Stability of nanofluids along with their promising properties has led to wide applications of nanoparticles (NPs) in enhanced oil recovery (EOR) projects. Nanofluids that are colloidal suspension of ...NPs in base fluids, can stay stable at harsh reservoir conditions where other chemical-EOR solutions made of surfactants and polymers start degrading and lose their stabilities and functionalities. Specific surface characteristics of NPs have made them to affect fluids and rock properties and their pair interactions in porous media in favor of EOR mechanisms. Nevertheless, applying NPs in subsurface projects needs a strong understanding of NPs behaviors and their functions in porous media. As such, this work aims to give deeper insight into NPs functionality in porous media needed for practical design of NPs-EOR projects. This review endeavors to analyze the nanoparticle behaviors in porous media in view of criteria needed for application in EOR subsurface projects. Different promising mechanisms for NPs assisted EOR followed by controlling factors to optimize the EOR efficiency are deliberated. Effect of interparticle interactions along with other hydrodynamic forces on dispersion stability, nanoparticle agglomerations and subsequent settling have been analyzed in order to prepare stable nanofluid(s) for their further implications in EOR. Transport of NPs through porous media with the associated challenges is also investigated. Recent studies on NPs assisted EOR techniques are also presented. Finally, EOR challenges using NPs and the needed future research are highlighted.
•Specific surface characteristics of NPs have made them potential candidates for EOR projects.•NPs affect fluids and rock properties and their interactions in benefit of EOR mechanisms.•Nanofluids are more stable as compared to surfactant based complex fluids.•Flow stability of nanofluids depends on interparticle interactions and hydrodynamic forces.•NPs can block up the pores in porous media that should be considered for EOR projects.
This paper investigates the phase behavior and mutual interactions between a light crude oil and CO2 at high pressures and high temperatures (HPHT). To do so, we have measured PVT properties of the ...CO2-oil system at HPHT using a PVT setup. We have also tried to present a detailed methodology for measuring PVT properties of CO2-oil systems and highlight the difficulties such as oil vaporization by CO2 during the experiments. A crude oil sample, collected from a Malaysian oil field, was used here. Our experiments indicated that, CO2 solubility in the oil increased at higher pressures when measured at a fixed temperature. Our experiments also showed that increasing the test temperature would reduce CO2 solubility in the oil, while its effect is more significant at higher pressures. The swelling factor (SF) measurements showed an increasing trend with pressure up to a certain value so-called extraction pressure, at which, the SF started to be reduced even became less than one. The measurements of oil viscosity indicated that CO2 dissolution in the oil sample could reduce the mixture viscosity up to 61%. The interfacial tensions between CO2 and the crude oil at different pressures were also measured while the results were used to estimate the minimum miscibility pressure (MMP) and the first contact miscibility (FCM) pressure. The IFT measurements at various pressures displayed a reduction trend as a result of more CO2 dissolution in the oil but with two different slopes. That is, at lower pressure values, the measured IFTs were sharply reduced with pressure, while the reduction rate of the IFT became less when pressures exceeded the extraction pressure. This study helps with determining the optimum pressure and temperature conditions of CO2-oil systems to have a minimum IFT, a maximum CO2 solubility and SF, and a minimum oil viscosity that are favorable for CO2-enhanced oil recovery projects. Additionally, the methodology presented here gives guidelines on how to design PVT experiments of CO2-oil systems for petroleum and chemical engineering applications.
Increased emissions of greenhouse gasses into the atmosphere has adversely been contributing to global warming as a result of burning fossil fuels. Therefore, the energy sectors have been looking ...into renewable sources such as wind, solar, and hydro energy to make electricity. However, the strongly fluctuating nature of electricity from such energy sources requires a bulk energy storage system to store the excess energy as a buffer and to fulfill the demand constantly. Underground storage is a proven way to store a huge amount of energy (electricity) after converting it into hydrogen as it has higher energy content per unit mass than other gases such as methane and natural gas. This paper reviews the technical aspects and feasibility of the underground storage of hydrogen into depleted hydrocarbon reservoirs, aquifers, and manmade underground cavity (caverns). Mechanisms of underground hydrogen storage (UHS) followed by numerous phenomena such as hydrodynamics, geochemical, physiochemical, bio-chemical, or microbial reactions have been deliberated. Modeling studies have also been incorporated in the literature to assess the feasibility of the process that are also reviewed in this paper. Worldwide ongoing lab study, field study together with potential storage sites have been reported as well. Technical challenges along with proper remedial techniques and economic viability have been briefly discussed. Finally, this paper delivers some feasible strategies for the underground hydrogen storage process, which would be helpful for future research and development of UHS.
•Underground hydrogen storage (UHS) is comprehensively reviewed.•Potential storage sites and their characteristics are discussed.•Mechanisms of UHS are discussed.•The challenges and proper recommendations for UHS are deliberated.
•Mass transfer parameters of CO2 in crude oils at high pressures are estimated.•Two ‘pressure decay’ mass transfer experiments are analyzed mathematically.•Oil swelling effect due to CO2 dissolution ...is also considered in this study.
The rate of CO2 dissolution in crude oils is primarily controlled by mass transfer between CO2 and oil phases. In particular, mass transfer of CO2 component across the CO2-oil interface and the molecular diffusion of CO2 inside the oil phase control the rate of CO2 dissolution in the oil. The values of interface mass transfer coefficient (k) and diffusion coefficient (D) are needed to estimate the mass transfer rate by molecular diffusion and to determine the CO2 dissolution rate in a crude oil. When CO2 is dissolved in a crude oil, the oil volume usually increases (oil swelling) that should be considered. This paper aims to accurately estimate and quantify the mass transfer parameters of CO2 in crude oils (k and D coefficients) and also the oil swelling percentage by analyzing the data of the pressure decay experiment. A mathematical model has been developed when a numerical method is used to solve the governing equations with a moving boundary condition. The model is used to analyze the data of pressure decay experiments of a heavy and also a light crude oil-CO2 system. The model has estimated the k and D coefficients of CO2 in crude oils using an optimization procedure, and also has predicted the dynamic process of oil swelling due to CO2 dissolution. The mass transfer process is discussed and the estimated mass transfer parameters (k and D) are compared with some data from the literature. The results show that the k and D values and also the oil swelling percentage for the light oil-CO2 system are larger than those for the heavy oil-CO2 system. This study gives an insight into the mass transfer process between CO2 and oil phases that can be used to describe the mass transfer process in any gas-liquid system.
•A CWI coreflood experiment performed in a mixed-wet core is studied mathematically.•Compared to CWI in a water-wet core, a different simulation procedure is suggested.•The contribution of both ...wettability alteration and oil swilling mechanisms is discussed.
In this paper, our previously developed model (simulator) has been used to simulate and study a different CWI coreflood experiment from the literature performed in a mixed-wet sandstone core. The developed model that was based on mass transfer kinetics had been used before to simulate a coreflood experiment performed in a water-wet sandstone rock. In this paper, a different procedure has been applied for the simulation of CWI in the mixed-wet core. That is, in contrast to the water-wet coreflood test where only mass transfer parameter was tuned, here, both mass transfer parameter and relative permeability curves have been obtained through a history matching experiment applying our genetic algorithm (GA) based optimization program. Furthermore, using the simulation results, it has been observed that in addition to oil swelling and contrary to the water-wet core, wettability alteration is also an important recovery mechanism for the mixed-wet core. The potential of CO2 storage during the mixed-wet CWI coreflood experiment has also been investigated. The results obtained in this paper can help to crosscheck and verify the performance of the developed simulator and also to explore its generic capability. Moreover, the results of this paper give an insight into different recovery mechanisms contributing during CWI coreflood experiments.
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•Synthesis and characterization of ChiNCs are presented.•Controlled sol-nematic gel transformation of ChiNCs is discussed.•Key parameters for ChiNCs based complex fluids (dispersion, ...foam, emulsion and gel) are elaborated.•Ground breaking current and future applications of ChiNCs are demonstrated.•The untapped investigations are highlighted to widen up the applicability and adoptability of ChiNCs.
Chitin biopolymer has received significant attention recently by many industries as a green technology. Nanotechnology has been used to make chitin nanocrystals (ChiNCs) that are rod-shaped natural nanomaterials with nanoscale size. Owing to the unique features such as biodegradability, biocompatibility, renewability, rod-shape, and excellent surface and interfacial, physiochemical, and thermo-mechanical properties; ChiNCs have been green and attractive products with wide applications specifically in medical and pharmaceutical, food and packaging, cosmetic, electrical, and electronic, and also in the oil and gas industry. This review aims to give a comprehensive and applied insight into ChiNCs technology. It starts with reviewing different sources of chitin and their extraction methods followed by the characterization of ChiNCs. Furthermore, a detailed investigation into various complex fluids (dispersions, emulsions, foams, and gels) stabilized by ChiNCs and their characterisation have been thoroughly deliberated. Finally, the current status including ground-breaking applications, untapped investigations, and future prospective have been presented.
Low Salinity Water Injection (LSWI) has been a well-researched EOR method, with several experimental and theoretical scientific papers reported in the literature over the past few decades. Despite ...this, there is still an ongoing debate on dominant mechanisms behind this complex EOR process, and some issues remain elusive. Part of the complexity arises from the scale of investigation, which spans from sub-pore scale (atomic and electronic scale) to pore scale, core scale, and reservoir scale. Molecular Dynamics (MD) simulation has been used as a research tool in the past decade to investigate the nano-scale interactions among reservoir rock (e.g., calcite, silica), crude oil, and brine systems in presence of some impurities (e.g., clay minerals) and additives (e.g., nanoparticles). In this paper, fundamental concepts of MD simulation and common analyses driven by MD are briefly reviewed. Then, an overview of molecular models of the most common minerals encountered in petroleum reservoirs: quartz, calcite, and clay, with their most common types of potential function, is provided. Next, a critical review and in depth analysis of application of MD simulations in LSWI process in both sandstone and carbonate reservoirs in terms of sub-pore scale mechanisms, namely electrical double layer (EDL) expansion, multi-ion exchange (MIE), and cation hydration, is presented to scrutinize role of salinity, ionic composition, and rock surface chemistry from an atomic level. Some inconsistencies observed in the literature are also highlighted and the reasons behind them are explained. Finally, a future research guide is provided after critically discussing the challenges and potential of the MD in LSWI to shed more light on governing mechanisms behind LSWI by enhancing the reliability of MD outcomes in future researches. Such insights can be used for design of new MD researches with complementary experimental studies at core scale to capture the main mechanisms behind LSWI.
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•Application of Molecular Dynamics (MD) simulation in low salinity water injection of sandstone and carbonate reservoirs is comprehensively reviewed.•Low salinity water injection mechanisms are discussed from a sub-pore scale perspective.•Current challenges and potentials are identified for future research.
•Carbonated water injection (CWI) as an EOR and CO2 storage strategy is studied here.•A new mathematical model is developed to capture the CO2 transfer kinetics during CWI.•The mathematical model is ...used to simulate and study a real CWI coreflood experiment.
Mathematical modeling of carbonated water injection (CWI) as an EOR and CO2 storage technique is studied in this paper. When carbonated water (CO2 saturated water) contacts oil during injection into oil reservoirs, CO2 will migrate from water into the oil phase as it has higher solubility in hydrocarbons. Consequently, oil mobility, and in turn oil recovery, will increase. In addition, CO2 can also be stored securely in the reservoir during CWI. The simulation study of CWI coreflood experiments presented in the literature show that during CWI, the CO2 transfer between water and oil phases is slow and equilibrium state is not reached instantaneously. Hence, in this paper, a new compositional simulator is developed by including the kinetics of CO2 transfer and a set of CWI coreflood experiment from the literature is simulated and studied in detail. A genetic algorithm based optimizer is applied to obtain the unknown parameters during simulation through a history matching experiment. The performance of the developed simulator is also compared with ECLIPSE300 commercial compositional simulator. The CO2 storage profile is also studied using the simulation results. Generally, the developed simulator can be used to better understand the physics of CWI process for practical field applications and also as a solid foundation for kinetic based study of transport phenomena in porous media where the mass transfer is important and not instantaneous.
CO2 molecular diffusion in subsurface porous media is one of the key mechanisms in high-pressure–high-temperature CO2 geosequestration and CO2-based enhanced oil recovery projects. The mass transfer ...rate of injected supercritical CO2 and its dissolution in reservoir fluids are mainly described by the gas diffusion coefficient. Over the past decades, numerous efforts have been made to investigate the CO2 molecular diffusion process in both hydrocarbon reservoirs and saline aquifers. However, various experimental methods and mathematical models with simplified assumptions were used to determine the CO2 diffusivity, which sometimes led to inaccurate or contradicting results. Hence, it is essential to critically review and compare the CO2-diffusion-related literature for better application in geoscience, chemical, and petroleum engineering fields. In this review, we critically review the physics of CO2 diffusion in porous and nanoporous media, including the diffusion theory, factors affecting the CO2 diffusion coefficient in hydrocarbon reservoirs and saline aquifers, analysis of laboratory measurement methods, their advantages and disadvantages and limitations, and also evaluation of previously developed mathematical models and their uncertainties and empirical correlations, in detail. Additionally, we briefly discuss CO2 dispersion in porous media from various aspects. Finally, potential research areas related to CO2 diffusion in porous media are proposed.
Carbon dioxide (CO2) is one of the main greenhouse gases that its high concentration in the atmosphere has caused the global warming issue. Sequestering CO2 in a suitable geological subsurface ...formation can be a feasible method to reduce the CO2 concentration in the atmosphere. CO2 sequestration in saline aquifers can store a significant volume of CO2 underground for thousand years. However, injecting CO2 into such formations does not guarantee a safe storage because CO2 could leak back to surface or contaminate the formation water. Hence, a proper evaluation of the sequestration site is required. In this study, a case study regarding CO2 sequestration in saline aquifers was conducted using CMG-GEM compositional simulator to study the effects of aquifer permeability, injection pressure and well trajectory on CO2 trapping mechanisms during sequestration process. A field-scale model with one injector well in which CO2 was injected into the aquifer for ten years and simulated for hundred years was studied. The results showed that, CO2 solubility trapping is the dominant mechanism with less risk of leakage when the aquifer has a good vertical permeability and the injection pressure is not high regardless of the well trajectory.
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