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The correct selection of the value of p is a complex and iterative procedure that requires experience in the interpretation of the obtained interpolated maps. Inverse Distance Weighting is a method applied to the porosities of the K and L hydrocarbon reservoirs discovered in the Neogene (Lower Pontian) subsurface sandstones in northern Croatia (Pannonian Basin System). They represent small and large data samples. Also, a standard statistical analysis of the data was made, followed by a qualitative–quantitative analysis of the maps, based on the selection of different values for the power distance exponent (p-value) for the K and L reservoir maps. According to the qualitative analysis, for a small data set, the p-value could be set at 1 or 2, giving the optimal result, while for a large data set, a p value of 3 or 4 could be applied. For quantitative analysis, in the case of a small data set, p = 2 is recommended, resulting in a root mean square error value of 0.03458, a mean absolute error of 0.02013 and a median absolute deviation of 0.00546. In contrast, a p-value of 3 or 4 is selected as appropriate for a large data set, with root mean square errors of 0.02435 and 0.02437, mean square errors of 0.01582 and 0.01509 and median absolute deviations 0.00896 and 0.00444. Eventually for a small data set, it is recommended to use a p-value of 2, and for a large data set, a p-value of 3 or 4. [ABSTRACT FROM AUTHOR]

Rocks extracted from deep mining operations often undergo various complex temperature and dynamic load disturbances. In order to investigate the influence of temperature on the mechanical characteristics and fracture mechanisms of sandstone under different loading conditions, thermal treatments were conducted on sandstone samples at temperatures of 25 °C, 200 °C, 400 °C, 600 °C, 800 °C, and 1000 °C. Subsequently, the quasi-static and dynamic mechanical properties of the treated samples were tested and recorded using an electronic universal testing machine and a Split Hopkinson Pressure Bar (SHPB). Simultaneously, detailed analyses and discussions of thermal damage and failure mechanisms of the specimens were carried out using Energy-Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Raman spectroscopy. The results indicate that with increasing temperature, the mass, density, and peak stress of the sandstone specimens decrease, while the porosity and peak strain increase. Transgranular (TG) fracture was identified as the primary failure mode during loading, accompanied by a small amount of intergranular (IG) fracture. Furthermore, high temperatures cause changes in the chemical properties of the sandstone, resulting in thermal decomposition of crystal grains and evaporation of mineral components, which are key factors that weaken the mechanical properties of sandstone. The significance of this study is to provide theoretical and technical support for site selection and safety assessment of underground engineering projects. [ABSTRACT FROM AUTHOR]

Fracture within the rock is one of the main factors leading to rock destabilization and has a significant effect on the stability of the project. In this study, sandstone is used as a research target, specimens with crack inclination angles of 0°, 30°, 45°, 60°, and 90° are prefabricated, and the split Hopkinson pressure bar (SHPB) impact test of sandstone with cracks is carried out based on digital image recognition technology to explore the dynamic damage characteristics of the specimens with five angles. The basic mechanical parameters of sandstone are tested to determine the RHT model intrinsic parameters, and the numerical computational RHT model of sandstone containing crack defects is established, which is verified in comparison with the test to analyze the validity of the model. Finally, the failure characteristics of the numerical model under initial stress were carried out. The study shows the following: with the increase in the fracture angle, the dynamic compressive strength and deformation modulus are distributed in a slanting V-shape, and the inclination angle of 45° is the smallest. The strain rate and energy dissipation rate are distributed in a slanting N-shape, and the inclination angle of 45° is the largest. The transmittance shows a decreasing trend, which is the opposite of the reflectivity pattern. The crack angle determines the location and direction of the initial crack, which affects the failure mode. In addition, the parameters of the RHT constitutive model suitable for sandstone are obtained, and the damage and strength patterns of the established RHT model are highly consistent with the laboratory test results. The damage range of numerical models for crack defects with different inclination angles is negatively correlated with confining pressure values and positively correlated with axial pressure values. The damage zones are symmetrically distributed approximately perpendicular to the direction of cracks, and the confining pressure has a contributing role in the peak of the element stresses; however, the axial compression has no contribution in the peak of the element stresses. [ABSTRACT FROM AUTHOR]

The provenance of Upper Paleozoic sediments in the Western Carpathians was derived by a petrofacies analysis of sandstones, including the U–Pb geochronology of detrital zircons. The Upper Paleozoic sedimentary basins were formed sequentially by tectonic processes associated with the Variscan continental collision, as well as by subsequent transpressional/transtensional and extensional regimes. Fore-arc related and proforeland basins were formed in the Late Tournaisian/Visean and subsequently in the Bashkirian/Moscovian. Transpressional/transtensional and extensional basins were formed successively on both sides of the continental collisional suture, both in the proforeland and retroforeland parts in the Late Pennsylvanian and later in the Cisuralian and Guadalupian. The sandstone petrofacies, as well as the detrital zircon distribution, indicate source areas directly from the underlying crystalline basement: a magmatic arc, an uplifted continental block for the Central Western Carpathian basins, and a recycled orogen for the Inner Western Carpathian basins. Detrital zircon age spectra record distinct stages of protracted Ediacaran to Carboniferous tectonosedimentary processes. This indicates a different palinspastic position of source areas along the peri-Gonwanan realm, the West African Craton, and the Sahara Metacraton in the Neoproterozoic. [ABSTRACT FROM AUTHOR]

Sand production is a common issue in sandstone gas reservoir development, severely impacting the productivity of sandstone gas wells. In order to thoroughly investigate the sand production characteristics of high‐temperature and high‐pressure tight sandstone gas reservoirs, this study focuses on six core samples from tight sandstone gas reservoirs(three samples with fractures), under reservoir conditions (185 MPa, 160°C), sand production experiments were conducted to thoroughly investigate the sand production patterns in sandstone reservoirs under the combined influence of different effective stresses and production pressure differentials. The results indicate: (1) under the simultaneous increase of effective pressure and production pressure differential, sand production near the wellbore (r = 0.1 m) becomes more likely in the reservoir; (2) in actual reservoirs without fractures near the wellbore (r = 0.1 m), sand production phenomena do not occur; (3) reservoirs with fractures near the wellbore (r = 0.1 m) are more prone to sand production, under an effective stress of 90 MPa, with specimens containing fractures exhibiting a 76.48% lower critical sand production pressure gradient compared to those without fractures; (4) when the pore fluid pressure is 95 MPa, the maximum gas production rate for Well X without sand production is 12.4 × 104 m3/d. The experimental results have guiding significance for the rational production of gas wells in this type of reservoir. [ABSTRACT FROM AUTHOR]

The pore-throat structure is a critical factor in the study of unconventional oil and gas reservoirs, drawing particular attention from petroleum geologists, and it is of paramount significance to analyze to enhance oil and gas production. In tight sandstone, which serves as a significant hydrocarbon reservoir, the internal pore-throat structure plays a decisive role in the storage and migration of fluids such as water, gases, and hydrocarbons. This paper employs casting thin section (CTS), field emission scanning electron microscope (FE-SEM), high-pressure mercury injection (HPMI), and low-temperature nitrogen gas adsorption (LT−N2−GA) experimental tests to qualitatively and quantitatively analyze the characteristics of the pore-throat structure in tight sandstone. The results indicate that the pore types in tight sandstone include intergranular residual pores, dissolution pores, intercrystalline pores, and microfractures, while the throat types encompass sheet-shaped, curved-sheet-shaped, and tubular throats. Analysis of the physical and structural parameters from 13 HPMI and 5 LT−N2−GA samples reveals a bimodal distribution of pore-throat radii. The complexity of the pore-throat structure is identified as a primary controlling factor for reservoir permeability. The fractal dimension (D) exhibits an average value of 2.45, displaying a negative correlation with porosity (R2 = 0.22), permeability (R2 = 0.65), the pore-throat diameter (R2 = 0.58), and maximum mercury saturation (R2 = 0.86) and a positive correlation with threshold pressure (R2 = 0.56), median saturation pressure (R2 = 0.49), BET specific surface area (R2 = 0.51), and BJH total pore volume (R2 = 0.14). As D increases, reservoir pores tend to decrease in size, leading to reduced flow and deteriorated physical properties, indicative of a more complex pore-throat structure. [ABSTRACT FROM AUTHOR]

Outcrops of detrital sediments dating from the Moghrebian are found in the coastal basin of Tarfaya in southwestern Morocco. These sediments are still little studied and spectacularly extended and surmounted by a hard crust. Our study will focus on three objectives (1) to characterize the microfacies of Moghrebian sediments and to identify their diagenetic evolution, (2) to reconstruct the modalities of development of superficial crusts, and (3) to elucidate the origin of calcium carbonate in these sediments. The results show that the Moghrebian strata have alternating conglomerate beds, lumachel, sandstone, calcarenite, and a welldeveloped calcareous crust on the surface. The diagenetic evolution of these facies is very early and is characterized by corrosion and isovolumetric epigenesis of quartz by calcite, particularly in the superficial crust. Clay minerals of detrital origin characterize the fine fraction of these sediments. The oversaturation of the environment with calcium carbonate prompted the development of a crust where fibrous clays are newly formed, which reflects the development of climatic conditions with alternating dry and wet seasons in the basin during the postMoghrebian period. [ABSTRACT FROM AUTHOR]

The seismic attributes of water‐rich sandstone contain much information about the rock's physical properties and seismic wave parameters. They are commonly used to predict the rock's physical properties (e.g. porosity). However, the seismic attributes of water‐rich sandstone are affected by porosity, water saturation and thickness. To eliminate the influence of thickness on the porosity prediction of water‐rich sandstone and improve the accuracy of the porosity prediction, the authors propose a Lambert W–R transform method to isolate the contribution of thickness and porosity from seismic attributes. First, a rock physical model is used to calculate the equivalent elastic parameters of water‐rich sandstones with different porosity values and water saturation levels. Second, the seismic attribute dataset of water‐rich sandstone is established by forward modelling the seismic response of the wedge‐shaped water‐rich sandstone model, and the selection of sensitive physical properties is completed. Then, the transformation parameters (ζAhRs and ηAhRs) are obtained by Lambert W–R transformation, which is exponentially related to instantaneous amplitude. ζAhRs and ηAhRs are sensitive to thickness and porosity, respectively. Finally, an interpretative template for porosity prediction of water‐rich sandstone is established by cross‐plot analysis (ζAhRs and ηAhRs) and verified by a practical case. The verification results show that the porosity predicted by the interpretation template is consistent with drilling fluid consumption. However, it is lower than the porosity of logging constrained P‐wave impedance inversion. [ABSTRACT FROM AUTHOR]

This article presents data on lithology, biostratigraphy, and molluscan paleontological characteristics of the Lower Volgian–Upper Ryazanian interval of the Yanov Stan Formation obtained from the core of the Novoyakimovskaya-1 parametric well. The formation consists of mudstone-siltstone intercalation with rare sandstone beds and numerous levels with carbonate concretions. For the first time, abundant glendonites are reported from the Yanov Stan Formation, including stratigraphic intervals from which they have not been previously known. An almost complete 290-m core of the Yanov Stan Formation with abundant ammonites and bivalves was obtained. This enabled us to develop a detailed biostratigraphic zonation of the section based on ammonites and bivalves. The following succession of ammonite zones, known in Western Siberia and, mainly, in Eastern Siberia (from bottom to top), was established: Paravirgatites lideri, Pavlovia iatriensis, Dorsoplanites ilovaiskii, D. maximus, Epivirgatites variabilis, Praechetates exoticus, Craspedites okensis, Praetollia maynci, Hectoroceras kochi, and Surites subanalogus. The bivalve succession, distinguished based on the members of the genus Buchia, includes the following Buchiazones: Buchia mosquensis, B. unschensis, B. okensis, ?B. jasikovi, and B. volgensis. The molluscan assemblages of the studied core, starting at least from the upper Middle Volgian, are similar to the coeval assemblages from the eastern part of the Yenisei–Khatanga depression and the Laptev Sea coast but differ from those from Western Siberia. This suggests the existence of some environmental factors that prevented the free distribution of mollusks from the western part of the Yenisei–Khatanga depression into the West Siberian basin. [ABSTRACT FROM AUTHOR]

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The Cretaceous Houshigou Formation in Sanjiang Basin is the main ore-bearing layer of uranium deposit, developed with a large area of grey and light yellow gravel fine-medium sandstone. Taking the sandstone of Houshigou Formation in Songmuhe sag as the study object, the paper discusses the provenance composition, weathering intensity and tectonic setting of Houshigou Formation on the basis of detailed petrological and geochemical characteristics. The results show that the formation is mainly feldspar and lithic sandstone, with the major element SiO2 content of 58.91%-71.51%, total alkali content of 4.59%-10.05%, and Al content of 12.87%-16.12%. The total content of rare earth element (ΣREE) is 100.72x10-6-171.34x10-6, averagely 134.532x10-6, with obvious negative Eu anomaly (δEu=0.27-0.84), indicating that the rock originates from the upper crust. The element geochemical characteristics reveal that CIA is 13.13-45.25, ICV 0.74-1.02 and PIA 53.08-67.90, indicating that the sedimentary period of Houshigou Formation was in arid-semi arid environment, and the source area experienced weak weathering. The Sr/Ba ratio is mostly less than 1, the equivalent B content mostly less than 200x10-6 and the SiO2/Al2O3 ratio averagely 4.35, indicating that the sedimentary period of Houshigou Formation was in low salinity environment. The sandstone has the geochemical properties of active continental margin. Combined with the regional evolution history, it is believed that the source area should be the felsic rock developed in Jiamusi uplift. [ABSTRACT FROM AUTHOR]

This study delves into the micro-occurrence states and enrichment mechanisms of residual oil, pivotal for advancing the production from tight sandstone reservoirs, particularly from the Chang 8 Member of the Upper Triassic Yanchang Formation, Ordos Basin. Through an analysis of 23 core samples, employing high-pressure mercury injection, field emission scanning electron microscopy, thin section, and X-ray diffraction techniques, distinct reservoir types were categorized. The utilization of environmental scanning electron microscope, multi-solvent continuous extraction, and an oil components separation system facilitated an intricate analysis of residual oil micro-occurrence states and their subsequent effects on porosity and permeability reduction across varying reservoir types. The findings accentuate the integral role of reservoir type in determining residual oil distribution within tight sandstone reservoirs. Favorable pore throat sorting and connectivity in specified reservoir types are identified as conducive to residual oil enrichment with a higher concentration of light components. In contrast, elevated carbonatite and clay content in other reservoir types leads to adsorption of heavy components, disrupting pore throat connectivity, and impeding crude oil filling. The varied interactions between oil and rock, oil–oil, and pore throat sealing significantly impact the distribution of oil components of residual oil, culminating in a notable reduction of porosity and permeability by 2.63% and 0.197 mD, with corresponding reduction rates of 27.19% and 46.69%, respectively. The insights derived from this study furnish a theoretical foundation for augmenting tight oil recovery and comprehending the enrichment mechanism of residual oil driven by the heterogeneity of tight sandstone reservoirs. [ABSTRACT FROM AUTHOR]

Spontaneous water imbibition into matrix blocks can be a significant oil recovery mechanism in fractured reservoirs. Many enhanced oil recovery methods, such as injection of modified salinity brine, are proposed for improving spontaneous imbibition efficacy. Many scaling equations are developed in the literature to predict spontaneous imbibition oil recovery. However, almost none of them included the impact of the diversity in ionic composition of injected and connate brines and the blending/interaction of a low salinity imbibing brine with a higher salinity connate brine. In this research, these two issues are included to propose new scaling equations for the scaling of spontaneous imbibition oil recovery by modified salinity imbibing brines. This study uses experimental data of the spontaneous imbibition of modified salinity brines into oil-saturated rock samples with different lithologies containing an irreducible high salinity connate brine. The collected tests from the literature were performed at high temperatures and on aged altered wettability cores. The results of 110 available spontaneous imbibition laboratory experiments (85, 12 and 13 tests on chalks, dolomites and sandstones, respectively) are gathered. This research initially shows the poor ability of three selected convenient scaling equations from the literature to scale imbibition recovery by modified salinity brine. Then, our newly proposed technique to find the scaling equation for spontaneous imbibition recovery by modified salinity brine, during the abovementioned conditions in limestones (Bassir et al. in J Pet Explor Prod Technol 13(1): 79–99, 2023. https://doi.org/10.1007/s13202-022-01537-7) is used in chalks, dolomites and sandstones to develop the three new scaling equations. Finally, a new general equation to scale imbibition recovery by modified salinity brine for all four lithologies is presented. Moreover, for each of the four datasets (chalk, dolomite, sandstone and all the four lithologies), the scaled data by the new equations is matched by two mathematical expressions based on the Aronofsky et al. model and the Fries and Dreyer model. These mathematical expressions can be used to develop transfer functions in reservoir simulators for a more accurate prediction of oil recovery by spontaneous imbibition of modified salinity brine in fractured reservoirs. [ABSTRACT FROM AUTHOR]

[Objective] The maximum operating pressure for underground gas storage facilities designed for oil and gas reservoirs, both constructed and under construction in China, is currently set at the original formation pressure. There have yet to be successful cases of overpressure operation, which significantly impacts the economic benefits of converting depleted oil and gas reservoirs into underground gas storage facilities. This article aims to evaluate the maximum operating pressure and storage capacity of the Nanpu 1-29 gas storage facility from the perspective of the ultimate bearing capacity of cap layers and faults, with the goal of effectively enhancing the construction benefits of the facility. [Methods] The evaluation of the maximum operating pressure for the Nanpu 1-29 gas storage facility in eastern Hebei is based on the minimum principal stress measured in situ in the mining wells. Different effective porosity calculation methods are employed to quantitatively evaluate the effective storage capacity of gas and oil reservoirs, as well as the incremental capacity after pressure boosting operation, based on their development differences. [Results] The evaluation of the maximum operating pressure for the Nanpu 1-29 gas storage facility indicates that the minimum principal stress of the cap layers determined by the in-situ measurements in the mining wells is 34.00 MPa. Based on the tensile failure criteria determined by the minimum principal stress, the maximum operating pressure for the tensile failure of the cap layer is 27.20 MPa. Combined with the maximum safe injection pressure corresponding to shear failure of the cap layer (30.60 MPa) and the maximum safe injection pressure corresponding to unstable slip of the fault (27.60 MPa), the final maximum operating pressure for the Nanpu 1-29 gas storage facility is determined to be 27.20 MPa. Based on the effective storage capacity calculation model, considering factors such as the water content of the gas reservoir, residual water and edge porosity as well as the coefficient of influence, the efficiency of gas-driven fluid, and the utilization rate of oil-containing space, the maximum operating pressure increased from the original formation pressure of 22.50 MPa to 27.20 MPa. The practical storage capacity of the gas storage facility increased from 15.46x108 m³ to 18.14x108 m³, an increase of approximately 17.3%. [Conclusion] (1) The construction of gas storage facilities can be re-evaluated for the maximum operating pressure based on the minimum principal stress measured in situ in the mining wells, and overpressure design can be conducted under appropriate conditions. (2) Overpressure design can effectively increase storage capacity and improve the economic benefits of reservoir construction. [Significance] The research results have a certain reference value for the quantitative evaluation of the maximum operating pressure and storage capacity of other underground gas storage facilities, and are expected to significantly improve the economic benefits of overpressure-designed reservoir-type gas storage facilities in China. [ABSTRACT FROM AUTHOR]

Sandstone deterioration is one of the main problems affecting historical monuments. Therefore, to protect cultural heritage structures, introducing conservation strategies is necessary. The study aimed to assess bacterial and fungal diversity of non-hydrophobized and hydrophobized areas in the historic tomb chapel of Karol Scheibler in Poland after 10 years of the conservation treatment. The applied conservation treatment included hydrophobization with the Polish impregnates Konsil Z. Next-generation sequencing (NGS) exhibited significant changes in the microbial communities of the treated sandstones. Members belonging to the phylum Acidobacteriota, Chloroflexi, and Verrucomicrobiota and genera Pseudonocardia, Synechococcus, Rubrobacter, Bryobacter, Blastocatella, and Truepera showed significantly lower relative abundance in hydrophobized area. Moreover, fungi Ascomycota, mainly class of Dothideomycetes, were significantly less abundant in the hydrophobized samples—could be due to hydrophobization. However, some groups of microorganisms enhanced their relative abundance in hydrophobized area. These groups of bacteria such as Proteobacteria, Gammaproteobacteria, Rhizobiaceae, and Nocardioides could have caused the appearance of a green bloom on the sandstone 10 years after the impregnation. [ABSTRACT FROM AUTHOR]

Tortuosity has different definitions that are used by scientists and engineers to describe various fluid‐related processes in porous media. Two of the most commonly used definitions are electrical (describing the electrical current flow process) and diffusion (related to the molecular diffusive flow process) tortuosity. In this study, we investigate the impact of minerology (presence of clay) and fluid conductivity on the electrical‐diffusion tortuosity relationship. That is: whether or not electrical and diffusion tortuosity have one‐to‐one relationship in sandstones. Two groups of samples were used: clean Fontainebleau sandstones and clayey sandstones. Electrical resistivity was measured using four‐electrode method to obtain electrical formation factor and calculate the electrical tortuosity (τe) using a model that is applicable for consolidated rocks. Pulsed field gradient nuclear magnetic resonance (PFG NMR) measurements were employed to quantify diffusion tortuosity (τD). At lower fluid conductivity (3 S/m), our results show that τD ≈τe for clean sandstones, while τe << τD is observed for clayey sandstones. We propose that mineralogy has direct impact on the τe−τD relationship: the presence of clay minerals added surface conductivity which contributed to underestimating the intrinsic formation factor (F′) and consequently reducing τe. As the fluid conductivity increases, τe converges to τD until reaching the high salinity limit at which F′ is obtained and τD becomes in good agreement with τe for the clayey sandstone. The NMR diffusion approach presented here shows the potential of estimating F′ without the need for multi‐salinity data which can contribute to improved permeability prediction. Key Points: Electrical tortuosity (τe) is smaller than NMR‐derived diffusion tortuosity (τD) in the presence of clay and at low fluid conductivityThe use of high conductivity fluid reduces the impact of clay thus increasing formation factor and increasing τe which converges to τDThe NMR diffusion approach presented here can potentially estimate intrinsic electrical formation factor without multi‐salinity data [ABSTRACT FROM AUTHOR]

Based on the actual data collected from the tight sandstone development zone, correlation analysis using the Spearman method was conducted to determine the main factors influencing the gas production rate of tight sandstone fracturing. An integrated model combining geological engineering and numerical simulation of fracture propagation and production was completed. Based on data analysis, the hydraulic fracture parameters were optimized to develop a differentiated fracturing treatment adjustment plan. The results indicate that the influence of geological and engineering factors in the X1 and X2 development zones in the study area differs significantly. Therefore, it is challenging to adopt a uniform development strategy to achieve rapid production increase. The data analysis reveals that the variation in gas production rate is primarily affected by the reservoir thickness and permeability parameters as geological factors. On the other hand, the amount of treatment fluid and proppant addition significantly impact the gas production rate as engineering factors. Among these factors, the influence of geological factors is more pronounced in block X1. Therefore, the main focus should be on further optimizing the fracturing interval and adjusting the geological development well location. Given the existing well location, there is limited potential for further optimizing fracture parameters to increase production. For block X2, the fracturing parameters should be optimized. Data screening was conducted to identify outliers in the entire dataset, and a data-driven fracturing parameter optimization method was employed to determine the basic adjustment direction for reservoir stimulation in the target block. This approach provides insights into the influence of geological, stimulation, and completion parameters on gas production rate. Consequently, the subsequent fracturing parameter optimization design can significantly reduce the modeling and simulation workload and guide field operations to improve and optimize hydraulic fracturing efficiency. [ABSTRACT FROM AUTHOR]

The main purpose of the study is to identify the thin-bed reservoirs of the Eastern Folded Belt (Sylhet and Bandarban) and characterize them with diligence. A detailed qualitative and quantitative analysis has been carried out. It is based on thin-section petrographic analyses of sandstone samples. These samples are from the reservoir horizons of the Sylhet region and Bandarban region fields. The purpose of this analysis is to characterize the textural and mineralogical properties. Additionally, it aims to evaluate the post-depositional diagenetic changes. The results obtained from the field and laboratory analysis are studied extensively to characterize the thin-bed reservoirs. Samples from the Sylhet area are medium-coarse-grained, fairly sorted, tight packing, submature-mature sublithic characteristics. Contrarily, samples from the Bandarban region are mature-submature sublithic arenites, which are fine-medium-grained, moderately well-sorted, and moderately loosely packed. Despite the similarity of the detrital elements (quartz, feldspar, lithic grains, mica, etc.) in the two areas, silica cementation is more frequent in Sylhet region samples than early carbonate cementation in Bandarban region samples. Comparatively speaking, the sediments in the Sylhet region are more compact than those in the Bandarban region. The most important outcome of this study is that the thin bed of the unconventional reservoir and the conventional reservoir are in close proximity. The Thin-bed reservoir units of the Eastern Folded Belt are found to be medium to fine-grained and well sorted, with frequent alteration of sand-shale with the prevalence of parallel bedded sandstone. Average porosity is 4% to 12%, and pore spaces are interconnected. So, the permeability rate is good enough to flow the hydrocarbon through these pore spaces. Most importantly, the thin bed and tight reservoir (average porosity 4% to 12%, but pore spaces are not interconnected) are not more prominent than 1 meter or 2 meters. Subsequently, though the vertical thickness is not so high, they keep up a momentous tirelessness of horizontal progression. On the contrary, at whatever point it comes to a conventional reservoir, the vertical thickness is higher than that of the unconventional reservoir. But their lateral persistence is not as long as unconventional ones. [ABSTRACT FROM AUTHOR]

In constructing rapid rock identification models for measurement while drilling (MWD) via neural network methods, collecting actual drilling data to train the model is extremely time-consuming and labor-intensive. This requires extensive drilling experiments in various rock types, resulting in limited neural network training data for rock identification that covers a limited range of rock types. To suitably address this issue, a dynamic numerical simulation model for rock drilling is established that generates extensive drilling data. The input parameters for the simulations include torque, drill bit rotation speed, and drilling speed. A neural network model is then developed for rock classification using large datasets from dynamic numerical simulations, specifically those of granite, limestone, and sandstone. Building upon this model, transfer learning is appropriately applied to store the knowledge obtained in the rock identification based on the neural network model. Further training through transfer learning is conducted with smaller datasets obtained during actual drilling, making the model suitable for practical rock identification and prediction in the drilling processes. The neural network rock classification model, incorporating dynamic numerical simulation and transfer learning, achieves a prediction accuracy of 99.36% for granite, 99.53% for sandstone, and 99.82% for limestone. This reveals an enhancement in prediction accuracy of up to 22.94% compared to the models without transfer learning. [ABSTRACT FROM AUTHOR]

The strength of jointed rock is a fundamental factor in the slope stability of rock mass. This research investigates the effect of infill thickness on the strength of jointed rock specimens. Unlike previous studies involving artificial rock-like materials and saw-tooth surfaces, this work has been conducted on two natural types of sandstone with various rock surfaces. Natural low-plasticity clay of different thicknesses (1 mm to 3 mm) was used as the infill material. A series of shear box tests with a range of initial normal stresses from 0.5 MPa to 1.5 MPa were performed to obtain high-quality data regarding the shear strength of natural rock and to provide insights into the effect of infill and rock surface roughness on shear strength. The obtained results were also used to improve the current methods of rock strength predictions, which were initially designed to estimate the strength of artificial rock-like material. Based on the obtained laboratory data and the strength estimation using different methods, a newly proposed procedure was proved to provide more accurate estimations of the shear strength of jointed rock. [ABSTRACT FROM AUTHOR]

A numerical model of hydraulic fracture propagation is introduced for a representative reservoir (Yuanba continental tight sandstone gas reservoir in Northeast Sichuan). Different parameters are considered, i.e., the interlayer stress difference, the fracturing discharge rate and the fracturing fluid viscosity. The results show that these factors affect the gas and water production by influencing the fracture size. The interlayer stress difference can effectively control the fracture height. The greater the stress difference, the smaller the dimensionless reconstruction volume of the reservoir, while the flowback rate and gas production are lower. A large displacement fracturing construction increases the fracture-forming efficiency and expands the fracture size. The larger the displacement of fracturing construction, the larger the dimensionless reconstruction volume of the reservoir, and the higher the fracture-forming efficiency of fracturing fluid, the flowback rate, and the gas production. Low viscosity fracturing fluid is suitable for long fractures, while high viscosity fracturing fluid is suitable for wide fractures. With an increase in the fracturing fluid viscosity, the dimensionless reconstruction volume and flowback rate of the reservoir display a non-monotonic behavior, however, their changes are relatively small. [ABSTRACT FROM AUTHOR]

The sandstone reservoir in the Lule River group of Mahai East District is strong, densely dense, and the expansion of clay material is very easy to block the pores. Therefore, the new pressure cracks and cationic cluster stabilizers with double-season ammonium salt clay stabilizers are used. Experimental analysis is performed under the circumstances of the perimeter. Use nuclear magnetic real-time testing different fracture liquids to drive the pore structure structure changes before and after the sandstone, combined with differential theory to calculate the fractal dimensions of sandstone. As a result, under the condition of water full, as the perimeter pressure increases, the rocks are increased, and the rocks are increased, and the rocks are increased. The matrix occurs under the common action of the fence and the fracture fluid to prevent the inflation of clay minerals under the combined action of the fence and the fracture fluid, which causes a significant reduction in large holes and increased micropores and medium holes. Exploring different fracture liquids to reservoirs is of great significance to the development of dense sandstone reservoirs. [ABSTRACT FROM AUTHOR]

Protecting stone on facades or exterior art works from deterioration is primarily about protecting them from rainwater. Hydrophobic coatings are widely used for this purpose. Here, two factors affecting the long-term efficiency of some coatings applied on stones were investigated: the number of coating layers and the curing time after their application. Tests of water absorption by capillarity, absorption at total immersion in water, and a visual check of the penetration depth have been carried out. The coating's efficiency coefficient Cef was defined as the ratio of the maximum water absorption of a treated sample to an untreated one. Two commercial silicon-based coatings were applied on the highly porous Hořice sandstone alternatively. Curing times of 2 days vs. 2 weeks, and 2 coating layers vs. 3 layers were compared. The experiments showed that the coating's efficiency is affected more by the curing time than by the number of applied coating layers. The curing time of 2 days after coating's application is too short, but 2 weeks proved to be sufficient for both tested coatings. There was no big difference regarding the number of coating layers; two layers seem to be sufficient if a long rain-free curing time can be guaranteed. [ABSTRACT FROM AUTHOR]

In order to study the hydration absorption behaviors and characteristics of sandstone in Mogao Grottoes in China, the pressure-less hydration absorption experiment on the outcrop porous sandstone of Mogao Grottoes was carried out by using the self-developed real-time monitoring experimental system. The hydration absorption was measured and the curve of hydration absorption with time was drawn. At the same time, the digital image correlation method (DIC) was used to measure the full-field deformation, and the speckle pattern of the sample was analyzed using Match ID, and the displacement field and strain field of the sandstone sample at different hydration absorption moments were computed. Moreover, the sparse area and dense area of sandstone are used as regions of interest (ROI) for DIC analysis. According to the test results, it is concluded that the hydration absorption of sandstone increases rapidly in the initial stage, and gradually tends to be stable with the change of time. This corresponds well with the deformation characteristics of sandstone analyzed using DIC. In the initial stage, the deformation of sandstone increases rapidly. With the change in time, the deformation of sandstone samples gradually slows down. When the hydration adsorption reaches saturation, the sandstone continues to deform for a period of time before stopping hydration absorption. The results of the mercury injection test and the XRD test show that the porosity of the sparse area is larger than that of the dense area and the particle content of the dense area is lower. When the sandstone is saturated with water, the liquid is immersed in the pores between the solid particles, which makes the sparse area more prone to stress concentration, and the deformation in the sparse area is larger. Therefore, when analyzing the hydration absorption deformation of sandstone, the porosity should be considered. [ABSTRACT FROM AUTHOR]

The pore geometry and topology properties of rocks are significant for a better understanding of the complex hydrologic and elastic properties. If the complexity of porous media is considered, reliable results can achieve. In three-dimensional imaging of cavities, these complexities are taken into account. In this study, by conducting different methods deep understanding from some sandstones pore space is undertaken. Three series of 2D microcomputed tomography sandstones binary images have been considered, each of them imagined as a 3D binary image. Using novel skeletonization and pore-throat partitioning algorithms some network properties have been evaluated and compared for three cases. Those properties are pore and grain size distribution, throat length frequency, and coordination number frequency. Also, geometric measures in 2D and 3D have been considered using Minkowski functionals. The area, the perimeter and the 2D Euler number of 2D binary images and the volume, the surface area, the mean breadth also known as integral of the mean curvature, and the 3D Euler Number of 3D binary images are considered. [ABSTRACT FROM AUTHOR]

Sandstone reservoirs often contain clay particles that can cause damage and reduce permeability during low-salinity water flooding. In this study, the effect of surfactants on fine migration in clay-rich sandstones and its impact on oil recovery was investigated. First, the impact of surfactants on interparticle forces in fine-matrix, fine-fine, and oil-matrix systems was modeled. The results showed that both CTAB (cetyltrimethyl ammonium bromide) and QS (quillaja saponin) cause EDL compaction, weakening the repulsive forces. However, SDS (sodium dodecyl sulfate) and TX (triton X-100) do not affect the EDL. Next, the effect of surfactants on IFT reduction and wettability alteration was experimentally investigated. All surfactants reduced IFT due to the surface excessive concentration mechanism. The wettability alteration experiment illustrated that although QS and CTAB compact EDL around oil and matrix particles leading to attraction force augmentation, they both alter wettability through adsorption on matrix and carboxylic groups present in crude oil, respectively. Surfactant aqueous solutions were then injected into various clay-rich sandstone sanpacks, which resulted in increased oil recovery. However, the mechanisms leading to enhanced oil recovery variedby surfactant type. CTAB increased recovery by 10% through IFT reduction and wettability alteration, while SDS and TX increased recovery by 12% and 9%, respectively, through wettability alteration and extreme fine migration. In contrast, partial fine migration in the QS flooding experiment reached a recovery increase of 18%. Permeability trends through experiments were also recorded. During CTAB injection, permeability did not reduce, while QS aqueous solution reduced rock permeability to 5 mD. SDS and TX reduced the magnitude of permeability to 2 mD. In conclusion, this study demonstrates that surfactants can effectively improve oil recovery in clay-rich sandstones by altering the interparticle forces, reducing IFT, and changing wettability. The results suggest that the type of surfactant used should be carefully selected to achieve the desired recovery increase without affecting the permeability of the reservoir. [ABSTRACT FROM AUTHOR]

Reservoir sensitivity is a parameter that is used to evaluate the degree of change in reservoir permeability under the influence of external fluids. Accurate evaluation of reservoir sensitivity is conducive to the optimization of fluid parameters during exploration and development. Taking the Wenchang Formation and Enping Formation of the Paleogene in the Huilu area of the Pearl River Mouth Basin as the research object, reservoir sensitivity experiments were carried out. Combined with the corresponding experimental results obtained using methods such as thin section identification, scanning electron microscopy (SEM), X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), and screening analysis, based on mineral sensitization and pore structure sensitization, qualitative and quantitative evaluations of reservoir sensitivity were carried out, and factors affecting sensitivity and sensitization mechanisms were analyzed. This work shows the following: (1) The sandstone reservoirs in the two areas have the same clay type, but the total clay content of the Wenchang Formation is greater than that of the Enping Formation. The porosity of the Wenchang Formation is less developed than the Enping Formation. (2) The Wenchang Formation has weak or moderately weak water sensitivity and moderately weak or moderately strong flow velocity sensitivity. The water sensitivity of the Enping Group samples is moderately weak or moderately strong, the flow rate sensitivity is moderately weak, the alkali sensitivity is weak, the acid sensitivity is moderately weak, and the salinity sensitivity is moderately weak or moderately strong. (3) The sensitivity of the Wenchang Formation is mainly affected by the content of clay minerals. The sensitivity of the Enping Formation is also affected by the clay content and type. Although the clay content is not high, the permeability is more susceptible to sensitivity due to the pore structure and debris particle distribution characteristics. These conclusions are beneficial for the selection of fluid parameters and efficient reservoir development. [ABSTRACT FROM AUTHOR]

This paper demonstrates the importance of a proper contact algorithm selection when a constitutive model is correlated and validated, especially in the case of brittle materials. A parametric study is carried out to study the influence of contact parameters on the outcomes of the numerical simulations of a dynamic compression test. The split Hopkinson pressure bar (SHPB) model is developed, and sandstone rock is considered as a representative material having considerably different properties compared to SHPB bars. The finite element method (FEM) and smoothed particle hydrodynamics (SPH) were used to simulate specimen behaviour using a LS-Dyna solver. Two contact types based on the penalty method are analysed: nodes to surface (FEM and SPH) and surface to surface (FEM only). Furthermore, three approaches of contact stiffness calculation are used for each contact type. The waveform data and failure patterns are then compared among all simulated cases and the corresponding experimental outcomes. It is found that the soft constraint stiffness (SOFT = 1) provides the best outcomes, especially in the case of one-way contact, and is nearly insensitive to stiffness scaling parameters. By contrast, standard (SOFT = 0) and segment-based (SOFT =2) approaches require a substantial effort in adjusting the stiffness scaling parameters to obtain satisfactory results. This paper provides valuable guidance for correlating and validating parameters of constitutive models for rock and other brittle materials in the SHPB test. [ABSTRACT FROM AUTHOR]

The shallow river channel sandstone reservoirs of Jurassic in the western Sichuan Basin are rich in natural gas. The gas-bearing sweet-spot has a 'sausage-like' distribution feature, with complex gas water distribution. Analyses of seismic data at different angles show that gas-bearing reservoir formation has different seismic attenuation features from the water-bearing formations, and such differences have a certain correlation with gas production. Accordingly, a gas-bearing detection technology based on angle-dependent seismic attenuation feature is proposed. First, the matching-pursuit time-frequency analysis method is used to extract high-resolution time-frequency spectra from seismic data at different incidence angles. Then, the angle-dependent seismic attenuation attribute is estimated using the extracted time-frequency spectra. Finally, the attribute is combined with the inverted impedance for gas-bearing detection. With the advantages of lower uncertainty and being less affected by reservoir porosity, the application results of the developed method have a high coincidence rate with the drilled wells, and the drilling wells deployed based on the detection results have achieved high production. [ABSTRACT FROM AUTHOR]

The Sebei gas field is in the Sanhu depression area of the Qaidam Basin, which is the main gas-producing area and a key profit pillar for the Qinghai oilfield. The Sebei gas field within the Qinghai oilfield is characterized by high mud content, poor lithology, interflow between gas and water layers, and a propensity for sand production. The reservoir rocks are predominantly argillaceous siltstone with primarily argillaceous cement. These rocks are loose and tend to produce sand, which can lead to blockage. During its development, the Sebei gas field exhibited significant issues with scale formation and sand production in gas wells. Conventional acidization technologies have proven to be slow acting and may even result in adverse effects. These methods can cause loose sandstone to disperse, exacerbating sand production. Therefore, it is necessary to elucidate the mechanisms of wellbore plugging and to develop an acidizing system for plug removal that is tailored to unconsolidated sandstone reservoirs. Such a system should not only alleviate gas well plugging damage but also maintain reservoir stability and ensure efficient and sustained stimulation from acidization treatments. In this paper, the stability of unconsolidated sandstone reservoirs and the acid dissolution plugging system, along with the technological methods for stabilizing sand bodies, are studied through mineral component analysis, acid dissolution experiments, core immersion experiments, and other laboratory tests. The principle of synergistic effects between different acids is applied to achieve "high-efficiency scale dissolution and low sandstone dissolution". Three key indicators of dispersion, sand dissolution rate, and scale dissolution rate were created. The acid plugging solution formula of "controlled dispersion and differentiated dissolution" was developed to address these indicators. Laboratory tests have shown that the sandstone is predominantly composed of quartz and clay minerals, with the latter mainly being illite. The primary constituent of the wellbore blockage scale sample is magnesium carbonate, which exhibits nearly 100% solubility in acid. By adding a stabilizer prior to acid corrosion, the core's corrosion can be effectively mitigated, particle dispersion and migration can be controlled, and the rock structure's stability can be maintained. Laboratory evaluations indicate that the scale dissolution rate is greater than or equal to 95%, the sand dissolution rate is below 25%, and the system achieves a differentiated corrosion effect without dispersion for 24 h. Field tests demonstrate that the new acid solution plugging removal system enhances average well production and reduces operational costs. The system effectively mitigates the challenges of substantial sand production and reservoir dispersion, thereby furnishing a theoretical foundation and practical direction for acid plugging treatments in unconsolidated sandstone gas fields. [ABSTRACT FROM AUTHOR]

The deep rock mass within coal mines situated in a challenging environment are characterized by high ground stress, high geotemperature, high osmotic water pressure, and dynamic disturbances from mechanical excavation. To investigate the impact of this complex mechanical environment on the dynamic characteristics of roof sandstone in self-formed roadways without coal pillars, standard specimens of deep sandstone from the 2611 upper tunnel working face of the Yongmei Company within the Henan Coal Chemical Industry Group in Henan, China were prepared, and an orthogonal test was designed. Using a self-developed geotechnical dynamic impact mechanics test system, triaxial dynamic impact tests under thermal-hydraulic-mechanical coupling conditions were conducted on deep sandstone. The results indicate that under high confining pressure, deep sandstone exhibits pronounced brittle failure at low temperatures, with peak strength gradually decreasing as temperature and osmotic water pressure increase. Conversely, under low confining pressure and low temperature, the brittleness of deep sandstone weakens gradually, while ductility increases. Moreover, sandstone demonstrates higher peak strength at low temperatures under high axial pressure conditions, lower peak strength at high temperatures, and greater strain under low axial pressure and high osmotic water pressure. Increases in impact air pressure and osmotic water pressure have proportionally greater effects on peak stress and peak strain. Approximately 50% of the input strain energy is utilized as effective energy driving the sandstone fracture process. Polar analysis identifies the optimal combination of factors affecting the peak stress and peak strain of sandstone. Under the coupling effect, intergranular and transgranular fractures occur within the sandstone. SEM images illustrate that the damage forms range from minor damage with multiple fissures to extensive fractures and severe fragmentation. This study elucidates the varied dynamic impact mechanical properties of deep sandstones under thermal-hydraulic-mechanical coupling, along with multifactor analysis methods and their optimal factor combinations. [ABSTRACT FROM AUTHOR]

The Cerro Colorado Natural and Cultural Reserve, Córdoba, Argentina, is well known for its impressive rock paintings on sandstone formations. While previous research in the area has focused mainly on archaeological sites, this study aims to provide geomorphological data through an updated landform inventory and geomorphometric diversity index map, as the basis for managing the geo-cultural heritage area and potential sites for geo-tourism and geo-education. ALOS PALSAR DEMs at 12.5 m spatial resolution were used as a primary data source for mapping the study area. Features were digitally drawn into a geographical information system (GIS) and checked during a field survey. The results indicate that the landforms and points of geological interest give this region high geodiversity, which underlines the importance of including a geoperspective in the protection of nature and a sustainable use of the territory. The cavernous landforms contain native rock paintings, which make them unique in the region. The conservation of archaeological sites requires geomorphological knowledge in order to prevent degradation and loss of cultural and natural heritage. In addition to scientific interest, the history of the landscape through its geodiversity is relevant for educational, communicational, and geo-tourism purposes. [ABSTRACT FROM AUTHOR]

As global CO2 levels increase, the storage of CO2 in saline aquifers is considered a large-scale and cost-effective method for mitigating CO2 emissions. To examine the impact of cyclic CO2 injection on sandstone formations within various saline aquifers, five cyclic injections of differing durations were performed, and the effects of the frequency and duration of CO2 injection cycles on sandstone pore structure were monitored using nuclear magnetic resonance. Additionally, ICP-OES was employed to assess changes in the total dissolved solids and metal ion concentrations in the saline water layer post-injection. The findings reveal that sandstone samples experience structural degradation as a result of cyclic injection. Initially, the proportion of macropores in sandstone samples increases with the number of injections but subsequently decreases. SO42– ions exert a more significant influence on the sandstone pore structure compared to Cl−ions. The concentrations of Ca2+ and Mg2+ ions in the solution initially rise, followed by a subsequent decline. By integrating the principles of pore structure and considering the formation of crystals through the combination of metal cations and anions, the mechanism underlying the changes in sandstone pore structure due to cyclic injection is elucidated. This study explores the effects of CO2 cyclic injection on reservoir sandstone and evaluates how different saline aquifer types affect pore structure deterioration. The research offers valuable reference points and a foundation for laboratory investigations of underground CO2 storage in saline aquifers.

Due to lithological and environmental differences, the weathering degree of stone heritage varies even within the same area. Various factors dominate the weathering process at different stages. Implementing preventive measures has reduced the impact of controllable factors such as human activities. However, salt weathering caused by atmospheric pollutants, water, and salt migration in rock formations has emerged as a major contributor to the deterioration of stone heritage. Understanding the re-weathering characteristics of stone cultural heritage at different weathering degrees is crucial for preventive protection. This study investigated the weathering status of Nanshiku Temple and designed an experimental scheme based on field monitoring data. By controlling the number of freeze-thaw cycles, stones with different weathering degrees were prepared, and sulfate weathering simulations were conducted. The results revealed severe damage to sandstone due to Na2SO4 crystallization. Higher initial weathering degrees resulted in more pronounced deterioration and faster weathering rates. Surface hardness analysis approximated the decay process using a logarithmic function within a certain range but could not fully capture the overall weathering of the stone. Uniaxial compressive strength showed a strong correlation with weathering indices like p-wave velocity. These findings provide a theoretical basis for preventive protection efforts in stone cultural heritage.

Abstract Rockburst is a common geological hazard in deep underground engineering, and it often occurs in strata consisting of brittle rocks. In this study, the moisture content effect on the rockburst intensity of sandstones is systematically studied. A series of triaxial unloading compression tests along with the acoustic emission monitoring are performed for sandstone specimens with different moisture content levels. The mechanical properties, failure characteristics, and dilatancy behaviors of sandstone specimens are then properly compared. Comparative results reveal that the triaxial compressive strength and total strain energy of the saturated specimen decrease by about 30% and 35%, respectively, as compared to those of the dry specimen. Moreover, the magnitude of elastic strain energy tends to decrease with the increasing water content. The effect of moisture content on the rockburst intensity of sandstones is, therefore, significant. Besides, it is also found that the onset of dilatancy is generally unaffected by the water content, whereas the extent of dilatancy significantly decreases with the increasing water content. Numerical simulations for a tunnel excavation model confirm that injecting water into the surrounding rock is an effective way of reducing the rockburst intensity during tunnel excavations. These results have a guiding significance for the prevention and control of rockbursts in underground engineering.

Abstract I/II/III mixed mode fractures of intersecting joint fissures often occur in natural rock masses, and jointed rock masses are prone to rockbursts in deep underground engineering when subjected to long-term crustal stresses. However, most studies of the mechanical mechanisms of these intersected joints have been conducted by simplifying two-dimensional joint model tests. Furthermore, the fracture mechanisms of two-dimensional intersected joints under tension and compression are completely different from those of three-dimensional joints. This paper presents a novel prefabricated specimen with combinations of intersecting joints capable of detecting the failure behaviours of rock I/II/III mixed mode fractures under creep loading. Uniaxial compression and multistage creep tests are performed on prefabricated sandstone specimens with intersecting joints of 0°/0°, 0°/30°, 0°/60°, and 0°/90°. The experimental results show that with the increase in the number of prefabricated intersecting joints, the uniaxial compressive strength and elastic modulus values of the sandstone specimens gradually decrease. In addition, the sandstone specimens experience relatively few AE events and minor axial strain variations in the first creep stage and the second creep stage of the multistage creep test. The axial strain increases sharply due to the sharp increase in the number of AE events in the third creep stage. The 0°/60° sandstone specimen undergoes accelerated creep failure, resulting in mixed X-shaped tensile‒shear rupture. The RA value is high based on the quantification of the creeping cracks using the acoustic emission parameters of the rise angle (RA) and average frequency (AF). The AF values of the 0°/0°, 0°/30°, and 0°/90° sandstone specimens are high. The experimental results show that a larger joint intersection angle leads to greater mutual restraints and greater effects of prefabricated crack propagation in the rock specimens, thus increasing the final failure strength. Finally, based on the acoustic emission count, a characteristic variable D suitable for characterizing the creep damage evolution of a joint rock mass is established. The findings of this paper can facilitate an effective understanding of the creep effect of I/II/III mixed mode fracture and its micromechanism. The research results will have a certain reference value for the detection and risk mitigation of instantaneous and time-delayed rockbursts.

3D printing is widely adopted to quickly produce rock mass models with complex structures in batches, improving the consistency and repeatability of physical modeling. It is necessary to regulate the mechanical properties of 3D-printed specimens to make them proportionally similar to natural rocks. This study investigates mechanical properties of 3D-printed rock analogues prepared by furan resin-bonded silica sand particles. The mechanical property regulation of 3D-printed specimens is realized through quantifying its similarity to sandstone, so that analogous deformation characteristics and failure mode are acquired. Considering similarity conversion, uniaxial compressive strength, cohesion and stress–strain relationship curve of 3D-printed specimen are similar to those of sandstone. In the study ranges, the strength of 3D-printed specimen is positively correlated with the additive content, negatively correlated with the sand particle size, and first increases then decreases with the increase of curing temperature. The regulation scheme with optimal similarity quantification index, that is the sand type of 70/140, additive content of 2.5‰ and curing temperature of 81.6 ℃, is determined for preparing 3D-printed sandstone analogues and models. The effectiveness of mechanical property regulation is proved through uniaxial compression contrast tests. This study provides a reference for preparing rock-like specimens and engineering models using 3D printing technology.

Abstract Detrital composition of sandstone is the most important data for siliciclastic studies including sandstone classification, provenance analysis, oil and gas exploration. A large amount of detrital composition data has accumulated over the past decades, however, they are scattered in publications without unified standards. Here we constructed a global dataset of detrital components of sandstones from 646 peer‐reviewed publications using Gazzi‐Dickinson method. A total of 19,861 samples from Precambrian to Quaternary are involved in this dataset. For each sample, we present details on reference information, geographic information, geological background, depositional age and the original data. It is a high‐quality dataset for the information on each sandstone sample from different studies which was standardized. The dataset can be used widely, such as for stratigraphic comparison, provenance analysis, exploring the general laws of the source‐to‐sink process and geological engineering.