3D Fracture Research Articles

Numerical simulation of 3D fracture propagation problem with reproducing kernel peridynamic method

The non-ordinary state-based peridynamic (NOSB-PD) method has significant advantages in solving crack propagation problems due to its non-local characteristics, but it also faces problems such as numerical oscillations and boundary effects. In order to solve the above defects, the paper first discusses the NOSB-PD method within the Galerkin framework. After that, the peridynamic differential operator (PDDO) approximation was introduced by extending the calculation of the deformation gradient tensor F in NOSB-PD. Since the zero-order approximations in the PDDO approximation and the reproducing kernel (RK) approximation are identical, the distinctions between the two approximations have been thoroughly analysed. Although the two approximations show the same consistency, only the RK approximation satisfies the integrable condition. Therefore, a RK-PD coupling method is proposed in the paper, and an implicit iterative algorithm suited to the RK-PD method is presented as well. At last, several numerical examples demonstrate that the proposed method does not suffer from numerical oscillations and can be used to solve the three-dimensional crack propagation problems.

Effects of Dead‐End Fractures on Non‐Fickian Transport in Three‐Dimensional Discrete Fracture Networks

AbstractUnderstanding mechanistic causes of non‐Fickian transport in fractured media is important for many hydrogeologic processes and subsurface applications. This study elucidates the effects of dead‐end fractures on non‐Fickian transport in three‐dimensional (3D) fracture networks. Although dead‐end fractures have been identified as low‐velocity regions that could delay solute transport, the direct relation between dead‐end fractures and non‐Fickian transport has been elusive. We systematically generate a large number of 3D discrete fracture networks with different fracture length distributions and fracture densities. We then identify dead‐end fractures using a novel graph‐based method. The effect of dead‐end fractures on solute residence time maximizes at the critical fracture density of the percolation threshold, leading to strong late‐time tailing. As fracture density increases beyond the percolation threshold, the network connectivity increases, and dead‐end fractures diminish. Consequently, the increase in network connectivity leads to a reduction in the degree of late‐time tailing. We also show that dead‐end fractures can inform about main transport paths, such as the mean tortuosity of particle trajectories. This study advances our mechanistic understanding of solute transport in 3D fracture networks.

Fluid flow and mass transport in fractured media with curved fractures and varying apertures: A 3D modeling approach

AbstractFractured media have been extensively studied due to their significant impact on hydraulic properties of subsurface systems. However, accurately modeling and simulating flow and transport in complex 3D fractured media still remains a challenge. For this purpose, this work aims to develop a new 3D modeling approach and investigate flow and mass transport in fractured media. First, a modeling approach is presented for generating 3D complex structures and high quality finite element grids. This approach allows for the presence of a range of complex geometries, including curved fracture, multiple fractures and the coexistence of fracture‐inclusions. The resulting models and grids are of high quality, enabling accurate simulation and analysis of complex systems. Furthermore, stress‐dependent aperture and roughness are integrated in the computational scheme using Barton–Bandis law. The Galerkin finite element method is used for numerical discretization, then pressure and concentration are calculated in a unified formulation. Later, numerical tests are performed to analyze the role of 3D fractures in flow and mass transport. Simulation results show that fractures have a larger impact on pressure distribution and flow rate compared to inclusions. Fracture roughness increases the aperture then the effective conductivity is improved as well. Curved fractures may reduce flow rate more than planar fractures due to the tortuosity effect. The variation of equivalent permeability tensor is analyzed with varying orientation, roughness, and number of fractures. The impact of stress and fracture roughness causes a variation of fracture permeability and a high pressure gradient on the fracture‐matrix interface, resulting in different patterns of concentration evolution. Overall, this investigation provides insights into the role of 3D fractures in subsurface flow and transport, with implications for various applications.

3D fractures analysis and conservation assessment of wrought iron javelin through advanced non-invasive techniques

3D imaging is a powerful tool of high resolution and non-destructive imaging technology for the study of ancient weapons and military technology, which reveals the original microstructures and corrosion patterns that threaten these artefacts. Here we report quantitative analysis of the 3D distribution and the orientation of fractures, and uncorroded metal particles within a wrought iron javelin unearthed at the Phoenician-Punic site of Motya, Italy. The study aimed to gain a better understanding of the relationship between corrosion and local stresses within the artifact and to evaluate its manufacturing technology, as well as the effects of post-treatment with Paraloid B72 on concretion and mineralized layers. The cracks were quantified in terms of content, size, and orientation. The condition of artefact storage was evaluated by a multi-analytical approach, including X-ray microscopy, field emission electron microscopy and micro-Raman spectroscopy. The results indicated that a specific technique was used to create a sturdy, lightweight javelin with a central shaft for piercing or thrusting. The fractures appear elongated in the direction of the longitudinal axis of the blade, showing the forging direction of the original metallic block. The study concluded that the artifact had not yet been stabilized due to the presence of lepidocrocite.

A novel voxel-particle energy approach to predict 3D microscopic fracture surface of porous geomaterials and fracture permeability modeling

Characterizing and predicting 3D microscopic fractures are rarely reported due to the challengeable difficulty to determine its spatial trajectories. In this study, a double threshold segmentation algorithm is proposed to obtain 3D microstructure models of porous geomaterials by X-ray computing tomography (CT) images. A novel voxel-particle energy (VPE) approach is proposed to predict 3D fracture characteristics, and fracture permeability modeling is conducted. Results show that excellent agreements are found between the experimental and numerical results, showing the accuracy of proposed VPE method. As dynamic viscosity increases, microscopic fracture permeability increases. Microscopic fracture permeability decreases with increasing input pressure, and it increases with increasing voxel scale. The proposed VPE method provides an effective tool to predict 3D cracks and its spatial trajectories, which is helpful for the deep resource and underground space development.

Quantitative Evaluation of the Fracturing State of Crystalline Rocks Using Infrared Thermography

The fracturing state of rocks is a fundamental control on their hydro-mechanical properties. It can be quantified in the laboratory by non-destructive geophysical techniques that are hardly applicable in situ, where biased mapping and statistical sampling strategies are usually exploited. We explore the suitabilty of infrared thermography (IRT) to develop a quantitative, physics-based approach to predict rock fracturing starting from laboratory scales and conditions. To this aim, we performed an experimental study on the cooling behaviour of pre-fractured gneiss and mica schist samples, whose 3D fracture networks were reconstructed using Micro-CT and quantified by unbiased fracture abundance measures. We carried out cooling experiments in both controlled (laboratory) and natural (outdoor) environmental conditions and monitored temperature with a thermal camera. We extracted multi-temporal thermograms to reconstruct the spatial patterns and time histories of temperature during cooling. Their synthetic description show statistically significant correlations with fracture abundance measures. More intensely fractured rocks cool at faster rates and outdoor experiments show that differences in thermal response can be detected even in natural environmental conditions. 3D FEM models reproducing laboratory experiments outline the fundamental control of fracture pattern and convective boundary conditions on cooling dynamics. Based on a lumped capacitance approach, we provided a synthetic description of cooling curves in terms of a Curve Shape Parameter, independent on absolute thermal boundary conditions and lithology. This provides a starting point toward the development of a quantitative methodology for the contactless in situ assessment of rock mass fracturing.

A new implicit gradient damage model based on energy limiter for brittle fracture: Theory and numerical investigation

We present a general form of the gradient-enhanced damage theory and its numerical implementation using finite element method (FEM) in modeling quasi-static brittle crack growth in one- (1D), two- (2D) and three-dimensional (3D) bodies. Coupled equations of the equilibrium and a new implicit gradient damage formulation are introduced to govern the deformation of the solid and evolution of the damage. The resulting nonlocal damage evolution equation featuring the growth of diffusive crack is integrated with a characteristic length scale to eliminate the common mesh-bias issue in FEM implementation. In contrast to the traditional gradient-enhanced damage approaches, the nonlocal damage field here is defined as the primary variable of the damage evolution equation without interpolation mismatch between the displacement and nonlocal damage fields. For derivation of the material constitutive law and local damage parameter, a novel strain energy density (SED) function based on the energy limiter theory for brittle crack growth problems under small strain regime is introduced. To further improve the performance of the developed model, an initial SED threshold, which is used for determining the critical point when damage starts to initiate in the material, is integrated into the novel energy limiter theory. For preventing nonphysical failure in compression domains, the spectral decomposition technique for the strain tensor is adopted to split the reference SED. With integrating the energy limiter into the developed theory, unlike the conventional nonlocal damage theories where the interpretation of the length scale is still ambiguous, the developed nonlocal damage model defines the length scale parameter as the problem-dependent factor. The performance and ability of the proposed model are demonstrated via a set of representative numerical examples in 1D, 2D and 3D fracture problems.

A global inertial permeability for fluid flow in rock fractures: Criterion and significance

Fluid flow in rock fractures is described by Darcy's law and its nonlinear extension, the Forchheimer equation in form of a quadratic polynomial. Since the nonlinearity of the Forchheimer equation, determining its key coefficient of inertial permeability (i.e., the quadratic coefficient representing inertial losses) requires a series of flow tests under different hydraulic gradients. However, how to choose the volumetric flux range for deriving inertial permeability is never scrutinized. Here we report a seemly irrational dependency of inertial permeability on volumetric flux range by massive direct numerical simulations of fluid flow in rock fractures. This variation presents traceability and is closely related to the evolution of microscale eddies and macroscale flow regimes. A concept of global inertial permeability is thus proposed from this traceable variation, which can reproduce the whole flow regime in rock fractures. Two parametrized criterion models are subsequently established for calculating global inertial permeability using the lowest cost and ensuring its accuracy: one in terms of minimum Reynolds number for practical purposes, and the other in terms of minimum eddy volume ratio for mechanistic interpretation. Further discussions indicate that the proposed global inertial permeability is of great importance to non-Darcian flow prediction and flow regime assessment. Moreover, the parameterized criterion models in the form of power-law function for determining global inertial permeability, drawn from 2D fracture simulations, can apply to 3D fractures and large-scale fractured rock aquifers. The findings and results in this study are of great significance for accurately evaluating the hydraulic conductivity of rock fractures, especially at relatively high flow rates, and are useful for many geophysical and industrial applications.

Optimization of process parameters for acid fracturing assisted herringbone well SAGD

Zhong18 wellblock of Fengcheng oilfield developed with low permeability interlayer and had strong heterogeneity, which caused steam chamber of conventional steam assisted gravity drainage (SAGD) process cannot extend lengthwise continuously and serious steam heat loss. To address this problem, a method of acid fracturing assisted SAGD process is proposed to enhance the oil drainage and improve oil recovery. Based on the herringbone well SAGD being used in Zhong18 wellblock, the orthogonal experimental design and oil reservoir numerical simulation are used to determine the significance level and fracture parameter optimization of the acid fracturing process. The priority of optimization sequence is: fracture permeability, fracture width, fracture half-length, fracture spacing. The optimal parameters are as: 3D fracture permeability, 2.8 mm fracture width, 80 m fracture half-length and 80 m fracture spacing. A 10-year simulation using optimized parameters can improve the recovery by 9.2 % compared with the conventional SAGD process. The result proved that acid fracturing assisted herringbone well SAGD process can effectively penetrate the low permeability interlayer, expand the sweep range of steam chamber, and improve the oil recovery degree of the reservoir.

Three-dimensional high aspect ratio interface elements for simulating 3D hydraulic fracturing in deformable porous media

Hydraulic fracturing (HF) is a technique widely used in the oil industry to stimulate low permeability reservoirs and enable their production. However, to model the HF is necessary to consider at least three main coupling process: (i) the fluid pressure deforming the fracture walls, (ii) the fluid flow inside the fracture, and (iii) the fracture propagation through the porous medium. In this context, this work aims to expand the applicability of the high aspect ratio interface elements (HAR-IE) to simulate the formation and propagation of induced hydraulic fracture in three-dimensional scenarios. The proposed methodology considers a deformable porous media in which the fluid flow is governed via Darcy’s law. A proper tension continuum damage model is employed to deal with the fracture formation process and the classical cubic law defines the fluid flow in the fracture. A fully-coupled method solves the system of equations and the numerical results focus on the validation of the method via comparisons against analytical solutions. All the results showed that 3D HAR-IEs satisfactorily reproduce the main characteristics associated with HF, as fracture aperture, length and injection pressure.

Three-dimensional morphological study of type B lateral malleolar fractures with special reference to the end-tip location of proximal apexes.

Objective: We aimed to describe the morphological characteristics of Danis-Weber type B lateral malleolar fractures, with special attention given to the end-tip locations of fracture apexes, and to construct a 3D (three-dimensional) fracture line map. Methods: A total of 114 surgically treated cases of type B lateral malleolar fractures were retrospectively reviewed. The baseline data were collected, and computed tomography data were reconstructed in a 3D model. We measured the morphological characteristics and the end-tip location of the fracture apex on the 3D model. All the fracture lines were superimposed on a template fibula to generate a 3D fracture line map. Results: Among these 114 cases, 21 were isolated lateral malleolar fractures, 29 were bimalleolar fractures, and 64 were trimalleolar fractures. All the type B lateral malleolar fractures demonstrated a spiral or oblique fracture line. As measured from the distal tibial articular line, the fracture started at -6.22 ± 4.62mm anteriorly and terminated at 27.23 ± 12.32mm posteriorly, and the average fracture height was 33.45 ± 11.89mm. The fracture line inclination angle was 56.85° ± 9.58°, and the total fracture spiral angle was 269.81° ± 37.09°, with fracture spikes of 156.20° ± 24.04°. The proximal end-tip location of the fracture apex was classified into four zones in the circumferential cortex: zone I (lateral ridge) in seven cases (6.1%), zone II (posterolateral surface) in 65 cases (57%), zone III (posterior ridge) in 39 cases (34.2%), and zone IV (medial surface) in three cases (2.6%). Altogether, 43% (49 cases) of fracture apexes were not distributed on the posterolateral surface of the fibula, as 34.2% (39 cases) were located on the posterior ridge (zone III). The aforementioned morphological parameters in fractures with zone III, sharp spikes, and further broken spikes were greater than those in zone II, blunt spikes, and fractures without further broken spikes. The 3D fracture map suggested that the fracture lines with the zone-III apex were steeper and longer than those with the zone-II apex. Conclusion: Nearly half of type B lateral malleolar fractures had their proximal end-tip of apexes not on the posterolateral surface, which may impair the mechanical application of antiglide plates. A steeper fracture line and longer fracture spike indicate a more posteromedial distribution of the fracture end-tip apex.

Influence of 3D Fracture Geometry on Water Flow and Solute Transport in Dual-Conduit Fracture

The geometry of the fracture exerts an important impact on the flow of the fractures and the transport of the solutes. Herein, Forchheimer’s law and the weighted-sum ADE (WSADE) model were alternatively employed, and the obtained pressure gradient versus discharge curves for the fitting reveal that Forchheimer’s law adequately described the non-Darcy flow behavior and the robust capability of WSADE in capturing the non-Fickian transport in dual-conduit fractures (DCFs). Different boundary layer effects brought about obvious differences in water flow and solute transport trends between 2D and 3D fractures. Moreover, with the change in the distance between the main conduit and the diversion conduit, the hydraulic parameters were correlated with the fitting parameters in Forchheimer’s law and WSADE. The solute mixing process is dramatically altered by the results, which directly demonstrate major flow patterns at the intersection. The prediction of solute transport in naturally fractured rocks depends primarily on the depicted flow and its effects on mixing. The findings help to increase the understanding of transport processes in such systems, especially for characterizing the dual-peaked BTCs obtained in aquifers.

Nonlinear flow and permeability anisotropy characteristics in hydraulic fracturing-induced rock fractures subjected to various normal compressive stresses

Well productivity after hydraulic fracturing is strongly affected by the flow behaviors in created fracture complexity. In this study, gas flow tests were conducted in splitting fractures (induced by Brazilian splitting) and hydraulic fractures (created by hydraulic fracturing) to study the nonlinear fluid flow behaviors in rough fractures. 3D fracture surfaces were first digitally reproduced with a scanner and then the fracture geometry parameters (roughness profile index R_{p}, the root mean square of the fracture profile wall slope Z_{2}), aperture distributions were computed for both fractures. The influence of the fracture geometry characteristics on the nonlinear flow behaviors were systematically analyzed. The permeability anisotropy was numerically examined in detail. The results show that R_{p}, Z_{2} and mean aperture of hydraulic fractures are relatively smaller, indicating that the fracture surfaces are smoother. The transmissivity of splitting fracture is relatively higher than that of hydraulic ones, and the ratio of splitting to hydraulic one varies from 2.51 at sigma_{c} = 1 MPa to 60.95 at sigma_{c} = 40 MPa. By contrast, splitting fractures have larger critical Reynolds number and lower critical pressure gradient, implying that nonlinearity is easier to occur in splitting fractures. The average Forchheimer coefficient for splitting fractures is 0.00577, which is 1.5 times larger than that (0.0041) for hydraulic ones. In addition, the fractures exhibit strong permeability anisotropy and this anisotropic effect is significantly dependent on the loading stress. In general, the permeability anisotropy in hydraulic fracture is more significant, showing that their permeability anisotropy ratios K are larger and more sensitive to the loading. The obtained results confirm that there exist some discrepancies in flow behaviors between splitting and hydraulic fractures and for more accurate evaluation in engineering practice, hydraulic fractures should be fully considered.

A New Equivalent Thickness Model for Fracture Prediction on Round Rods with Elliptic Surface Cracks

An equivalent thickness model is proposed to develop the fracture prediction method for round rods with elliptic surface cracks on the basis of a constraint equivalence principle and detailed three-dimensional (3D) stress field analysis near crack fronts with various elliptical shape factors t ([Formula: see text] 0.33, 0.4, 0.5, 0.67, 1) and crack depths a ([Formula: see text] 1/3, 2/3). The equivalent thickness is a function of crack depth a, elliptical shape factor t, elliptical parameter angle [Formula: see text] and radius of the round rod R. The reported fracture test data for the 20CrMo steel round rods with various elliptic surface cracks are adopted to validate the proposed equivalent thickness model. It is found that the improved 3D fracture prediction method by introducing the equivalent thickness is more effective than the traditional two-dimensional (2D) fracture prediction method. The prediction error is reduced from 10.5% to 3.1% for given round rods with elliptic surface cracks under tensile loading in this paper.

A three-dimensional meso-scale approach to the fracture analysis of ultrahigh performance concrete based on micropolar peridynamics

A three-dimensional (3D) meso-scale approach is proposed to simulate the fracture of ultrahigh performance concrete (UHPC) within the framework of peridynamics (PD). Micropolar PD, as an improved form of bond-based PD, is adopted to model the cementitious matrix. A PD constitutive model considering strain-hardening and strain-softening is introduced to simulate the mechanical behavior of UHPC. To improve the computational efficiency, a semi-discrete technique is employed to simulate the fibers. Meanwhile, to compensate for the drawbacks of the semi-discrete technique in analyzing fiber deformation, the effects of fiber inclination and end deformation on the fiber–matrix interface are incorporated into the fiber pullout model. In the analysis of cracking in UHPC, uniaxial tensile and uniaxial compressive tests were simulated to calibrate the proposed 3D PD model. Then, mode Ⅰ fracture and mixed-mode fracture of UHPC beams under three-point bending were simulated. Satisfactory agreement is achieved between PD analysis and experimental observations in terms of crack paths and load–displacement curves. Additionally, the numerical results show that the random distribution of fibers has a stronger impact on the 3D fracture surface for mixed-mode fracture compared to mode Ⅰ fracture.

Finite Element Analysis of the Mechanical Strength of Phalangeal Osteosynthesis Using Kirschner Wires.

Background: Kirschner wire (K-wire) fixation is widely used to repair metacarpal and phalangeal fractures. In this study, we simulated K-wire osteosynthesis of a 3-dimensional (3D) phalangeal fracture model and investigated the fixation strength at various K-wire diameters and insertion angles to clarify the optimal K-wire fixation method for phalangeal fractures. Methods: The 3D phalangeal fracture models were created by using computed tomographic (CT) images of the proximal phalanx of the middle finger in five young healthy volunteers and five elderly osteoporotic patients. Two elongated cylinders representing K-wires were inserted according to various cross-pinning methods; the wire diameters were 1.0, 1.2, 1.5 and 1.8 mm, and the wire insertion angles (i.e. the angle between the fracture line and the K-wire) were 30°, 45° and 60°. The mechanical strength of the K-wire fixed fracture model was investigated by using finite element analysis (FEA). Results: The fixation strength increased with increasing wire diameter and insertion angle. Insertion of 1.8-mm wires at 60° achieved the strongest fixation force in this series. Fixation strength was generally stronger in the younger group than the elderly group. Dispersion of stress to cortical bone was a critical factor to increase fixation strength. Conclusions: We developed a 3D phalangeal fracture model into which we inserted K-wires; using FEA, we clarified the optimal crossed K-wire fixation method for phalangeal fractures. Level of Evidence: Level V (Therapeutic).

Theoretical and experimental exploration on the combined mode I + III fracture toughness of shale using the edge-notched disk bending method with acoustic emission monitoring

The combined mode I + III fracture toughness of shale plays a significant role in the exploitation of shale gas. To investigate the combined mode I + III fracture characteristics of shale, the ENDB (edge-notched disk bending) fracture experiments with AE (acoustic emission) monitoring are implemented to accomplish the full range of fractures from pure mode I (tension) to pure mode III (tearing). By considering the contribution of the mean strain energy to the onset of fracturing, this work develops the 3D-MSED (mean strain energy density) criterion. The measured results indicate that the fracturing energy of the ENDB shale increases linearly with the move from pure tension to pure tearing, while the effective fracture toughness for the ENDB shale decreases linearly. In comparison with the published 3D fracture criteria, the developed 3D-MSED criterion can predict an excellent combined mode I + III fracture toughness envelope for the ENDB shale. Interestingly, the Gaussian function can adequately describe the distribution of AE amplitudes, and the distribution discrepancy in AE amplitudes is insignificant for the ENDB shale specimens under different loading types. However, the percentage of the AE high dominant frequency for the tearing-dominated loading case is relatively greater than that of the tension-dominated loading case, and the tearing-dominated fracturing response is characterized by the nonplanar shear deformation.

3D mapping: has the mystery of proximal tibia fractures been solved?

One of the major limitations of the 2D fracture evaluation (Schatzker classification) is its failure to adequately assess fracture lines in the frontal plane and fracture displacement in the antero-posterior direction. 3D fracture line mapping includes steric assessment which can aid decision making with regards to the surgical approach and fixation scheme. We hypothesized that there are consistent fracture patterns and zones of comminution for proximal tibial fractures. Radiographic data of 228 proximal tibia fractures were retrospectively included in this study. Fracture lines and zones of comminution were graphically superimposed onto a 3D template of an intact tibia after virtual reduction and normalization to identify major patterns of fracture and comminution. Out of 206 male and 21 female patients, 89 had a fracture of the lateral condyle only (Schatzker I and II), 53 involved the medial plateau only (Schatzker IV) and 86 had a high-grade fracture involving both the condyles (Schatzker V and VI). 64.5% of the fracture lines involving the medial plateau alone were in the coronal plane, and this number was even lesser (44.2%) in medial plateau involvement of bicondylar fractures. In bicondylar fractures, lines were usually not seen to pass directly through the posteromedial region. Medial tibial plateau fractures have a mix of coronal or sagittal fracture alignment. A clearer understanding of the 3D orientations of fractures based on CT scans can aid in diagnosing the pattern of fracture and adequate positioning of plates can be done to eventually improve operative outcomes.

An enriched phase-field method for the efficient simulation of fracture processes

The efficient simulation of complex fracture processes is still a challenging task. In this contribution, an enriched phase-field method for the simulation of 2D fracture processes is presented. It has the potential to drastically reduce computational cost compared to the classical phase-field method (PFM). The method is based on the combination of a phase-field approach with an ansatz transformation for the simulation of fracture processes and an enrichment technique for the displacement field as it is used in the extended finite element method (XFEM) or generalised finite element method (GFEM). This combination allows for the application of significantly coarser meshes than it is possible in PFM while still obtaining accurate solutions. In contrast to classical XFEM / GFEM, the presented method does not require level set techniques or explicit representations of crack geometries, considerably simplifying the simulation of crack initiation, propagation, and coalescence. The efficiency and accuracy of this new method is shown in 2D simulations.

Characterization of fractures in low‐permeability thin tight sandstones: A case study of Chang 6 Member, Yanchang Formation, western Ordos Basin

Structural fractures are formed when the underground rock mass deforms and exceeds its own strength limit, so they represent the complex geomechanical properties of rock. Small or core‐scale fractures usually extend less than 10 m in length, which affects the productivity of tight sandstone. Therefore, core‐scale fracture is the core factor for the prediction of reservoir sweet spots. In this paper, the research on the evolution and prediction of natural fractures in tight sandstone is investigated using the core, thin section, logging materials and numerical simulation methods. The results show that a large number of vertical and horizontal sliding fractures with shearing properties are developed in the tight sandstones of the Yanchang Formation. The particle size affects the compactible space inside the reservoir, which then affects the fracture development degree. Since the superimposed thin sand bodies are formed by the frequent lateral migration of the underwater distributary channels in the study area, therefore, the natural fractures in the thin sand bodies at the edge of river channels are relatively developed. According to statistics, the vertical extension distance of fractures is usually less than 2 m. Meanwhile, the fractured zones are mainly located in the cumulative sand body thickness range of 3 ~ 10 m. Moreover, the fractured zones are generally located in the high part of the structure and its wings. Regional structure and thin sand body distribution jointly affect the evolution of fractures in tight sandstones. Through this study, we found that fractures are more developed in thin sand bodies, and the controlling factors include lithology, sedimentary microfacies, sand thickness and local structure. The comprehensive evaluation of fractures in tight sandstones with high accuracy from 1D to 3D was achieved using core observation, logging interpretation, and three‐dimensional (3D) fracture modelling.