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Zhengzheng C, Xiangqian Y, Zhenhua L, Cunhan H, Feng D, Wenqiang W, Xianjie N, Shuai L, Zhen L. Fracture propagation and pore pressure evolution characteristics induced by hydraulic and pneumatic fracturing of coal. Sci Rep 2024; 14:9992. [PMID: 38693305 DOI: 10.1038/s41598-024-60873-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 04/29/2024] [Indexed: 05/03/2024] Open
Abstract
A two-dimensional unsteady seepage model for coal using a finite element program is developed, and the temporal variations of key factors such as water pressure and hydraulic gradient are analyzed in this paper. Additionally, the triaxial rock mechanical experiment and utilized pneumatic fracturing equipment on raw coal samples to investigate both hydraulic and pneumatic fracturing processes are conducted. Through these experiments, the relationship between pressure and crack formation and expansion are examined. The analysis reveals that the pore pressure gradient at the coal inlet reaches its peak during rapid surges in water pressure but diminishes over time. Conversely, the pore pressure gradient at the outlet side exhibits a gradual increase. Hydraulic fracturing is most likely to occur at the water inlet during sudden increases in water pressure. Besides, as the permeability of coal decreases, the duration for seepage stabilization prolongs due to the intensified pore pressure gradient resulting from sudden increases in water pressure. Moreover, an extended period of high hydraulic gradient further increases the risk of hydraulic fracturing. The experimental findings indicate that coal samples initially experience tensile failure influenced by water and air pressure. Subsequently, mode I cracks form under pressure, propagating along the fracture surface and becoming visible. The main types of failure observed in hydraulic and pneumatic fracturing are diametrical tensile failure, and the development of fractures can be categorized into three distinct stages, which contains the initial stage characterized by slight volume changes while water pressure increases, the expansion stage when pressure reaches the failure strength, and the crack closure stage marked by little or even decreasing volume changes during pressure unloading. The acoustic emission signal accurately corresponds to these three stages.
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Affiliation(s)
- Cao Zhengzheng
- International Joint Research Laboratory of Henan Province for Underground Space Development and Disaster Prevention, School of Civil Engineering, Henan Polytechnic University, Jiaozuo, 454000, Henan, China
| | - Yang Xiangqian
- International Joint Research Laboratory of Henan Province for Underground Space Development and Disaster Prevention, School of Civil Engineering, Henan Polytechnic University, Jiaozuo, 454000, Henan, China
| | - Li Zhenhua
- Henan Mine Water Disaster Prevention and Control and Water Resources Utilization Engineering Technology Research Center, Henan Polytechnic University, Jiaozuo, 454000, Henan, China.
- Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization, Jiaozuo, 454000, Henan, China.
| | - Huang Cunhan
- Henan Mine Water Disaster Prevention and Control and Water Resources Utilization Engineering Technology Research Center, Henan Polytechnic University, Jiaozuo, 454000, Henan, China.
- Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization, Jiaozuo, 454000, Henan, China.
| | - Du Feng
- Henan Mine Water Disaster Prevention and Control and Water Resources Utilization Engineering Technology Research Center, Henan Polytechnic University, Jiaozuo, 454000, Henan, China
- Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization, Jiaozuo, 454000, Henan, China
| | - Wang Wenqiang
- Henan Mine Water Disaster Prevention and Control and Water Resources Utilization Engineering Technology Research Center, Henan Polytechnic University, Jiaozuo, 454000, Henan, China
- Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization, Jiaozuo, 454000, Henan, China
| | - Ni Xianjie
- State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines, Anhui University of Science and Technology, Huainan, 232001, Anhui, China.
- China Coal Xinji Energy Limited Liability Company, Huainan, 232001, Anhui, China.
| | - Liu Shuai
- Henan Mine Water Disaster Prevention and Control and Water Resources Utilization Engineering Technology Research Center, Henan Polytechnic University, Jiaozuo, 454000, Henan, China
- Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization, Jiaozuo, 454000, Henan, China
| | - Li Zhen
- College of Safety and Emergency Management Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi, China
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Cheng J, Liu Y, Xu C, Xu J, Sun M. Study on the influence of pore water pressure on shear mechanical properties and fracture surface morphology of sandstone. Sci Rep 2024; 14:5761. [PMID: 38459079 PMCID: PMC10923814 DOI: 10.1038/s41598-024-55834-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 02/28/2024] [Indexed: 03/10/2024] Open
Abstract
To further investigate the weakening effect of pore water pressure on intact rock mechanics properties and characteristics of fracture surface after failure, direct shear tests of sandstone were conducted under different pore pressure. A 3D scanner was employed to digitize the morphology of the post-shear fracture surface. The variogram function was applied to quantify the anisotropic characteristics of post-shear fracture surface. The relationship between deformation during shear failure of intact rock and quantitative parameters of fracture surface after shear failure was initially established. It can be found that amplitudes of the sinusoidal surface determine the maximum value of variogram, and period affect lag distance that reach the maximum value of variogram. Test results revealed that the increase of pore pressure has obvious weakening effect on shear strength and deformation of rock. Moreover, the increase of pore pressure makes the shear fracture surface flatter. It can be obtained that both Sillmax and Rangemax are positively related to shear strain, but negatively related to normal strain.
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Affiliation(s)
- Jiaxin Cheng
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China
- State Key Laboratory of Mining Disaster Prevention and Control Co-Founded By Shandong Province and Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, 266590, China
| | - Yixin Liu
- State Key Laboratory of Safety and Health for Metal Mine, Maanshan, 243071, China.
- Sinosteel Maanshan General Institute of Mining Research Co., Ltd, Maanshan, 243071, China.
- College of Resources and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou, 342399, China.
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China.
- State Key Laboratory of Mining Disaster Prevention and Control Co-Founded By Shandong Province and Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, 266590, China.
| | - Chuanhua Xu
- State Key Laboratory of Safety and Health for Metal Mine, Maanshan, 243071, China
- Sinosteel Maanshan General Institute of Mining Research Co., Ltd, Maanshan, 243071, China
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China
| | - Jiang Xu
- State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, China
| | - Mingzhi Sun
- State Key Laboratory of Safety and Health for Metal Mine, Maanshan, 243071, China
- Sinosteel Maanshan General Institute of Mining Research Co., Ltd, Maanshan, 243071, China
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Alkafeef SF. Approximation of electrical double-layer thickness in hydrocarbon systems flowing through the pores of reservoir rocks. Adv Colloid Interface Sci 2023; 320:102985. [PMID: 37734251 DOI: 10.1016/j.cis.2023.102985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 07/24/2023] [Accepted: 08/17/2023] [Indexed: 09/23/2023]
Abstract
In porous systems, such as in oil reservoir rock formations, the double layers from opposite sides of the pores may overlap if the pore size is narrow. This overlap is relatively likely to occur under low-electrolyte concentrations, such as those in crude oil, thus markedly affecting the electrokinetic measurements. This article evaluates the effects of overlap of the diffuse layers in the narrow capillaries of the reservoir rock cores in oils. Methods were developed to estimate the double-layer thickness in hydrocarbon systems, and to predict the effects of double-layer overlap on the streaming current and hence on the calculation of surface potentials for flat-sided capillaries. These methods are used to interpret results from sandstone cores in crude oil and hydrocarbon solvents. The estimation of double-layer thickness in non-aqueous solvents on the basis of 1:1 charge carriers by analogy to water systems, with correction for viscosity and permittivity differences provides good results with respect to those from streaming current measurements.
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Affiliation(s)
- Saad F Alkafeef
- Petrophysics & Surface Chemistry Research Laboratory, Petroleum Engineering Department, College of Technological Studies, P.O. Box 32, Hadyia 52851, Kuwait.
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Jin ZH, Janes JG, Peterson ML. A Chemo-poroelastic Analysis of Mechanically Induced Fluid and Solute Transport in an Osteonal Cortical Bone. Ann Biomed Eng 2020; 49:299-309. [PMID: 32514933 DOI: 10.1007/s10439-020-02544-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 06/02/2020] [Indexed: 10/24/2022]
Abstract
It is well known that transport of nutrients and wastes as solute in bone fluid plays an important role in bone remodeling and damage healing. This work presents a chemo-poroelastic model for fluid and solute transport in the lacunar-canalicular network of an osteonal cortical bone under cyclic axial mechanical loading or vascular pressure. Analytical solutions are obtained for the pore fluid pressure, and fluid and solute velocities. Numerical results for fluid and calcium transport indicate that under a cyclic stress of 20 MPa, the magnitudes of the fluid and calcium velocities increase with an increase in the loading frequency for the frequency range considered (≤ 3 Hz) and peak at the inner boundary. The peak magnitude of calcium velocity reaches 18.9 μm/s for an osteon with a permeability of 1.5 × 10-19 m2 under a 3 Hz loading frequency. The magnitude of calcium velocity under a vascular pressure of 50 mmHg is found to be two orders of magnitude smaller than that under the mechanical load. These results have the potential to be important in understanding fundamental aspects of cortical bone remodeling as transport characteristics of calcium and other nutrients at the osteon scale influence bone metabolism.
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Affiliation(s)
- Z-H Jin
- Department of Mechanical Engineering, University of Maine, Orono, ME, 04469, USA.
| | - J G Janes
- Department of Veterinary Science, University of Kentucky, Lexington, KY, 40546, USA
| | - M L Peterson
- Department of Biosystems and Agricultural Engineering, University of Kentucky, Lexington, KY, 40546, USA
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Nhabanga OJ, Ringrose PS. Assessment of mudstone compaction in exploration wells in the Rovuma Basin, offshore Mozambique. Heliyon 2019; 5:e02641. [PMID: 31687500 PMCID: PMC6820305 DOI: 10.1016/j.heliyon.2019.e02641] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/11/2019] [Accepted: 10/08/2019] [Indexed: 11/26/2022] Open
Abstract
In order to develop an improved pore pressure prediction model for the overburden mudstones in the Rovuma Basin, offshore Mozambique, we apply Eaton's method to example well data from three exploration wells, which intersect Quaternary, Tertiary and Cretaceous sediments over depth intervals down to ∼3 km below seafloor. The predictive method only included the effects of mechanical compaction, which is a reasonable assumption for the low-temperature shallow sections. We found that Eaton's method applied to resistivity and acoustic log attributes works well and can be used to identify the mudstones that display over-pressured or normally pressured sections. The predicted pore pressures showed a good match to pore pressures in permeable formations. Using this calibration, we derived an improved pore-pressure prediction method for these wells and for the Rovuma Basin in general. The resulting model should give a good basis for future analysis of compaction processes and pore pressure in this basin.
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Completo A, Bandeiras C, Fonseca F. Comparative assessment of intrinsic mechanical stimuli on knee cartilage and compressed agarose constructs. Med Eng Phys 2017; 44:87-93. [PMID: 28318948 DOI: 10.1016/j.medengphy.2017.02.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 02/15/2017] [Accepted: 02/20/2017] [Indexed: 11/28/2022]
Abstract
A well-established cue for improving the properties of tissue-engineered cartilage is mechanical stimulation. However, the explicit ranges of mechanical stimuli that correspond to favorable metabolic outcomes are elusive. Usually, these outcomes have only been associated with the applied strain and frequency, an oversimplification that can hide the fundamental relationship between the intrinsic mechanical stimuli and the metabolic outcomes. This highlights two important key issues: the firstly is related to the evaluation of the intrinsic mechanical stimuli of native cartilage; the second, assuming that the intrinsic mechanical stimuli will be important, deals with the ability to replicate them on the tissue-engineered constructs. This study quantifies and compares the volume of cartilage and agarose subjected to a given magnitude range of each intrinsic mechanical stimulus, through a numerical simulation of a patient-specific knee model coupled with experimental data of contact during the stance phase of gait, and agarose constructs under direct-dynamic compression. The results suggest that direct compression loading needs to be parameterized with time-dependence during the initial culture period in order to better reproduce each one of the intrinsic mechanical stimuli developed in the patient-specific cartilage. A loading regime which combines time periods of low compressive strain (5%) and frequency (0.5Hz), in order to approach the maximal principal strain and fluid velocity stimulus of the patient-specific cartilage, with time periods of high compressive strain (20%) and frequency (3Hz), in order to approach the pore pressure values, may be advantageous relatively to a single loading regime throughout the full culture period.
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Affiliation(s)
- A Completo
- Mechanical Engineering Department, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal .
| | - C Bandeiras
- Mechanical Engineering Department, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - F Fonseca
- Coimbra Hospital and University Centre, Av. Bissaya Barreto, 3000-075 Coimbra, Portugal
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