Simulation of multi-period tectonic stress fields and distribution prediction of tectonic fractures in tight gas reservoirs: A case study of the Tianhuan Depression in western Ordos Basin, China

Guo, Peng; De-sheng, Ren; Xue, Yuhua

doi:10.1016/j.marpetgeo.2019.06.026

Cited by 23 publications

(6 citation statements)

References 21 publications

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“…As reported by Dang et al [16], the intermediate principal stress in Ordos basin was almost vertical. Most zones within Ordos basin are flat, so the shafts run perpendicular to the structural convergence plane, but it was oblique of the convergence plane within the orogen-basin transition zone [16,18,21]. Convergence was the independent reason for altering the orientation of intermediate principal stress.…”

Section: C-t Fractures and Discussionmentioning

confidence: 99%

“…According to the obtained publications in the petroleum geology field, the terrains of these coalbearing basins are generally flat with almost no faults or folds growing within them. However, there are tectonic fractures that are distinguished from the diagenetic and natural fractures widely distributed within these coal-bearing basins, and this phenomenon is more remarkable near the orogen-basin transition zone [15][16][17][18][19][20][21]. The formation of tectonic fractures has been associated with convergence actions close to or even far away from strike-slip faults and transpressional structures [18,22].…”

Section: Introductionmentioning

confidence: 99%

“…However, there are tectonic fractures that are distinguished from the diagenetic and natural fractures widely distributed within these coal-bearing basins, and this phenomenon is more remarkable near the orogen-basin transition zone [15][16][17][18][19][20][21]. The formation of tectonic fractures has been associated with convergence actions close to or even far away from strike-slip faults and transpressional structures [18,22]. In other words, where there was structural convergence, there was compression and torsion (C-T) action because convergence is usually asymmetric [23,24].…”

Section: Introductionmentioning

confidence: 99%

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Experimental Study on Compression and Torsion Fracture within 3D Printed Cementation-Weak and Porosity-High Sandstones

et al. 2023

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Cretaceous sandstones have weak cementation and high porosity while exhibit a high apparent brittleness. Compression and torsion (C-T) fractures are widely distributed in Cretaceous sandstones due to asymmetric tectonic convergence action. However, studies on C-T fracture formation and the mechanisms causing variability in Cretaceous sandstones containing no oil or gas are rare due to the challenges in sampling intact sandstone cores, despite their significance to mine shaft sinking. Therefore, this study used binder jetting-based 3D printing to prepare artificial Cretaceous sandstone and developed a real-time X-ray computed tomography- (CT-) aided torsion shear apparatus to test them. The test results showed that the 3D printed (3DP) sandstone had characteristic indexes that approached and even exceeded the lower limits of Cretaceous sandstone cores, thereby accurately representing the unavailable cores. Furthermore, the 3DP sandstones had anisotropic properties comparable to the sandstone cores. Under C-T action, the 3DP sandstone exhibited a pronounced strain gradient of 2.0 %/mm perpendicular to fracture inclination. The inclination angles of fractures formed under C-T action tended to increase as the cell pressure increased, and that approached the orientation angles of maximal principal stress. The maximal and minimal principal stresses exerted inclination-slip and width-stretching effects, respectively, on C-T fractures. But the effect of inclination-slip on the C-T fractures was stronger than that of width-stretching. This insight into C-T fracture formation will guide future studies on the fracture evolution and its disaster-dominating mechanisms arisen from disturbances by shaft sinking.

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Section: C-t Fractures and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental Study on Compression and Torsion Fracture within 3D Printed Cementation-Weak and Porosity-High Sandstones

et al. 2023

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“…In addition, the primary joints and fissures provide a convenient channel for the water-rock reaction, which promotes crack propagation and coalescence [19][20][21]. Due to various geological tectonic effects, the minerals, joints, and fissures in soft rocks are distributed disorderly, complicating the evolution of crack propagation of soft rock [22]. Jiang et al [23] concluded that the water absorption swelling of soft rocks is anisotropic with the swelling deformation being more significant in the vertical bedding direction, and therefore, cracks are more likely to propagate in the parallel layered direction.…”

Section: Introductionmentioning

confidence: 99%

Evolution Mechanism of Mesocrack and Macrocrack Propagation in Carbonaceous Mudstone under the Action of Dry-Wet Cycles

Huang

Liang

et al. 2022

Geofluids

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The crack propagation evolution of carbonaceous mudstone under the action of dry-wet cycles is an important cause of the unstable failure of this type of slope. This paper attempts to reveal the evolution mechanism of mesocrack and macrocrack propagation in carbonaceous mudstone under the action of dry-wet cycles from chemical, physical, and mechanical perspectives. Firstly, the soaking solution of carbonaceous mudstone during the dry-wet cycles was extracted for an ion concentration test to analyze the chemical reactions of carbonaceous mudstone. Then, CT scans were performed on the carbonaceous mudstone samples to study the changing pattern of mesostructure of carbonaceous mudstone during the dry-wet cycles. In the end, the mechanical properties and failure characteristics of carbonaceous mudstone after dry-wet cycles were studied by triaxial compression tests. The results showed that chemical reactions such as calcite dissolution, potassium feldspar hydrolysis, and sodium feldspar hydrolysis occurred during the dry-wet cycle of carbonaceous mudstone. Affected by the dry-wet cycles, the mesostructure of the carbonaceous mudstone gradually changed from face-face contact and edge-face contact to edge-corner contact and corner-corner contact, and the interlayer flake structure was opened and was locally curled and fractured. With the increase in the number of dry-wet cycles, the failure characteristic of carbonaceous mudstone transformed from tensile failure to shear failure, the failure surface of carbonaceous mudstone was deflected from 90° to 60°, and the crack propagation path of carbonaceous mudstone became more complicated. The chemical reaction of carbonaceous mudstone minerals during the dry-wet cycle is an important reason for the initiation and development of pores. The dry-wet cycle aggregates the propagation of mesocracks and structural disorder, transforming the uniform stress state of the rock mesostructure to the concentrated stress state, which is the important reason for the macrocrack propagation evolution of carbonaceous mudstone.

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“…This Basin is a typical low-permeability formation with an average permeability of less than 1 mD. Except for the Chang 6 reservoir with developed horizontal bedding [25,26], the horizontal stress in most areas of the basin is greater than the vertical stress, which means that the fractures generated by hydraulic fracturing are mainly vertical fractures [27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

An Automatic Classification Method of Well Testing Plot Based on Convolutional Neural Network (CNN)

Chu

Dong

et al. 2019

Energies

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The precondition of well testing interpretation is to determine the appropriate well testing model. In numerous attempts in the past, automatic classification and identification of well testing plots have been limited to fully connected neural networks (FCNN). Compared with FCNN, the convolutional neural network (CNN) has a better performance in the domain of image recognition. Utilizing the newly proposed CNN, we develop a new automatic identification approach to evaluate the type of well testing curves. The field data in tight reservoirs such as the Ordos Basin exhibit various well test models. With those models, the corresponding well test curves are chosen as training samples. One-hot encoding, Xavier normal initialization, regularization technique, and Adam algorithm are combined to optimize the established model. The evaluation results show that the CNN has a better result when the ReLU function is used. For the learning rate and dropout rate, the optimized values respectively are 0.005 and 0.4. Meanwhile, when the number of training samples was greater than 2000, the performance of the established CNN tended to be stable. Compared with the FCNN of similar structure, the CNN is more suitable for classification of well testing plots. What is more, the practical application shows that the CNN can successfully classify 21 of the 25 cases.

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Simulation of multi-period tectonic stress fields and distribution prediction of tectonic fractures in tight gas reservoirs: A case study of the Tianhuan Depression in western Ordos Basin, China

Cited by 23 publications

References 21 publications

Experimental Study on Compression and Torsion Fracture within 3D Printed Cementation-Weak and Porosity-High Sandstones

Experimental Study on Compression and Torsion Fracture within 3D Printed Cementation-Weak and Porosity-High Sandstones

Evolution Mechanism of Mesocrack and Macrocrack Propagation in Carbonaceous Mudstone under the Action of Dry-Wet Cycles

An Automatic Classification Method of Well Testing Plot Based on Convolutional Neural Network (CNN)

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