viscosity, altering surface wettability, and stabilizing foams and emulsions. The polymer coating enhances nanoparticle dispersion and stability in the oil phase, increasing their effectiveness in EOR processes.2
A study published in Nanomaterials investigated the potential of various polymer-coated silica nanoparticles as additives in seawater injection for EOR. Experiments were conducted on neutral-wet Berea sandstone core samples at ambient conditions, assessing both secondary and tertiary oil recovery.8
The study evaluated oil recovery through mechanisms such as IFT reduction, log-jamming, and wettability modification. Results showed that polymer-coated silica nanoparticles improved the efficiency of water flooding, achieving 60–72 % original oil in place (OOIP) in secondary recovery, compared to 56 % OOIP with standard water flooding.8
In tertiary recovery, incremental oil recovery ranged from 2.6 % to 5.2 % OOIP. Additionally, the presence of coated silica nanoparticles reduced the oil-water IFT from 10.6 to 2.5-6.8 mN/m.8
Polymer-Grafted Nanoparticles
PGNPs were developed to reduce aggregation and accumulation, which can impact nanoparticle performance. Polymer molecules are grafted onto inorganic, organic, and nonmetallic nanoparticle surfaces to enhance surface topology and chemical characteristics, creating PGNPs tailored for specific oil types to optimize EOR through targeted interactions.2
A study published in the Journal of the Taiwan Institute of Chemical Engineers described the synthesis of a water-soluble nanocomposite using radical polymerization to graft a polymeric chain onto the silica nanoparticle surface.9
The polymer chains improved the surface properties of the silica nanoparticles, resulting in reduced IFT and modified rock surface wettability. Simulation studies validated that this nano-composite could mobilize the residual oil left in sand packs following secondary recovery.9
Conclusion
Organic nanoparticles offer potential benefits for EOR by reducing IFT, improving wettability, and supporting oil recovery efficiency. By examining the different types of organic nanoparticles and their specific applications, researchers and engineers can develop optimized strategies to improve oil recovery processes.
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References and Further Reading
- The University of Melbourne. (n.d.). Organic Nanoparticles [Online] The University of Melbourne. Available at https://uml.chemistry.unimelb.edu.au/organic-nanoparticles/ (Accessed on 05 November 2024)
- Hosny, R. et al. (2023). Nanotechnology Impact on Chemical-Enhanced Oil Recovery: A Review and Bibliometric Analysis of Recent Developments. ACS Omega. DOI: 10.1021/acsomega.3c06206, https://pubs.acs.org/doi/full/10.1021/acsomega.3c06206
- Sircar, A., Rayavarapu, K., Bist, N., Yadav, K., Singh, S. (2022). Applications of nanoparticles in enhanced oil recovery. Petroleum Research. DOI: 10.1016/j.ptlrs.2021.08.004, https://www.sciencedirect.com/science/article/pii/S2096249521000636
- Yahya, N., Ali, AM., Wahaab, FA., Sikiru, S. (2020). Spectroscopic analysis of the adsorption of carbon based nanoparticles on reservoir sandstones. Journal of Materials Research and Technology. DOI: 10.1016/j.jmrt.2020.02.058, https://www.sciencedirect.com/science/article/pii/S2238785420301575
- Haq, B. et al. (2020). The role of carbon nanotubes (CNTs) and carbon particles in green enhanced oil recovery (GEOR) for Arabian crude oil in sandstone core. The APPEA Journal. DOI: 10.1071/AJ19017, https://www.publish.csiro.au/ep/AJ19017
- Rosestolato, JC., Pérez-Gramatges, A., Lachter, ER., Nascimento, RS. (2019). Lipid nanostructures as surfactant carriers for enhanced oil recovery. Fuel. DOI: 10.1016/j.fuel.2018.11.027, https://www.sciencedirect.com/science/article/pii/S0016236118319112
- Zhou, Y., et al. (2020). Polymer nanoparticles based nano-fluid for enhanced oil recovery at harsh formation conditions. Fuel. DOI: DOI: 10.1016/j.fuel.2020.117251, https://www.sciencedirect.com/science/article/abs/pii/S0016236120302465
- Bila, A., Stensen, JÅ., Torsæter, O. (2019). Experimental investigation of polymer-coated silica nanoparticles for enhanced oil recovery. Nanomaterials. DOI: 10.3390/nano9060822, https://www.mdpi.com/2079-4991/9/6/822
- Maurya, NK., Kushwaha, P., Mandal, A. (2017). Studies on interfacial and rheological properties of water soluble polymer grafted nanoparticle for application in enhanced oil recovery. Journal of the Taiwan Institute of Chemical Engineers. DOI: 10.1016/j.jtice.2016.10.021, https://www.sciencedirect.com/science/article/abs/pii/S1876107016303996
