Publications
116 results found
Rovelli A, Brodie J, Rashid B, et al., 2024, Effects of core size and surfactant choice on fluid saturation development in surfactant/Polymer corefloods, Energy and Fuels, Vol: 38, Pages: 2844-2854, ISSN: 0887-0624
Surfactant/polymer flooding allows for a significant increase in oil recovered at both laboratory and field scales. Limitations in application at the reservoir scale are, however, present and can be associated with both the complexity of the underlying displacement process and the time-intensive nature of the up-scaling workflow. Pivotal to this workflow are corefloods which serve to both validate the extent of oil recovery and extract modeling parameters used in upscaling. To enhance the understanding of the evolution of the saturation distribution within the rock sample, we present the utilization of X-ray computed tomography to image six distinct surfactant/polymer corefloods. In doing so, we visualize the formation and propagation of an oil bank by reconstructing multidimensional saturation maps. We conduct experiments on three distinct core sizes and two different surfactants, an SBDS/isbutanol formulation and an L-145-10s 90 formulation, in order to decouple the effect of these two parameters on the flow behavior observed in situ. We note that the oil production post oil bank breakthrough is primarily influenced by the surfactant choice, with the SDBS/isobutanol formulation displaying longer tailing production of a low oil cut. On the other hand, the core size dominated the extent of self-similarity of the saturation profiles with smaller cores showing less overlap in the self-similarity profiles. Consequently, we highlight the difference in applicability of a fractional flow approach to larger and smaller cores for upscaling parameter extraction and thus provide guidance for corefloods where direct imaging is not available.
Azzan H, Danaci D, Petit C, et al., 2023, Unary adsorption equilibria of hydrogen, nitrogen and carbon dioxide on y-type zeolites at temperatures from 298 to 393 k and at pressures up to 3 MPA, Journal of Chemical and Engineering Data, Vol: 68, Pages: 3512-3524, ISSN: 0021-9568
The equilibrium adsorption of CO2, N2, and H2 on commercially available Zeolite H–Y, Na–Y, and cation-exchanged NaTMA–Y was measured up to 3 MPa at 298.15, 313.15, 333.15, 353.15, and 393.15 K gravimetrically using a magnetic suspension balance. The chemical and textural characterization of the materials was carried out by thermogravimetric analysis, helium gravimetry, and N2 (77 K) physisorption. We report the excess and net isotherms as measured and estimates of the absolute adsorption isotherms. The latter are modeled using the simplified statistical isotherm (SSI) model to evaluate adsorbate–adsorbent interactions and parametrize the data for process modeling. When reported per unit volume of zeolite supercage, the SSI model indicates that the saturation capacity for a given gas takes the same value for the three adsorbents. The Henry’s constants predicted by the model show a strong effect of the cation on the affinity of each adsorbate.
An S, Wenck N, Manoorkar S, et al., 2023, Inverse Modeling of Core Flood Experiments for Predictive Models of Sandstone and Carbonate Rocks, Water Resources Research, Vol: 59, ISSN: 0043-1397
Field-scale observations suggest that rock heterogeneities control subsurface fluid flow, and these must be characterized for accurate predictions of fluid migration, such as during CO2 sequestration. Recent efforts characterizing multiphase flow in heterogeneous rocks have focused on simulation-based inversion of laboratory observations with X-ray imaging. However, models produced in this way have been limited in their predictive ability for heterogeneous rocks. We address the main challenges in this approach through an algorithm that combines new developments: a 3-parameter capillary pressure model, spatial heterogeneity in absolute permeability, improved image processing to capture more experimental data in the calibration, and the constraint of history match iterations based on marginal error improvement. We demonstrate the improvements on two sandstones and three carbonate rocks, with varying heterogeneity, some of which could not be previously modeled. The algorithm results in physically representative models of the rock cores, reducing non-systematic error to a level comparable to the experimental uncertainty.
Wedler C, Ferre A, Azzan H, et al., 2023, Competitive high-pressure adsorption of CO2/CH4 mixtures on NIST reference zeolite Y (RM8850), Thermodynamik Kolloquium 2023
Ward A, Li K, Pini R, 2023, Assessment of dual-adsorbent beds for CO2 capture byequilibrium-based process design, Separation and Purification Technology, Vol: 319, ISSN: 0950-4214
We have carried out a model-based assessment of dual-adsorbent beds for post-combustion CO capture, whereby we consider systems in which two distinct adsorbent materials are homogeneously mixed to form a fixed bed adsorber. We have employed an equilibrium-based process model (D-BAAM) to simulate and optimize the process performance of a four-step vacuum swing adsorption cycle for CO capture with a dual-adsorbent bed. We have used the developed framework to screen the performance of 2,850 binary combinations of adsorbents from a database of 76 promising materials for post-combustion capture, which includes zeolites, activated carbons, metal organic frameworks (MOFs) and zeolitic imidazolate frameworks (ZIFs). Through unconstrained purity/recovery process optimization, we determine that only one pure material in a material pair needs to itself satisfy regulatory constraints on CO purity/recovery for post-combustion capture to yield a dual-adsorbent process which satisfies the constraints. For these dual-adsorbent combinations, we have assessed the optimal process performance in the constrained working capacity/energy usage Pareto plane and have identified nine distinct categories of process behavior. Five of these categories have the potential to allow for a reduction in the energy penalty of the separation, as compared to the constituent single-adsorbent processes. We have observed reductions in the energy penalty of the separation of approximately 20%. We contend that such processes may be economically optimal depending on a process specific balance of capital, operating and material costs, and should be investigated in more detail using dynamic process modeling and an associated techno-economic assessment.
Bikane K, Yu J, Shah SM, et al., 2023, High pressure CO<sub>2</sub> gasification of Morupule coal: Kinetics and morphological development of chars, CHEMICAL ENGINEERING JOURNAL, Vol: 462, ISSN: 1385-8947
Nguyen HGT, Toman B, van Zee RD, et al., 2023, Reference isotherms for water vapor sorption on nanoporous carbon: results of an interlaboratory study, Adsorption, Vol: 29, Pages: 113-124, ISSN: 0929-5607
This paper reports the results of an international interlaboratory study sponsored by the Versailles Project on Advanced Materials and Standards (VAMAS) and led by the National Institute of Standards and Technology (NIST) on the measurement of water vapor sorption isotherms at 25 °C on a pelletized nanoporous carbon (BAM-P109, a certified reference material). Thirteen laboratories participated in the study and contributed nine pure water vapor isotherms and four relative humidity isotherms, using nitrogen as the carrier gas. From these data, reference isotherms, along with the 95% uncertainty interval (Uk=2), were determined and are reported in a tabular format.
Joewondo N, Garbin V, Pini R, 2023, Experimental evidence of the effect of solute concentration on the collective evolution of bubbles in a regular pore-network, CHEMICAL ENGINEERING RESEARCH & DESIGN, Vol: 192, Pages: 82-90, ISSN: 0263-8762
Iruretagoyena D, Fennell P, Pini R, 2023, Adsorption of CO2 and N2 on bimetallic Mg-Al hydrotalcites and Z-13X zeolites under high pressure and moderate temperatures, CHEMICAL ENGINEERING JOURNAL ADVANCES, Vol: 13, ISSN: 2666-8211
Anto-Darkwah E, Kurotori T, Pini R, et al., 2023, Estimating Three-Dimensional Permeability Distribution for Modeling Multirate Coreflooding Experiments, SUSTAINABILITY, Vol: 15
Eckel A-ME, Liyanage R, Kurotori T, et al., 2023, Spatial moment analysis of convective mixing in three-dimensional porous media using X-ray CT images, Industrial and Engineering Chemistry Research, Vol: 62, Pages: 762-774, ISSN: 0888-5885
Dissolution trapping is one of the primary mechanisms of carbon dioxide (CO2) storage in deep saline aquifers. The determination of the realized rates of CO2 dissolution requires an understanding of the mixing process that takes place following the emplacement of CO2 into the formation. Owing to the difficulty of reproducing the time-dependent convective process in porous media, experiments so far have largely focused on 2D systems (e.g., Hele-Shaw cells) and used analogue fluid pairs with properties that differ from the subsurface CO2/brine system. Here, we present a novel experimental approach to investigate the evolution of the convective mixing process in 3D porous media (homogeneous packings of glass beads) using X-ray computed tomography (CT). We explore a range of Rayleigh numbers (Ra = 3000–55000) and observe directly the mixing structures that arise upon dissolution. We compute from the images the temporal evolution of the spatial moments of the concentration distribution, including the cumulative dissolved mass, the location of the center of mass, and the standard deviation of the concentration field. The scalings of the spatial moments suggest an impact of hydrodynamic dispersion on the longitudinal mixing. We propose a simplified representation of the mixing process by analogy with the 1D advection–dispersion model. This enables the estimation of the bulk advective velocity and the effective longitudinal dispersion coefficient for each bead packing. These estimates suggest that the presence of the finger pattern and the counter-current flow structure enhance the longitudinal spreading of the solute by roughly 1 order of magnitude compared to unidirectional dispersion of a single-solute plume.
Delle Piane C, Ansari H, Li Z, et al., 2023, Influence of Organic Matter Type on Porosity Development in Organic-Rich Shales: Combining Microscopy, Neutron Scattering and Physisorption Approaches, Neutron News, Vol: 34, Pages: 8-9, ISSN: 1044-8632
Low M-YA, Barton LV, Pini R, et al., 2023, Analytical review of the current state of knowledge of adsorption materials and processes for direct air capture, Chemical Engineering Research and Design, Vol: 189, Pages: 745-767, ISSN: 0263-8762
Significant research interest has been directed towards the deployment of direct air capture (DAC) as a net-negative CO2 emissions technology to help limit global temperature rise to below 2 °C. The scope of this review is to outline the advancement of adsorption-based DAC technologies, as well as to highlight the still-existing data gaps, for both materials’ development and process design in the period 2016 – 2021. On the material side, we highlight the available and missing data on adsorbent properties in relation to what is needed for process modelling and design. We cover material densities, textural properties, thermal properties, adsorption isotherms (i.e. CO2, N2, O2, H2O), adsorption kinetics, and adsorbent stability towards humidity, oxidation, and cycling. On the process side, we provide a detailed look at key process studies conducted in the same time frame by considering the trade-offs to be expected in the design of the adsorption-based DAC process. We focus on process configuration and contactor design, desorption processes, and the need for systematic reporting of key performance indicators to allow for accurate comparisons and benchmarking. Throughout the review, we identify the lack of synergy between material and process development which must be addressed to advance the field of DAC by adsorption.
Ward A, Pini R, 2022, Efficient Bayesian optimisation of industrial-scale pressure-vacuum swing adsorption processes for CO2 capture, Industrial and Engineering Chemistry Research, Vol: 61, Pages: 13650-13668, ISSN: 0888-5885
The design of adsorption systems for separation of CO2/N2 in carbon capture applications is notoriously challenging because it requires constrained multiobjective optimization to determine appropriate combinations of a moderately large number of system operating parameters. The status quo in the literature is to use the nondominated sorting genetic algorithm II (NSGA-II) to solve the design problem. This approach requires 1000s of time-consuming process simulations to find the Pareto front of the problem, meaning it can take days of computational time to obtain a solution. As an alternative approach, we have employed a Bayesian optimization algorithm, the Thompson sampling efficient multiobjective optimization (TSEMO). For constrained productivity/energy usage optimization, we find that the TSEMO algorithm is able to find an essentially identical solution to the design problem as that found using NSGA-II, while requiring 14 times less computational time. We have used the TSEMO algorithm to design a postcombustion carbon capture system for a 1000 MW coal fired power plant using two adsorbent materials, zeolite 13X and ZIF-36-FRL. Although ZIF-36-FRL showed promising process-scale performance in previous studies, we find that the industrial-scale performance is inferior to the benchmark zeolite 13X, requiring a 21% greater cost per tonne of CO2 captured. Finally, we have also tested the performance of the Bayesian design framework when coupled with a data-driven machine learning process modeling framework. In this instance, we find that the incumbent NSGA-II offers better computational performance than the Bayesian approach by a factor of 3.
Azzan H, Rajagopalan AK, L'Hermitte A, et al., 2022, Simultaneous estimation of gas adsorption equilibria and kinetics of individual shaped adsorbents, Chemistry of Materials, Vol: 34, Pages: 6671-6686, ISSN: 0897-4756
Shaped adsorbents (e.g., pellets, extrudates) are typically employed in several gas separation and sensing applications. The performance of these adsorbents is dictated by two key factors, their adsorption equilibrium capacity and kinetics. Often, adsorption equilibrium and textural properties are reported for materials. Adsorption kinetics are seldom presented due to the challenges associated with measuring them. The overarching goal of this work is to develop an approach to characterize the adsorption properties of individual shaped adsorbents with less than 100 mg of material. To this aim, we have developed an experimental dynamic sorption setup and complemented it with mathematical models, to describe the mass transport in the system. We embed these models into a derivative-free optimizer to predict model parameters for adsorption equilibrium and kinetics. We evaluate and independently validate the performance of our approach on three adsorbents that exhibit differences in their chemistry, synthesis, formulation, and textural properties. Further, we test the robustness of our mathematical framework using a digital twin. We show that the framework can rapidly (i.e., in a few hours) and quantitatively characterize adsorption properties at a milligram scale, making it suitable for the screening of novel porous materials.
Hwang J, Azzan H, Pini R, et al., 2022, H2, N2, CO2, and CH4 unary adsorption isotherm measurements at low and high pressures on zeolitic imidazolate framework ZIF-8, Journal of Chemical & Engineering Data, Vol: 67, Pages: 1674-1686, ISSN: 0021-9568
Excess adsorption of CO2, CH4, N2, and H2 on ZIF-8 was measured gravimetrically in the pressure range ranging from vacuum to 30 MPa at 298.15, 313.15, 333.15, 353.15, and 394.15 K using a magnetic suspension balance. The textural properties of the adsorbent material─i.e., skeletal density, surface area, pore volume, and pore-size distribution─were estimated by helium gravimetry and N2 (77 K) physisorption. The adsorption isotherms were fitted with the Sips isotherm model and the virial equation, and the values of isosteric heat of adsorption and Henry constants for the gases were determined using the latter.
Pini R, Siderius DW, Siepmann JI, 2022, Preface to Adsorption and Diffusion in Porous Materials Special Issue: Equilibrium Adsorption Data for Energy and Environmental Applications, JOURNAL OF CHEMICAL AND ENGINEERING DATA, Vol: 67, Pages: 1597-1598, ISSN: 0021-9568
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Fan D, Chapman E, Khan A, et al., 2022, Anomalous transport of colloids in heterogeneous porous media: a multi-scale statistical theory, Journal of Colloid and Interface Science, Vol: 617, Pages: 94-105, ISSN: 0021-9797
HypothesisTransport of suspended colloids in heterogeneous porous media is a multi-scale process that exhibits anomalous behavior and cannot be described by the Fickian dispersion theory. Although many studies have documented colloids’ transport at different length scales, a theoretical basis that links pore- to core-scale observations remains lacking. It is hypothesized that a recently proposed pore-scale statistical kinetic theory is able to capture the results observed experimentally.ExperimentsWe implement a multi-scale approach via conducting core-flooding experiments of colloidal particles in a sandstone sample, simulating particles flowing through a sub-volume of the rock’s digital twin, and developing a core-scale statistical theory for particles’ residence times via upscaling the pore-scale kinetic theory. Experimental and computational results for solute transport are used as benchmark.FindingsBased on good agreement across the scales achieved in our investigation, we show that the macroscopically observed anomalous transport is particle-type dependent and stems from particles’ microscopic dispersion and deposition in heterogeneous flow fields. In particular, we reveal that residence-time distributions (i.e., breakthrough curve) obey a closed-form function that encompasses particles’ microscopic dynamics, which allows investigations of a whole transition from pre-asymptotic to asymptotic behavior. The physical insights attained could be useful for interpreting experimental data and designing colloidal tracers.
Ward A, Pini R, 2022, Integrated uncertainty quanti cation and sensitivity analysis of single-component dynamic column breakthrough experiments, Adsorption, Vol: 28, Pages: 161-183, ISSN: 0929-5607
We have carried out the traditional analysis of a set of dynamic breakthrough experiments on the CO2/He system adsorbing onto activated carbon by fitting a 1D dynamic column breakthrough model to the transient experimental profiles. We have quantified the uncertainties in the fitted model parameters using the techniques of Bayesian inference, and have propagated these parametric uncertainties through the dynamic model to assess the robustness of the modelling. We have found significant uncertainties in the outlet mole fraction profile, internal temperature profile and internal adsorption profiles of approximately ±15%. To assess routes to reduce these uncertainties we have applied a global variance-based sensitivity analysis to the dynamic model using the Sobol method. We have found that approximately 70% of the observed variability in the modelling outputs can be attributed to uncertainties in the adsorption isotherm parameters that describe its temperature dependence. We also make various recommendations for practitioners, using the developed Bayesian statistical tools, regarding the choice of the isotherm model, the choice of the fitting data for the extraction of system specific parameters and the simplification of the wall energy balance.
Ansari H, Gong S, Trusler J, et al., 2022, Hybrid pore-scale adsorption model for CO2 and CH4 storage in shale, Energy and Fuels, Vol: 36, ISSN: 0887-0624
Making reliable estimates of gas adsorption in shale remains a challenge becausethe variability in their mineralogy and thermal maturity results in a broad distributionof pore-scale properties, including size, morphology and surface chemistry. Here, wedemonstrate the development and application of a hybrid pore-scale model that usessurrogate surfaces to describe supercritical gas adsorption in shale. The model is basedon the lattice Density Functional Theory (DFT) and considers both slits and cylindrical pores to mimic the texture of shale. Inorganic and organic surfaces associatedwith these pores are accounted for by using two distinct adsorbate-adsorbent interaction energies. The model is parameterised upon calibration against experimentaladsorption data acquired on adsorbents featuring either pure clay or pure carbon surfaces. Therefore, in its application to shale, the hybrid lattice DFT model only requiresknowledge of the shale-specific organic and clay content. We verify the reliability ofthe model predictions by comparison against high-pressure CO2 and CH4 adsorptionisotherms measured at 40 ◦C in the pressure range 0.01–30 MPa on four samples fromthree distinct plays, namely the Bowland (UK), Longmaxi (China) and Marcellus shale1(USA). Because it uses only the relevant pore-scale properties, the proposed model canbe applied to the analysis of other shales, minimising the heavy experimental burdenassociated with high pressure experiments. Moreover, the proposed development hasgeneral applicability meaning that the hybrid lattice DFT can be used to the characterisation of any adsorbent featuring morphologically and chemically heterogeneoussurfaces.
Huang Z, Kurotori T, Pini R, et al., 2022, Three-Dimensional Permeability Inversion Using Convolutional Neural Networks and Positron Emission Tomography, WATER RESOURCES RESEARCH, Vol: 58, ISSN: 0043-1397
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Siepmann JI, Gardas R, Kofke DA, et al., 2022, The <i>Journal of Chemical</i> & <i>Engineering Data</i>: Introduction of Topical Sections and Updates from the Editorial Team, JOURNAL OF CHEMICAL AND ENGINEERING DATA, Vol: 67, Pages: 1-2, ISSN: 0021-9568
Joewondo N, Garbin V, Pini R, 2022, Nonuniform collective dissolution of bubbles in regular pore networks, Transport in Porous Media, Vol: 141, Pages: 649-666, ISSN: 0169-3913
Understanding the evolution of solute concentration gradients underpins the prediction of porous media processes limited by mass transfer. Here, we present the development of a mathematical model that describes the dissolution of spherical bubbles in two-dimensional regular pore networks. The model is solved numerically for lattices with up to 169 bubbles by evaluating the role of pore network connectivity, vacant lattice sites and the initial bubble size distribution. In dense lattices, diffusive shielding prolongs the average dissolution time of the lattice, and the strength of the phenomenon depends on the network connectivity. The extension of the final dissolution time relative to the unbounded (bulk) case follows the power-law function, Bk/ℓ, where the constant ℓ is the inter-bubble spacing, B is the number of bubbles, and the exponent k depends on the network connectivity. The solute concentration field is both the consequence and a factor affecting bubble dissolution or growth. The geometry of the pore network perturbs the inward propagation of the dissolution front and can generate vacant sites within the bubble lattice. This effect is enhanced by increasing the lattice size and decreasing the network connectivity, yielding strongly nonuniform solute concentration fields. Sparse bubble lattices experience decreased collective effects, but they feature a more complex evolution, because the solute concentration field is nonuniform from the outset.
Delle Piane C, Ansari H, Li Z, et al., 2022, Influence of organic matter type on porosity development in the Wufeng-Longmaxi Shale: A combined microscopy, neutron scattering and physisorption approach, International Journal of Coal Geology, Vol: 249, Pages: 1-15, ISSN: 0166-5162
The upper Ordovician Wufeng Shale and lower Silurian Longmaxi Shale are part of the Fuling shale gas play located in the south-eastern part of the Sichuan Basin, southern China, representing the first commercial shale gas production project outside North America. We studied the occurrence of porosity at the micro- and nano-scale in samples of contrasting organic richness representing the typical lithofacies from the post-mature part of the Wufeng-Longmaxi gas play. Using a combination of site specific, high-resolution scanning and transmission electron microscopy with bulk measurements based on small angle neutron scattering and cryogenic Argon physisorption, along with conventional organic petrology, we highlight the impact of different types of organic matter (OM) (primary versus secondary) on the development of OM-hosted porosity. The results indicate that at the bulk scale the overall porosity in the samples is proportional to their organic content and organic hosted pore account for 30–40% of the total pore volume of the rocks. Nevertheless, most of the pores identified via electron microscopy imaging seem to reside in the organic matter, indicating that potentially a large part of the pores volume detected by neutron scattering and Argon physisorption is visually not detected. Organic matter focused nanoscale imaging revealed that mesopores are preferentially present in the solid bitumen and not in the primary detrital organic particles. Organic lean samples show low porosity and dominance of micropores, while organic-rich samples show higher porosity and a broader spectrum of pore sizes. Importantly, most of the meso pores are located in organic matter petrographically interpreted as solid bitumen, while detrital organic particles like graptolites show minimal visible porosity under high resolution electron microscopy and pore sizes in the micro pore range (i.e. <2 nm).Distinguishing between primary and secondary OM is therefore important for underst
Huang Z, Kurotori T, Pini R, et al., 2021, Three-Dimensional Permeability Inversion Using Convolutional Neural Networks and Positron Emission Tomography
Kuusela P, Pour-Ghaz M, Pini R, et al., 2021, Imaging of reactive transport in fractured cement-based materials with X-ray CT, Cement and Concrete Composites, Vol: 124, Pages: 1-12, ISSN: 0958-9465
The need to improve the understanding of the properties of cement-based materials calls for the development of tools for visualizing and quantifying chemicalreactions and flows of fluids within them. In this paper, we report the results ofan experimental study where a sample of fractured cement-paste was subjectedto injection of fluids (krypton, CO2 and water) and imaged simultaneously byX-ray computed tomography (CT). Initial porosity of the sample was estimatedusing a subtraction method based on CT scans taken initially and during krypton injection. The CT reconstructions were segmented to visualize crack patterns and fluid flow in three-dimensions and to quantify the evolution of porosityduring the experiment. The results show that CT captures the formation of acarbonate phase in the sample during CO2 injection, and the flow of water inthe fractured media. We quantify the reduction of porosity resulting from thecarbonation reaction. We observe that the newly formed carbonated layer impedes water flow and, locally, can lead to crack healing. The results demonstratethe ability of CT to image reactive transport in cement-based materials, andsupport the feasibility of this imaging tool for their characterization.
Ansari H, Rietmann E, Joss L, et al., 2021, A shortcut pressure swing adsorption analogue model to estimate gas-in-place and CO2 storage potential of gas shales, Fuel: the science and technology of fuel and energy, Vol: 301, Pages: 1-13, ISSN: 0016-2361
Natural gas extraction from shale formations has experienced a rapid growth in recent years, but the low recovery observed in many field operations demonstrates that the development of this energy resource is far from being optimal. The ambiguity in procedures that account for gas adsorption in Gas-in-Place calculations represents an important element of uncertainty. Here, we present a methodology to compute gas production curves based on quantities that are directly accessed experimentally, so as to correctly account for the usable pore-space in shale. We observe that adsorption does not necessarily sustain a larger gas production compared to a non-adsorbing reservoir with the same porosity. By analysing the entire production curve, from initial to abandonment pressure, we unravel the role of the excess adsorption isotherm in driving this behaviour. To evaluate scenarios of improved recovery by means of gas injection, we develop a proxy reservoir model that exploits the concept of Pressure Swing Adsorption used in industrial gas separation operations. The model has three stages (Injection/Soak/Production) and is used to compare scenarios with cyclic injection of CO2 or N2. The results show that partial pressure and competitive adsorption enhance gas production in complementary ways, and reveal the important trade-off between CH4 recovery and CO2 storage. In this context, this proxy model represents a useful to tool to explore strategies that optimise these quantities without compromising the purity of the produced stream, as the latter may introduce a heavy economic burden on the operation.
Fan D, Pini R, Striolo A, 2021, A seemingly universal particle kinetic distribution in porous media, Applied Physics Letters, Vol: 119, Pages: 1-6, ISSN: 0003-6951
We study many-particle transport in randomly jammed packing of spheres at different particle Péclet numbers (𝑃𝑒∗). We demonstrate that a modified Nakagami-m function describes particle velocity probability distributions when particle deposition occurs. We assess the universality of said function through comparison against Lagrangian simulations of various particle types as well as experimental data from the literature. We construe the function's physical meaning as its ability to explain particle deposition in terms of 𝑃𝑒∗ and the competition between distributions of energy barriers for particle release and particles' diffusive energy.
Ma L, Fauchille A-L, Ansari H, et al., 2021, Linking multi-scale 3D microstructure to potential enhanced natural gas recovery and subsurface CO2 storage for Bowland Shale, UK, Energy and Environmental Science, Vol: 14, Pages: 4481-4498, ISSN: 1754-5692
Injection of CO2 into shale reservoirs to enhance gas recovery and simultaneously sequester greenhouse gases is a potential contributor towards the carbon-neutral target. It offers a low-carbon, low-cost, low-waste and large-scale solution during energy transition period. A precondition to efficient gas storage and flow is a sound understanding of how the shale’s micro-scale impacts on these phenomena. However, the heterogeneous and complex nature of shales limits the understanding of microstructure and pore systems, making feasibility analysis challenging. This study qualitatively and quantitatively investigates the Bowland shale microstructure in 3D at five length scales: artificial fractures at 10-100 µm scale, matrix fabric at 1-10 µm-scale, individual mineral grains and organic matter particles at 100 nm- 1 µm scale, macropores and micro-cracks at 10-100 nm scale and organic matter and mineral pores at 1-10 nm-scale. For each feature, the volume fraction variations along the bedding normal orientation, the fractal dimensions and the degrees of anisotropy were analysed at all corresponding scales for a multi-scale heterogeneity analysis. The results are combined with other bulk laboratory measurements, including supercritical CO2 and CH4 adsorption at reservoir conditions, pressure-dependent permeability and nitrogen adsorption pore size distribution, to perform a comprehensive analysis on the storage space and flow pathways. A cross-scale pore size distribution, ranging from 2 nm to 3 µm, was calculated with quantified microstructure. The cumulative porosity is calculated to be 8%. The cumulative surface area is 17.6 m2/g. A model of CH4 and CO2 flow pathways and storage with quantified microstructure is presented and discussed. The feasibility of simultaneously enhanced gas recovery and subsurface CO2 storage in Bowland shale, the largest shale gas potential formation in the UK, was assessed based using multi-scale microstructure
Savulescu GC, Rücker M, Scanziani A, et al., 2021, Atomic force microscopy for the characterisation of pinning effects of seawater micro-droplets in n-decane on a calcite surface, Journal of Colloid and Interface Science, Vol: 592, Pages: 397-404, ISSN: 0021-9797
Hypothesis: Roughness is an important parameter in applications where wetting needs to be characterized. Micro-computed tomography is commonly used to characterize wetting in porous media but the main limitation of this approach is the incapacity to identify nanoscale roughness. Atomic force microscopy, AFM, however, has been used to characterize the topography of surfaces down to the molecular scale. Here we investigate the potential of using AFM to characterize wetting behavior at the nanoscale.Experiments: Droplets of water on cleaved calcite under decane were imaged using quantitative imaging QI atomic force microscopy where a force-distance curve is obtained at every pixel.Findings: When the AFM tip passed through the water droplet surface, an attraction was observed due to capillary effects, such that the thickness of the water film was estimated and hence the profile of the droplet obtained. This enables parameters such as the contact angle and contact angle distribution to be obtained at a nanometer scale. The contact angles around the 3-phase contact line are found to be quasi-symmetrically distributed between 10–30°. A correlation between the height profile of the surface and contact angle distribution demonstrates a quasi-proportional relationship between roughness on the calcite surface and contact angle.
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