Rock Particle Size Research Articles

Prediction of Capillary Pressure Curves Based on Particle Size Using Machine Learning

Capillary pressure curves are usually obtained through mercury injection experiments, which are mainly used to characterize pore structures. However, mercury injection experiments have many limitations, such as operation danger, a long experiment period, and great damage to the sample. Therefore, researchers have tried to predict capillary pressure data based on NMR data, but NMR data are expensive and unstable to obtain. This study aims to accurately predict capillary pressure curves. Based on rock particle size data, various machine learning methods, such as traditional machine learning and artificial neural networks, are used to build prediction models and predict different types of capillary pressure curves, aiming at studying the best prediction algorithm. In addition, through adjusting the amount of particle size characteristic data, the best amount of particle size characteristic data is explored. The results show that three correlation coefficients of the four optimal algorithms can reach more than 0.92, and the best performance is obtained using the Levenberg–Marquardt method. The prediction performance of this algorithm is excellent, with the three correlation coefficients being all higher than 0.96 and the root mean square error being only 5.866. When partial particle size characteristics are selected, the training performance is gradually improved with an increase in the amount of feature data, but it is far less than the performance of using all the features. When the interpolation increases the particle size characteristics, the best performance is achieved when the feature data volume is 50 groups and the root mean square error is the smallest, but the Kendall correlation coefficient decreases. This study provides a new way to obtain capillary pressure data accurately.

Numerical and experimental studies on the motion and deposition of collapsing rock clusters: Effect of rock particle sphericity

In this paper, a series of experimental and numerical tests are carried out to study the effect of rock particle sphericity on the motion and deposition of collapsing rock clusters. To this end, three kinds of typical rock particles with different sphericity (i.e., pebble, rubble and block) are used for experiments and a special laboratory setup that involves a chute with two inclined sections is designed to reproduce their natural motion. Then, a three-dimensional modelling of collapsing rock cluster incorporating rock particles with different sphericity is developed using spherical harmonics function reconstruction. The sphericity of particle effect on the motion and deposition of rock cluster is studied experimentally and numerically in terms of the average velocity and deposition zone. There has a good agreement between them. In addition, some potential factors such as rock particle size, cluster mass and component are investigated and discussed. The obtained results may facilitate the current knowledge on the dynamic behavior of collapsing rock clusters effect of particle sphericity.

The Effect of Volcanic Stone and Metakaolin on the Compressive Properties of Ultrahigh-Performance Concrete Cubes

Over the past few decades, ultrahigh-performance concrete (UHPC) has been widely studied and applied because of its outstanding mechanical properties, such as its high strength and notable durability. However, because of its high cost and easy shrinkage cracking during early pouring in mass concrete construction, to reduce the cost of UHPC and reduce the cracks caused by early pouring, volcanic stone was used as a new type of UHPC coarse aggregate, while metakaolin (MK) was added to the system at the same time, and then two parameters, namely the volcanic rock particle size group and the MK dispersion ratio, were set. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric (TG) microanalysis methods were used to reveal the influence of changes in the material microstructure, phase composition, material composition and crystallinity of the mineral composition on the compressive properties of the UHPC cubes. The results show that the mechanical “lock-in effect” of the structure formed by the volcanic rock holes and mortar can effectively improve the shear resistance of the UHPC–volcanic rock interface, and the compressive strength of the UHPC cubes increases with the volcanic stone’s particle size. When the MK dispersion ratio is less than 4%, the cube compressive strength of the UHPC and the contents of CaCO3 crystals, C-S-H gel and travertine in the UHPC increase with an increasing MK dispersion ratio. At an age of 28 days, compared with the addition of 1% MK, the addition of 4% MK increases the production of C-S-H gel and travertine in the UHPC matrix by 24.82%. When the MK dispersion ratio is 4%, the crystallinity values of the C-S-H gel, travertine and limestone in the UHPC are greater. Adding MK at a 4% dispersion ratio can promote the crystallization of limestone into a large amount of calcite, which can increase the strength of UHPC. On the one hand, the addition of volcanic coarse aggregate results in the retention of more free water and bound water; on the other hand, it also makes it difficult to crystallize CaCO3. The combined action of MK at a 4% dispersion ratio and volcanic rock significantly inhibits CaCO3 crystallization.

Prevention and suppression of coal dust explosion in underground coal mines: Role of rock dust type, particle size, proportion, concentration, and thermal properties

Rock dust inertant is commonly used for prevention and suppression of coal dust explosion in underground coal mines. The effects of rock dust type, proportion, particle size, thermal conductivity, and specific heat capacity on minimum ignition temperature (MIT) of coal-rock dust mixtures and intensity of explosion propagation under different experimental conditions were examined using Godbert-Greenwald furnace integrated with a high-speed camera. MIT of coal-rock dust mixtures significantly increased with increase in rock dust proportion. With decrease in particle size from < 850 to < 75 µm, the mean MIT increased from 616 to 657 °C and 627 to 665 °C for dolomite and limestone dust, respectively. With increase in dust concentration from 500 to 3000 g/m3, the ignition temperature (IT) of coal-rock dust mixtures decreased by 28 % and 30 % for dolomite and limestone dust, respectively. Moreover, the MIT significantly increased with increase in thermal conductivity and specific heat capacity of coal-rock dust mixtures. Limestone dust proved to be a better explosion suppressant compared to dolomite dust.

Цифровые технологии для взрывных работ: интеллектуальный автономный программно-аппаратный комплекс компании «ДАВТЕХ» для анализа гранулометрического состава горных пород

Rock blasting is the first stage of rock crushing and it plays a defining part in the process chain of mining and processing of minerals. The difficulties in correlating the data on particle size distribution in the muck pile with the blast, the rock properties and the energy characteristics of explosives define the need to solve a wide range of scientific and practical tasks. Contemporary approaches to optimizing the particle size distribution ("fragmentation") are based on considering the energy efficiency of explosives and controlled distribution of the blast energy during the blast. At the current development stage of digital technologies in the mining industry, the qualitative and quantitative characteristics in assessing the particle size distribution are determined with the help of tools that estimate the size of the rock pieces by analyzing two- or three-dimensional images obtained by various technical means. The authors of the article present a study of the rock particle size distribution analysis based on digital technologies using a Russian innovative hardware and software suite developed by the DAVTECH Company. During a full-scale study the authors confirmed that the hardware and software suite ensures satisfactory results for a preliminary assessment of blasting operations due to faster sampling using a fully autonomous system, and it provides reliable information and allows visualizing and comparing the data of a large number of measurements. The studied hardware and software suite also secures improved safety by eliminating manual sampling directly at the muck pile, thus avoiding work in high-risk areas.

Research and analysis of the impact of the pore structure on the mechanical properties and fracture mechanism of sandstone

Rock pore structure, including porosity, pore size, and particle size, plays a crucial role in determining rock mechanical properties. This study investigates the impact of pore structure on rock mechanical properties through laboratory experiments and numerical simulation methods on sandstones with varying porosity and pore size. The pore structure characteristics of sandstone were determined using XRD, SEM, and NMR microscopic techniques. Additionally, the influence of rock porosity on rock mechanical properties was analyzed by combining Uniaxial compression test with DIC technology, revealing the fracture mechanism caused by porosity in rocks. Numerical models were constructed to simulate sandstones with different porosities and pore diameters, followed by uniaxial compression simulation tests to explore the influence of varying pore diameters on rock mechanical properties and the fracture mechanism. The study reveals the presence of four distinct pore types in the sandstone: micropores in the matrix (0–0.002 µm), intergranular pores (0.002–0.2 µm), dissolution pores (0.2–4 µm), and fracture pores (4–30 µm). Among these, intergranular pores and dissolution pores are the predominant types, accounting for approximately 92–96% of the total pore volume in the sandstone. It is observed that an increase in porosity leads to a decrease in the mechanical strength of sandstone and an increase in Poisson's ratio while keeping the pore size constant. Similarly, when the porosity remains constant, an increase in pore size results in a decrease in the mechanical strength and an increase in Poisson's ratio. Additionally, the study also finds that as the porosity and pore diameter of sandstone increase, the area of internal equivalent stress expands, leading to a shorter crack initiation time and accelerated crack penetration speed, ultimately resulting in a decline in the mechanical properties of sandstone. Numerical simulation experiments further demonstrate that large pores exhibit higher stress concentration compared to small pores, thereby exerting a more significant influence on the mechanical properties of sandstone.

Theoretical evaluation on CO2 removal potential of enhanced weathering based on shrinking core model

The discrepancy between current CO2 emission trend and the targeted 1.5 °C warming requires the implementation of carbon dioxide removal (CDR) technologies. Among the engineered CDRs, enhanced weathering (EW) is expected to exhibit substantial potential for CO2 removal, owing to the availability of abundant reserves of ultramafic rocks and demonstration of worldwide liming practice. While the shrinking core model (SCM) has been commonly adopted in previous theoretical and experimental studies, there still lacks a comprehensive assessment on the impacts of model parameters, such as rock particle size, size distribution, weathering rate and time length on the weathering kinetics and the resultant CDR potential. Herein, this study incorporates particle size distribution of rock powder into the surface reaction-controlled SCM, and conducts sensitivity analysis on EW’s CDR potential quantitatively. Even fully powered by low-carbon energy in the optimistic case, the application of EW with olivine only achieves maximum CDR per unit of rock and energy consumption of 0.01 kg CO2 per kg rock and 19 g per kWh at size of 8 and 22 μm respectively, indicating the limitations of EW. The derived optimal application parameters with olivine powers within 3.7–79 μm provide valuable insights into the practical real-world applications to achieve net CO2 removal.

Coupled CFD-DEM simulation and experimental study of particle distribution and accumulation during tailings seepage process

The movement of tailings particles in waste rock systems under different flow rates was studied using experimental and numerical methods, aiming to provide theoretical guidance for preventing particle infiltration. The research results established a calculation relationship between pressure drop, porosity, and waste rock thickness. They also revealed the self-similarity of blockage accumulation within the waste rock. The overall study indicates that smaller particles can pass through the waste rock, but larger particles face greater difficulties. It becomes highly challenging for particles to pass through when they exceed the pore spaces between the largest waste rock particles. The distribution pattern of blockage decreases gradually from the upper part to the lower part of the waste rock pile, with proportions of blockages at different depths being 35.2%, 22.7%, 15.5%, 15%, and 11.6%. The study also examined the cumulative distribution of tailings particles passing through the waste rock under varying flow velocities (0.2 m/s, 0.3 m/s), showing that the quantity of tailings particles passing through the waste rock at 0.3 m/s is approximately 1.15 times that at 0.2 m/s. Additionally, the effectiveness of using geotextile for sealing was investigated, providing theoretical support for determining the application of waste rock particle size, thickness, and geotextile in sealing tailings particles. Moreover, understanding the self-similarity and velocity variation patterns of particles helps in selecting suitable waste rock characteristics.

Enhanced U-Net model for rock pile segmentation and particle size analysis

Segmenting blasted stockpile particles in open-pit mines is essential for improving mining operations. However, complex rock textures often challenge traditional segmentation models. This paper presents an enhanced U-Net model that leverages depth-separable convolution and feature depth concatenation to enhance segmentation performance while reducing model complexity and training time. We evaluate our model on a homemade open pit burst pile ore segmentation dataset and report an average accuracy improvement of 1.53 % over the U-Net model. Our work contributes to the field of mining engineering and shows the potential of deep learning methods to improve mining operations.

Study on hard rock particle size division based on Mars rover traction performance

To simplify the dynamic solution of the contact between the rigid wheel of Mars rover and the spherical hard stone on the mixed terrain, a model for hard stone particle size division based on the traction performance of Mars rover is proposed. On the mixed terrain of hard rock and soft soil, the movement of hard rock will affect the traction performance of the rigid wheels of Mars rover. According to the different effects of the hard stones on the traction performance of rigid wheels, stones are divided into three types. The static sinkage of rigid wheels is calculated according to the Bekker bearing model, and the calculation formula of sliding sinkage of rigid wheels and hard stone sinkage is proposed. The type of hard stones is determined by comparing the sinkage of hard stones and rigid wheels. Finally, three kinds of hard stones with slip ratios of 0.2, 0.5, and 0.7 were substituted into the single wheel simulation platform and the soil trough experiment platform for simulation and experiment. The results show that on mixed terrain, the error of simulation and experimental results of fixed hard stones under three slip rates is below 5.4%, the error of drawbar pull in simulation and experimental results of movable hard stones is above 126%, and the error of simulation and experimental results of scattered small hard stones is below 2%, which verifies the effectiveness of the hard stone particle size division model.

A coupled model of asymmetric GIMP and tetrahedron CPDI based on the penalty contact algorithm for simulating dynamic rock splitting

A coupled material point model (MPM) based on the asymmetric generalized interpolation material point (aGIMP) and the tetrahedron convected particle domain interpolation (CPDI-Tet4) was established to simulate the dynamic splitting of a rock Brazilian disc under small deformation. Furthermore, a boundary-based contact algorithm was developed to accurately describe the contact force between the split bar's aGIMP particles and the rock's CPDI-Tet4 particles. The proposed aGIMP technology enabled particles to move on a non-uniform background grid by changing the original basis functions. A good simulation effect was achieved. It was concluded that the rock particle size plays an important role in the accuracy of the contact algorithm. Two shear failure bands were generated near the contact zones first after the rock specimen reached the force equilibrium state, and then the four arc fracture surfaces grew from the two sides of the shear failure bands and coalesced to a radial fracture surface on the mid-cross section of the specimen. In addition, the tensile strength calculated by the MPM model exhibited the typical rate effect of rock material and was slightly lower than the practical tensile strength of the particle on the radial fracture surface.

Discussion and application of ball mill in preparation of particle size samples of fine grained sedimentary rocks

The grain size of clastic rocks is one of the most important structural characteristics of clastic sediments, which can directly reflect the hydrodynamic conditions of ancient sedimentary period. The preparation of conventional clastic rock particle size samples is usually done by hand wet grinding with a grinding hammer by experienced experimenter. For the fine-grained sedimentary rocks, the conventional method for preparing grain size samples has the disadvantages of long time and low efficiency. This paper introduces a method of preparing grain size samples of fine grained sedimentary rocks by separating rock particles with ball mill. By carrying out the experiments of separating rock particles by ball mill, the influence of different sample quality and ball mill parameters on the particle size and particle size distribution of fine grained sedimentary rock in the process of rock particle fragmentation by ball mill was discussed. The conditions for separating particles of fine grained sedimentary rocks by ball mill are determined as follows: sample mass is 0.14 g ~ 0.20 g, ball mill frequency is 10 Hz, ball milling time is 3 min, the efficiency of particle size sample preparation is greatly improved. The final particle suspension samples were tested by laser particle size analyzer, and the particle size distribution characteristics of fine-grained sedimentary rocks were given, which provides a basis for the study of lithology classification, lithofacies characteristics and hydrocarbon reservoir heterogeneity, and plays an important role in the exploration and development of unconventional oil and gas.

Formation Timing and Features of Stylolites and Controlling Factors for the Second-Period Stylolites in the Carboniferous KT-I Formation of NT Oilfield

The formation timing of stylolites, which is of great importance for analyzing the controls of stylolites, has nearly never been examined. In this paper, based on the data of cores, imaging logging, conventional logging, and mercury injection, the characteristics of stylolites formed in different stages of tectonic movement were investigated, and the controlling factors of oil-stained stylolites, formed in the second period of tectonic movement, were analyzed in particular. Furthermore, the influence of different controlling factors on the development of stylolites was compared, by using grey correlation analysis. The results show that there are three periods of stylolites in the study area, and all three periods developed both low-angle stylolites and high-angle stylolites. The prominent characteristics of both the low-angle and high-angle stylolites of the second period, are being oil-stained. The higher the structural location, the greater the buried depth, the lower the dolomite content, the higher the calcite content, the higher the clay content, the smaller the rock density, the greater the porosity, the smaller the rock grain size, the easier it is to develop both the low-angle stylolites and the high-angle stylolites. The influence of different controlling factors on the development of low-angle stylolites is given by depth, porosity, curvature, rock density, rock grain size, clay content, dolomite content, and calcite content, in this order. The importance of the influences on the development of high-angle stylolites proceeds as follows: curvature, calcite content, depth, rock particle size, clay content, rock density, dolomite content, and porosity. Tectonism is the most important influencing factor on the development of stylolites.

Influence of Different Particle Size and Rock Block Proportion on Microbial-Solidified Soil–Rock Mixture

This paper focuses on the influencing factors of MICP solidification of soil–rock mixture. After selecting the best soil–rock ratio through screening, the MICP process is tested from two aspects of rock content and particle size. The results show that the soil–rock mixture is not a uniform carrier of the medium, and the force on the surface of the sample is not uniform. With the increase in stress load, the stress–strain curve shows a sawtooth upward trend and peak value. The microbial cemented soil–rock mixture had a particle size of 0.2–0.4 cm and 0.4–0.6 cm under the rock block proportion of 50%. The unconfined compressive strength of the microbial cemented soil–rock mixture with a rock particle size of 0.6–0.9 cm reaches the highest at 60% rock block proportion. When the rock content is 20–50%, the unconfined compressive strength decreases with the increase in particle size. When the rock content is 60%, the value of unconfined compressive strength first decreases and then increases with the increase in particle size; both SEM and XRD test results proved that Sporosarcina pasteurii could effectively induce the formation of calcium carbonate and crystallizes at the pores of the particles to improve the mechanical properties of the soil.

Fracturing criterion of rock hydrofracturing considering pore pressure effect

Traditional hydraulic fracturing theory believes that as the initial pore pressure increases, the breakdown pressure of the rock will decrease. Previous experimental studies have shown that the breakdown pressure of rock hydraulic fracturing may increase with the increase of initial pore pressure (gradient), which cannot be explained by traditional theory. The current understanding of the effect of pore pressure and its gradient during hydraulic fracturing is still unclear. In this study, the pore pressure effect of rock hydraulic fracturing is analyzed based on a large number of macroscopic and microscopic phenomena of rock hydraulic fracturing in the previous study. Then, a new fracture criterion of rock fracturing is built considering the pressure-gradient effect. This new fracture criterion can reflect the main influence factors, including the rock particle size, porosity, pumping flow, inner diameter of open hole section, length of main fracture, height of main fracture (or length of open hole section), fluid viscosity, pore pressure, minimum initial in situ stress and rock tensile strength. The new fracture criterion is examined by the rock fracturing experiment which considering the pressure-gradient effect. The results show that the proposed fracture criterion considering the pore pressure effect can well predict the breakdown pressure of rock, and the prediction trend is consistent with the experimental results. The average error is less than 1% when adopting the present fracture criterion. The parameter sensitivity of the fracture criterion is analyzed. Results show that the fracture pressure increases with the rock porosity and this trend becomes more apparent with a larger initial pore pressure. It shows that the fracture pressure increases with the pumped flow rate. Besides, it shows that the fracture pressure decreases when increasing the particle size of the rock, but the decreasing trend gradually slows down. The research results can provide a theoretical basis for the mechanism of rock hydraulic fracturing and the structural modification effect of fluids in rock engineering.

Investigation on the erosion and deposition process of granular collapse flow on an erodible inclined plane

The occurrence of slope disasters mainly depends on the terrain slope, size and amount of soil and rock particles, and the presence of heavy rain. If particles erode and entrain soil and rock in the bottom bed as they flow after the slope collapse, a massive avalanche can occur, threatening human life and causing substantial property damage. We employed an experimental approach to investigate the effects of the particle size of granular beds (including column and erodible beds) and the initial aspect ratio on their erosion and deposition behavior in granular collapse flows. We found that the erosion area increases when the particle size of the column bed increases, whereas the particle size of the erodible bed remains the same. The final erosion area increases slightly when the initial aspect ratio increases, and subsequently decreases as the initial aspect ratio increases in the presence of a bigger particle size of the erodible bed. However, when the particle size of the erodible bed is smaller than that of the column bed, the final erosion area increases significantly as the aspect ratio increases. Furthermore, we explored the flow trends of the column and erodible bed particles over time at different locations. For different particle sizes of the erodible bed, the potential energy loss of the column bed may be transformed into erosion of the erodible bed, or may be lost due to the friction and collisions between particles, and thus cannot cause significant variation in erosion behavior.

Coupled GIMP and CPDI material point method in modelling blast-induced three-dimensional rock fracture

Three-dimensional rock fracture induced by blasting is a highly complex problem and has received considerable attention in geotechnical engineering. The material point method is firstly applied to treat this challenging task. Some inherent weaknesses can be overcome by coupling the generalized interpolation material point (GIMP) and the convected particle domain interpolation technique (CPDI). For the media in the borehole, unchanged GIMP-type particles are used to guarantee a homogenous blast pressure. CPDI-Tetrahedron type particles are employed to avoid the fake numerical fracture near the borehole for the rock material. A blasting experiment using three-dimensional single-borehole rock was simulated to examine the applicability of the coupled model under realistic loading and boundary conditions. A good agreement was achieved between the simulation and experimental results. Moreover, the mechanism of three-dimensional rock fracture was analyzed. It was concluded that rock particle size and material parameters play an important role in rock damage. The reflected tensile waves cause severe damage in the lower part of the model. Rayleigh waves occur on the top face of the rock model to induce a hoop failure band.

Experimental Simulation Study of Mine Water Acidification under the Action of Pyrite

The discharge of acidic water has become an environmental issue of great concern worldwide. In order to investigate the characteristics and mechanism of acidic water induced by pyrite in sulfur-rich mines, indoor static precipitation and dynamic leaching simulation experiments were carried out under the conditions of pyrite content, rock particle size, media combination, and ambient temperature. At the same time, this paper used the gray correlation method to quantitatively analyze the influencing factors. The results showed that the degree of groundwater acidification was negatively correlated with the rock particle size and temperature and positively correlated with the pyrite content. The quantitative analysis of the effect of each factor on acid mine drainage pH was pyrite content &gt; temperature &gt; rock size. When considering different media conditions, the combined effect of the three media on reducing the acidification degree of mine water was limestone &gt; gangue &gt; coal. In addition, dynamic leaching and static soaking have different effects on the acidification of the mine water, with the latter acidifying more rapidly. It is also concluded that although pyrite enrichment was the main controlling factor affecting the acidification of mine water in nature, complexation of trivalent iron ions adsorbed in the formation was more likely to be the main causal mechanism for the rapid acidification of mine water in coal mining areas.

Multilevel Structural Characteristics of Jinshajiang Main Fault and Its Influence on Engineering

It is of great significance to study the geological characteristics of faults and the corresponding displacement patterns for the tunnel engineering crossing active faults. On the basis of field investigation and geological data analysis, it is found that the secondary weak structures, such as narrow cleavage bands, narrow joint bands, fault gouge zones, and small folds, often appear in the fault fracture zones and affected zones. The multilevel structure of fault is proposed from mechanics and engineering by summarizing their main characteristics. Taking the outcrop of fracture zones of Batang section, Jinshajiang main fault in the Qinghai-Tibet Plateau as the research object, the geometric characteristics of rock masses, the particle size, mineral composition, and mechanical characteristics of rocks in the fault are studied through field investigation, geological mapping, mineral composition analysis, and mechanical tests. In addition, a displacement model of multilevel structure fault is presented by numerical simulation. The results show that the Jinshajiang main fault comprises a primary structure and several secondary weak structures, which has a typical structure of multilevel fault. There are several secondary weak structures in the outcrop of the fracture zone. Compared with the rock masses in the primary structure, the joints of the rock masses in the secondary weak structure are more developed, and the rock particle size is smaller, the mud content is higher, and the mechanical strength is lower. The geometric morphology, mineral composition, and mechanical properties of the rock masses in the secondary weak structure are obviously different from those of the primary structure. The overall displacement mode of multilevel structural fault is S-shaped distribution, and the secondary weak structure will affect the displacement distribution pattern and have the possibility of sliding when the fault moves. Therefore, the secondary weak structure section in the tunnel should be a priority for prevention and control when designing tunnels through active faults. The multilevel structure of the fault, together with centralized structure, distributed structure, and stepped structure of the fault, can be used as a structure classification method of fault structure, which provides a reference for the study of disaster mechanisms, and prevention and control measures of tunnels crossing active faults.

Microscopic sand production simulation and visual sanding pattern description in weakly consolidated sandstone reservoirs

To visually describe the sanding pattern, this study constructs a new particle-scale microstructure model of weakly consolidated formation, and develop the corresponding methodology to simulate the sanding process and predict sand cavity shape. The microstructure model is a particle-objective model, which focuses on the random sedimentation of every sand grain. In the microstructure, every particle has its own size, sphericity and inclination angle. It is used to simulate the actual structure of cemented granular materials, which considers the heterogeneity and randomness of reservoir properties, provides the initial status for subsequent sanding simulation. With the particle detachment criteria, the microscopic simulation of sanding can be visually implemented to investigate the pattern and cavity shapes caused by sand production. The results indicate that sanding always starts initially from the borehole border, and then extends along the weakly consolidated plane, showing obvious characteristic of randomness. Three typical microscopic sanding patterns, concerning pore liquefaction, pseudo wormhole and continuous collapse, are proposed to illustrate the sanding mechanism in weakly consolidated reservoirs. The nonuniformity of sanding performance depends on the heterogeneous distribution of reservoir properties, such as rock strength and particle size. Finally, the three sanding patterns are verified by visually experimental work. The proposed integrated methodology is capable of predicting and describing the sanding cavity shape of an oil well after long-term sanding production, and providing the focus objective of future sand control measure.