Li, Shidong (Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research A*STAR) | Hadia, Nanji J (Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research A*STAR) | Lau, Hon Chung (National University of Singapore) | Torsæter, Ole (PoreLab Research Center, Department of Geoscience and Petroleum, Norwegian University of Science and Technology) | Stubbs, Ludger P (Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research A*STAR) | Ng, Qi Hua (Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research A*STAR)
Oil and gas industry is witnessing a rapid increase of interest in application of nanotechnology. Since last few years, nanotechnology is being studied as an alternative enhanced oil recovery (EOR) method and laboratory experiments have shown its potential. However, the adsorption behavior of nanoparticles in porous media and underlying mechanisms for improving oil recovery are still not well understood. The objective of this study was to investigate silica nanoparticles adsorption and displacement mechanisms at the pore scale within a micromodel. Another objective was to stabilize silica nanoparticles in the presence of crude oil at a high salinity and a high temperature for a longer period of time.
A turbidity scanner was utilized to test stability of silica nanoparticles suspension in the presence of crude oil under 60°C. Turbidity stability index was used to evaluate stability of nanoparticles suspension and hydrochloric acid (HCl) was used as stabilizer to improved stability of nanoparticles suspension. The interfacial tensions (IFT) and contact angle between crude oil and the nanoparticles suspension with stabilizer were also measured. Both single-phase and two-phase flooding experiments were conducted for nanoparticles with and without stabilizer by using glass micromodels to visualize the nanoparticles adsorption and displacement behavior at the pore scale. Oil recovery was determined with image analysis to evaluate the potential of these nanoparticles for EOR applications. In addition, microscope images were taken and analyzed to investigate EOR mechanisms of nanoparticles suspension.
Results of turbidity scanner showed nanoparticles behavior changed from aggregation to sedimentation. Silica nanoparticles suspension with HCl showed much better stability than the one without HCl under 3.8 wt. % synthetic sea water and 60°C condition. Wettability alteration between crude oil and water were observed with silica nanoparticles. For single-phase visualization flooding experiments, nanoparticles suspension with a stabilizer had less adsorption than the one without a stabilizer, and it could flow through micromodel without significant plugging. Nanoparticles adsorption can alter wettability of the micromodel to more water-wet. For two-phase visualization flooding experiments, injection of silica nanoparticles suspension with a stabilizer had better EOR result under high flow rate and can increase oil recovery about 3%. Wettability alteration and emulsification were proposed as main EOR mechanisms for nanoparticles.
Silica nanoparticles stability behavior in the presence of crude oil under a high salinity and a high temperature was studied and the stability of nanoparticles suspension was quantified by using turbiscan stability index. Adding HCl as a stabilizer can reduce adsorption of nanoparticles in micromodel and avoid plugging. Enhanced oil recovery mechanisms of nanoparticles were investigated by using visualization micromodel flooding for better understanding of nanoparticles flooding.
Arshad, Muhammad Waseem (Technical University of Denmark DTU, DTU Chemical Engineering, Center for Energy Resources Engineering, Søltofts Plads 229, DK-2800 Kongens Lyngby) | Loldrup Fosbøl, Philip (Technical University of Denmark DTU, DTU Chemical Engineering, Center for Energy Resources Engineering, Søltofts Plads 229, DK-2800 Kongens Lyngby) | Shapiro, Alexander (Technical University of Denmark DTU, DTU Chemical Engineering, Center for Energy Resources Engineering, Søltofts Plads 229, DK-2800 Kongens Lyngby) | Thomsen, Kaj (Technical University of Denmark DTU, DTU Chemical Engineering, Center for Energy Resources Engineering, Søltofts Plads 229, DK-2800 Kongens Lyngby)
Smart water flooding is an advanced method for enhanced oil recovery (EOR) in which the composition of injected brine is altered by varying the concentration of selected ions that can increase the oil recovery from various carbonate reservoirs. Besides wettability alteration mechanism, the formation of water-soluble oil emulsions has been reported as a possible reason to explain the observed increase in oil recovery using smart water. The formation of water-soluble oil emulsions takes place on the interaction of insoluble salts (fines) with oils. However, the interaction of these fines with the crude oil is not very well studied for carbonate reservoirs. This work presents emulsion formation in water-oil systems in the presence of water-insoluble fines. The effect of amount of fines on emulsion formation is also examined.
Synthetic seawater (SSW) and deionized water (DIW) were used as water phase, two model oils (decane (D) and 1:1 vol. ratio of hexane-hexadecane (HH) mixture) and North Sea crude oil (NSCO) were used as oil phase, and fines of CaCO3 (≤ 30 µm) and CaSO4 (≈ 44 µm) were used as solid phase. Branson Sonifier® SFX250 was used for emulsion formation (based on the principle of ultrasonic processing). All the experiments were performed for the same conditions of 5 minutes of ultrasonic processing at an output power of 30 W by using 6.5 mm tapered microtip (sonication probe). Emulsion characterization was done by using an optical microscope (Axio Scaope.A1).
Several combinations of water-oil-fines were tested. The tests consisted of control experiments (in which only water-oil without any fines were tested) and water-oil-fines experiments. In the control experiments (without fines), SSW did not show any tendency to emulsify neither with the model oils nor with NSCO. However, DIW showed clear tendency to emulsify with model oils and NSCO. Amongst model oils, DIW emulsified with HH better compared to decane. Similar results were observed in the water-oil-fines experiments. SSW did not form any emulsion with the model oils in the presence of fines of CaCO3 and CaSO4. However, significant amounts of emulsion formation were observed when DIW was sonicated with model oils and fines. HH formed more emulsions compared to decane. For NSCO case, both SSW and DIW formed a significant amount of emulsions with both types of fines (CaCO3 and CaSO4). An increase in amount of fines showed an increase in emulsion formation and a better emulsion stabilization. Sonication is a quick and reliable technique to screen out emulsion formation in different combinations of water-oil-fines.
This work will further develop our understanding of emulsion formation in the water-oil-fines systems.