CO2 Emulsion Research Articles

CO2 Geostorage and Enhanced Oil Recovery: Challenges in Controlling Foam/Emulsion Generation and Propagation.

CO2 injection in subterranean reservoirs for storage, oil recovery, or both is challenging because of its very high mobility. Using a CO2 foam or emulsion is a way to remedy this problem by increasing CO2's apparent viscosity. However, the generation of the foam and its propagation in porous media present several issues that have to be overcome for this process to be economically realistic in practice. For example, it may take time, i.e., a number of pore volumes to be injected, before the foam is created. It is the objective of this Article to investigate these issues thoroughly and to identify the mechanisms underlying them by looking at the effects of various parameters. It is found that surfactant adsorption on the surface of the rock is an important factor involved in the delay of foam formation, but this may not explain all of the results. The nature and morphology of the porous medium may be, in some cases, the dominant factors for foam generation and propagation. From an understanding of the origin of the encountered problem, relevant mitigation strategies are envisioned and evaluated. It is found, for example, that when appropriately formulated and injected with the proper process, foam or emulsion generation is strongly accelerated, which very significantly shortens the delay for achieving CO2 storage.

Flow synthesis of silver nanoparticles using water in supercritical CO2 emulsion

Rapid and continuous synthesis of metal nanoparticles using green solvent system is still a serious challenge for both fundamental and practical research. In this work, we report a new flow process using water in supercritical CO2 (w/scCO2) emulsion and applied it to the synthesis of silver nanoparticles (AgNPs). To investigate the performance of our system, AgNPs were synthesized by batch, flow and w/scCO2 emulsion flow system at 40 ºC while using AgNO3, NaBH(OAc)3, trisodium citrate and Aerosol-OT as precursor, reducer, stabilizer and emulsifier. As a result, we demonstrated that water droplets in w/scCO2 emulsion significantly contribute to a rise in the size controllability and productivity (product yield). Additionally, w/scCO2 emulsion flow process allowed the control of mean size from 4.0 to 36.6 nm and yield from 25% to 65% by changing the CO2 pressure and Aerosol-OT concentration. Furthermore, synthesized AgNPs successfully gave citrate-modified surface with high zeta potential of –54 mV and the transparent water dispersion with unimodal size distribution, showing promising potential to allow various practical applications.

Experimental investigation on using CO2/H2O emulsion with high water cut in enhanced oil recovery

CO2 emulsions used for EOR have received a lot of interest because of its good performance on CO2 mobility reduction. However, most of them have been focusing on the high quality CO2 emulsion (high CO2 fraction), while CO2 emulsion with high water cut has been rarely researched. In this paper, we carried out a comprehensive experimental study of using high water cut CO2/H2O emulsion for enhancing oil recovery. Firstly, a nonionic surfactant, alkyl glycosides (APG), was selected to stabilize CO2/H2O emulsion, and the corresponding morphology and stability were evaluated with a transparent PVT cell. Subsequently, plugging capacity and apparent viscosity of CO2/H2O emulsion were measured systematically by a sand pack displacement apparatus connected with a 1.95-m long capillary tube. Furthermore, a high water cut (40 vol%) CO2/H2O emulsion was selected for flooding experiments in a long sand pack and a core sample, and the oil recovery, the rate of oil recovery, and the pressure gradients were analyzed. The results indicated that APG had a good performance on emulsifying and stabilizing CO2 emulsion. An inversion from H2O/CO2 emulsion to CO2/H2O emulsion with the increase in water cut was confirmed. CO2/H2O emulsions with lower water cuts presented higher apparent viscosity, while the optimal plugging capacity of CO2/H2O emulsion occurred at a certain water cut. Eventually, the displacement using CO2/H2O emulsion provided 18.98% and 13.36% additional oil recovery than that using pure CO2 in long sand pack and core tests, respectively. This work may provide guidelines for EOR using CO2 emulsions with high water cut.

Testing the encapsulation of phase change materials using supercritical emulsion extraction

Continuous supercritical CO2 emulsion extraction (SEE-C) technology is proposed for the first time to test the encapsulation of two fatty acids: Stearic acid and isopropyl myristate, to be used as model Phase Change Materials (PCM) in a PMMA shell. Spherical microcapsules with smooth surface and a mean diameter between 163-431 nm have been produced. Encapsulation efficiencies larger than those in the literature and up to a max of 91 % were measured. Therefore, supercritical PCM encapsulation can open new perspectives in thermal energy storage application.

Pickering interfacial biocatalysis with enhanced diffusion processes for CO2 mineralization

Utilization of carbon dioxide (CO2) has become a crucial and anticipated solution to address environmental and ecological issues. Enzymes such as carbonic anhydrase (CA) can efficiently convert CO2 into various platform chemicals under ambient conditions, which offers a promising way for CO2 utilization. Herein, we constructed a Pickering interfacial biocatalytic system (PIBS) stabilized by CA-embedded MOFs (ZIF-8 and ZIF-L) for CO2 mineralization. Through structure engineering of MOFs and incorporation of Pickering emulsion, the internal and external diffusion processes of CO2 during the enzymatic mineralization were greatly intensified. When CO2 was ventilated at a flow rate of 50 mL min–1 for 1 h, the pH value of PIBS dropped from ~8.00 to ~6.50, while the average pH value of free system only dropped to ~7.15, indicating that the initial reaction rate of CO2 mineralization of PIBS is nearly twice that of the free system. After the 8th cycle reaction, PIBS can still produce more than 9.8 mg of CaCO3 in 5 min, realizing efficient and continuous mineralization of CO2.

Study on the factors affecting the sealing performance and mechanical stability of CO2 hydrate cap during gas production from methane hydrate

An innovative idea of “reservoir reformation” was proposed earlier and verified to be feasible for enhancing methane gas recovery efficiency and CO2 sequestration by constructing an artificial impermeable CO2 hydrate cap between the methane hydrate reservoir and overburden. However, the effects of different factors on the sealing performance and mechanical stability of the CO2 hydrate cap need to be further clarified for the optimization of this new technology. In this study, experiments were conducted to simulate methane hydrate gas production by depressurization and analyze the influence of CO2 emulsion injection temperature, injection rate and overlying pressure by controlling these variables. The results indicated that the desired CO2 hydrate cap was formed by decreasing the injection temperature and rate. A cyclic process of “hydrate formation-fracture-regeneration” was proposed at a controlled injection rate of 3 mL/min. The degeneration rate of the CO2 hydrate layer was accelerated with an increase in the overlying pressure. The mechanical stability of CO2 hydrate cap was determined by the combined effects of methane hydrate decomposition and an increase of axial load.

Unlock the Potentials to Further Improve CO2 Storage and Utilization with Supercritical CO2 Emulsions When Applying CO2-Philic Surfactants

Supercritical CO2 (ScCO2) emulsion has attracted lots of attention, which could benefit both climate control via CO2 storage and industry revenue through significantly increased oil recovery simultaneously. Historically, aqueous soluble surfactants have been widely used as stabilizers, though they suffer from slow propagation, relatively high surfactant adsorption and well injectivity issues. In contrast, the CO2-soluble surfactants could improve the emulsion performance remarkably, due to their CO2-philicity. Here, comprehensive comparison studies are carried out from laboratory experiments to field scale simulations between a commercially available aqueous soluble surfactant (CD 1045) and a proprietary nonionic CO2-philic surfactant whose solubility in ScCO2 and partition coefficient between ScCO2/Brine have been determined. Surfactant affinity to employed oil is indicated by a phase behavior test. Static adsorptions on Silurian dolomite outcrop are conducted to gain the insights of its electro-kinetic properties. Coreflooding experiments are carried out with both consolidated 1 ft Berea sandstone and Silurian dolomite to compare the performances as a result of surfactant natures under two-phase conditions, while harsher conditions are examined on fractured carbonate with presence of an oleic phase. Moreover, the superiorities of ScCO2 foam with CO2-philic surfactant due to dual phase partition capacity are illustrated with field scale simulations. ScCO2 and WAG injections behaviors are used as baselines, while the performances of two types of CO2 emulsions are compared with SAG injection, characterized by phase saturations, CO2 storage, oil production, CO2 utilization ratio and pressure distribution. A novel injection strategy, named CO2 continuous injection with dissolved surfactant (CIDS), which is unique for a CO2-philic surfactant, is also studied. It is found that the CO2-soluble surfactant displays much lower oil affinity and adsorption on carbonate than CD 1045. Furthermore, in a laboratory scale, a much higher foam propagation rate is observed with the novel surfactant, which is mainly ascribed to its CO2 affinity, assisted by the high mobility of the CO2 phase. Field scale simulations clearly demonstrate the potentials of CO2 emulsion on CO2 storage and oil recovery over conventional tertiary productions. Relative to traditional aqueous soluble surfactant emulsion, the novel surfactant emulsion contributes to higher injectivity, CO2 storage capability, oil recovery and energy utilization efficiency. The CIDS could further reduce water injection cost and energy consumption. The findings here reveal the potentials of further improving CO2 storage and utilization when applying ScCO2-philic surfactant emulsion, to compromise both environmental and economic concerns.

Electrochemical Investigation of Cu Electroplating with Supercritical CO2 Emulsion Using a Rotating Disk Electrode under High Pressure

The electrochemical properties of Cu deposition by plating solution with supercritical CO2 emulsion (Sc-CO2-E) were investigated using a specially constructed electrochemical measuring apparatus with a rotating disk electrode operable under high pressure. Polarization characteristics were examined with and without mixing Sc-CO2-E into the CuSO4-H2SO4 electroplating solution. Further, the relationship between the limiting current density and the rotation speed of the rotating electrode, that is, Levich plot, was obtained. As a result, a significant increase in the limiting current was observed by mixing Sc-CO2-E. In addition, as a result of estimating the diffusion coefficient D 0 of Cu ion and kinematic viscosity coefficient ν of the plating solution when Sc-CO2-E was mixed from gradients of the Levich plot, it was clarified that D 0 increased more than twice and ν decreased less than 1/2 compared to before mixing Sc-CO2-E. Therefore, it was suggested that mixing to emulsify the supercritical CO2 and the plating solution can greatly enhance the transfer of Cu ions by convection. Consequently, the use of Cu electrodeposition with Sc-CO2-E should enable plating in narrow spaces where convection cannot reach the level of supply of Cu ions, which was difficult with conventional plating.

A novel method to enhance methane hydrate exploitation efficiency via forming impermeable overlying CO2 hydrate cap

To enhance the exploitation efficiency of natural gas hydrate by decreasing the yield of water, a novel “reservoir reformation” concept is proposed that involves the reformation of a natural gas hydrate reservoir by constructing an artificial impermeable overlying CO2 hydrate cap. The feasibility of this concept has been demonstrated in this laboratory-scale experiment. After reformation by injecting CO2 emulsion into the permeable overburden, a confined environment with an impermeable CO2 hydrate cap is successfully constructed for depressurization operation. The cap can maintain mechanical stability until the end of production process. With the protection provided by the artificial CO2 hydrate cap, the production efficiency was greatly improved to 83.3% and the water yield is remarkably decreased. Moreover, the optimal CO2/H2O volume ratio of the emulsion for forming the desired CO2 hydrate cap was confirmed to be 1:1. The formation of CO2 hydrate cap can also protect the geological stability of depleted methane hydrate zones and seal a large amount of CO2, which is of both energetic and environmental significance; however, intensive and extensive research should be conducted in the future.

Fabrication of Co−Ni−P film with excellent wear and corrosion resistance by electroplating with supercritical CO2 emulsion

Abstract To avoid the defects caused by the hydrogen evolution and improve the corrosion and wear properties of the electroplated films in the traditional aqueous bath electrodeposition, a supercritical carbon dioxide (Sc-CO2) emulsion was proposed to electrodeposite ternary nanocrystalline Co−Ni−P alloy films. Microstructure, corrosive and tribological properties of the Co−Ni−P films were investigated and compared with the ones electroplated by conventional method. The results show that the Co−Ni−P films produced with Sc-CO2 assisted electrodeposition exhibit a more compact microstructure. The preferred orientation plane of hcp (110) for the Co−Ni−P films produced in conventional aqueous bath is changed to be hcp (100) for the one prepared in emulsified Sc-CO2 bath. The microhardness, corrosion resistance and tribological properties of the Co−Ni−P films are substantially improved with the assistance of Sc-CO2 in the electrodeposition bath.

Novel Alkyl-Amine Surfactants for CO2 Emulsion Assisted Enhanced Oil Recovery

Novel CO2-soluble surfactants are designed for generating stable CO2 emulsion/foam at high temperature (110 °C) and high salinity (220 g/L NaCl). The novel surfactants only consist of alkyl chains and amine heads without any fluorine, silicon, or poly alkyl-oxide groups and outperform the surfactants in literature regarding the solubility, thermal stability, and emulsifying ability in harsh conditions. 0.2 wt % of the novel surfactants are soluble in 220 g/L NaCl brine at pH ≤ 8 from 20 to 120 °C and are soluble in CO2 at high temperature (110 °C) and relatively low pressure (91 bar). The surfactants are thermally stable at 110 °C and pH = 4 under anaerobic conditions. Strong CO2 emulsion can be readily generated in bulk and in porous media at 25–110 °C and 150 bar. Unlike the common surfactants in literature, the performance of the novel surfactants can be profoundly enhanced by salinity and temperature. The strategy for designing these novel molecules and tuning the surfactant formulation for emulsion-a...

Technology Focus: CO2 Applications (July 2018)

Technology Focus In my previous features, I discussed the challenges facing carbon dioxide (CO2), both technical and economic. By far the biggest use of CO2 is in enhanced oil recovery (EOR). In this feature, the focus is on overcoming the biggest challenges facing CO2 EOR—gravity override and mobility. When CO2 is injected into a reservoir, it has a tendency to rise and segregate to the top of the reservoir, thereby bypassing some of the remaining oil. This is primarily because of the density difference between CO2 and reservoir fluids. CO2 also fingers through the oil because of its high mobility and lower viscosity. One way to control CO2 mobility and improve its sweep efficiency (and thus improve the incremental oil recovery) is by injecting a CO2 foam or CO2 emulsion. The foam, because of its high viscosity, diverts the CO2 away from the paths already created and conforms it to previously bypassed areas of the reservoir. It does so by blocking the flow channels, thus improving reservoir sweep. During the past several decades, and especially the last few years, consider able effort has been made to address this challenge. Most of this research has been in either viscosifying or densifying the CO2. Some of the mobility- and conformance-control methods that have been tried include surfactants that create CO2 foams, direct thickening of CO2 using polymers and gels, and nanoparticle-stabilized CO2 foams. Some of the leading research on CO2 foams/emulsions is being carried out by, in no particular order, George Hirasaki’s group at Rice University Quoc Nguyen’s group at The University of Texas at Austin Texas A&M University Delft University of Technology Robert Enick’s group at the University of Pittsburgh Arne Graue at the University of Bergen IFP Energies Nouvelles in France The papers that follow are meant to be a starting point for understanding this phenomenon and further research. The focus in the coming months and years should be on extending the field deployment of this emerging technology. Recommended additional reading at OnePetro: www.onepetro.org. CMTC 486622 Surfactant and a Mixture of Surfactant and Nanoparticles Stabilized CO2/Brine Foam for Gas-Mobility Control and Enhanced Oil Recovery by Z.A. AlYousef, Texas A&M University, et al. SPE 190176 Fluoroacrylate Polymers as CO2-Soluble Conformance-Control Agents by Robert M. Enick, University of Pittsburgh, et al.

CO2-Foam Field Pilot Test in a Sandstone Reservoir

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 190312, “CO2-Foam Field Pilot Test in Sandstone Reservoir: Complete Analysis of Foam-Pilot Response,” by P.D. Patil, T. Knight, A. Katiyar, SPE, and P. Vanderwal, The Dow Chemical Company; J. Scherlin, SPE, Fleur De Lis Energy; P. Rozowski, SPE, The Dow Chemical Company; M. Ibrahim and G.B. Sridhar, SPE, Schlumberger; and Q.P. Nguyen, SPE, The University of Texas at Austin, prepared for the 2018 SPE Improved Oil Recovery Conference, Tulsa, 14–18 April. The paper has not been peer reviewed. This paper presents an analysis of a CO2-foam-injection pilot in the Salt Creek Field, Natrona County, Wyoming. The pilot was successful in demonstrating deeper conformance control and improvement in sweep efficiency, which resulted in 25,000 bbl of incremental oil. A 22% decrease in the amount of CO2 injected also was realized as a result of better use of CO2 compared with the baseline. Introduction Foam-assisted CO2 enhanced oil recovery (EOR), commonly referred to as CO2-foam EOR, has been proposed as an effective technology for correcting sweep inefficiencies caused by gravity segregation and reservoir heterogeneity. The central concept of CO2-foam EOR is the in- situ generation of a viscous emulsion of CO2 and water stabilized by a surfactant at reservoir conditions. Because the apparent viscosity of a CO2/water/surfactant system is much higher than that of CO2 itself, the mobility of CO2 is significantly reduced. In the reservoir, the generation of foam occurs first in the zones preferentially swept by CO2, gradually diverting CO2 to unswept zones where oil saturation is typically higher. An important feature of the CO2 foam is that the foam strength, and hence the mobility reduction, weakens in the zones where there is substantial oil saturation. As a result, the foam does not interfere with the CO2 displacement process once the CO2 is diverted into zones with substantial oil saturation. Salt Creek Foam Pilot Although the CO2 flood in the Salt Creek Field, begun in 2004, has been very successful, certain isolated patterns were seen to exhibit high CO2 production and inefficient CO2 use, most likely because of the channeling of fluids through high-permeability, low-volume zones and the gravity override of the injected fluid. A CO2-foam pilot was undertaken to test whether these conditions could be remediated. An inverted-five-spot pattern in the Phase V area of the field was screened as the best candidate for the CO2-foam EOR pilot (Fig. 1). The pilot injector was labeled as 22SE30 and the four production wells to be monitored were wells 15SE30, 14SE30, 26SE30, and 28SE30. While other papers have been devoted to the Salt Creek foam pilot, this paper focuses on the injection-well response, the interwell tracer analysis, and the production response from the monitored producer wells in the pilot area. The authors discuss the injection and production responses for 2 years and 8 months of data. The foam injection in the field was completed in June 2016.

Applicability of nonionic surfactant alkyl polyglucoside in preparation of liquid CO2 emulsion

The essential characteristic of CO2 makes most surfactants futile to form stable CO2 emulsion. In this work, a green surfactant named alkyl polyglucoside (APG) was applied to prepare liquid CO2 emulsion. The performance of surfactant on CO2 emulsion stability was assessed in a sapphire cell by delamination time of emulsion under the operating conditions about 284.5 K and 5.2 MPa. The results demonstrate that APG has a potential to be used in CO2 emulsion preparation and the suitable dosage of APG is about 3.0 wt% water quality. The phase-inversion point of water-in-CO2 and CO2-in-water was determined as ranging from 15 vol% to 17.5 vol% (water cut) after examining the systems at different water cuts with 3.0 wt% APG. Two surfactants, fatty alcohol polyoxyethylene ether (AEO) and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) were also tested. To consider the applicability of CO2 emulsion in fields such as submarine hydrate exploitation and CO2 sequestration, the performance of surfactants in saline solution was examined. The experimental results show that APG can be used as surfactant in preparing liquid CO2 emulsion with or without NaCl. The adding of 1.0 wt% NaCl for CO2 emulsion with 3.0 wt% APG was proved to change the phase-inversion point to higher water cut. In comparison, anion surfactant AOT was futile in saline solution.

CO2/Water Emulsions Stabilized by Partially Reduced Graphene Oxide.

Using functional materials to stabilize emulsions of carbon dioxide (CO2) and water is a promising way to expand the utility of CO2 and functional materials. Here we demonstrate for the first time that the partially reduced graphene oxide (rGO) can well stabilize the emulsion of CO2 and water without the aid of any additional emulsifier or surface modification for rGO. More interestingly, such a novel kind of emulsion provides a facile and versatile route for constructing highly porous three-dimensional rGO materials, including rGO, metal/rGO, and metal oxide/rGO networks. The as-synthesized Au/rGO composite is highly active in catalyzing 4-nitrophenol reduction and styrene epoxidation.

Metal–Organic Framework for Emulsifying Carbon Dioxide and Water

AbstractForming emulsions of carbon dioxide (CO2) and water can largely expand the utility of CO2. Herein we propose for the first time the utilization of a metal–organic framework (MOF) for emulsifying CO2 and water. Owing to the hybrid composition, MOF particles can easily assemble at the CO2/water interface to create a rigid protective barrier around the dispersed droplet. The MOF‐stabilized CO2 and water emulsion has exceptional stability compared to those emulsions stabilized by surfactants or other solids. Moreover, the CO2 and water emulsion stabilized by MOF is “tunable” due to the designable features of MOFs and adjustable character of CO2. Such a novel kind of emulsion composed of CO2, water, and MOF provides a facile route for constructing MOF superstructures with many advantages. The macroporous networks and hollow capsules of different kinds of MOFs have been successfully derived from CO2 and water emulsions.

Metal-Organic Framework for Emulsifying Carbon Dioxide and Water.

Forming emulsions of carbon dioxide (CO2 ) and water can largely expand the utility of CO2 . Herein we propose for the first time the utilization of a metal-organic framework (MOF) for emulsifying CO2 and water. Owing to the hybrid composition, MOF particles can easily assemble at the CO2 /water interface to create a rigid protective barrier around the dispersed droplet. The MOF-stabilized CO2 and water emulsion has exceptional stability compared to those emulsions stabilized by surfactants or other solids. Moreover, the CO2 and water emulsion stabilized by MOF is "tunable" due to the designable features of MOFs and adjustable character of CO2 . Such a novel kind of emulsion composed of CO2 , water, and MOF provides a facile route for constructing MOF superstructures with many advantages. The macroporous networks and hollow capsules of different kinds of MOFs have been successfully derived from CO2 and water emulsions.

Effect of annealing on mechanical properties of nickel electrodeposited using supercritical CO2 emulsion evaluated by micro-compression test

Nanocrystalline nickel film was electrodeposited with supercritical CO2 emulsion. The effects of annealing on nanocrystalline nickel were evaluated with scanning electron microscopy. The deposited films had a grain size of 16nm with 2at.% of interstitial carbon. A slight grain growth to 30nm grain size was observed after low temperature (<200°С) annealing. Higher temperature (>300°С) annealing caused Ni3C precipitation at grain boundaries and prominent grain growth above 300nm grain size. Micro-compression samples of each annealed films and as-deposited film were fabricated to investigate the mechanical properties. Low temperature annealed nickel was fractured by cracking with higher yield strength compared to the as-deposited nickel while high temperature annealed nickel simply had a decrease in strength. The brittle fracture after annealing is suggested to be related to the redistribution of carbon and relaxation of grain boundaries. High yield strength of 1GPa after 400°С annealing is achieved thanks to the fine precipitates of Ni3C.

Application of Different Cooling Strategies in Drilling of Metal Matrix Composite (MMC)

Conventional cutting fluids are known for being expensive, polluting and a non-sustainable part of modern manufacturing processes. Global industrial trends are leaning towards environmental and health friendly technologies. CO2 cooling is an innovative and sustainable method, capable of replacing conventional oil-based cutting fluids under various conditions. The current study intends to cover the indexable insert drilling of aluminium-silicon carbide (Al-SiC) metal matrix composite (MMC) using different diamond coated carbide inserts. Al-SiC composite containing 20% wt. of SiC was used as workpiece material under different cooling strategies. Response Surface Methodology (RSM) and SEM analysis were incorporated to evaluate the tool performance and to understand the wear development in drilling of MMC. Performance tests were carried out at various cutting data and cooling strategies (external CO2, external emulsion, internal CO2 and internal emulsion) in order to study the output in terms of tool life, surface finish and diameter difference of the holes. The results revealed an advantage in the favour of CO2 cooling concerning tool life, precision and surface finish. Drilling with internal supply of CO2 significantly improves the tool life. The internal supply of CO2 generated the best precision and surface finish compared to the other cooling strategies. The test results clearly indicate that the tool failure for internal CO2 is governed by the flaking of the diamond coating in contrast to a combination of flank wear and flaking for emulsion. The results from the external cooling strategy show that there is no significant difference between emulsion and CO2 while the internal cooling strategy shows that CO2 provides the best results. Since the shape and the surface of the hole are generated by the cutting edge of the periphery insert, the wear development on the periphery insert is the main factor which governs the tool life, surface finish and the diameter difference. This can be explained by the internal CO2 strategy that protects the periphery insert.

Fly ash nanoparticles as a CO2 foam stabilizer

In this study, the use of coal fly ash nanoparticles as a stabilizer to generate stable CO2 foams was explored. Considering the heterogeneous nature of fly ash, the samples were pretreated or separated into several different types of varying carbon content. The carbonaceous material present in the fly ash samples played an important role in generating stable oil/water (O/W) emulsions. As the carbon content in the fly ash sample increased, more emulsion was generated; also, the droplet size decreased and uniformity improved. A similar trend was observed in the CO2 emulsion tests. The fly ash samples containing carbonaceous material produced more emulsion phases with denser structures. It was difficult to generate stable CO2 foams without additives. However, fly ash nanoparticles combined with additives such as surfactants or collectors, specifically dodecyltrimethylammonium bromide and turpentine oil, produced stable and dense CO2 foams.