Arshad, Muhammad Waseem (Technical University of Denmark) | Feilberg, Karen Louise (Technical University of Denmark) | Shapiro, Alexander (Technical University of Denmark) | Thomsen, Kaj (Technical University of Denmark)
Characterization of emulsion formation (amount and droplet size) in the brine-oil-nanoparticle systems as a function of varying size of nanoparticles and modified brine salinity is presented. Different brines were used with a range from zero salinity for deionized water (DIW) to synthetic seawater (SSW), mimicking the salinity of North Sea water. Brines (FW1 and FW2) representing the composition of formation water obtained from different production wells (North Sea) were also used. Two model oils (decane (D) and hexane-hexadecane (HH) mixture of 1:1 vol. ratio) and a sample of North Sea crude oil (NSCO) were used. CaCO3 nanoparticles of three different sizes of 15-40, 50, and 90 nm were used. Nanoparticles characterization was performed with Transmission Electron Microscopy (TEM). A commercially available sonication equipment, Branson Sonifier® SFX250, was employed for emulsion formation in brine-oil-nanoparticles systems. All the experiments were performed at room temperature for the same experimental conditions of 5 minutes of ultrasonic processing by using a 6.5 mm tapered microtip (sonication probe) with an output power of 30 W. Emulsion characterization (emulsion droplet size) was performed with an optical microscope (Axio Scope.A1).
The effect of size of CaCO3 nanoparticles and brine salinity on emulsion formation was investigated for different brine-oil systems. The results showed that the emulsion formation in brine-model oil (D and HH) systems was an inverse function of the size of nanoparticles i.e., a large amount of emulsion formation was observed for the smaller sized nanoparticles and vice versa. Emulsion characterization for these systems showed that the emulsion droplet size increased with an increase in size of the nanoparticles. The brine salinity also showed a significant effect on emulsion formation in brine-model oil systems i.e., a decrease in brine salinity showed an increase in emulsion formation and correspondingly smaller emulsion droplet sizes. However, the brine salinity did not affect the emulsion formation and emulsion droplet size for 15-40 nm nanoparticles. Contrary to the brine-model oil results, the results of brine-NSCO systems neither showed any dependence on the size of nanoparticles nor on the brine salinity. This might be due to the presence of polar fractions (polar acids and polar bases) in the crude oil.
The characterization study presented in this paper can provide a foundation for future development of calcite nanoparticle based EOR applications in the carbonate reservoirs.
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.