Enhanced Oil Recovery Research Articles

Thermodynamic properties and structure of interfacial boundaries in nonionic fluids from the multilayer quasichemical model

The interfacial properties and structure of nonuniform fluids containing complex chainlike molecules and associating species are very much needed in a variety of different fields, including enhanced oil recovery, drug delivery, pharmacy, cosmetics, food processing, etc.Recently, we described the Multilayer Quasichemical Model (MQuM) of a nonuniform fluid that provides a remarkably detailed structural information, including the local concentration and orientation of functional groups of the molecules, the orientation profiles of the chemical bonds in molecular chains and the orientation profiles of the hydrogen bonds in the mixture.In this work, we focus on the description of thermodynamic properties with the aid of MQuM, including the interfacial tension and the profiles of normal and transverse pressures. Before proceeding to more complex systems, a test is performed through comparison with the previously known results from the Scheutjens-Fleer theory for the planar liquid–vapor interface and spherical droplet in one-component fluid of nonpolar monomeric molecules. The model is applied then for planar interfaces between the liquid phases in mixtures of water with n-alkanes of different chain length and for spherical drops in model systems that contain an associating solvent, a nonpolar chain and a nonionic amphiphile. Our theoretical results are compared with experiment, predictions from iSAFT and MD simulation data from the literature. For the spherical droplets, we discuss the model description of the dependence of the interfacial tension on the curvature and estimate the Tolman length. For the planar interface between the equilibrium liquid phases in water – n-alkane mixtures, the interfacial tensions predicted from the model are in good agreement with experiment.

New Insights into the Understanding of High-Pressure Air Injection (HPAI): The Role of the Different Chemical Reactions

High-pressure air injection (HPAI) is an enhanced oil recovery process in which compressed air is injected into deep, light oil reservoirs, with the expectation that the oxygen in the injected air will react with a fraction of the reservoir oil at an elevated temperature to produce carbon dioxide. The different chemical reactions taking place can be grouped into oxygen addition, thermal cracking, oxygen-induced cracking, and bond scission reactions. The latter reactions involve the combustion of a flammable vapor as well as the combustion of solid fuel, commonly known as “coke”. Since stable peak temperatures observed during HPAI experiments are typically below 300 °C, it has been suggested that thermal cracking and combustion of solid fuel may not be important reaction mechanisms for the process. The objective of this work is to assess the validity of that hypothesis. Therefore, this study makes use of different oxidation and combustion HPAI experiments, which were performed on two different light oil reservoir samples. Modeling of those tests indicate that thermal cracking is not an important reaction mechanism during HPAI and can potentially be ignored. The work also suggests that the main fuel consumed by the process is a flammable vapor generated by the chemical reactions. This represents a shift from the original in situ combustion paradigm, which is based on the combustion of coke.

Three-dimensional stagnation point motion of bioconvection nanofluid via moving stretching sheet with convective and anisotropic slip condition

The current article deals with the SM of a NFs on a 3D moving surface containing bioconvection, microorganisms, and convective conditions over anisotropic slip. This work reports describes the characteristics of bioconvection aspects of nanofluid containing microorganisms with anisotropic slip condition. The study may be important from the application point of view in microfluidic devices, antibiotics, enhanced oil recovery and many other areas. Applying the similarity variables, the basic gov. Eqs are translated to ordinary ones, and such Eqs are calculate by R-K-F fourth order programming with shooting scheme by MATLAB software. The physical parameters on the moving surface are explained in detail via graphs. We found that the temperature increases with a higher revolution and larger numerical numbers (convection parameter), while the HTR declined for various values of the SFP. The HTR enhances with surface convection, and therefore, the convection condition is helpful in reducing the viscous drag on the moving SS.

Water-soluble chitosan polymer for enhanced oil recovery in the carbonate reservoir

Numerous surfactants, nanoparticles and polymers have been developed and utilized for enhanced oil recovery applications, irrespective of their environmental impact. Most of these oilfield chemicals were prepared through multi-steps from fossil-based starting materials using hazardous solvents. However, there is a desire to advance eco-friendly and sustainable materials to reduce CO2 emissions and enhance the sustainability of oil production. Herein, we propose the development of chitosan salt, a solely green polymer, prepared in water in the presence of acetic acid (0.1% v/v). The resulting water-soluble polymer demonstrated excellent stability under reservoir conditions and was tested for enhanced oil recovery in the carbonate reservoir. The oil-wet rock wettability was significantly reduced after using chitosan salt solution. Nuclear magnetic resonance (NMR) experiments were used to show the oil displacement at different pores regions using relaxation time (T2 distribution). Imbibition and coreflooding experiments showed that the chitosan salt is able to increase the enhanced oil recovery by extra 16.2% which surpass the recovery obtained from commercial surfactants such as α-olefin sulfonate (AOS) and cetrimonium bromide (CTAB). This study shows that green materials are promising candidates for oil recovery and upstream applications.

Experimental and theoretical determination of minimum miscibility pressure of supercritical CO2 and alkanes at nanoconfinement

The minimum miscibility pressure (MMP) is crucial for CO2 Enhanced Oil Recovery (EOR). However, accurately determining MMP within nanoconfinement has been challenging due to intricate molecular interactions and reduced permeability. This study leveraged nanofluidic technology to determine MMP for supercritical CO2-alkanes at the nanoscale by observing the vanishing interface, noting a 5.1 % reduction for CO2-octane at 30 nm versus 1 μm at 80 ℃. It further explored the impact of alkane type and temperature on nanoconfinement, elucidating the underlying mechanisms. Additionally, a theoretical method was developed to estimate MMP ranging from 10 to 1000 nm, aligning well with the experimental results. The findings highlight the lower nanoscale MMP values compared to the bulk phase. This research presents methods for investigating thermodynamic properties under nanoconfinement, providing insights into the abnormal behaviors of fluids at the nanoscale and contributing to EOR.

Importance of Clay Swelling on the Efficacy of Cyclic Steam Stimulation in the East Moldabek Formation in Kazakhstan

Both steam and hot water flooding of high-viscosity oils in the presence of swelling clays are difficult methods for producing oil efficiently because of potential formation permeability reduction. This paper pertains to heavy oil recovery from the East Moldabek formation where the oil API gravity is about 22 and is inundated with swelling clays. To achieve this, we used the IntersectTM reservoir simulator to compare oil recovery economics using both hot water and steam injection as a function of steam cycle duration, temperature, and steam dryness. We also studied clay swelling in the East Moldabek formation where clay poses a significant challenge due to its impact on permeability reduction. In this research, we developed an equation based on experimental data to establish a relationship between water mineralization and permeability in the East Moldabek formation. The equation provides valuable insight on how to mitigate clay swelling which is crucial for enhancing oil recovery efficiency—especially in sandstone reservoirs. Our modeling studies provide the recovery efficiencies for salinities of the hot water EOR versus cyclic steam EOR methods in a formation containing swelling clays. Specifically, the reduction in formation permeability as a function of the distilled water fraction is the controlling parameter in hot water or steam flooding—when the formation water mixture becomes less saline, oil recovery decreases. Our research shows that clay swelling can significantly impact cyclic steam stimulation outcomes, potentially reducing its effectiveness, while hot water flooding may offer a more cost-effective and operationally feasible solution in formations where clay swelling is a concern. Economic analysis reveals the potential for achieving an optimal favorable condition for hot water injection. Therefore, this paper provides a guideline on how to conduct thermal oil recovery for heavy oils in fields with high clay content such as the East Moldabek deposit.

The imbibition mechanism for enhanced oil recovery by gel breaking fluid of SiO2-enhanced seawater-based VES fracturing fluid in offshore low permeability reservoir

Nanoparticles have been proven to be potential additives for hydraulic fracturing fluid. However, the application of nanoparticle-enhanced fracturing fluid systems in offshore low-permeability reservoirs are limited, and the mechanism by which the corresponding gel breaking fluid enhances oil recovery (EOR) is unclear. In this work, a SiO2-enhanced seawater-based viscoelastic surfactant (VES) fracturing fluid system was initially prepared, and the imbibition influencing factors of the SiO2-enhanced gel breaking fluid were systematically investigated. Subsequently, the imbibition mechanism by SiO2-enhanced gel breaking fluid was explored through examining its synergistic effect on interface properties and the distribution laws of oil-water phases in micropores during the imbibition process. The results showed that proposed system could maintained stability for more than 6 months, and exhibited rheological performance, yielding an increase 26% in temperature/shear resistance. Moreover, the corresponding gel breaking fluid performed an exceptional capacity for imbibition oil production, the oil recovery was increased by 7.92% compared to the conventional gel breaking fluid system and the imbibition time was extended from 30 h to 70 h. The synergistic adsorption of nano-SiO2 and surfactants on the interface was responsible for wettability alteration and interfacial tension (IFT) reduction. Imbibition primarily occurred in mesopores, nano-SiO2 reduced the flow resistance of oil-water two phases in pores, and the residual oil within the pores was exceedingly mobilized. This work provides foundation research of application of SiO2-enhanced seawater-based VES fracturing fluid in offshore low permeability reservoirs.

Sustainable Nanofluids Constructed from Size-Controlled Lignin Nanoparticles: Application Prospects in Enhanced Oil Recovery.

Lignin, a widely available, cost-effective, and structurally stable natural polymer, has recently attracted significant attention due to its diverse potential applications. A promising approach is to prepare lignin nanoparticles (LNPs) as a substitute for conventional nanoparticles to fulfill a variety of functions. In this study, LNPs with controlled size, regular morphology, and excellent dispersibility were synthesized by using industrial alkali lignin. The antisolvent method was employed, utilizing an aqueous solution of the anionic surfactant sodium apolyolefin sulfonate (AOS) as the antisolvent. Subsequently, the prepared LNPs were used to formulate nanofluids in combination with AOS and nonionic surfactant coconut diethanolamide (CDEA). The incorporation of LNPs has significantly enhanced the interfacial activity of the resulting nanofluids, thereby improving their emulsion stabilization, spreading on quartz surfaces, and oil droplet removal capabilities, which establish a strong foundation for the AOS/CDEA/LNPs nanofluid to achieve high performance in enhanced oil recovery (EOR), which was validated through microscopic visual physical model experiments. The quartz crystal microbalance with the dissipation monitoring (QCM-D) technique was employed to investigate the adsorption of surfactants onto quartz surfaces. It was found that the incorporation of LNPs significantly reduces the adsorption loss of surfactants, presenting a potential solution to overcome the challenges associated with surfactant adsorption in chemically enhanced oil recovery (EOR) processes, such as high cost and unreliable efficiency. This study reveals the good performance of LNPs/surfactant nanofluids and provides a potential approach to the advancement of green, sustainable, and intelligent EOR technologies.

The Why, What, Who, When, and Where of Carbon Capture and Storage in Southern Ontario

This paper reviews the five Ws (Why, What, Who, When, and Where) of carbon capture and storage in southwestern Ontario. This area is home to nearly one quarter of Canada’s population and approximately three-quarters of one million people work in the manufacturing sector. Fifteen of the province’s top 20 CO2 emission point sources are in this area. The industries responsible for these emissions include steel mills, refineries and petrochemical plants, and cement plants. These industries are part of the hard-to-abate sector, in that CO2 is used or generated as an integral part of the industrial process. As such, eliminating or even reducing emissions from these industries is a difficult task. Carbon capture and storage (CCS) projects aim to sequester that gas in sedimentary basins over periods exceeding several thousand years. To this end, deeply buried (> 800 m) porous and permeable rocks (a repository) must be overlain by impermeable rocks that act as a seal, preventing the upward migration of CO2 into the atmosphere. The possibility that injection activities could trigger seismicity is but one of the additional considerations. When operational, CCS projects have a negative carbon footprint and the desirability of developing and using this technology has been established for over 20 years. True CCS projects differ from carbon capture, utilization, and storage (CCUS) projects in that the former are only designed with sequestration in mind. One type of CCUS project involves using CO2 for enhanced oil recovery (EOR) and this technology has been employed for several decades. Cambrian sandstones are the most suitable injection targets for CCS in southwestern Ontario because previous oil and gas drilling has shown the rocks to have the necessary characteristics. They are buried below 800 m, can be tens of metres thick, and have adequate porosity and permeability. However, the Cambrian section is lithologically and stratigraphically heterogeneous and oil, gas, and brine can all be present in the pore space. The extent to which this complexity will affect CO2 injection has not yet been evaluated.

Impact of the Hydrophobic Phase on the Interfacial Dilational Rheology of Alkoxy Carboxylate/Cetyltrimethyl Ammonium Chloride Mixtures.

Despite extensive investigations on the interfacial activities of mixed anionic and cationic surfactants (Sa/c), the influence of the hydrophobic phase on their interfacial assembly and dilational rheology remains unaddressed. In this study, the interfacial dilational rheology of alkoxy carboxylate (anionic)/cetyltrimethylammonium chloride (cationic) surfactant mixtures was studied at various interfaces. The dilational modulus of Sa/c increases linearly with interfacial pressure at the interfaces of air, n-hexane/n-octane/n-hexadecane, and toluene. The limit elasticity (ε0) is similar at air and alkane interfaces but significantly decreases at the toluene interface. To explain these phenomena, all-atom molecular simulation was carried out to investigate the microscopic features of surfactants at the interface. The findings emphasize the crucial role of anionic/cationic surfactant bound pairs in regulating interfacial rheology. Sa/c tend to form large aggregates at the air/water surface. When mixed with alkanes like octane, most Sa/c remain as ion pairs. However, when toluene is employed, the coordination number between anionic and cationic surfactants sharply decreases due to π-π interactions between the toluene molecules and the phenyl groups in the anionic surfactant. This leads to a much lower interfacial modulus because interactions between oil molecules and surfactants cannot compensate for weakened interactions among anionic/cationic surfactants. These results suggest that Sa/c in this study tolerate alkanes but are not resistant to aromatics, which helps explain why Sa/c demonstrate excellent performance for the chemical enhanced oil recovery of a high-wax reservoir and further provides fundamental knowledge of their potential applications, such as gas well deliquification using foamers in the presence of condensate oil, textiles, etc.

Experimental Study on Improving the Recovery Rate of Low-Pressure Tight Oil Reservoirs Using Molecular Deposition Film Technology

The intricate geological characteristics of tight oil reservoirs, characterized by extremely low porosity and permeability as well as pronounced heterogeneity, have led to a decline in reservoir pressure, substantial gas expulsion, an accelerated decrease in oil production rates, and the inadequacy of traditional water injection methods for enhancing oil recovery. As a result, operators encounter heightened operational costs and prolonged timelines necessary to achieve optimal production levels. This situation underscores the increasing demand for advanced techniques specifically designed for tight oil reservoirs. An internal evaluation is presented, focusing on the application of molecular deposition film techniques for enhanced oil recovery from tight oil reservoirs, with the aim of elucidating the underlying mechanisms of this approach. The research addresses fluid flow resistance by employing aqueous solutions as transmission media and leverages electrostatic interactions to generate nanometer-thin films that enhance the surface properties of the reservoir while modifying the interaction dynamics between oil and rock. This facilitates the more efficient displacement of injected fluids to replace oil during pore flushing processes, thereby achieving enhanced oil recovery objectives. The experimental results indicate that an improvement in oil displacement efficiency is attained by increasing the concentration of the molecular deposition film agent, with 400 mg/L identified as the optimal concentration from an economic perspective. It is advisable to commence with a concentration of 500 mg/L before transitioning to 400 mg/L, considering the adsorption effects near the well zone and dilution phenomena within the reservoir. Molecular deposition films can effectively reduce injection pressure, enhance injection capacity, and lower initiation pressure. These improvements significantly optimize flow conditions within the reservoir and increase core permeability, resulting in a 7.82% enhancement in oil recovery. This molecular deposition film oil recovery technology presents a promising innovative approach for enhanced oil recovery, serving as a viable alternative to conventional water flooding methods.

TEMPO oxidized cellulose nanofiber-reinforced sodium alginate encapsulated poly(acrylamide) microcapsules and its releasing behaviours for enhancing oil recovery

Poly(acrylamide) (PAM) has excellent thickening ability as a conventional flooding agent. However, PAM confronts the problems of high injection pressure and high shear loss in the process of oil extraction, which have limited its application in this field. In this work, 2, 2, 6, 6-Tetramethylpiperidinooxy oxidized cellulose nanofibers (TOCNFs) enhanced sodium alginate (SA) shell was used to encapsulate PAM to form microcapsule. The composition, morphology, structure and the releasing behaviours of TOCNFs enhanced microcapsules was tested. Mechanical stirring was used to simulate the state of polymer subjected to shear during stratigraphic transport. The release performance of the microcapsules was characterized by measuring the change of viscosity with time. The ratio of the shell material with the best performance was explored, and the enhancement mechanism of the SA shell by TOCNFs was discussed. The experiments showed that the release time of PAM from the microcapsules was significantly prolonged with the addition of TOCNFs. The longest release time was observed when the ratio of SA and TOCNFs was 5: 1, with the release time of the microcapsules from the original 8 h to 16 h. The enhanced shear resistance of the microcapsules was attributed to the semi-interpenetrating network structure of SA and TOCNFs via Ca2+ cross-linking as well as hydrogen bonding. The prepared microcapsules have promising applications in enhancing oil recovery.

Heuristic algorithm for calculating the component composition of recombination gas without an adapted equation of state

Background. To conduct laboratory research of projects of gas enhanced oil recovery methods, a large volume of reservoir system is required. Often its replenishment by depth and/or separator samples is not economically feasible. Therefore, the task of fluid recombination from wellhead liquid sample and natural gas simulator arises. Objective. To calculate the component composition of recombination gas under the conditions of the task. Materials and methods. The heuristic calculation algorithm uses the tools of: modeling, inverse problems of physics, set theory, mathematical programming. Special focus is given to its empirical and theoretical justification. Results. The paper considers the limitations of the thermodynamic method. The conditions of the problem to be solved are outlined and justified. The applied algorithm of the solution is formulated and derived. The efficiency of the algorithm for oil systems is experimentally confirmed. Conclusions. The work will be of interest for specialists in the field of laboratory research projects of gas enhanced oil recovery methods. The issues of improving the accuracy of the applied algorithm and its further development are still under discussion.

Biosurfactants: Chemical Properties, Ecofriendly Environmental Applications, and Uses in the Industrial Energy Sector

The exploitation of nature and the increase in manufacturing production are the cause of major environmental concerns, and considerable efforts are needed to resolve such issues. Oil and petroleum derivatives constitute the primary energy sources used in industries. However, the transportation and use of these products have huge environmental impacts. A significant issue with oil-related pollution is that hydrocarbons are highly toxic and have low biodegradability, posing a risk to ecosystems and biodiversity. Thus, there has been growing interest in the use of renewable compounds from natural sources. Biosurfactants are amphipathic microbial biomolecules emerging as sustainable alternatives with beneficial characteristics, including biodegradability and low toxicity. Biosurfactants and biosurfactant-producing microorganisms serve as an ecologically correct bioremediation strategy for ecosystems polluted by hydrocarbons. Moreover, synthetic surfactants can constitute additional recalcitrant contaminants introduced into the environment, leading to undesirable outcomes. The replacement of synthetic surfactants with biosurfactants can help solve such problems. Thus, there has been growing interest in the use of biosurfactants in a broad gamut of industrial sectors. The purpose of this review was to furnish a comprehensive view of biosurfactants, classifications, properties, and applications in the environmental and energy fields. In particular, practical applications of biosurfactants in environmental remediation are discussed, with special focus on bioremediation, removal of heavy metals, phytoremediation, microbial enhanced oil recovery, metal corrosion inhibition, and improvements in agriculture. The review also describes innovating decontamination methods, including nanobioremediation, use of genetically modified microorganisms, enzymatic bioremediation, modeling and prototyping, biotechnology, and process engineering. Research patents and market prospects are also discussed to illustrate trends in environmental and industrial applications of biosurfactants.

Slow release of surfactant by smart thermosensitive polymer-functionalized mesoporous silica for enhanced oil recovery: Synthesis and characterization

The efficiency of surfactant flooding can be improved through slow-release technology, which enables stimuli-sensitive and gradual release of surfactant. In this study, we synthesized a novel nanocomposite capsule composed of mesoporous silica functionalized with thermosensitive poly N-vinyl caprolactam (PNVCL). Well-optimized nanocarriers were synthesized by conducting sensitivity analyses on key synthesis parameters such as pH, reaction duration, and hydrophobic phase, resulting in hydrodynamic diameters ranging from 47 to 109 nm. Characterization of the nanocarrier structure was performed using dynamic light scattering (DLS), Brunauer–Emmett–Teller (BET) analysis, and field emission scanning electron microscopy (FESEM), while Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and energy-dispersive X-ray spectroscopy (EDS) were employed to analyze the nanocarrier composition. Poly N-vinyl caprolactam (NVCL)-functionalized mesoporous silica exhibited high surfactant loading (approximately 52 % w/w) and a large specific surface area (542.88 m2/g), featuring ink-bottle pores. Additionally, it demonstrated thermosensitive behavior, with the lower critical solution temperature of 39 °C. Gradual release of cetyltrimethylammonium bromide (CTAB) was observed in both deionized water and formation brine, with release rates increasing with temperature. Overall, the synthesized nanocomposite carrier holds significant potential as an ideal candidate for effectively controlling the release of surfactants in reservoirs subjected to high-temperature and high-salinity conditions.

Chemical enhanced oil recovery from shale‐rich tight carbonate reservoirs using 2‐butoxyethanol as a mutual solvent and diluted seawater

AbstractOil production from tight reservoirs due to their very low permeability and high capillary pressure requires complex operations and materials, so that hydraulic fracturing in these reservoirs is recommended before any chemical injection. This operation turns the reservoir into a fractured one that can produce more oil by activating the imbibition mechanism. The interfacial tension (IFT) of oil and water and reservoir rock wettability as key parameters of overproduction from this type of reservoir can affect this mechanism. In this study, the potential of 2‐butoxyethanol as a mutual solvent for enhanced oil recovery (EOR) was investigated with a focus on the oil production under imbibition in this type of reservoir through performing experiments and calculations of IFT, oil swelling, contact angle, and oil production. The analysis of the results shows that the mechanisms of IFT reduction, wettability alteration, and oil swelling, which all directly affect the oil production under imbibition, reached the desired values using 2‐butoxyethanol in the appropriate concentration along with the dilution of seawater. The lowest values for interfacial tension and contact angle at 0.03 M concentration of the solvent and 5000 ppm salinity at 90°C temperature were 1.315 mN/m and 71.57°, respectively. These values are much lower compared to the values obtained by similar additives, while solvents, unlike 2‐butoxyethanol, are effective in much higher volume ratios. The oil swelling increased by about 14% using 2‐butoxyethanol due to its mass transfer between water and oil phases through the interface. Finally, the oil recovery factors of 42% and 59% were achieved under one‐ and multi‐dimensional spontaneous imbibition (ODSI and MDSI), respectively.

Application of MgO based‐nanofluid for controlling the growth of asphaltene flocs under static and micromodel dynamic conditions

AbstractIn this study, the impact of magnesium oxide (MgO) nanoparticles on the control of asphaltene aggregates growth was examined. The investigation began with static testing, followed by dynamic testing, where nanofluid was injected into a constructed glass micromodel simulating a porous medium. The results obtained from light microscopy and asphaltene dispersant tests demonstrated that the MgO nanoparticles with an average diameter of 50 nm postpone the asphaltene onset point (AOP) and delay the growth of asphaltene aggregates in crude oil. Also, the results obtained from these experiments illustrated the performance of synthesized nanoparticles in various concentrations on inhibition of asphaltene deposit in the crude oil medium, in the order of 750 > 1500 > 100 > 1000 > 500 ppm. The results from both microscopy and ADT experiments strongly validate the effectiveness of MgO nanoparticles across varying concentrations, highlighting the optimal dosage of 750 ppm. Images of nanofluid flooding at the optimal concentration in the glass micromodel demonstrate effective nanoparticle inhibition and enhanced oil recovery from the porous medium. These findings corroborate the results obtained from ADT and microscopy tests. The results of FT‐IR analysis show the adsorption of asphaltene particles on the surfaces of MgO nanoparticles in wavelengths of 2900–3000 cm−1. Moreover, dynamic light scattering (DLS) analysis results indicated that the average diameter of suspended particles was 3580 nm before adsorption and 6230 nm after adsorption, indicating the controlled adsorption of asphaltene onto the surface of MgO nanoparticles. The findings from this study can be applied to manage asphaltene formation across all stages of oil processing and production.

Mono- and di-rhamnolipids mixtures from Pseudomonas aeruginosa for use in extreme conditions of pre- and post-salt oil reservoirs compared with synthetic surfactants

Rhamnolipids are multipurpose molecules known as natural glycolipid biosurfactants that are often biosynthesized by Pseudomonas aeruginosa strains. They are readily biodegradable, have less impact on the environment and are less toxic than conventional surfactants. They can be applied in ex situ microbial enhanced oil recovery. However, there is still a lack of knowledge concerning the drastic environmental conditions of post and pre-salt reservoirs. In this study, different mixtures with different proportions of homologs of rhamnolipids from two genetically modified strains (GMOs) of P. aeruginosa and a non-GMO strain compared to commercial surfactants (Arquad C-50 and/or Ultrasperse II®) regarding their efficiency under high pressure, temperature and salinity conditions. Wettability reversal and interfacial tension tests were performed together with central composite rotational designs. Both genetically modified P. aeruginosa strains produced mainly di-rhamnolipids, whereas the non-GMO strain produced approximately 50 % mono- and 50 % di-rhamnolipids. Rhamnolipids and Arquad C-50 reversed 100 % of the wettability under pre-salt and post-salt conditions, whereas Ultrasperse II® achieved 73.3 % and 34.2 % (100 ppm) wettability, respectively. Interfacial tension presented the lowest values for rhamnolipids, with values of 0.4 mN/m and 0.5 mN/m, whereas Ultrasperse II® presented values of 2.6 and 2.5 mN/m, respectively under post-salt and pre-salt conditions at the +1 level of the tested variables. All rhamnolipid congeners tested here were more effective under post and pre-salt reservoirs conditions than commercial surfactants, thus expanding their potential for use not only in environmental bioremediation but also in oil industry processes.

Exploring the Impact of Mineralogy on Pore Structure and Fluid Dynamics in Tight Reservoir Rocks: Insights for Enhanced Oil Recovery and Gas Storage

Exploring the Impact of Mineralogy on Pore Structure and Fluid Dynamics in Tight Reservoir Rocks: Insights for Enhanced Oil Recovery and Gas Storage

Geochemistry in Geological CO2 Sequestration: A Comprehensive Review

The increasing level of anthropogenic CO2 in the atmosphere has made it imperative to investigate an efficient method for carbon sequestration. Geological carbon sequestration presents a viable path to mitigate greenhouse gas emissions by sequestering the captured CO2 deep underground in rock formations to store it permanently. Geochemistry, as the cornerstone of geological CO2 sequestration (GCS), plays an indispensable role. Therefore, it is not just timely but also urgent to undertake a comprehensive review of studies conducted in this area, articulate gaps and findings, and give directions for future research areas. This paper reviews geochemistry in terms of the sequestration of CO2 in geological formations, addressing mechanisms of trapping, challenges, and ways of mitigating challenges in trapping mechanisms; mineralization and methods of accelerating mineralization; and the interaction between rock, brine, and CO2 for the long-term containment and storage of CO2. Mixing CO2 with brine before or during injection, using microbes, selecting sedimentary reservoirs with reactive minerals, co-injection of carbonate anhydrase, and enhancing the surface area of reactive minerals are some of the mechanisms used to enhance mineral trapping in GCS applications. This review also addresses the potential challenges and opportunities associated with geological CO2 storage. Challenges include caprock integrity, understanding the lasting effects of storing CO2 on geological formations, developing reliable models for monitoring CO2–brine–rock interactions, CO2 impurities, and addressing public concerns about safety and environmental impacts. Conversely, opportunities in the sequestration of CO2 lie in the vast potential for storing CO2 in geological formations like depleted oil and gas reservoirs, saline aquifers, coal seams, and enhanced oil recovery (EOR) sites. Opportunities include improved geochemical trapping of CO2, optimized storage capacity, improved sealing integrity, managed wellbore leakage risk, and use of sealant materials to reduce leakage risk. Furthermore, the potential impact of advancements in geochemical research, understanding geochemical reactions, addressing the challenges, and leveraging the opportunities in GCS are crucial for achieving sustainable carbon mitigation and combating global warming effectively.