Experimental Investigation of Mechanisms in Functionalized Multiwalled Carbon Nanotube Flooding for Enhancing the Recovery From Heavy-Oil Reservoirs

Abstract

Summary In the past few years, nanoparticle flooding has displayed significant potential for enhancing oil recovery. Among different nanoparticles, hydrophilic (functionalized) nanotubes have not been tested yet. Therefore, in this study, functionalized multiwalled carbon nanotubes (MWCNT) were used in three concentrations—0.01, 0.05, and 0.1 wt%—to conduct micromodel, interfacial–tension (IFT), wettability, viscosity, phase–behavior, and static–adsorption tests. In addition, constancy of nanofluids in the presence of sodium chloride (NaCl) was investigated qualitatively. Obtained results illustrated that by increasing the nanoparticle concentration from 0.01 to 0.1 wt%, nanofluid/oil IFT decreased, because MWCNT were placed between the surfaces of the oil and the nanofluid. Also, viscosity of the nanofluid improved slightly when the nanoparticle concentration increased. Moreover, contact angle was measured before and after coating with nanosuspensions, and the achieved data showed a change from oil–wet to water–wet. The resulting emulsion was a water–in–oil type; therefore, as MWCNT concentration increased, the size and number of water droplets in the oil also increased. This augmentation improved the effectiveness of the emulsion viscosity. Stability tests also provided evidence confirming that the nanofluids were stable for 10 days in concentrations of 0.01 and 0.1 wt% and in salinities of 1 and 0.5 wt%, respectively. Besides, the addition of 0.05 wt% sulfonated polymer to the nanofluids ensured their stability in higher salinities. Moreover, the results of the micromodel test revealed that by increasing the concentration of nanoparticles, sweep efficiency increased and the fingering phenomenon was reduced. In addition, the ultimate recovery of oil obtained by nanosuspension flooding in concentrations of 0.01, 0.05, and 0.1 wt% was, respectively, 12.6, 16.4, and 20% higher than that of waterflooding. Static adsorption on sandstone was found to be 0.575, 1.25, and 1.76 mg/m2 at 0.01, 0.05, and 0.1 wt%, respectively, and it reached its fixed amounts within 24 hours. Therefore, functionalized MWCNT might help increase heavy–oil recovery through mechanisms of reducing IFT, changing wettability from oil–wet to water–wet in oil–wet reservoirs, increasing viscosity (slightly), and developing a water–in–oil emulsion.

Experimental and Computational Fluid Dynamics Investigation of Mechanisms of Enhanced Oil Recovery via Nanoparticle-Surfactant Solutions

“…An equilibrium exists between the solid–liquid IFT (γ sl ), liquid–gas IFT (γ lg ), and solid–gas IFT (γ sg ), as the water droplet was placed on the rock surface during the contact angle measurement, as indicated in the following equation , γ sg = cos nobreak0em.25em⁡ θ normalc γ lg + γ sl The results of previous studies demonstrated that solid–liquid IFT (γ sl ) plays a prominent role when contact angle measurement is conducted with the sessile drop technique. In addition, the contact angle between the glass surface and liquid droplets is smaller at a higher γ sl value. ,− Hydrogen bonds could be formed between the surface agents (the surfactant and nanomaterials) and water molecules. The formation of a hydrogen bond increases γ sl ; thus, the contact angle reduces when the NPS solution droplets are placed on rock surfaces.…”

Nanoparticles for Enhancing Heavy Oil Recovery: Recent Progress, Challenges, and Future Perspectives

“…Ghalamizade et al detected the EOR potential of hydrophilic multiwalled carbon nanotubes. Visual micromodel tests disclosed that nanoparticles increased the sweep efficiency and reduced the viscous fingering phenomenon.…”

Application of ion-engineered Persian Gulf seawater in EOR: effects of different ions on interfacial tension, contact angle, zeta potential, and oil recovery

“…Then, smart water was injected into the micromodel at a rate of 0.05 mL/h. It should be noted that this flow rate was chosen to avoid turbulence behavior in the micromodel (Ghalamizade Elyaderani et al 2019). Next, the picture of micromodel was taken by a camera at constant time intervals to measure the oil recovery factor.…”