Effective Porosity Research Articles

Petrophysical characterization, BIB-SEM imaging, and permeability models of tight carbonates from the Upper Jurassic (Malm ß), SE Germany

Tight carbonate rocks are important hydrocarbon and potential geothermal reservoirs, for example, in CO2-Enhanced Geothermal Systems. We report a study of outcrop samples of tectonically undeformed tight carbonates from the upper Jurassic “Malm ß” formation in Southern Germany near the town of Simmelsdorf (38 km NE of Nuremberg) to understand bulk petrophysical properties in relation to microstructure and to compare models for permeability prediction in these samples. We applied Archimedes isopropanol immersion, Helium pycnometry, mercury injection, gamma density core logging, and gas permeability measurements, combined with microstructural investigations and liquid metal injection (LMI-BIB-SEM). In addition, ultrasonic velocity was measured to allow geomechanical comparison of stratigraphically equivalent rocks in the South German Molasse Basin (SGMB). Results show only small variations, showing that the formation is rather homogeneous with bulk porosities below 5% and argon permeabilities around 1.4E−17 m2. The presence of stylolites in some of the samples has neither a significant effect on porosity nor permeability. Pores are of submicron size with pore throats around 10 nm and connected as shown by Mercury injection and Liquid Metal injection. Samples have high dynamic Young’s Modulus of 73 ± 5 GPa as expected for lithified and diagenetically overmature limestones. Moreover, no trends in properties were observable toward the faults at meter scale, suggesting that faulting was post-diagenetic and that the matrix permeabilities were too low for intensive post-diagenetic fluid–rock interaction. Petrophysical properties are very close to those measured in the SGMB, illustrating the widespread homogeneity of these rocks and justifying the quarry as a reasonable reservoir analog. Permeability prediction models, such as the percolation theory-based Katz-Thompson Model, Poiseuille-based models, like the Winland, the Dastidar, the capillary tube, and the Kozeny-Carman Models, as well as several empirical models, namely, the Bohnsack, the Saki, and the GPPT Models, were applied. It is shown that the capillary tube Model and the Saki Model are best suited for permeability predictions from BIB-SEM and mercury injection capillary pressure results, respectively, providing a method to estimate permeability in the subsurface from drill cuttings. Matrix permeability is primarily controlled by the pore (throat) diameters rather than by the effective porosity.

Exploration of new hydrocarbon leads in the eastern flank of Abu Gharadig Basin, North Western Desert, Egypt

The present study aims to understand better the structural elements controlling the hydrocarbon potentiality and productivity for the upper Cretaceous reservoirs in the Eastern flank of the Abu Gharadig Basin in the Western Desert of Egypt. The major sandstone reservoirs in this area are found within Abu Roash “G” Member and Upper Bahariya Formation, characterized by lateral facies changes with major structure uncertainty and unleashed hydrocarbon potential. Therefore, we aimed to identify the lateral distribution of the studied reservoirs regionally in Abrar, Ferdaus, Ganna, Rawda, Sidra, and Rayan fields at the North Bahariya Concession and Aqsa and Yamma-SE fields at the East Bahariya Concession through integrated geological and geophysical studies for further exploration activities in this area. As a result, we produced regional depth contour maps covering most of the producing fields with the lateral distribution of hydrocarbon occurrences through the area. Moreover, the petrophysical parameter maps for the Middle and Lower Abu Roash “G” reservoirs, such as net pay thickness, shale volume, effective porosity, and hydrocarbon saturation are prepared to understand the hydrocarbon potentiality. This, in turn, allowed us to determine nine promising structural traps for future exploration with high certainty.

Application of isotopic tools to understand the hydrological processes and groundwater dynamics of Mianwali area-Punjab, Pakistan

AbstractThe study was conducted to investigate the hydrological system of ‘Mianwali’ area, which comprises an alluvium aquifer. Groundwater dynamics including groundwater direction, velocity and recharge mechanism were investigated to assess the groundwater sources conservation in the area. Hydrological samples were collected and analyzed for stable isotopes (18O and 2H); radioisotopes (3H), chloroflourocarbons (CFCs) and groundwater real and filtration velocities measured to understand the groundwater dynamics. Isotopic data suggested a variant recharge mechanism due to localize impacts of canals, lake and river. Groundwater residence time, using Tracer Lump Parameter Model (LPM), and CFCs data suggest a very young water in the range of 14–59 years old. The real and filtration velocities of groundwater found to be 22.2 cm/day and 10.94 cm/day, respectively, in south-west direction and in-situ effective porosity of the aquifer was 49.3%. The hydraulic conductivity of the aquifer was estimated using grain size analysis that varies from 48 to 278 m/day with average value of 139 m/day.

Unsupervised machine learning technique for classifying production zones in unconventional reservoirs

Significant amounts of information are rapidly increasing in bulk as a consequence of the rapid development of unconventional tight reservoirs. The geomechanical and petrophysical characteristics of the wellbore rocks influence the sweet and non-sweet areas of tight unconventional reservoirs. Using standard approaches, such as data from cores and commercial software, it is difficult and costly to locate productive zones. Furthermore, it is difficult to apply these techniques to wells that do not have cores. This study presents a less costly way for the systematic and objective detection of productive and non-productive zones via well-log data using clustering unsupervised and supervised machine learning algorithms. The method of cluster analysis has been used in order to classify the productive and non-productive reservoir rock groups in the tight reservoir. This was accomplished by assessing the variability of the reservoir characteristics data that are forecasted by looking at the dimensions of the well logs. The Support vector machine as a supervised machine learning algorithm is then used to evaluate the classification accuracy of the unsupervised algorithms based on the clustering labels. The application made use of approximately ten different variables of rock characteristics including zonal depth, effective porosity, permeability, shale volume, water saturation, total organic carbon, young's modulus, Poisson's ratio, brittleness index, and pore size. The findings show that both clustering techniques identified the sweet areas with high accuracy and were less time-consuming.

Soil hydraulic properties and pore dynamics under different tillage and irrigated crop sequences

Soil hydraulic properties and pore continuity are important parameters of soil quality and may differ among tillage systems, crop rotations, and change over time. However, there are some contrasting results, depending on soil type, climate and cultivation history on the spatial and temporal variations. The objective of this study was to determine spatio-temporal dynamics of soil hydraulic properties and pore characteristics (i.e., pore volume, effective porosity, and continuity) on a silt loam long-term tillage field experiment, in Agramunt, NE Spain, during two cropping years. Undisturbed soil samples were used to determine soil water retention, θ(Ψ), and soil hydraulic conductivity, K(Ψ), curves in two different tillage systems (intensive tillage, IT vs no-tillage, NT), two crop sequences (short fallow-maize, FM vs legume-maize, LM) and two positions (within the row of crops, W-row vs between the rows of crops, B-row). The results revealed that LM had greater specific hydraulic conductivity, Kpc in its macroporosity (>1000 µm) than FM due to greater number of effective pores, Npc and effective porosity, εpc. Soil water content, θ was greater under IT than under NT at higher soil water matric potential, Ψ (≥-3 cm H2O), whilst the opposite was observed at lower Ψ (≤ − 50 cm H2O). Long-term NT showed greater hydraulic conductivity, K at higher Ψ (≥ − 10 cm H2O) than IT, and no difference at lower Ψ. Although IT had greater pore volume, ϕpc than NT in the macroporosity and coarse mesoporosity (1000–60 µm) pore size classes, NT had two times greater Kpc than IT due to increased Npc, εpc, and pore continuity, Cwpc. K(Ψ) and pore characteristics showed spatial variations (W-row vs B-row). W-row had significantly greater K at higher Ψ (≥ − 3 cm H2O) than B-row. Temporal dynamics of soil hydraulic properties and pore characteristics were not evident under IT during crop succession. This study shows that LM increases specific hydraulic conductivity of soil macroporosity by increasing the number of effective macropores and the effective porosity. In a Mediterranean climate, this may improve the hydrological functions of agricultural soil and associated crop yield. Further, long-term NT formed a stable number of effective macropores and coarse mesopores, and showed a greater pore continuity in coarse and fine mesopores, resulting in improved soil water flux.

The Strength and Elastic Modulus of Pervious Concrete Considering Pore and Fiber during Freeze–Thaw Cycles

The interface between aggregate and cement matrix and the strength of the cementation layer between aggregates are the key factors affecting the strength of pervious concrete. The purpose of this paper is to evaluate the effects of porosity, compressive strength and elastic modulus of pervious concrete before and after freeze–thaw cycles. The effective porosity and total porosity were obtained by the underwater weighing and CT (computed tomography) image analysis methods. Uniaxial and triaxle compression tests were carried out to obtain the strength and elastic modulus of pervious concrete considering pore and fiber. The results indicated that the effective modulus and effective stress were closely related to the porosity, and the continuous fracture of cementation points between aggregates caused damage to pervious concrete. Inclined shear failure of pervious concrete occurred under uniaxial pressure, and the strength and elastic modulus increased with increases in confining pressure. With the increase in freeze–thaw cycles, the porosity increased linearly, the strength and elastic modulus decreased and a mutational point appeared between 40 and 50 times during the freeze–thaw cycles. The fiber enhanced the strength of the cementation layer and increased the connection between aggregates, thus improving the strength and integrity of pervious concrete. This work is needed to serve as a reference for the fracture mechanism of pervious concrete and the effect of freeze–thaw cycles considering pore and fiber.

A novel gas sands characterization and improved depositional modeling of the Cretaceous Sembar Formation, Lower Indus Basin, Pakistan

The Lower Indus Basin of Pakistan has substantial hydrocarbon potential with the Cretaceous Sembar Formation as its principal source rock. While studies have identified the shale gas potential of the Sembar Formation, no extensive research has been conducted to evaluate the hydrocarbon potential of thick packages of sands encountered within it. This study is intended to fill this research gap by identifying the hidden-untapped thick packages of sands of the Sembar Formation for the first time in the Khewari and Gambat areas. We use well log and seismic reflection data to define the thickness, depth distribution, and petrophysical properties for reservoir characterization. This integrated modeling identifies favorable zones for gas production and the spatial distribution of sand packages with excellent reservoir properties in thickness (≈200 m), almost continuous sand packages suitable for hydrocarbon exploration. The Suleman-01 well has a very good hydrocarbon reservoir potential with 70% sand volume, approximately 13% effective porosity, 3.57 millidarcys average permeability, and approximately 58–60% hydrocarbon saturation. We suggest that the post-collisional tectonics of the Indian and Eurasian plates affected the depositional geometry of the Sembar Formation in such a way that it trends from shallower to deeper from western to eastern parts of the study area. Similarly, reservoir quality sands follow the positive upward trend from west to east toward the Indian shield. We propose that the approach implemented in this study is applicable to the entire Lower Indus Basin and further toward the Rajasthan Basin in India in the east and Zagros fold-and-thrust belt in Iran in the west. This approach would help assess the undeveloped hydrocarbon potential of the Sembar Formation sands and related formations in South Asia and worldwide.

The Mishrif Reservoir Characteristics Utilizing Well Log Data Interpretation in the Fauqi Oilfield in Maysan, Southern Iraq

The Mishrif Formation was deemed the main oil reservoir in the Fauqi oilfield, southern Iraq. This paper aims to predict characteristic properties of the Mishrif Formation depending on the interpretation of well logs data. The data were collected from five wells of log images which had been digitized with Didger software version 5. 12. 1762 to be analyzed and interpreted using interactive petrophysics 3.5.1.2 software. The main lithology of the Mishrif Formation in this region was determined using standard (M-N xplot) based on the integration of density-neutron logs. The results confirmed that the Mishrif Formation is mainly composed of limestone units. A Gamma-ray log was used to estimate the shale volume in the Mishrif Formation depending on old rock function. As a result, shale volume relative to the bulk volume was about 19%, and an increasing volume was noticed in the upper reservoir, reaching the highest in the MA and MB11 units. The Mishrif Formation porosity was calculated using the interpretation of neutron, density, and sonic logs. The results showed that the Mishrif Formation is distinctive with low to medium porosity values (4.8 to 17%). The calculation of cores manifested the dominance of secondary porosity in the MB21 unit of the formation in comparison to the other stratigraphic units in the studied area. These results led to a the fact that the MB21 unit was more exposed to dissolution diagenetic processes in the south dome, which provided a good permeability integrated with the medium effective porosity, puttinh it as the main reservoir unit.

The Asmari Formation Petrophysical Parameters in the Abu Ghirab Oil Field of the Zagros Fold Belt Basin, Southeastern Iraq, Using Well Log Data Interpretation

The current study represents the evaluation of petrophysical characteristics, lithological analysis, and identification of the Asmari Formation for the main and sub-reservoir units in the Abu Ghirab oil field, Maysan, southeast of Iraq. This petrophysical assessment was accomplished using the interpretations of well log data to know the properties of the Asmari Formation reservoir. The available logs such as resistivity, gamma ray, neutron and density logs were converted to digital data using the Diger Sotware. The lithic properties of the reservoir like porosity, total shale saturation, oil and water saturation were interpreted and calculated using the interactive petrophysics software. The lithic and mineral study was completed and the type of mineral filling was known through the cross-plot of the porosity logs for different wells. The petrophysical properties were calculated and represented on the CPI profile. Depending on the petrophysical characteristics, the Asmari Formation was divided into main and sub units, which are: Jeribe-Euphrates and its sub-units A1, A2, and A3; Upper Kirkuk unit and B1, B2, B3, B4 sub-units; and Middle-Lower Kirkuk unit and C subunit. The results showed that the reservoir has economic oil productivity. The subunits B2, B3 in Upper Kirkuk were characterized by high effective porosity values and high hydrocarbon content, and they are the highest produced units in Upper Kirkuk in studied wells. The vary on lithology represents as dolomites in the Jeribe, Euphrates, limestones in the Kirkuk group, and the mineral components were calcite and dolomite.

Saturated Hydraulic Conductivity Estimation Using Artificial Intelligence Techniques: A Case Study for Calcareous Alluvial Soils in a Semi-Arid Region

The direct estimation of soil hydraulic conductivity (Ks) requires expensive laboratory measurement to present adequately soil properties in an area of interest. Moreover, the estimation process is labor and time-intensive due to the difficulties of collecting the soil samples from the field. Hence, innovative methods, such as machine learning techniques, can be an alternative to estimate Ks. This might facilitate agricultural water and nutrient management which has an impact on food and water security. In this spirit, the study presents neural-network-based models (artificial neural network (ANN), deep learning (DL)), tree-based (decision tree (DT), and random forest (RF)) to estimate Ks using eight combinations of soil data under calcareous alluvial soils in a semi-arid region. The combinations consisted of soil data such as clay, silt, sand, porosity, effective porosity, field capacity, permanent wilting point, bulk density, and organic carbon contents. The results compared with the well-established model showed that all the models had satisfactory results for the estimation of Ks, where ANN7 with soil inputs of sand, silt, clay, permanent wilting point, field capacity, and bulk density values showed the best performance with mean absolute error (MAE) of 2.401 mm h−1, root means square error (RMSE) of 3.096 mm h−1, coefficient of determination (R2) of 0.940, and correlation coefficient (CC) of 0.970. Therefore, the ANN could be suggested among the neural-network-based models. Otherwise, RF could also be used for the estimation of Ks among the tree-based models.

Lattice Boltzmann simulation of the structural degradation of a gas diffusion layer for a proton exchange membrane fuel cell

The aging of a gas diffusion layer (GDL) significantly impacts water drainage and mass diffusion within a proton exchange membrane fuel cell (PEMFC). This study employs a stochastic algorithm to reconstruct a 2D microstructure of carbon fiber-type GDL with various different aged degrees. Subsequently, a multiphase lattice Boltzmann method (LBM) is employed to examine water transport within the reconstructed GDLs. Results support the finding that as the GDL ages, its water elimination performance remarkably decreases and much water is retained inside the GDLs. Compared with the degradation of carbon fibers, the degradation of polytetrafluoroethylene (PTFE) leads to a more hydrophilic GDL, thereby reducing the local capillary pressure and forming multipaths for water transport, resulting in a more severe water flooding problem. A proper increase in PTFE content favors GDL antiaging performance, but an excessively high content can occupy pores and reduce the effective porosity, thus reducing the fuel cell performance. These results demonstrate that GDL with a PTFE content of 10 wt% shows better antiaging performance and the highest effective porosity. The study here provides an accurate assessment of liquid water drainage performance of GDL with various different aged degrees and guideline for designing GDLs with high antiaging performance.

Time- and frequency-domain determination of aquifer hydraulic properties using water-level responses to natural perturbations: A case study of the Rongchang Well, Chongqing, southwestern China

Effective management of groundwater resources requires accurate estimates of aquifer hydraulic parameters. One approach for estimating these parameters is to use aquifer water-level responses to natural perturbations, such as barometric pressure and earth tides. In this study, the time- and frequency-domain methods of barometric pressure and earth tide response are used to estimate aquifer hydraulic properties (transmissivity and specific storage), and taking the Rongchang well in Southwest China as an example in application. The results show that the specific storage and transmissivity estimated by the four different methods vary widely, with specific storage ranging from 8.43×10−7 − 4.68×10−5/m and transmissivity ranging from 6.90×10−7 − 3.40×10−6 m2/s. However, the differences in aquifer transmissivity are smaller than the aquifer specific storage. The transmissivity obtained by the slug test is one order lager than those from Barometric (frequency), Barometric (time) and Tidal-Turnadge methods, and two orders of magnitude greater than those of Tidal-Merrit method. The Ss value obtained by the Barometric (time) method is closer to the results of the slug test, while the Ss values obtained by the other three methods are one or two orders of magnitude smaller than the slug test results. In the Tidal-Turnadge method, the uncertainty in the effective porosity introduces an additional uncertainty in the results. The errors in the calculation process are minor in comparing to the uncertainties caused by the model assumptions. For the Rongchang well, the tidal response method averages the hydraulic properties on a larger area than that of CBP model.

Reservoir characterization using integrated seismic attributes and petrophysical parameters in an onshore field of Niger delta basin

An integrated approach of reservoir characterization of a field was performed using seismic attributes and petrophysical parameters for the evaluation of subsurface geological features and hydrocarbon potential of an onshore field in Niger Delta Basin. Four reservoir intervals were identified within the field wells based on their position within the stratigraphic column, and the reservoir correlation, which was aided using the principle of uniform horizontality, based on the simple rule that sediments are deposited horizontally and basic understanding of sequence stratigraphy. The study revealed that, the four reservoirs were predominantly sand units intercalated with shale within the reservoir units. The petrophysical evaluation revealed the Net to Gross (NTG) values ranges from 79% to 87% within the reservoir units, while the effective porosity ranges from 17% to 21%, the permeability ranges between 1307mD to 1678mD across the reservoir units, while the water saturation ranges from the lowest of 35% (Reservoir C) to 78% in reservoir D. A total of fifteen faults were interpreted using the seismic data, while the surface maps (Time and depth surface maps) revealed the identified closures which are anticlinal structures that are fault dependent. The characterization of the reservoir was further enhanced using the seismic attributes (structural and stratigraphic) extracted such as Reflection intensity, Sweetness, Variance, Envelope, Instantaneous frequency, Time gain, Trace AGC, Local structural dip, Gradient magnitude and RMS amplitude. The results shows moderate to high sweetness (sweet spots) within the zone of interest, while the Envelope attribute show acoustic impedance contrasts indicating discontinuities, lithology changes and possible present of hydrocarbon (Bright spots). The variances and gradient magnitude enhanced the signal to map out discontinuities caused by faults and fractures which are signature that enabled delineation of the zone. The integrated approach validates the lithology discrimination of the elastic properties from the well logs and its effectiveness in optimizing and proper understanding of the subsurface, thus identifying and unmasking hidden features within the reservoir (probable bypass) in the field. The study has revealed that the integration of seismic attributes with petrophysical parameters is a better characterization method for fluid and lithology discrimination of a field in any given reservoir study.

Dynamic Effective Porosity Explains Laboratory Experiments on Watertable Fluctuations in Coastal Unconfined Aquifers

Watertable fluctuations are a characteristic feature of coastal unconfined aquifers. They interact with the vadose zone creating a dynamic effective porosity, for which a new (empirical) expression is proposed based on a dimensionless parameter related to the fluctuation frequency. After comparing with both experimental data and numerical simulations, the new expression is implemented into a modified Boussinesq equation, allowing for examination of the effects of the dynamic effective porosity on watertable fluctuations. The dispersion relation arising from the modified Boussinesq equation predicts laboratory experimental data accurately, highlighting the importance of the dynamic effective porosity in modeling watertable fluctuations in coastal unconfined aquifers. This in turn confirms the applicability of the real-valued expression of the dynamic effective porosity. An outcome is that the phase lag between the total moisture (above the watertable) and watertable height measured in laboratory experiments using vertical soil columns (1D systems) can be ignored when predicting watertable fluctuations in coastal unconfined aquifers (2D systems). The dynamic effective porosity is always smaller than the soil porosity, and so by comparison there is a reduction in vertical water exchange between the saturated and vadose zones. Consequently, watertable waves can propagate further landward without standing wave behaviors.

Flow Characterization in Triply Periodic Minimal Surface (TPMS)-Based Porous Geometries: Part 1—Hydrodynamics

The modeling of flow and heat transfer in porous media systems has always been a challenge, and the extended Darcy transport models are used for macro-level analysis. However, these models are subjected to the limitations depending upon the porous geometry such as pore size, pore type, effective porosity, tortuosity, permeability, and the flow characteristics. The forced convective flow of an incompressible viscous fluid through a channel filled with four different types of porous geometries constructed using the Triply Periodic Minimal Surface (or TPMS) model is presented in this study. Four TPMS lattice shapes, namely Diamond, I-WP, Primitive, and Gyroid, are created with same volume fraction of solid subdomain as 0.68 (or void fraction as 0.32). Using different configurations for the solid subdomain by treating it as (a) solid, (b) fluid, and (c) porous zone, three different classes of porous structures are further generated for each TPMS lattice. The present study is executed with the objective to investigate the effect of shape–morphology, tortuosity, microporosity, and effective porosity on permeability and inertial drag factor. A pore-scale direct numerical simulation approach is performed for the first two types of porous media by solving the Navier–Stokes equations. The specific microporosity is quantitatively induced in the solid subdomain where Darcy–Forchheimer equation is solved, whereas the Navier–Stokes equations are solved for the void subdomain in the third type of porous media. The results reveal that Darcy flow regime exists up to the mean velocity value of U < 0.0025 m/s (Re < 10) for all the cases discussed here, and it deviates at the higher mean velocity. The conductance to the flow shown by Darcy number has the maximum and minimum values for the Primitive Type 2 and I-WP Type 1 cases. The inertial drag coefficient is minimum in Diamond lattice and maximum in Primitive lattice at lower porosity (0.32), while Primitive lattice has minimum and I-WP lattice has maximum value of inertial drag coefficient for higher porosity (~ 1).

Petrophysical Characterization of Shaly Sand Reservoirs in Well UK-05 Eastern Niger Delta Basin, Nigeria

A petrophysical evaluation of Well UK-05 in the eastern Niger Delta Basin was carried out in order to determine reservoir zones, their porosity, permeability, fluid saturation and the effect of shaliness on the petrophysical parameters. Using interactive petrophysics software version 3.5, twenty five (25) reservoir zones were identified. The porosity values range from 15.77- 4.66% and permeability from 2.76-546.54 mD. The Archie’s, Simandoux, Dual-porosity, Waxman and Smith, and the Indonesian models were used to determine the fluid saturation. The water and hydrocarbon saturation values using the Indonesian model are 21.67-50.49% and 49.51-78.33% respectively. They slightly differ from the ones obtained using Simandoux, Dual Water and Waxman and Smith model (20.72-49.88% and 50.12- 9.22%, 18.26-50.49% and 49.51-81.74%, 14.67-48.26% and 51.74-5.33% for water and hydrocarbon saturation respectively). The interpreted lithology shows that the formation penetrated by the Well UK-05 is dominated by alternating sands and shales with the sand being the dominant lithology. These lithostratigraphic characteristics correspond to those of the parallic Agbada Formation. The effective porosity values obtained range from 14.93 to 34.66%, which are lower than 0.013% to 94.08% obtained by other authors since they did not take into consideration the effect of shaliness. This shows that the more the shale volume, the higher the uncertainty of actual porosity of the reservoir.

Aquifer-wide estimation of longitudinal dispersivity by the combination of empirical equations, inverse solution, and aquifer zoning methods

Longitudinal dispersivity is a crucial parameter for the numerical simulation of groundwater quality, which is highly variable. The use of empirical equations and the inverse solution are two main methods of estimating longitudinal dispersivity. This study investigates the estimation of value and aquifer-wide spatial distribution of longitudinal dispersivity parameters using a combination of the empirical equation, the inverse solution method, and the aquifer zoning technique. The combined approach is applied to Bandar-e-Gaz aquifer in northern Iran, and Willmott’s index of agreement was used to assess the simulation precision of total dissolved solids in this aquifer. The values of this criterion were 0.9985–0.9999 and 0.9756–0.9992 in calibration and validation periods showing the developed combined approach obtained high precision for both calibration and validation periods, and the simulation shows remarkable consistency. Also, the one-way sensitivity analysis indicates that the longitudinal dispersivity is more sensitive than the effective porosity in this simulation. The investigation of the spatial distribution of the estimated longitudinal dispersivity by the combined approach indicates that the value of the parameter has a decreasing trend from the south to the north (50–8 m) in the aquifer environment, which is consistent with the changes in the characteristics of porous media in this study area. Therefore, it concludes that the combined approach provides a reliable and appropriate estimation of the spatial distribution of longitudinal dispersivity.

Additive manufacturing design approach to strut-based functionally graded porous structures for personalized implants

This study aims to create mathematical models (MMs) and maps that will facilitate personalized implant design and provide the selection of design parameters that give desired mechanical and physical properties. For this purpose, strut-based functionally graded porous structures (FGPSs) were designed using three different unit cell structures, unit cell sizes, and strut thicknesses. A total of nine specimens were produced by L-PBF using Ti-6Al-4V. The porosities were measured by dry weighing and Archimedes methods. In addition, three MMs were derived that give the effective porosity of the specimens based on the unit cell structures. A relationship was established between the modulus of elasticity obtained from the compression test and the design parameters. MMs that give the elastic modulus and porosity of FGPSs depending on unit cell size and strut thickness have been derived. By using these models, maps giving the mechanical and physical properties of the functionally graded porous structures were generated. Thanks to these models and maps, personalized implant design will be facilitated, and biocompatibility will be increased. Thus, undesired problems such as early revision and repetitive surgeries will be minimized and the quality of life of the patients will be increased.

Application of Particle Trace Morphology and Sensitivity Analysis in Delineation of Drinking Water Protection Zone in the Luan River, North China

The appropriate division of underground drinking water source protection zones is a low-cost method of preventing water source pollution and ensuring a supply of safe drinking water. Based on FEFLOW, a groundwater flow model of large water sources was established for Luan River, North China. Trace lines of particle reverse migration for 100 and 1000 days were obtained by random walks. According to the trace morphology, the water sources in the riverside water source area were divided into four categories. The first- and second-grade protection areas were delimited by ArcGIS, with areas of 0.375 and 1.20 km2. The local and global sensitivity of the permeability coefficient (K) and effective porosity (ne) effects on the area of groundwater protection zones were calculated. The area of the protection zones was positively correlated with K and negatively correlated with ne. The variation in the protected zone caused by the simultaneous changes in K and ne is the same as that of ne alone, and the global sensitivity is closer to the local sensitivity of ne. This indicates that ne has a greater impact than K on the scope of groundwater protection zones. Moreover, global sensitivity is not simply a superposition of local sensitivity, and the interaction between parameters can reduce the effect of a parameter acting alone on the delineation of protection zones. This also shows that the global sensitivity is closer to the actual situation than the local sensitivity, thus providing a scientific basis for the delimitation and monitoring of water source protection zones.

Spatial distribution of micro- and nanoporosity in Oligocene Menilite and Cretaceous Lgota mudstones (Outer Carpathians): Organic porosity development as a key to understanding unconventional hydrocarbon reservoirs?

The Oligocene Menilite Beds are considered the most important source rock for hydrocarbon accumulation in the Polish Carpathian region, whereas the Cretaceous Lgota Beds have been regarded as an additional potential source rock. Understanding their petrophysical and geochemical properties is essential for evaluating the hydrocarbon potential of these beds.This paper presents mineral and organic porosity characterization and focuses on factors responsible for the development of organic pores as a reflection of the depositional and diagenetic processes. Mudstones were evaluated as potential source and reservoir rocks, describing their diagenetic and thermal history and examining their effective porosity and permeability. The results show that the Lgota Beds mudstone in the Huczwice quarry is thermally mature (late oil/early gas window, Tmax 460–470 °C), containing type III kerogen and TOC between 0.68 wt% and 4.2 wt%, in contrast to the Menilite Beds mudstone (Monasterzec outcrop), which is thermally immature (Tmax<426 °C), containing type II kerogen and TOC content from 1.24 wt% to 8.7 wt%. The geochemical properties show that the Lgota mudstone is currently an ineffective source rock, whereas the Menilite mudstone can be a potential source rock. SEM-identified pores include mineral pores, organic pores and microfractures. Organic porosity is observable both in immature oil-prone type II kerogen and highly mature gas-prone type III kerogen. The amount of pores in organic matter increases with maturity, and no relation between TOC and organic porosity development has been observed. Palynofacies analysis showed that the Menilite and Lgota mudstones are dominated by amorphous organic matter, and that the Lgota mudstone also contains opaque woody material. MICP measurements indicate high (up to 15%) effective porosity values for the Menilite Beds and up to 8% for the Lgota Beds, with very low permeability values (<0.1 mD) in both cases. Isotherms obtained from nitrogen adsorption are type IV for the Lgota Beds and type II for the Menilite Beds, while the BET surface areas are around 13 m2/g and 3 m2/g, respectively. The Lgota Beds demonstrate advanced diagenetic processes such as compaction, cementation, dissolution, replacement, and transformation, which contributed to the significant reduction in porosity, while the Menilite Beds represent an early stage of burial with the prevailing impact of compaction and thus less destruction of original pores. Finally, the Menilite Beds from the Monasterzec outcrop do not demonstrate sufficient conditions for shale-oil/-gas source rock due to the lack of proper thermal maturity. Such criterion is fulfilled by the Lgota Beds in the Huczwice quarry, but due to very low hydrocarbon potential, the Lgota mudstone is an ineffective source rock. However, given the other petrophysical and geochemical properties, the analysed formations may constitute a basis for further research on the occurrence of unconventional reservoirs in the entire Carpathian region.