Abstract
Low-frequency resistivity logging plays an important role in the field of petroleum exploration, but the complex resistivity spectrum of rock also contains a large amount of information about reservoir parameters. The complex resistivity spectra of 15 natural sandstone cores from western China, with different water saturations, were measured with an impedance analyzer. The pore space of each core was saturated with NaCl solution, and measurements were collected at a frequency range of 40–15 MHz. The results showed a linear relationship between the real resistivity at 1 kHz and the maximum values of imaginary resistivity for each core with different water saturations. The slopes of the linear best-fit lines had good linear relationships with the porosity and the permeability of cores. Based on this, a permeability estimation model was proposed and tested. In addition, the maxima of imaginary resistivity had power exponential relationships with the porosity and the water saturation of the cores. A saturation evaluation model based on the maxima of imaginary resistivity was established by imitating Archie’s formula. The new models were found to be feasible for determining the permeability and saturation of sandstone based on complex resistivity spectrum measurements. These models advance the application of complex resistivity spectrum in petrophysics.
1 Introduction
Archie’s formula uses the electrical resistivity of rocks to provide a quantitative evaluation of oil and gas saturation [1]. As a result, resistivity logging occupies an irreplaceable position in the petroleum industry. Conventional resistivity logging tools use relatively low frequencies for their measurements. It was not until Snyder et al. [2] discovered that the resistivity dispersion spectrum of a formation contains abundant useful information that scientists began to pay attention to the complex resistivity spectra of formations. Klein and Sill [3] manufactured artificial shaly sandstones and explored the resistivity dispersion characteristics of the samples in the frequency range of (1/128)–1,024 Hz. They found that the resistivity dispersion of the samples in this frequency band was consistent with the Cole–Davidson model, and the time constant τ had a strong correlation with the pore size distribution of the sample. The complex resistivity spectra of natural shaly sandstone samples in the frequency range of 1–1,000 Hz were measured, and a dispersion model that accounted for the shale content, water salinity, and oil saturation was established in ref. [4]. Khairy and Harith [5] studied the effects of pore geometry, confining pressure, and water saturation on the complex resistivity of argillaceous sandstones with frequencies ranging from 1 Hz to 0.2 MHz. Kavian et al. [6] measured the complex resistivity of natural cores at four frequencies (105 kHz, 332 kHz, 665 kHz, and 1.05 MHz) and found that the relationships between their real components of each frequency, porosity, and water saturation follow Archie’s law. Zisser et al. [7,8] studied the complex resistivity characteristics of sandstones and tried to use this information to predict their permeability. The resistivity and dielectric dispersion of natural cores in the frequency range of 0.1 Hz to 1 kHz were studied by Liu et al., who defined the degree of frequency dispersion of the permittivity or resistivity values to evaluate the water saturation of the cores [9]. Norbisrath et al. [10] estimated the permeability of a dolomite formation based on its complex resistivity spectra in the frequency range of 0.1 Hz to 100 kHz. Most similar studies used induced polarization exploration, so the frequency bands in their research are relatively low and are not suitable for well logging. Few studies have focused on the complex resistivity dispersion of the high-frequency band. Tong and Tao [11] measured the complex resistivity spectra of natural shaly cores from 100 to 20 MHz, and they found that the slope of the real component curve of the complex resistivity spectrum is strongly correlated with porosity and permeability. Li et al. [12] produced artificial pure sandstones and shaly sandstones and measured their complex resistivity spectra in the frequency range of 40–15 MHz. The experimental data were fitted with a second-order Cole–Cole equation, and a saturation evaluation model was established based on the time constant. Jiang et al. [13] designed a set of logging tools to obtain the complex resistivity spectrum of a formation in the frequency range of 1–500 kHz, and they used the frequency corresponding to the bottom of the imaginary component to evaluate the water-filled porosity.
The information extracted from the complex resistivity spectra in the previous research is immensely important to geophysical exploration. However, the existing literature has not considered all characteristics related to reservoir parameters contained in the complex resistivity spectra. In addition, previous research used complex resistivity spectra to calculate reservoir parameters mostly based on various empirical resistivity dispersion models, such as the Cole–Cole model. While such models can accurately describe the resistivity dispersion of formation in most cases, they are not universal and sometimes yield results that diverge from the measured data. Therefore, the accuracy of their evaluation method used depends largely on the applicability of the dispersion model that is selected. In this study, the spectra of 15 pure sandstone cores from western China in the frequency range of 100–15 MHz were analyzed, and some useful information were discovered from the spectra.
2 Spectrum measurement
2.1 Core features
We collected 15 cores from western China (Table 1). All core contained less than 10% shale, so they can be considered as pure sandstone cores. The depths of these cores ranged from 4731.25 to 4780.48 m, with porosity of 4.8–26.5% and permeability of 2.9–669.12 mD.
Parameters of core samples
Sample number | Depth (m) | Shale contents (%) | Porosity (%) | Permeability (mD) | Group |
---|---|---|---|---|---|
YD-12 | 4738.5 | 1.90 | 5.10 | 2.9 | A |
YD-38 | 4750.68 | 3.60 | 7.70 | 15.49 | |
YD-18 | 4741.39 | 8.60 | 22.80 | 23.16 | |
YD-43 | 4752.93 | 8.30 | 18.50 | 112.25 | |
YD-50 | 4759.18 | 5.20 | 23.80 | 221.36 | |
YD-49 | 4758.6 | 6.10 | 23.90 | 468.66 | |
YD-2 | 4731.25 | 2.90 | 22.60 | 550.23 | |
YD-37 | 4750.05 | 5.60 | 20.30 | 669.12 | |
YD-47 | 4757.73 | 3.00 | 4.80 | 10.81 | B |
YD-67 | 4769.38 | 2.00 | 6.70 | 17.64 | |
YD-65 | 4768.24 | 3.10 | 10.30 | 24.12 | |
YD-84 | 4780.48 | 5.00 | 21.80 | 179.38 | |
YD-35 | 4749.56 | 4.70 | 22.90 | 433.56 | |
YD-23 | 4743.43 | 2.40 | 24.50 | 505.7 | |
YD-61 | 4766.33 | 3.40 | 24.00 | 585.12 |
2.2 Experimental methodology
We used the two-electrode method to measure the complex resistivities of the core samples with a 4194A impedance analyzer (HP, USA) operating with measurement frequencies from 100 to 15 MHz (Figure 1). The cores were saturated with NaCl solution with a salinity of 1,00,000 ppm, and then measurements were made at room temperature and at a constant confining pressure of 10 MPa. The solution in the core was displaced with kerosene by a pump during the measurement to change the water saturation of the core. The metering tube was used to collect the liquid displaced from the core, which allowed us to calculate the water saturation of the core at different moments. The complex resistivity spectra of each core were collected at different water saturation levels by the impedance analyzer.

Experimental schematic.
3 Results
3.1 Spectrum characteristics
Figure 2 shows the complex resistivity spectra of core YD-43, with different levels of water saturation. When the measurement frequency was lower than 10 kHz, both the imaginary part and the real part (absolute value) of the complex resistivity decreased slowly as the frequency used to make the measurements increased, but were relatively stable overall. When the measurement frequency reached about 10 kHz, the imaginary resistivity began to increase gradually with the frequency until it reached an extreme value and then began to decrease again, a pattern reflected in the local minimum, labeled

Complex resistivity spectra of core YD-43. Each level of water saturation is depicted by a matching colored line (real resistivity) and colored dashed line (imaginary resistivity).
Because the impedance of the rock matrix is much greater than that of aqueous pore solution, higher water saturation will result in a smaller real resistivity measurement in the low-frequency band. Similarly, the impedance of kerosene is much larger than that of aqueous solution, and displacement of water will cause an intensification of interfacial polarization in the pores because of the more complex surface morphology of aqueous pore solution. The migration path of ions becomes complicated, and it takes longer to complete the polarization process, so smaller water saturation will cause higher Rxb and smaller corresponding frequencies. A power exponential relationship was identified between the maxima of the imaginary resistivity of each core and the saturation values (Figure 3a). Figure 3b shows the maxima of the imaginary resistivity of different cores with water saturation of 100% and the power exponential relationship between these values and porosity.

Plots of the power exponential relationships between the maxima of imaginary resistivity and (a) water saturation and (b) porosity.
The phenomenon can be explained qualitatively by means of the polarization mechanism. When an alternating current is applied to water-bearing rocks, various polarization phenomena occur in the rocks, which will cause the amplitude of the current to decay and the phase to shift [14]. When this happens, complex models are needed to characterize the impedance of rocks [15]:
where ρ*(ω), ρ′(ω), and
The intensities of various polarization phenomena change in response to the frequency of the alternating current, so the complex resistivity of the core changes with the frequency used to make the measurement. When the frequency is lower than 1 MHz, the interfacial polarization phenomenon (Maxwell–Wagner effect) in the core is most obvious [10]. This is mainly caused by the accumulation of ions on the inner surface of pores under the action of the electric field.
The interface polarization leads to the generation of the imaginary component of the rock’s impedance. The position of the maximum value of the imaginary resistivity corresponds to the frequency at which the interface polarization is the strongest. When the porosity of the core is small, or after the kerosene enters the pore space, the interface morphology of the solution with other components becomes more complicated, and it takes longer for the ions to accumulate at the interface. Thus, as water saturation and porosity decrease, interface polarization is more intense, and rocks have smaller Rxb at a smaller frequency.
A capacitance model can also be used to understand the effects of porosity and water saturation on the imaginary part of the complex resistivity spectrum. A pore of rock can be imagined as a capacitor, where the fluid in the pore is the dielectric and the pore inner surface constitutes the capacitive plates. The phases of the voltage and the current across the capacitor are always 90° different, so the reactance of the capacitor contributes to the imaginary component of the complex resistivity. The larger the porosity of the core is, the larger the distance between the plates of the capacitor is and the smaller the capacitive reactance of the capacitor will be, resulting in a smaller maximum in imaginary resistivity. The dielectric constant of water is larger than that of hydrocarbons and matrix, and smaller water saturation will also result in great imaginary resistivity maximum values just like the porosity is getting smaller.
3.2 New characterization parameters
Our measurement results revealed good power exponential relationships between the maxima of imaginary resistivity, porosity, and the water saturation of the core. These are similar to the relationships between porosity, water saturation, and the low-frequency resistivity of the formation obtained by traditional resistivity logging tools. Therefore, the real resistivity corresponding to 1 kHz was extracted from the complex resistivity spectrum to investigate the relationship with the maximum of imaginary resistivity. Surprisingly, there was a nearly perfect linear relationship between the maxima of imaginary resistivity and the real resistivity at 1 kHz, for a core with different water saturation levels, as shown in Figure 4. In other words, when the porosity and the permeability of the core are held constant, the ratio between the real resistivity at 1 kHz and the maxima of the imaginary resistivity is constant and independent of the water saturation of the core. This slope of fitted line is expressed as βRX.

A plot of the real resistivity at 1 kHz (R1k) and the maxima of imaginary resistivity (Rxb) of cores YD-43 and YD-12, showing their nearly perfect linear relationship.
It should be noted that the frequencies corresponding to Rxb and
Figure 5 shows the relationship between βRX and porosity in these natural cores, revealing a good linear relationship between porosity and βRX. When the porosity is high, the distribution of data points in the figure is disorderly. The inset figure shows the relationship between permeability and βRX for the seven cores with porosities greater than 22%, showing another good linear relationship. Therefore, the disorderly distribution of data points when the porosity is greater than 22% can be attributed to the differences in their permeability values.

An illustration of the linear relationship between βRX and core porosity. The inset shows the good linear relationship between βRX and the permeability for those cores with porosities greater than 22%.
There is also a good linear relationship between βRX and the permeability of the cores, as shown in Figure 6. The distribution of data points in the figure deviates from the fitting line when the permeability is less than 100 mD. The linear relationship between porosity and βRX of the six cores with permeability less than 100 mD is also strong, as shown in the inset (Figure 6). Therefore, this deviation when the permeability is less than 100 mD is driven by their different porosities.

A plot demonstrating the linear relationship between βRX and the permeability of the cores. There is also a good linear relationship between βRX and porosity when the permeability is less than 100 mD (inset).
4 Discussion
The experimental results of this study confirm strong linear relationships between porosity, permeability, and βRX. These relationships provide a new idea for estimating permeability based on complex resistivity spectra. Porosity and permeability of cores can be treated as independent variables, with βRX as a dependent variable for binary linear fitting. Many logging curves can provide the porosity of a formation, such as acoustic logging, neutron-density and NMR logging, so permeability can be estimated based on the fitting result when βRX is determined from the complex resistivity spectra.
Since this study did not use actual logging data, half of the cores were selected to build the model and the remaining cores were used to verify the model. The 15 cores were ranked by permeability from smallest to largest, and the eight cores with an odd ranking (group A in Table 1) were selected to fit the relationship between the three parameters. The resulting equation is given as follows:
where K and ϕ are the permeability and the porosity, respectively.
A new slope (βRXa) for the remaining seven cores (group B in Table 1) was obtained by plugging their porosity and permeability values into equation (2). As shown in Figure 7, the relative error between βRXa and βRX, which was extracted directly from the complex resistivity spectra, is small. The data points in Figure 7 are roughly distributed on the angular bisector of the first quadrant, which proves that the relationships between porosity, permeability, and βRX can be described by a binary first-order equation.

A plot of βRX, which was extracted directly from the complex resistivity spectra, and βRXa, which was calculated from group B cores with equation (2). The blue line is the angular bisector of the first quadrant.
Figure 8 shows the relationship between the measured permeability (K) and the calculated permeability (Ka) of the seven cores in group B. While these two permeability metrics were derived from very different sources, the data points still distribute along the angular bisector of the first quadrant. This demonstrates the feasibility of estimating permeability with equation (2).

A plot of measured permeability (K) and calculated permeability (Ka) of the seven cores of group B. The blue line is the angular bisector of the first quadrant.
There should be a strong positive correlation between porosity and permeability for sedimentary rocks from the same sedimentary environment. However, the cores used in this study were collected from a range of depths and exhibited a poor correlation between porosity and permeability (Figure 9). This may impact the accuracy of the permeability estimation method based on βRX.

A plot of the correlation between porosity and permeability of the 15 cores used in this study.
Estimating permeability has always been a difficult problem in well-logging interpretation, and the various existing permeability estimation methods struggle to achieve the desired accuracy. Although the accuracy of the permeability estimates made with the method developed here is not perfect in this example, the results are sufficient to show a strong correlation between porosity, permeability, and βRX in these sandstone cores. This approach may encourage other researchers and industry scientists to pay attention to βRX, to obtain more accurate permeability estimates, and to further refine these methods.
4.1 Saturation estimation
The maxima of imaginary resistivity have a power exponential relationship similar to that of porosity and permeability in cores like the real resistivity of low frequency. Therefore, we can try to calculate the water saturation based on the maxima of the imaginary resistivity spectra. Imitating the formation factor and resistivity increase factor, the following definitions were made:
where Rxb is the maximum of the imaginary part of core’s complex resistivity spectrum, F′ is the formation factor related to Rxb, I′ is the increase factor related to
To obtain the imaginary resistivity of the solution, a plastic pipe with an inner diameter of 3 mm and a length of 2.4 m was filled with NaCl solution, and the complex resistivity spectrum of the solution was measured by an impedance analyzer with the electrodes inserted into the nozzles of the plastic pipe. The Rxbw value was calculated from the complex resistivity spectrum.
By fitting the relationship between I′ and Swwith a power function, the values of n′ and b′ were obtained. Figure 10 shows the relationship between I′ and Sw of core YD-43. According to the definition, Rxb = Rxb0 and I′ = 1 when water saturation reaches 100%. Therefore, before fitting the relationship between I′ and Sw for each core, ten additional points with coordinates (1,1) were added to the measured datasets to bring the curve closer to the theoretical relationship.

A plot of the power relationship between I′ and Sw in core YD-43, with ten artificial data points added at (1,1).
The eight cores of group A were selected to build the model, and the seven cores of group B were used to verify the model. Figure 11 shows the relationship and the fitting result between F′ and ϕ for the cores of group A. In an approach similar to that used for I′ and Sw, ten additional points with coordinates (1,1) were added to the datasets because Rxbw = Rxb0 and F′ = 1 when ϕ is equal to 1.

A plot of the power relationship between F′ and ϕ for the eight cores of group A.
We then used a model similar to Archie’s formula to calculate the water saturation of the seven cores of group B by using the imaginary part of complex resistivity:
Any calculated saturation values that were greater than 1 were set to exactly 1. Figure 12 shows the relationship between the water saturation calculated from the complex resistivity spectrum (Swa) and the water saturation recorded during the experiment (Sw). The correlation between the two datasets is very high, and the data points are distributed along the angular bisector of the first quadrant. This model can be used to effectively calculate the water saturation sandstone cores.

A plot of water saturation as calculated from the complex resistivity spectrum (Swa) against water saturation recorded during the experiment (Sw) for the seven cores of group B. The red line depicts the angular bisector of the first quadrant.
Although the structure of the new model is similar to Archie’s formula, it is different in several essential ways. For example, Archie’s formula uses the real resistivity of low frequencies to evaluate the water saturation, whereas the model in this article is based on imaginary resistivity. Real resistivity is largely affected by the conductivity of the medium being analyzed, while imaginary resistivity is mainly affected by the dielectric constant. In addition, the real resistivity used in Archie’s formula comes from a constant, predetermined determined frequency, whereas the frequency corresponding to the maximum value of imaginary resistivity varies, and it is related to the water saturation of the medium. The frequency corresponding to the maximum value of imaginary resistivity varies with the water saturation and other parameters of the medium, so the model proposed in this study is based on a dimension of the frequency domain that is different from that used by Archie’s formula.
5 Conclusion
The complex resistivity spectra of 15 natural sandstone cores in western China were measured with a frequency range of 100–15 MHz. Our analysis revealed a nearly perfect linear relationship between the real resistivity at 1 kHz and the maxima of imaginary resistivity. Moreover, the slopes of the linear fitting lines had strong linear correlations with both the porosities and permeabilities of the cores. We developed a permeability estimation model based on these slopes, and it proved effective at estimating the permeability of sandstone samples, even the samples with poor correlations between porosity and permeability.
As with low-frequency resistivity, the maximum values of imaginary resistivity had power relationships with porosity and water saturation. The saturation evaluation model demonstrated high accuracy and reliability in its saturation predictions by using the maxima of imaginary resistivity. These models and the conceptual understanding that underlies them should help popularize the use of complex resistivity spectra in the field of geophysics.
Acknowledgments
This research is supported by the National Oil and Gas Major Projects (No. 2011ZX05020-009). The authors would like to thank Dr. Ming Jiang and Bing Zhang for their guidance. In addition, special thanks are given to Qining Zhao for her continued support.
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© 2020 Jiang Jia et al., published by De Gruyter
This work is licensed under the Creative Commons Attribution 4.0 International License.
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- Hydrochemical differences between river water and groundwater in Suzhou, Northern Anhui Province, China
- The relationship between heat flow and seismicity in global tectonically active zones
- Modeling of Landslide susceptibility in a part of Abay Basin, northwestern Ethiopia
- M-GAM method in function of tourism potential assessment: Case study of the Sokobanja basin in eastern Serbia
- Dehydration and stabilization of unconsolidated laminated lake sediments using gypsum for the preparation of thin sections
- Agriculture and land use in the North of Russia: Case study of Karelia and Yakutia
- Textural characteristics, mode of transportation and depositional environment of the Cretaceous sandstone in the Bredasdorp Basin, off the south coast of South Africa: Evidence from grain size analysis
- One-dimensional constrained inversion study of TEM and application in coal goafs’ detection
- The spatial distribution of retail outlets in Urumqi: The application of points of interest
- Aptian–Albian deposits of the Ait Ourir basin (High Atlas, Morocco): New additional data on their paleoenvironment, sedimentology, and palaeogeography
- Traditional agricultural landscapes in Uskopaljska valley (Bosnia and Herzegovina)
- A detection method for reservoir waterbodies vector data based on EGADS
- Modelling and mapping of the COVID-19 trajectory and pandemic paths at global scale: A geographer’s perspective
- Effect of organic maturity on shale gas genesis and pores development: A case study on marine shale in the upper Yangtze region, South China
- Gravel roundness quantitative analysis for sedimentary microfacies of fan delta deposition, Baikouquan Formation, Mahu Depression, Northwestern China
- Features of terraces and the incision rate along the lower reaches of the Yarlung Zangbo River east of Namche Barwa: Constraints on tectonic uplift
- Application of laser scanning technology for structure gauge measurement
- Calibration of the depth invariant algorithm to monitor the tidal action of Rabigh City at the Red Sea Coast, Saudi Arabia
- Evolution of the Bystrzyca River valley during Middle Pleistocene Interglacial (Sudetic Foreland, south-western Poland)
- A 3D numerical analysis of the compaction effects on the behavior of panel-type MSE walls
- Landscape dynamics at borderlands: analysing land use changes from Southern Slovenia
- Effects of oil viscosity on waterflooding: A case study of high water-cut sandstone oilfield in Kazakhstan
- Special Issue: Alkaline-Carbonatitic magmatism
- Carbonatites from the southern Brazilian Platform: A review. II: Isotopic evidences
- Review Article
- Technology and innovation: Changing concept of rural tourism – A systematic review
Articles in the same Issue
- Regular Articles
- The simulation approach to the interpretation of archival aerial photographs
- The application of137Cs and210Pbexmethods in soil erosion research of Titel loess plateau, Vojvodina, Northern Serbia
- Provenance and tectonic significance of the Zhongwunongshan Group from the Zhongwunongshan Structural Belt in China: insights from zircon geochronology
- Analysis, Assessment and Early Warning of Mudflow Disasters along the Shigatse Section of the China–Nepal Highway
- Sedimentary succession and recognition marks of lacustrine gravel beach-bars, a case study from the Qinghai Lake, China
- Predicting small water courses’ physico-chemical status from watershed characteristics with two multivariate statistical methods
- An Overview of the Carbonatites from the Indian Subcontinent
- A new statistical approach to the geochemical systematics of Italian alkaline igneous rocks
- The significance of karst areas in European national parks and geoparks
- Geochronology, trace elements and Hf isotopic geochemistry of zircons from Swat orthogneisses, Northern Pakistan
- Regional-scale drought monitor using synthesized index based on remote sensing in northeast China
- Application of combined electrical resistivity tomography and seismic reflection method to explore hidden active faults in Pingwu, Sichuan, China
- Impact of interpolation techniques on the accuracy of large-scale digital elevation model
- Natural and human-induced factors controlling the phreatic groundwater geochemistry of the Longgang River basin, South China
- Land use/land cover assessment as related to soil and irrigation water salinity over an oasis in arid environment
- Effect of tillage, slope, and rainfall on soil surface microtopography quantified by geostatistical and fractal indices during sheet erosion
- Validation of the number of tie vectors in post-processing using the method of frequency in a centric cube
- An integrated petrophysical-based wedge modeling and thin bed AVO analysis for improved reservoir characterization of Zhujiang Formation, Huizhou sub-basin, China: A case study
- A grain size auto-classification of Baikouquan Formation, Mahu Depression, Junggar Basin, China
- Dynamics of mid-channel bars in the Middle Vistula River in response to ferry crossing abutment construction
- Estimation of permeability and saturation based on imaginary component of complex resistivity spectra: A laboratory study
- Distribution characteristics of typical geological relics in the Western Sichuan Plateau
- Inconsistency distribution patterns of different remote sensing land-cover data from the perspective of ecological zoning
- A new methodological approach (QEMSCAN®) in the mineralogical study of Polish loess: Guidelines for further research
- Displacement and deformation study of engineering structures with the use of modern laser technologies
- Virtual resolution enhancement: A new enhancement tool for seismic data
- Aeromagnetic mapping of fault architecture along Lagos–Ore axis, southwestern Nigeria
- Deformation and failure mechanism of full seam chamber with extra-large section and its control technology
- Plastic failure zone characteristics and stability control technology of roadway in the fault area under non-uniformly high geostress: A case study from Yuandian Coal Mine in Northern Anhui Province, China
- Comparison of swarm intelligence algorithms for optimized band selection of hyperspectral remote sensing image
- Soil carbon stock and nutrient characteristics of Senna siamea grove in the semi-deciduous forest zone of Ghana
- Carbonatites from the Southern Brazilian platform: I
- Seismicity, focal mechanism, and stress tensor analysis of the Simav region, western Turkey
- Application of simulated annealing algorithm for 3D coordinate transformation problem solution
- Application of the terrestrial laser scanner in the monitoring of earth structures
- The Cretaceous igneous rocks in southeastern Guangxi and their implication for tectonic environment in southwestern South China Block
- Pore-scale gas–water flow in rock: Visualization experiment and simulation
- Assessment of surface parameters of VDW foundation piles using geodetic measurement techniques
- Spatial distribution and risk assessment of toxic metals in agricultural soils from endemic nasopharyngeal carcinoma region in South China
- An ABC-optimized fuzzy ELECTRE approach for assessing petroleum potential at the petroleum system level
- Microscopic mechanism of sandstone hydration in Yungang Grottoes, China
- Importance of traditional landscapes in Slovenia for conservation of endangered butterfly
- Landscape pattern and economic factors’ effect on prediction accuracy of cellular automata-Markov chain model on county scale
- The influence of river training on the location of erosion and accumulation zones (Kłodzko County, South West Poland)
- Multi-temporal survey of diaphragm wall with terrestrial laser scanning method
- Functionality and reliability of horizontal control net (Poland)
- Strata behavior and control strategy of backfilling collaborate with caving fully-mechanized mining
- The use of classical methods and neural networks in deformation studies of hydrotechnical objects
- Ice-crevasse sedimentation in the eastern part of the Głubczyce Plateau (S Poland) during the final stage of the Drenthian Glaciation
- Structure of end moraines and dynamics of the recession phase of the Warta Stadial ice sheet, Kłodawa Upland, Central Poland
- Mineralogy, mineral chemistry and thermobarometry of post-mineralization dykes of the Sungun Cu–Mo porphyry deposit (Northwest Iran)
- Main problems of the research on the Palaeolithic of Halych-Dnister region (Ukraine)
- Application of isometric transformation and robust estimation to compare the measurement results of steel pipe spools
- Hybrid machine learning hydrological model for flood forecast purpose
- Rainfall thresholds of shallow landslides in Wuyuan County of Jiangxi Province, China
- Dynamic simulation for the process of mining subsidence based on cellular automata model
- Developing large-scale international ecological networks based on least-cost path analysis – a case study of Altai mountains
- Seismic characteristics of polygonal fault systems in the Great South Basin, New Zealand
- New approach of clustering of late Pleni-Weichselian loess deposits (L1LL1) in Poland
- Implementation of virtual reference points in registering scanning images of tall structures
- Constraints of nonseismic geophysical data on the deep geological structure of the Benxi iron-ore district, Liaoning, China
- Mechanical analysis of basic roof fracture mechanism and feature in coal mining with partial gangue backfilling
- The violent ground motion before the Jiuzhaigou earthquake Ms7.0
- Landslide site delineation from geometric signatures derived with the Hilbert–Huang transform for cases in Southern Taiwan
- Hydrological process simulation in Manas River Basin using CMADS
- LA-ICP-MS U–Pb ages of detrital zircons from Middle Jurassic sedimentary rocks in southwestern Fujian: Sedimentary provenance and its geological significance
- Analysis of pore throat characteristics of tight sandstone reservoirs
- Effects of igneous intrusions on source rock in the early diagenetic stage: A case study on Beipiao Formation in Jinyang Basin, Northeast China
- Applying floodplain geomorphology to flood management (The Lower Vistula River upstream from Plock, Poland)
- Effect of photogrammetric RPAS flight parameters on plani-altimetric accuracy of DTM
- Morphodynamic conditions of heavy metal concentration in deposits of the Vistula River valley near Kępa Gostecka (central Poland)
- Accuracy and functional assessment of an original low-cost fibre-based inclinometer designed for structural monitoring
- The impacts of diagenetic facies on reservoir quality in tight sandstones
- Application of electrical resistivity imaging to detection of hidden geological structures in a single roadway
- Comparison between electrical resistivity tomography and tunnel seismic prediction 303 methods for detecting the water zone ahead of the tunnel face: A case study
- The genesis model of carbonate cementation in the tight oil reservoir: A case of Chang 6 oil layers of the Upper Triassic Yanchang Formation in the western Jiyuan area, Ordos Basin, China
- Disintegration characteristics in granite residual soil and their relationship with the collapsing gully in South China
- Analysis of surface deformation and driving forces in Lanzhou
- Geochemical characteristics of produced water from coalbed methane wells and its influence on productivity in Laochang Coalfield, China
- A combination of genetic inversion and seismic frequency attributes to delineate reservoir targets in offshore northern Orange Basin, South Africa
- Explore the application of high-resolution nighttime light remote sensing images in nighttime marine ship detection: A case study of LJ1-01 data
- DTM-based analysis of the spatial distribution of topolineaments
- Spatiotemporal variation and climatic response of water level of major lakes in China, Mongolia, and Russia
- The Cretaceous stratigraphy, Songliao Basin, Northeast China: Constrains from drillings and geophysics
- Canal of St. Bartholomew in Seča/Sezza: Social construction of the seascape
- A modelling resin material and its application in rock-failure study: Samples with two 3D internal fracture surfaces
- Utilization of marble piece wastes as base materials
- Slope stability evaluation using backpropagation neural networks and multivariate adaptive regression splines
- Rigidity of “Warsaw clay” from the Poznań Formation determined by in situ tests
- Numerical simulation for the effects of waves and grain size on deltaic processes and morphologies
- Impact of tourism activities on water pollution in the West Lake Basin (Hangzhou, China)
- Fracture characteristics from outcrops and its meaning to gas accumulation in the Jiyuan Basin, Henan Province, China
- Impact evaluation and driving type identification of human factors on rural human settlement environment: Taking Gansu Province, China as an example
- Identification of the spatial distributions, pollution levels, sources, and health risk of heavy metals in surface dusts from Korla, NW China
- Petrography and geochemistry of clastic sedimentary rocks as evidence for the provenance of the Jurassic stratum in the Daqingshan area
- Super-resolution reconstruction of a digital elevation model based on a deep residual network
- Seismic prediction of lithofacies heterogeneity in paleogene hetaoyuan shale play, Biyang depression, China
- Cultural landscape of the Gorica Hills in the nineteenth century: Franciscean land cadastre reports as the source for clarification of the classification of cultivable land types
- Analysis and prediction of LUCC change in Huang-Huai-Hai river basin
- Hydrochemical differences between river water and groundwater in Suzhou, Northern Anhui Province, China
- The relationship between heat flow and seismicity in global tectonically active zones
- Modeling of Landslide susceptibility in a part of Abay Basin, northwestern Ethiopia
- M-GAM method in function of tourism potential assessment: Case study of the Sokobanja basin in eastern Serbia
- Dehydration and stabilization of unconsolidated laminated lake sediments using gypsum for the preparation of thin sections
- Agriculture and land use in the North of Russia: Case study of Karelia and Yakutia
- Textural characteristics, mode of transportation and depositional environment of the Cretaceous sandstone in the Bredasdorp Basin, off the south coast of South Africa: Evidence from grain size analysis
- One-dimensional constrained inversion study of TEM and application in coal goafs’ detection
- The spatial distribution of retail outlets in Urumqi: The application of points of interest
- Aptian–Albian deposits of the Ait Ourir basin (High Atlas, Morocco): New additional data on their paleoenvironment, sedimentology, and palaeogeography
- Traditional agricultural landscapes in Uskopaljska valley (Bosnia and Herzegovina)
- A detection method for reservoir waterbodies vector data based on EGADS
- Modelling and mapping of the COVID-19 trajectory and pandemic paths at global scale: A geographer’s perspective
- Effect of organic maturity on shale gas genesis and pores development: A case study on marine shale in the upper Yangtze region, South China
- Gravel roundness quantitative analysis for sedimentary microfacies of fan delta deposition, Baikouquan Formation, Mahu Depression, Northwestern China
- Features of terraces and the incision rate along the lower reaches of the Yarlung Zangbo River east of Namche Barwa: Constraints on tectonic uplift
- Application of laser scanning technology for structure gauge measurement
- Calibration of the depth invariant algorithm to monitor the tidal action of Rabigh City at the Red Sea Coast, Saudi Arabia
- Evolution of the Bystrzyca River valley during Middle Pleistocene Interglacial (Sudetic Foreland, south-western Poland)
- A 3D numerical analysis of the compaction effects on the behavior of panel-type MSE walls
- Landscape dynamics at borderlands: analysing land use changes from Southern Slovenia
- Effects of oil viscosity on waterflooding: A case study of high water-cut sandstone oilfield in Kazakhstan
- Special Issue: Alkaline-Carbonatitic magmatism
- Carbonatites from the southern Brazilian Platform: A review. II: Isotopic evidences
- Review Article
- Technology and innovation: Changing concept of rural tourism – A systematic review