Pore Space Of Rocks Research Articles

Analysis of the changes in filtration and capacity properties of the oil and gas condensate field reservoirs using X-ray computed tomography methods

Objective. To study the nature of changes in structural, capacity and filtration properties of the Chayanda oil and gas condensate field reservoir resulting from mechanical and hydrodynamic testing and to improve the quality of laboratory assessment of the reservoir properties of rocks by applying the digital approach. Materials and methods. A high-resolution X-ray micro-CT scanner ProCon X-Ray CT-MINI was used for computed tomography. Digital analysis of images was carried out in GeoDict software. Results. The results of digital analysis of changes in the pore space of hydrocarbon reservoir by computer tomography methods after the tests with fluid filtration under baric conditions are presented, including comparison of macroscopic changes in the pore space and determination of the nature of changes in reservoir porosity and pore geometry at the macro level. Porosity values were determined using digital methods and compared with laboratory data. Numerical modeling of filtration processes on the created 3D models of the rock was performed. The fact of nonuniform distribution of filtration flows was established: filtration in the rock occurs mainly through isolated alternating channels. It was determined that the change in the rock pore space occurred mainly due to deformation and expansion of the walls of the main filtration channels. Conclusions. Nonuniformity of changes in filtration-capacitance properties of rock specimens caused by mechanical and hydrodynamic tests can lead to incorrect estimation of porosity and permeability when applying traditional laboratory methods. The results of nondestructive digital studies can be advised as a supplement to laboratory studies of core material properties. Joint application of digital and traditional laboratory methods allows obtaining the most complete range of data on reservoir properties to solve problems arising during development.

Digital rock modeling of deformed multi-scale media in deep hydrocarbon reservoirs based on in-situ stress-loading CT imaging and U-Net deep learning

Deep and ultra-deep hydrocarbon reservoirs are regarded as an attractive target for onshore oil and gas exploration and development in China. The multi-scale fractures are widely distributed in this type of reservoir. The fluid-solid coupling effect is strong, which can greatly affect the fluid flow, resulting in a low hydrocarbon recovery with the average value less than 15%. To explore the underlying flow dynamics during efficient development of deep and ultra-deep hydrocarbon reservoirs, it is of great importance to characterize the multi-scale fracture-pore structure evolution of rock affected by strong geo-stress field variation. To tackle the above issues, an actual rock drilled from a typical ultra-deep reservoir in Tarim Basin are selected to conduct in-situ stress-loading computed tomography (CT) scanning experiments, and the CT gray images of rock microstructure under different dynamic loading conditions are obtained. A fully convolutional neural network (U-Net) deep learning segmentation algorithm is introduced to accurately distinguish the rock skeleton, pore space and fractures in deep rock. The three-dimensional (3-D) digital rock model of deformed multi-scale fracture-porous media under different dynamic loading conditions is ultimately established to investigate the evolution of fracture morphology and deep rock microstructure as the in-situ stress is gradually loaded. It indicates that, the U-Net deep learning semantic segmentation algorithm can accurately segment CT images of deep rocks, and the established 3D digital rock model of fractured porous media can accurately represent the pore-throat distribution, fracture morphology, and pore-scale topological connectivity. At the initial stage of stress loading, there are few micro-fractures inside the rock, and the fracture connectivity is poor. Due to effect of rock compaction, the average pore throat radius increases while pore throat ratio, coordination number and tortuosity greatly decrease. As the effective stress is gradually loaded, the micro-fractures begin to propagate, leading to stronger heterogeneity of micro-fractures’ distribution and better topological connectivity, and both the coordination number and tortuosity gradually increase. After the deep rock is fractured, micro-fractures run through a fracture network and all the above topological parameters increase greatly.

Comparative Assessment of U-Net-Based Deep Learning Models for Segmenting Microfractures and Pore Spaces in Digital Rocks

Summary Segmentation of high-resolution X-ray microcomputed tomography (µCT) images is crucial in digital rock physics (DRP), affecting the characterization and analysis of microscale phenomena in the porous media. The complexity of geological structures and nonideal scanning conditions pose significant challenges to conventional image segmentation approaches. Motivated by the recent increasing popularity of deep learning (DL) techniques in image processing, this work undertakes a comparative study of DL models, specifically U-Net and its variants, for segmenting multiple targets with distinguished features in digital rocks, including discrete fracture networks (DFNs), pore spaces, and solid rock. Particularly, DFNs have a smaller volumetric fraction over others, bringing in a substantial challenge of imbalanced segmentation. The primary focus is to evaluate the architecture and feature enhancement strategies of various DL models, including U-Net, attention U-Net, residual U-Net, U-Net++, and residual U-Net++. The models were designed as 2.5D, utilizing a central 2D image and its two adjacent upper and lower 2D images as input to provide a pseudo-3D context. In addition, because the ground truth of segmentation was unknown for real-world digital rocks, we created a benchmark data set following the inverse operations of segmentation. The data synthesis started from the label images (i.e., solid rock, pore spaces, and DFNs), followed by simulating partial volume blurring, adding random background noise, and introducing ring artifacts to mimic real raw X-ray µCT images. The data set, which included various rock types (i.e., sandstone and artificial data), scanning resolution, and magnitudes of noise and artifacts, was divided into training and testing data sets with a 90% and 10% ratio, respectively. Moreover, in addition to the conventional pixel-wise evaluation metrics, the physics-based metric of the lattice-Boltzmann method (LBM) simulated permeability provided more comprehensive assessments. The results demonstrated that the residual connections, nested architectures, and redesigned skip connections contribute to the model performance and give the residual U-Net++ the highest accuracy. The improvements were mainly on the boundaries and small targets, especially the DFNs, which dominate the interconnectivity and therefore affect the permeability greatly. This study also rigorously evaluated the efficiency and generalization of each model, demonstrating that the sophisticated architectures achieved excellent practicability and maintained robust performance on completely unseen data, ensuring their suitability for diverse and challenging DRP applications.

The Phase Change Heat of Water in the Pore Space of Rocks Based on DSC Studies.

This research investigates the phase change behavior of water within the pore space of Devonian carbonate rock samples using Differential Scanning Calorimetry (DSC) across a temperature range of -80 to 0 °C. This study focuses on dolomite and limestone samples, all with porosities below 3%, an area not extensively covered in previous literature. Significant endothermic effects were observed at temperatures below -2 °C, challenging conventional understanding. The study reveals that the latent heat of phase change in these systems can exceed 334.2 J/g, the known value for bulk water, indicating unique thermodynamic properties of water in confined spaces. For the dolomite rock sample, observed endothermic heat effects below -2 °C were 23.5% and 26.7% of total phase change energy. The cumulative pore volume calculated using the thermoporometry method was found to be higher than expected from water occupancy alone, independent of assumptions about the thickness of the adsorbed unfreezable water layer or pore shape (spherical or cylindrical). This research provides novel insights into unfrozen water content calculations, significantly enhancing frost durability assessments and the geoengineering industry.

Positron emission tomography quantifies crystal surface reactivity during sorption reactions

Mechanistic understanding and prediction of solute transport and surface reactions in the pore space of rocks and soils is critical for a variety of processes, including sediment diagenesis, contaminant remediation, and long-term waste storage strategies. Positron emission tomography (PET) using β+-emitting radiotracers is an established and reliable method for investigating advective flow and diffusive flux in porous geomaterials. Here we present a conceptual strategy for spatially resolved quantification of crystal surface reactivity for sorption reactions based on PET techniques. The deconvolution of tracer breakthrough curves quantifies the sorption of F− tracer on calcite crystal surfaces and identifies the varying surface reactivity in the complex porous material. Using an artificial sediment as a model system, we demonstrate the quantifiability of sorption effects down to 10 pmol/mm3. The proposed strategy outlines how spatially resolved surface reactivities and their temporal changes over time can generally be determined using PET.

Directionality of gravitational and thermal diffusive transport in geologic fluid storage.

Diffusive transport has implications for the long-term status of underground storage of hydrogen (H_{2}) fuel and carbon dioxide (CO_{2}), technologies which are being pursued to mitigate climate change and advance the energy transition. Once injected underground, CO_{2} and H_{2} will exist in multiphase fluid-water-rock systems. The partially soluble injected fluids can flow through the porous rock in a connected plume, become disconnected and trapped as ganglia surrounded by groundwater within the storage rock pore space, and also dissolve and migrate through the aqueous phase once dissolved. Recent analyses have focused on the concentration gradients induced by differing capillary pressure between fluid ganglia which can drive diffusive transport ("Ostwald ripening"). However, studies have neglected or excessively simplified important factors, namely the nonideality of gases under geologic conditions, the opposing equilibrium state of dissolved CO_{2} and H_{2} driven by the partial molar density of dissolved solutes, and entropic and thermodiffusive effects resulting from geothermal gradients. We conduct an analysis from thermodynamic first principles and use this to provide numerical estimates for CO_{2} and H_{2} at conditions relevant to underground storage reservoirs. We show that while diffusive transport in isothermal systems is upwards for both gases, as indicated by previous analysis, entropic contributions to the free energy are so significant as to cause a reversal in the direction of diffusive transport in systems with geothermal gradients. For CO_{2}, even geothermal gradients less than 10^{∘}C/km (far less than typical gradients of 25^{∘}C/km) are sufficient to induce downwards diffusion at depths relevant to storage. Diffusive transport of H_{2} is less affected but still reverses direction under typical gradients, e.g., 30^{∘}C/km, at a depth of 1000m. This reversal occurs independent of the solute's thermophobicity or thermophilicity in aqueous solutions. The entropic contribution also modifies the magnitude of flux where geothermal gradients are present, with the largest diffusive fluxes estimated for CO_{2} with a 30^{∘}C/km gradient, despite the higher diffusion coefficient of H_{2}. We find a maximum flux on the order of 10^{-13} mol/(cm^{2}s) for CO_{2} in the 30^{∘}C/km scenario; significantly lower than literature estimates for maximum convective fluxes in moderate to high permeability formations. Contrary to previous studies, we find that in diffusion and convection will likely work in concert-both driving CO_{2} downwards, and both driving H_{2} upwards-for conditions representative of their respective storage reservoirs.

Geophysical evaluation and petrophysical assessment of the Abu Roash "F" Member: A probable unconventional oil reservoir in Heba Field, eastern Abu Gharadig Basin, Egypt

This study investigates the geophysical properties of the Abu Roash F Member (AR/F) as a potential unconventional oil reservoir in Heba Field, located in the eastern region of the Abu Gharadig Basin (Egypt). Analysis of seismic data reveals the influence of Late Cretaceous dextral wrenching tectonic activity, evidenced by the presence of ENE-WSW anticlinal folds and intersecting NW-SE as well as WNW-ESE extensional faults throughout the study area. This tectonic regime is believed to have played a significant role in the formation of micro-fractures within the AR/F carbonate, which can enhance the reservoir's potential by improving its permeability and porosity. Petrophysical assessment identifies favorable reservoir zones within specific depth intervals across multiple wells. These zones exhibit promising reservoir quality, characterized by low shale volume (below 0.20), which indicates a cleaner reservoir rock with less clay content. Additionally, the high total porosity (ranging from 0.20 to 0.25) and moderate effective porosity (ranging from 0.15 to 0.20) suggest that a substantial portion of the rock's pore space is available for storing hydrocarbons. The low water saturation (between 0.40 and 0.50) further supports the presence of hydrocarbons, as it indicates that the pores are not predominantly filled with water. Furthermore, the high hydrocarbon saturation (ranging from 0.50 to 0.60) confirms the significant presence of hydrocarbons within the reservoir. The quantitative assessment of these petrophysical properties across all analyzed wells further confirms the good reservoir quality and potential of the AR/F Member. The integration of seismic and petrophysical data provides a comprehensive understanding of the reservoir characteristics, highlighting the AR/F Member as a significant oil reservoir in the eastern border of the Abu Gharadig Basin, particularly in Heba Field. This study's findings complement the existing knowledge of oil-bearing formations in the region, suggesting that the AR/F Member could be a valuable addition to the basin's hydrocarbon resources. The results underscore the importance of further exploration and development of the AR/F Member to fully realize its potential as a major contributor to the area's oil production.

Investigation of petrophysical properties of synthetic carbonate plugs: Adding a novel 3D printing approach to control pore networks

The physical and chemical properties of rocks play a crucial role in understanding fluid-solid flow behavior at the pore level. Thus, studying pore space characteristics is important in evaluating and determining petrophysical properties of various rock types, including synthetic rocks, which can be designed to mimic natural rocks. This study investigates the petrophysical properties of synthetic carbonate plugs by using a new approach that correlates the base material and a 3D printing solution with porosity and permeability. The research shows that with precise particle size and morphology, pure mineral materials such as calcite, dolomite, quartz and a non-structural Portland cement may produce a controlled rock matrix. The synthetic plugs developed in this study exhibit controlled macro, meso, and micro porosities, including fractures and vuggys, by the solubilization of materials with controlled morphology by 3D printing, which provides valuable information on regulating pore space in synthetic carbonate rocks.

Assessing Rheology Effects and Pore Space Complexity in Polymer Flow Through Porous Media: A Pore‐Scale Simulation Study

AbstractNon‐Newtonian fluid flow within porous media, exemplified by polymer remediation of contaminated groundwater/aquifer systems, presents complex challenges due to the fluids' complex rheological behavior within 3D tortuous pore structures. This paper introduces a pore‐scale flow simulator based on the OpenFOAM open‐source library, designed to model shear‐thinning flow within porous media. Leveraging this developed solver, extensive pore‐scale flow simulations were conducted on μ‐CT images of various real and synthetic porous media with varying complexity for both power‐law and Cross‐fluid models. We focused on the macroscale‐averaged deviation between bulk viscosity and the in‐situ viscosity, commonly denoted by a shift factor. We provided an in‐depth evaluation of the shift factor's dependency on the fluid's rheological attributes and the rock's pore space complexity. The least‐squares fitted values of the shift factor fell in the range of 1.6–9.5. Notably, the most pronounced shift factor emerged for extreme flow behavior indices. Our findings highlight not just the critical role of rheological parameters, but also demonstrate how the shift factor fluctuates based on tortuosity, characteristic pore length, and the cementation exponent. In particular, less porous/permeable systems with smaller characteristic pore lengths exhibited larger shift factors due to higher variations of shear rate and local viscosity in narrower flow paths. Additionally, the shift factor increased as rock became more tortuous and heterogeneous. The introduced pore‐scale simulation proves instrumental in determining the macroscopic averaged shift factor. This, in consequence, is vital for precise computations of viscosity and pressure drop when dealing with non‐Newtonian fluid flow in porous media.

Water weakening and the compressive brittle strength of carbonates: Influence of fracture toughness and static friction

Water is ubiquitous within the pore space of rocks and has been shown to affect their physical and mechanical behaviour. Indeed, water can act on the rock strength via mechanical (i.e., reducing the effective stresses) or chemical effects (e.g., mineral dissolution, mineral alteration, subcritical crack growth, etc.). As rock macroscopic strength is controlled by both fracture toughness and friction at the grain-scale, these parameters should also be affected in presence of water. While some recent studies have measured the effect of water on both fracture toughness and frictional parameters to constrain the water weakening of porous rock compressive strength, the physical parameters, or rock characteristics, that influence this weakening are as of yet unclear. Here, we report a series of laboratory experiments in order to determine the influence of a water-saturated, as opposed to dry, environment on five limestones’ strengths. The uniaxial compressive strength, the mode-I fracture toughness and the static friction parameters are of interest. The experiments show that, for the tested limestones, water-saturated conditions provoke a reduction of the uniaxial compressive strength by up to 53 %. This reduction is accompanied by a reduction of the mode-I fracture toughness by up to 34 % and of the static friction by up to 16 %. Even though the water weakening of the uniaxial compressive strength is not influenced by the sample porosity, the mode-I fracture toughness reduction in the presence of water is accentuated for high-porosity limestones. Additionally, low porosity limestones appear to promote higher static friction reductions in water-saturated environments.

Parameterization of key rock pore space properties based on tomographic measurements

Celem pracy było wykonanie szerokiej analizy parametrów przestrzeni porowej otrzymanych na podstawie obrazów rentgenowskiej tomografii komputerowej. W pracy określono geometryczne i topologiczne parametry struktury wewnętrznej próbek skał, pełniące kluczową rolę dla prognozowania przepływu mediów złożowych. Materiał badawczy stanowiły próbki dolomitu z kanalikami robaczkowymi powstałymi w wyniku zabiegu kwasowania. Modele 3D przestrzeni porowej zostały wykonane przy zastosowaniu nowoczesnego specjalistycznego oprogramowania Avizo 3D Pro (Thermo Fisher Scientific). Praca polegała na określeniu szeregu parametrów geometrycznych, takich jak: objętość, powierzchnia właściwa, grubość, szerokość i długość oraz sferyczność, maksymalna i minimalna średnica Fereta, liczba Eulera i inne. Do wyliczenia parametrów, oprócz oprogramowania Avizo 3D Pro, wykorzystano również program poROSE (poROus materials examination SoftwarE, Akademia Górniczo-Hutnicza, Kraków). Następnie wybrano największe obiekty w każdej z próbek i przeprowadzono dla nich proces transformacji obrazu w szkielet, co pozwoliło na ich charakterystykę topologiczną. Uzyskano szereg informacji dotyczących kanalików porowych, m.in. o ich średnim promieniu, długości, krętości, liczbie połączeń (węzłów) i liczbie koordynacyjnej. Następnie porównano i przeanalizowano wszystkie parametry dla trzech obiektów pochodzących z trzech badanych próbek. Obiekt o największej objętości zidentyfikowano w próbce C. Wszystkie wybrane do analizy obiekty charakteryzowała podobna wartość średnia średniego promienia kanalików. Podobne są także średnie wartości liczby koordynacyjnej – wynoszą około 3. Najbardziej rozbudowaną strukturą charakteryzują się obiekty w próbkach B i C, na co wskazuje liczba Eulera. Przeprowadzone analizy pokazały, jak wiele informacji na temat szczegółów struktury porowej skał można uzyskać na podstawie wyników tomografii komputerowej. Otrzymane parametry mogą posłużyć do budowy modelu sieci porowej, a także do przeprowadzenia symulacji przepływu mediów przez skałę.

Changes in filtration and capacitance properties of highly porous reservoir in underground gas storage: CT-based and geomechanical modeling

The paper presents the results of comprehensive studies of filtration and capacitance properties of highly porous reservoir rocks of the aquifer of an underground gas storage facility. The geomechanical part of the research included studying the dependence of rock permeability on the stress-strain state in the vicinity of the wells, and physical modeling of the implementation of the method of increasing the permeability of the wellbore zone - the method of directional unloading of the reservoir. The digital part of the research included computed tomography (CT)-based computer analysis of the internal structure, pore space characteristics, and filtration properties before and after the tests. According to the results of physical modeling of deformation and filtration processes, it is found that the permeability of rocks before fracture depends on the stress-strain state insignificantly, and this influence is reversible. However, when downhole pressure reaches 7-8 MPa, macrocracks in the rock begin to grow, accompanied by irreversible permeability increase. Porosity, geodesic tortuosity and permeability values were obtained based on digital studies and numerical modeling. A weak degree of transversal anisotropy of the filtration properties of rocks was detected. Based on the analysis of pore size distribution, pressure field and flow velocities, high homogeneity and connectivity of the rock pore space is shown. The absence of pronounced changes in pore space characteristics and pore permeability after non-uniform triaxial loading rocks was shown. On the basis of geometrical analysis of pore space, the reasons for weak permeability anisotropy were identified. The filtration-capacitance properties obtained from the digital analysis showed very good agreement with the results of field and laboratory measurements. The physical modeling has confirmed the efficiency of application of the directional unloading method for the reservoir under study. The necessary parameters of its application were calculated: bottomhole geometry, stage of operation, stresses and pressure drawdown value.

Lithological and mineralogical signs of the formation and destruction of the Bashkirian stage oil deposits within the Sokskaya saddle

Oil deposits in sections of the Bashkirian stage of the Sokskaya saddle are considered. It has been established those oil-bearing limestones are represented by leached peloidal-clumpy grainstones. The rocks were formed within the shallow shelf of sedimentation basin of normal salinity. The active hydrodynamics of the aquatic environment predetermined the dense structural packing of organic residues. The migration of aggressive oil-water fluids contributed to leaching of calcite cement from grainstones. Subsequently, the pore-cavernous space was filled with oil. The introduction of edge formation waters into oil-bearing reservoirs contributed to the oxidation of oil and the manifestation of secondary diagenetic mineralization. The initial stage of waterflooding was indicated by dolomitization of reservoir rocks. Due to an increase in the partial pressure of carbon dioxide in the pore space of rocks, calcite is metasomatically replaced by diagenetic dolomite. At this stage of reservoir rock alteration, a relatively small amount of oil is recovered from oil-bearing formations. The introduction of formation waters enriched with sulfate ions into reservoir layers leads to the precipitation of gypsum-anhydrite aggregates in the pore space of oil-bearing limestones. Calcium sulfate minerals clog the pore-capacitive space of reservoir rocks, reducing their productivity. At the stage of precipitation of gypsum-anhydrite aggregates, mainly mineralized brines with an admixture of oil are extracted from reservoir rocks.

Investigating the evolution of pore space and magnetization rate of rocks under the effect of coal fire burning

Investigating the evolution of pore space and magnetization rate of rocks under the effect of coal fire burning

The structure of the pore space of Tournaisian reservoir rocks in the southeast of Tatarstan Republic

The article shows the main types of structures of the porosity of the Tournaisian reservoirs from the southeast of Tatarstan. The main type of pore space is intergrain porosity, while the fractures have a subordinate significance. They are analyzed in detail main factors of the origin of the pore space of the Tournaisian reservoir rock. There are include depositional, diagenetic, structural and tectonically factors. The depositional factor is the selectivity of rock types as reservoirs, only two lithological types of limestone have industrially significant reservoir properties and represented by peloidal and crinoid-peloidal packstones. The diagenetic factor realizes via secondary leaching of carbonate rocks during burial diagenesis of rocks. Leaching processes provide the main increase in rock porosity. On the one hand, the structural and tectonic factor provides the possibility of oil charge in the structure, on the other hand, it shows the heterogeneity of the distribution of porosity depending on the position of the reservoir rocks on the structure. The highest porosity values are characteristic for the crest part, lower for the flanks and minimal for the deflections of the oil-bearing structures.

Influence of the structure of the pore space of rocks on the wettability and adsorbed fluids of reservoir rocks

Theoretical and experimental studies of the effect of the geometry of the pore space on the wettability of collectors have been carried out. The special structure of the pore space of the Talinskaya area of the Krasnoleninsky deposit, due to the heterogeneity of the composition of rocks, leads to heterogeneity in the size and geometry of filtration channels and affects wettability. The specificity of the adsorption of polar components of oil causes changes in wettability and affects the amount of adsorbed oil. Keywords: pore space geometry; adsorbed fluids; wettability.

Study of structural characteristics of hydrocarbon reservoir pore space based on X-ray computed tomography images

Digital studies of pore space and internal structure of hydrocarbon reservoir were conducted on the basis of multiscale X-ray computed tomography images and the analysis of heterogeneities, cavernosity, fracturing and bedding in the rock. Main results. 3D models of rock pore space were created on the basis of computed tomography images through segmentation. Porosity estimation based on the digital approach was performed. It was shown that the digitally obtained data are in good agreement with the results of laboratory measurements. Analysis and visualization of the structure of the main filtration channels in the rock were performed. Pore size distributions in the specimen were obtained, and 3D visualization of the largest pore size was shown. Conclusions. The pore space characteristics obtained on the basis of tomographic approach are valuable data for filling reservoir models and can be used in solving the problems of permeability reduction during different kinds of reservoir impacts. Application of the obtained results in combination with geomechanical tests of rocks is intended to expand existing approaches to complex analysis of core material of reservoirs, as well as to supplement and refine mathematical and operational models of the studied objects.

Development of oil extraction screening methodology taking into account innovative methods using the example of the Ukrainian field

The object of research in the paper is the process of fluid transfer through the pore space of the reservoir rock. The traditional method of estimating oil recovery by flooding has a large number of uncertainties. In this study, to address limitations of the current approach to determining oil production, let’s introduce a systematic algorithm aimed at enhancing result precision. The methodology for calculating the oil recovery coefficient for determining the amount of oil that can be extracted by flooding is presented. In this work, the step-by-step process of determining the oil recovery coefficient was analytically established, which achieves a certain degree of accuracy due to the inclusion of a number of methods of calculation of scientists from different countries of the world. In particular, the lithofacies distribution of the reservoir using the kriging method, the use of a representative elementary volume (REV) to increase the accuracy of determining the irreducible water saturation of each facies, and the use of the Buckley-Leverett equation in the calculation of the oil recovery coefficient are proposed. The number of facies (sandstone, argillaceous sandstone, siltstone) was determined on the example of the B-16n horizon of the «Ukrainian deposit» and the oil recovery coefficients were calculated for each separately (0.53, 0.47, 0.29). Further determination of the average oil recovery coefficient is described in the researched and requires close integration of the obtained data in three-dimensional space, as it allows to calculate the fraction of facies content in the reservoir volume. The use of the proposed action algorithm will help to build a more reliable three-dimensional hydrodynamic model, will lead to a much lower degree of uncertainty of reservoir properties, and in particular irreducible water saturation, as well as more accurate distribution of lithological properties using kriging. Also, this methodology for calculating the oil recovery coefficient involves the use of the Buckley-Leverett equation and fractional flow curves, the data of which are based on relative permeabilities and depend on the irreducible water saturation determined in the laboratory for each lithofacies. These techniques justify the collection of additional core material, the importance of lithofacies dismemberment of the formation and are closely integrated in the three-dimensional space, which makes it possible to simulate the existing processes, reproduce the proposed methodology and perform the forecast.

Application of Petrographic and Stereological Analyses to Describe the Pore Space of Rocks as a Standard for the Characterization of Pores in Slags and Ashes Generated after the Combustion of Municipal Waste.

Slags and ashes generated in thermal waste treatment facilities require proper management. In line with the principles of the circular economy, new, more economical, and ecological possibilities for utilizing these substances are sought. These waste materials exhibit characteristics similar to rocks in many aspects. This study focuses on analyzing the similarities and differences between nine selected rocks and three samples of slags and ashes obtained from municipal waste incineration. The main research device used was a polarizing microscope, using reflected, transmitted, and fluorescent light. Additionally, low-pressure gas adsorption equipment, as well as helium and quasi-liquid pycnometers, were used for complementary analysis. The parameters analyzed mainly covered broadly defined petrographic properties of rocks and slags, with a particular emphasis on porosity, porous structure, and the spatial distribution of pores and fractures. The conducted analyses confirmed a significant similarity between slags and ashes and clastic sedimentary rocks such as sandstones and mudstones. The research results underscore the importance of petrographic microscopic studies for analyzing materials other than rocks. They also allow for exploring applications for slags and ashes in areas traditionally reserved for natural rock resources. The findings also indicate the necessity of using methods other than microscopic ones to describe the pore space of rocks. The lower measurement range of the optical microscope is limited to approximately 1 μm, covering only macropores. Other methods extend this characteristic to micro- and mesopores. Therefore, a combination of different methods is often employed to obtain a more comprehensive characterization of rock porosity.

New insights into reservoir on chip: Numerical investigation and experimental validation

The present study reports a numerical investigation of oil extraction from a pore-scale perspective using water as the injection fluid. The pore network is constructed from the statistical realization of the pore space of the reservoir rock. Conceptually, the pore network model used in the study miniaturizes the porous reservoir containing oil/gas onto a microfluidic platform, capturing the actual pore-level length scale and it complex features. The validity of the numerical model is established through an experimental investigation of single-phase flow. The experimentally calculated absolute permeability based on the Darcy law shows an excellent agreement with the numerically attained value. The two-phase numerical model uses the phase field technique to track the development of the interface between the two immiscible phases, i.e., oil and water. The numerical model shows a piston-like displacement and captures interesting pore-level phenomena like snap-off and trapping. Implementing the complete network for simulation reveals the unstable nature of the flooding, which is persistent with invasion percolation. The complete network simulation reveals the discontinuous flood front with a segregated flow configuration. Two-phase experiments conducted on a polydimethylsiloxane test chip with an equivalent pore level network also showed similar flow features, thereby establishing the credibility of our two-phase simulations. The recovery factor obtained from the simulation was found to be 0.78, which is in close agreement with experimental data reported in the literature. The modified Darcy law applied to the numerical model generates relative permeability plots similar to the experimental core flooding plots reported in the literature. The numerical model presented here provides valuable insight into the oil recovery process and its implications at field scale. To the best of our knowledge, this is the first instance involving numerical analysis of the full-scale system of Reservoir on a Chip system detailing the pore-level flow dynamics.