Foam Generation Research Articles

The Impact of Green Chelating Agent and Corrosion Inhibitor on Foam Rheology and Stability at High Temperature, Pressure, and Salinity

Summary This research fills the gap in understanding the impact of corrosion inhibitors (CIs) and a chelating agent on the rheology and stability of foam under harsh conditions. In this regard, a modified high-pressure, high-temperature (HPHT) foam rheometer and HPHT foam analyzer were used to investigate foam rheology and stability at 1,000 psi and 120 to 150°C with carbon dioxide (CO2) in the gas phase. Surfactant screening showed that Duomeen TTM and Armovis are thermally stable at high temperature and high water salinity and thus were used in this study. The liquid phase generally contained produced water (PW) (total dissolved solids ~ 24,611 ppm), 15 wt% chelating agent [L-glutamic acid-N, N-diacetic acid (GLDA)], and 1 wt% surfactant with and without a CI. First, we screened the viscosity and stability of Duomeen TTM and Armovis; the results showed that Duomeen TTM has a higher viscosity (at least by 82%) at a low shear rate, but both have similar viscosity at a higher shear rate. However, Armovis produced more stable foam. Once the GLDA was added to the Duomeen TTM solution, the viscosity increased significantly by 135% at a high shear rate (1,000–1,500). For the Armovis system, the viscosity improved by 77% and 68% at the low and high shear rates by adding GLDA. Additionally, foam stability was improved remarkably in both systems; half-life time almost doubled. Finally, we reported the effect of CI on the fluid systems, showing it considerably reduced the foam viscosity and stability. It reduced the half-life of the Armovis system by 79.4% and hindered the generation of foam for the Duomeen TTM system. A detailed discussion of foam properties, such as foamability, bubble count, and bubble radius, is provided. This study provides a wide-ranging understanding of additives’ impact on stimulating foam stability at HPHT.

Immobilization of Lipoxygenase, Catalase, and Lipase for a Reactor Design Targeting Linoleic Acid Hydroperoxidation

AbstractHydroperoxy‐9Z,11E‐octadecadienoic acid (13‐HPODE) can be obtained from safflower oil in an enzyme cascade utilizing lipase, lipoxygenase (LOX), and catalase for in situ oxygen generation. The application of immobilized enzymes may open a new path to a cost‐efficient production of 13‐HPODE, which is used for the synthesis of green note aroma hexanal. Ten immobilization supports are compared for immobilization of lipoxygenase‐1 from Glycine max (LOX‐1) and oxirane‐based Immobead 150 P proves to be best with a maximum LOX‐1 activity of 22 470 U g−1. The immobilizate is successfully recycled in eight consecutive batches and maintains full activity over a period of 16 h using a 3D‐printed column reactor. Catalase from Micrococcus lysodeikticus and LOX‐1 are co‐immobilized on Immobead 150 P allowing a constant production of 13‐HPODE for up to six cycles with a maximum product conversion of 45% and a 13‐regioselectivity of 83% . In this two‐enzyme system with H2O2‐dosage, foam generation is significantly reduced. Co‐immobilization of LOX‐1 and lipaseis possible; however, rapid lipase deactivation occurs. Therefore, a two‐reactor approach with oil hydrolysis in the first reactor is proposed. Immobilized lipases from C. rugosa are suitable for safflower oil hydrolysis and maintain full activity over ten hydrolysis cycles.Practical applications: Linoleic acid hydroperoxide (13‐HPODE) is the starting material for the synthesis of the green note aroma compound hexanal. The byproduct of the hydroperoxide splitting is ω‐oxododecenoic acid, which is currently not employed industrially. The bifunctional oxodocecenoic acid is interesting as precursor for the synthesis of polymer building blocks. Simple one‐step derivatization of the oxo‐group can yield suitable C12 monomers such as dicarboxylic acids, ω‐amino acids, or ω‐hydroxy acids. Cost‐efficiency is a key parameter to incorporate these new biobased building blocks for polymer applications. In this approach, immobilized enzymes are used for the synthesis of 13‐HPODE starting from safflower oil with in situ oxygen generation to prevent excessive foam formation. A two‐reactor concept is designed to circumvent hydroperoxide‐induced lipase deactivation. Direct comparison of both batch and continuous process is performed and provides information for the implementation of the enzyme cascade and the design of an optimized reactor system.

Research on the Mixing Mechanism and Parameter Optimization of Liquid Nitrogen Foam Generator

Nitrogen foam is expected to be an effective method to extinguish large-scale fires and suppress explosions. The key to its foaming process is that gas nitrogen (N2) and a foam solution are mixed uniformly in a foam generator. Moreover, liquid nitrogen (LN2) has been proposed as a source of gas nitrogen to generate nitrogen foam in previous experimental works. In this paper, the flow and heat transfer characteristics between liquid nitrogen and the foam solution are explored by numerical methods, which are then utilized to optimize the parameters of the foam generator. It is found that the flow pattern of the foam generator with a cone spoiler is a stratified flow by establishing the mixture and Lee’s evaporation-condensation model in ANSYS Fluent. Moreover, the spoiler in the foam generator plays a crucial role in breaking LN2 into droplets and increasing the contact area between phases, and a distance of 10 mm from the inlets to the spoiler is recommended. From previous results, an unreasonable flow rate ratio of LN2 to a foam solution may lead to icing or a low volume fraction of nitrogen, thus a flow rate ratio of 1:50 is determined in the foam generator. As for the shape of the spoiler, the spiral spoiler shows the best foaming performance compared to cone and semisphere spoilers, due to its fluid rotation instead of translation, which effectively increases the N2 volume fraction of foam from 0.616 to 0.717. Therefore, the mixing characteristics of the foam generator in this work lays a foundation for devising a practical nitrogen foam generator.

Experimental Study of the Influence of Inorganic Salts on Foam Stability

The aqueous film-forming foam (AFFF) extinguishing agent is suitable for fighting various hydrocarbon fuel fires due to its dual fire-fighting effect of foam and liquid film. Because the action law and microscopic mechanism of inorganic salts on the stabilization process of surfactant-generated AFFF are not perfect, this paper employs an experimental approach to investigate the effects of inorganic salt types and concentrations on sodium dodecyl sulfate-containing foam systems (SDS). Prior to critical micelle concentration (CMC), increasing inorganic salt concentration decreased solution surface tension, but the opposite was true after CMC. The CMC value of an SDS solution decreases as inorganic salt concentration increases, and the "salting effect" of inorganic salt cations also has an effect on the CMC value. Based on the resistance of the liquid film at the gas-liquid interface affecting gas transport, the foam evolution was divided into three stages: foam generation, liquid drainage, and gas transfer. The effect of inorganic salts on these three stages was studied at the molecular level, and it was discovered that the addition of NH4Cl and MgCl2 could improve the saturation adsorption at the gas-liquid interface, reduce the surface tension of the surfactant solution, and improve foam stability. Meanwhile, inorganic salts can change the force of gas molecules, so the equilibrium force of gas across the liquid membrane increases as inorganic salt concentration increases. Additionally, the addition of inorganic salts raises the diffusive drainage coefficient, but the gravity drainage coefficient still reigns supreme in the predecay period.

Methane foam performance evaluation in water-wet unconsolidated porous media: A systematic experimental investigation at elevated pressure and temperature conditions

In the petroleum industry, enhanced oil recovery (EOR) techniques employ foam extensively to establish conformance control in heterogeneous and fractured reservoirs in order to increase the sweep efficiency. In such applications, foam performance evaluation under complex subsurface conditions is pivotal for the effective and optimized deployment of foam treatment. However, there is a scarcity of hydrocarbon gas foam generation and evaluation studies that examine the relationships between foam performance and the critical foam parameters at high-pressure and high-temperature conditions.This study aims at methodically investigating the effects of several foam parameters on methane foam performance in water-wet proppant packs under harsh operating conditions. This is in relation to the technical needs of hydrocarbon foam injection into hydraulically-induced, propped fractures in unconventional oil reservoirs. To this end, a state-of-the-art experimental foam generation apparatus was designed, fabricated, and commissioned. We performed a large number of foam flow experiments on proppant packs using methane gas and different foaming agents at 3500 psi and 115 °C. Anionic and amphoteric surfactants were employed to probe the effect of their ionic nature on foam performance. Foam performance sensitivities to various foam generation parameters and operating conditions, such as surfactant concentration, gas fraction, total injection rate, operating pressure, salinity, and proppant pack length were investigated. To this end, steady-state pressure drops across the proppant packs during foam generation and foam's apparent viscosity were measured to quantify the foam performance of surfactants. The results were then analyzed to determine optimum values of the foam parameters and the interplay between these parameters are discussed here. The systematic results achieved from this work are in agreement with the trends available in the literature and provide new insights into complexities of in situ foam generation in water-wet, unconsolidated porous media at extreme reservoir conditions.

A new technique for removing the accumulated liquids in gas-condensate pipelines and risers by foam generation in the presence of mixed surfactants

In the present work, a new technique for removing the accumulated liquids in gas-condensate pipes and risers by foam generation in the presence of methane gas and binary mixtures of SLES (sodium lauryl ether sulfate) and TX100 (Triton X-100) surfactants is presented for the first time. A new automated foam production system for assessment of liquid removal efficiency and a new set up for evaluation of foam stability at high pressures and temperatures are also developed. It is shown that at a high pressure of 70 bar and in the presence of optimum concentrations of SLES and TX100 binary surfactants, the generated foam is highly stable even after 24 h which is a new impressive result. It is also shown that in the presence of 1.4 CMC SLES and TX100 = 2 SLES, it is possible to obtain a considerable liquid removal efficiency as high 95 % at different operating conditions, suggesting the superior performance of the proposed technique. The suggested low cost foam pigging technique in the present work can have potential application as an alternative to the expensive risky mechanical pigging regarding continuous removal of the accumulated liquids in the gas wellbores, risers and high pressure gas condensate pipelines in oil and gas industries.

Efficient learning representation of noise-reduced foam effects with convolutional denoising networks.

This study proposes a neural network framework for modeling the foam effects found in liquid simulation without noise. The position and advection of the foam particles are calculated using the existing screen projection method, and the noise problem that occurs in this process is prevented by using the neural network. A significant problem in the screen projection approach is the noise generated in the projection map during the projecting of momentum onto the discretized screen space. We efficiently solve this problem by utilizing a denoising neural network. Following the selection of the foam generation area using a projection map, the foam particles are generated through the inverse transformation of the 2D space into 3D space. This solves the problem of small-sized foam dissipation that occurs in conventional denoising networks. Furthermore, by integrating the proposed algorithm with the screen-space projection framework, it is able to maintain all the advantages of this approach. In conclusion, the denoising process and clean foam effects enable the proposed network to model the foam effects stably.

Dynamic Behaviors and Mechanisms of Air-Foam Flooding at High Pressure and Reservoir Temperature via Microfluidic Experiments.

Air injection has been proven to be an effective improved oil recovery technique for deep and light oil reservoirs with low permeability and poor water injectivity. But the efficiency of air injection in highly heterogeneous reservoirs is low due to poor gas sweeping that may lead to early oxygen breakthrough caused by gas channeling and viscous fingering. Foam can be used to assist air injection to overcome the obstacles of early gas breakthrough and to increase the displacement and sweeping efficiency. In this paper, laser-etched visual microscopic pore models were used as microfluidic devices to study the air-foam flooding process in porous media at reservoir temperature and high pressure. The dynamic behaviors and relevant mechanisms of air-foam flooding were investigated. Typical mechanisms of foam generation in porous media are achieved in different parts of the micromodel, which can be listed as follows: lamella leave-behind, lamella division, and snap off. Analysis on flow states of air foam showed that foams migrate in porous media by bursting and regenerating during the flooding process. It can be observed that the flow mode of foam in porous media is the separate flow of gas and liquid through microscopic displacement experiments, suggesting that foam should not be treated as a homogeneous phase in heterogeneous porous media. The pressing, occupying, and selective blocking effects of foam in porous media exhibited different oil displacement performances with the presence of various pore geometries and networks. Tiny foams also showed stripping and carrying effects on larger oil droplets benefiting from the lipophilicity of foam. Through comprehensive analysis on overall and local oil displacement mechanisms, air-foam injection could enhance the microscopic sweep volume and improve the oil displacement efficiency.

Impact of fracture orientation on supercritical carbon dioxide -foam performance and optimization in sandstones

Natural or induced fractures pose a significant challenge for subsurface energy extraction, carbon storage, and aquifer contaminant remediation. They provide high permeability channels that disrupt the natural state of the flow. Fractures prevent pressure buildup and induce early breakthrough of displacing fluid, leaving most of the target fluids behind. Foams can alleviate this problem by providing fluid diversion. The primary function of fluid diversion is to reduce the mobility inside the higher permeable regions by increasing the viscosity, resulting in high pressure buildup and allowing the displacing fluid to be diverted to the low permeable regions of the matrix. However, foam optimization must be performed prior to field application to ensure the foam's stability and compatibility with in-situ fluids. Moreover, the nature of the reservoir rock plays a vital role in maintaining the integrity of the foam system required for subsurface applications. This is particularly important in the case of fractured porous media as fracture properties, such as roughness and orientation, could significantly impact the in-situ foam generation/destruction processes. This study systematically investigates the effect of fractures and their orientations on scCO2 foam performance in a homogeneous sandstone. Furthermore, the foam system was optimized in both unfractured and fractured sandstone rocks at reservoir conditions relevant to a target field for dual-purpose CO2 storage-oil recovery. The surfactant solution used for foam generation was developed using the zwitterionic surfactant Lauramine Oxide where the optimum composition was found to be 0.6 wt% surfactant and 15 wt% total salts with an 80:20 ratio NaCl:CaCl2. Results also confirmed a shear thinning behavior which is typical of a zwitterionic-based foam. Moreover, the 10° fractured core exhibited a 50% higher apparent viscosity than the unfractured one which proves the foam's great ability in fluid diversion.

Unsteady-State CO2 Foam Generation and Propagation: Laboratory and Field Insights

This work presents a multiscale experimental and numerical investigation of CO2 foam generation, strength, and propagation during alternating injection of surfactant solution and CO2 at reservoir conditions. Evaluations were conducted at the core-scale and with a field-scale radial simulation model representing a CO2 foam field pilot injection well. The objective of the experimental work was to evaluate foam generation, strength, and propagation during unsteady-state surfactant-alternating-gas (SAG) injection. The SAG injection rapidly generated foam based upon the increased apparent viscosity compared to an identical water-alternating-gas (WAG) injection, without surfactant. The apparent foam viscosity of the SAG continually increased with each subsequent cycle, indicating continued foam generation and propagation into the core. The maximum apparent viscosity of the SAG was 146 cP, whereas the maximum apparent viscosity of the WAG was 2.4 cP. The laboratory methodology captured transient CO2 foam flow which sheds light on field-scale CO2 foam flow. The single-injection well radial reservoir simulation model investigated foam generation, strength, and propagation during a recently completed field pilot. The objective was to tune the model to match the observed bottom hole pressure data from the foam pilot and evaluate foam propagation distance. A reasonable match was achieved by reducing the reference mobility reduction factor parameter of the foam model. This suggested that the foam generated during the pilot was not as strong as observed in the laboratory, but it has propagated approximately 400 ft from the injection well, more than halfway to the nearest producer, at the end of pilot injection.

Development of a High Efficient Compound Surfactant for Foam Drainage in Gas Wells

In this study, the foaming properties of a compound surfactant formula containing cetyltrimethylammonium chloride (CTAC), cocamidopropyl betaine (CDAB), fatty alcohol polyoxyethylene ether-7 (AEO7) and sodium alpha-olefin sulfonate (AOST) were evaluated to meet the application requirements for foam generation and foam drainage in gas wells. The results exhibited that the foaming volume and the half-life of the compound surfactant solution (0.05 wt % CTAC + 0.7 wt % CDAB + 0.6 wt % AEO7 + 0.05 wt % AOST) can reach the values of 550 mL and 23 min, respectively, which suggested that the foaming ability and stability were improved in comparison with each solution containing a single surfactant. It showed that the surface tension can be lowered to 22.4 mN/m with the presence of the compound surfactants. Simultaneously, the microstructure of the foam was observed using a polarizing microscope, and it was found that there were almost no polyhedron structures in the foam within a certain range of formula concentrations. The results of the experiments also clarify that the formula has well properties of temperature resistance and salt resistance (measured using a high-speed agitator).

The effects of pressure and column height on drainage behavior of oilfield foams

Unstable foams quickly lose their valuable properties. This article presents the results of an experimental study conducted on the drainage of aqueous foams at elevated pressures. During the investigation, the foam was generated and circulated in a flow loop. First, its rheology was measured to ensure proper foam generation. Then, its drainage was determined by trapping it in a vertical test section and measuring the pressure profile. The results show that increasing pressure reduces foam drainage, indicating foam stabilization at high pressures. In addition, column height decreases foam drainage because the drainage rate varies along the axis of the column.

Determining foaming regularities enabled by a five-nozzle foam generator for drilling technologies under conditions of abnormally low pressures

When studying the construction of oil and gas wells, it was found that the volume of drilling wells with abnormally low reservoir pressures increases over the years. This is due to significant difficulties such as a large absorption of drilling mud, possible clogging of a productive reservoir with drilling mud, and a failure to obtain the expected effect. These complications can be prevented by using gas-liquid mixtures as drilling mud, which have a number of advantages compared to washing liquids and make it possible to eliminate the above-mentioned negative phenomena. When opening productive horizons at low anomaly coefficients, foams must be used to flush wells. It has been established that at present in the practice of drilling oil and gas wells with foam there is no equipment that makes it possible to form foam with certain specified structure and dispersion. The use of a modernized foam generator for the preparation of foam has been proposed. To study the foaming process, computer modeling was carried out, with the help of which the processes that take place during the movement of flows of liquid, gas, and gas-liquid mixture along the foam generator were investigated, namely the distribution of pressure and speed in the longitudinal cross-section of the foam generator under changing boundary conditions, that is, at a pressure in the supply pipe of 10 and 7.5 MPa. Computer studies have confirmed the possibility of using an improved foam generator design to increase the efficiency of foaming. The results could be the basis for the development of foam generators and their experimental and industrial research and testing.

Modeling foam propagation in pore network with designated pressure constraints

Foam has been used for decades in petroleum industry for enhanced oil recovery (EOR) due to its mobility adjustment ability. A variety of mechanistic models have been proposed to study foam flow in porous media from multiple scales. In these models, such as population balance models, some important parameters (e.g., foam generation/coalescence rate, flowing foam fraction) are treated empirically since they cannot be obtained from conventional lab experiments. To improve the accuracy and reliability of foam description in these foam-assisted processes, pore network model interwoven with invasion percolation with memory (IPM) method has become a powerful tool in studying foam flow characteristics in porous media, which can predict relative permeability and flowing gas fraction with fully consideration of pore-scale mechanisms of foam generation, destruction, and propagation. However, the assumption of exactly sufficient incremental pressure difference used in conventional IPM-based pore-scale foam modeling is rigorous, not only making it difficult to conduct relevant experimental validations, but also creating potential algorithmic conflicts when simulates displacements in weak foam regime or displacements incorporated with foam coalescence mechanisms. In this study, a novel mixed-sorting rule, which proceeds the displacement by describing the transition between immobile foam bank and mobilized foam flow quantitively, is incorporated into IPM-based foam propagation model. In this way, the immobile foam bank is identified based on effective lamellae generation rate, whereas the mobilized foam flow is distinguished by frontal displacing velocity, respectively. Results estimated with proposed method successfully capture key properties that define pore-scale foam behavior at excessive pressure constraints from formation of immobile foam bank, foam mobilizing pressure thresholds, and fractal dimension of displacement pattern, etc.

Synthesis of Cocos nucifera derived surfactant and its application in growth kinetics of methane gas hydrates for energy storage and transportation

The impact of surfactants on the formation kinetics and storage of gaseous fuels such as methane, propane, and hydrogen in the form of gas hydrates is well known. However, the excess generation of stable, hard, and toxic foam is one of the significant operational challenges (for the scale-up of gas hydrate processes) associated with conventional surfactants. This study is an attempt to fulfill the quest for mild, inexpensive, biocompatible, and efficient hydrate former required to develop a sustainable gas hydrate process. The present investigation reports the synthesis and application of Cocosnucifera-derived surfactant (CDS). The synthesized surfactant CDS may help in filling the gap by opening new opportunities in the storage and transport of natural gas in the form of gas hydrates. Here, the synthesis of CDS was followed by its characterization by H1 NMR, C13 NMR, FTIR (ATR), µ-DSC/TGA, and XRD, in addition to property evaluation such as foam stability, wettability, recovery, and recyclability. The comparative methane gas hydrate investigations on sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), and CDS were launched to determine their gas uptake behavior and water conversion efficiencies. Moreover, the morphology study was conducted to determine the real-time gas hydrate growth patterns and behavior to predict its correlation with the gas uptake data and mass transfer limitations. Overall, CDS surfactant showed competitive growth of the methane gas hydrates and proved a promising substitute for kinetic promotion. Additionally, the gas storage and transportation studies were conducted using laboratory-developed pellets under controlled conditions, and a process flow diagram based on the gas hydrate technology was demonstrated.

Study on the control of high ore pass dust pollution by pre-injection foam dedusting technology in the ore bin.

The impact airflow generated by ore unloading in the chute raises the dust carried by the ore itself and the floating dust, and then, the dust raised enters the roadway with the airflow and pollutes the environment. In order to minimize the amount of dust entering the roadway and reduce the pollution of unloading dust, we conducted an experimental study of selection of best foam formula and pre-injection foam dust dedusting technology in ore bin. It was found that the optimal foaming formula was 1.0% sodium dodecyl benzene sulfonate (SDBS) + 0.5% sodium dodecyl sulfate (SDS) + (0.2 ~ 0.4%) sodium carboxymethyl cellulose CMC-Na and coconut oil monoethanolamide (CMEA) by the compound experiment using two evaluation criteria of initial foaming amount and foam defoaming rate. When the air pressure is 0.7MPa, the foaming rate of the foam generator is proportional to the gas and liquid flow rate and the best foaming gas and liquid flow ratio is 27.8. Under this circumstance, the foaming rate of the foaming formula is 500l/min. When the height of foam is controlled at 15cm, the effect of foam dust removal is the best. The dust emission rate from the foam to the fourth level can reach 60%, and the dust fall rate of the third level is 28%, which effectively reduces the dust production and relieves the pressure of the spray hole dust fall at the wellhead.

Microstructure characterization and stochastic modeling of open‐cell foam based on μCT‐image analysis

AbstractFoam is a cellular material whose mechanical properties are strongly determined by its complex microstructure. To study the microstructure, at first a foam characterization based on CT image processing is required. Here we present an image segmentation procedure and determine the foam's characteristics using the lattice cell‐based concept of intrinsic volumes. Information like porosity, pore size distribution, and ligament shape are derived. These data are then employed as input for the generation of stochastic foam volume elements with the corresponding morphology. The introduced microstructural characterization and foam generation procedures are validated by an inverse analysis, that is, by a CT image analysis of the stochastic foam volume element. Additionally, an example investigation of industrial polyurethane foam proves the concepts.

One-Step Generation of Alginate-Based Hydrogel Foams Using CO2 for Simultaneous Foaming and Gelation.

The reliable generation of hydrogel foams remains a challenge in a wide range of sectors, including food, cosmetic, agricultural, and medical applications. Using the example of calcium alginate foams, we introduce a novel foam generation method that uses CO2 for the simultaneous foaming and pH reduction of the alginate solution to trigger gelation. We show that gelled foams of different gas fractions can be generated in a simple one-step process. We macroscopically follow the acidification using a pH-responsive indicator and investigate the role of CO2 in foam ageing via foam stability measurements. Finally, we demonstrate the utility of interfacial rheology to provide evidence for the gelation process initiated by the dissolution of the CO2 from the dispersed phase. Both approaches, gas-initiated gelation and interfacial rheology for its characterization, can be readily transferred to other types of gases and formulations.

Unsteady-state CO2 foam injection for increasing enhanced oil recovery and carbon storage potential

The efficiency of CO2 injection for enhanced oil recovery and carbon storage is limited by severe viscosity and density differences between CO2 and reservoir fluids and reservoir heterogeneity. In-situ generation of CO2 foam can improve the mobility ratio to increase oil displacement and CO2 storage capacity in geological formations. The aim of this work was to investigate the ability of CO2 foam to increase oil production and associated CO2 storage potential, compared to other CO2 injection methods, in experiments that deploy field-scale injection strategies. Additionally, the effect of oil on CO2 foam generation and stability was investigated. Three different injection strategies were implemented in the CO2 enhanced oil recovery and associated CO2 storage experiments: pure CO2 injection, water-alternating-gas and surfactant-alternating-gas. Foam generation during surfactantalternating-gas experiments showed reduced CO2 mobility compared to water-alternatinggas and pure CO2 injections indicated by the increase in apparent viscosity. CO2 foam increased oil recovery by 50% compared to pure CO2 injection and 25% compared to water-alternating-gas. In addition, CO2 storage capacity increased from 12% during pure CO2 injection up to 70% during surfactant-alternating-gas injections. Experiments performed at high oil saturations revealed a delay in foam generation until a critical oil saturation of 30% was reached. Oil/water emulsions in addition to CO2 foam generation contributed to CO2 mobility reduction resulting in increased CO2 storage capacity with foam. Cited as: Sæle, A., Graue, A., Alcorn, Z. P. Unsteady-state CO2 foam injection for increasing enhanced oil recovery and carbon storage potential. Advances in Geo-Energy Research, 2022, 6(6): 472-481. https://doi.org/10.46690/ager.2022.06.04

Computational study on the three phase displacement characteristics of foam fluids in porous media

Foam technology has shown great potentials not only on enhancing oil recovery (EOR) but also on the Carbon Capture Storage Utilization (CCUS) applications. In this paper, the foam three phase displacement characteristics in the porous media is investigated based on the mechanistic Stochastic Bubble Population Balance (SBPB) model. With taking the foam generation rate Kg and maximum bubble density nmax as the key influential parameters, the dynamic distributions of the water, oil and gas phase saturations as well as the bubble densities along the foam flow direction are successfully obtained. Firstly, the overall computation frame is validated based on good agreements between the numerical and the reported experimental results on the foam displacement efficiency on water and oil phases. Then, the parameter studies are thoroughly performed concerning the two key factors of Kg and nmax in the SBPB model. Numerical results show the parameter of Kg dominates the foam flow behavoir in the inlet region of the porous media therefore doesn't show significant effect on the final oil and gas phase recovery rates. On the other hand, it is found larger nmax could lead to higher oil and water recovery ratio, which indicates to increase the nmax values of the foam fluid could act as the favorable means in oil recovery enhancement practices.