Micro-nano-scale pore stimulation of coalbed methane reservoirs caused by hydraulic fracturing experiments

Pan, Jienan; Mou, Pengwei; Ju, Yi‐Hsu; Wang, Kai; Zhu, Qingzhong; Ge, Taoyuan; Yu, Kun

doi:10.1016/j.petrol.2022.110512

Cited by 22 publications

(11 citation statements)

References 55 publications

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“…The extrusion hysteresis phenomenon appears during the HPMIP tests; the "hysteresis loop" of mercury intrusion and extrusion curves of coal can reflect the basic morphology of pores and their connectivity. As mentioned by many scholars (Song et al, 2019;Zhang et al, 2021;Pan et al, 2022), the open pores induce the mercury extrusion curve to form the "hysteresis loop," while semi-closed pores do not have the "hysteresis loop" due to the equal inlet and outlet mercury pressures. Thus, the sandy mudstone is mostly composed of open pores, while a given mass of semi-closed pores with weak connectivity is developed in coarse sandstone, medium sandstone, fine sandstone, and siltstone.…”

Section: Analysis Of the Mercury Intrusion/extrusion Curvementioning

confidence: 99%

Geochemical reactions altering the mineralogical and multiscale pore characteristics of uranium-bearing reservoirs during CO2 + O2in situ leaching

Zhou

Wang²,

Niu³

et al. 2023

Front. Earth Sci.

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CO2 + O2in situ leaching has been extensively applied in uranium recovery in sandstone-type uranium deposits of China. The geochemical processes impact and constrain the leaching reaction and leaching solution migration; thus, it is necessary to study the CO2 + O2–water–rock geochemical reaction process and its influence on the physical properties of uranium-bearing reservoirs. In this work, a CO2 + O2–water–rock geochemical reaction simulation experiment was carried out, and the mineralogical and multiscale pore characteristics of typical samples before and after this simulation experiment were compared by X-ray diffraction and high-pressure mercury intrusion porosimetry (HPMIP). The results show that the CO2 + O2–water–rock geochemical reaction has complicated effects on the mineral compositions due to the various reaction modes and types. After the CO2 + O2–water–rock geochemical reaction, the femic minerals decrease and the clay minerals in the coarse sandstone, medium sandstone, fine sandstone, and siltstone increase, while the femic minerals and clay minerals in sandy mudstone show a contrary changing trend. The CO2 + O2–water–rock geochemical reaction decreases the total pore volume of uranium-bearing reservoirs and then promotes pore transformation from small scale to large scale. The fractal dimensions of macropores are decreased, and the fractal dimensions of mesopores, transition pores, and micropores are increased. The effects of felsic mineral and carbonate dissolution, secondary mineral precipitate, clay mineral swelling, and mineral particle migration are simultaneously present in the CO2 + O2in situ leaching process, which exhibit the positive transformation and the negative transformation for the uranium-bearing reservoirs. The mineral dissolution may improve reservoir permeability to a certain degree, while the siltation effect will gradually reveal with the extension of CO2 + O2in situ leaching. This research will provide a deep understanding of the physical property response of uranium-bearing reservoirs during CO2 + O2in situ leaching and indicate the direction for the efficient recovery of uranium resources.

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Section: Analysis Of the Mercury Intrusion/extrusion Curvementioning

confidence: 99%

Geochemical reactions altering the mineralogical and multiscale pore characteristics of uranium-bearing reservoirs during CO2 + O2in situ leaching

Zhou

Wang²,

Niu³

et al. 2023

Front. Earth Sci.

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“…Pan et al measured the pore structure of coal during hydraulic fracturing using scanning electron microscopy, liquid nitrogen uptake, and mercury pressurization and the results showed that hydraulic fracturing led to better pore connectivity. 28 Lu et al monitored a series of in situ compression experiments using nuclear magnetic resonance methods and demonstrated that as the fracturing process progressed, the total porosity increased sharply and formed pore channels. 29 These studies illustrate that with the exploitation of reservoir resources, shale geological conditions and, especially, the connectivity are obviously changed.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Furthermore, with the application of hydraulic fracturing technology, a series of changes occur in the connectivity of shale nanopores. Pan et al measured the pore structure of coal during hydraulic fracturing using scanning electron microscopy, liquid nitrogen uptake, and mercury pressurization and the results showed that hydraulic fracturing led to better pore connectivity . Lu et al monitored a series of in situ compression experiments using nuclear magnetic resonance methods and demonstrated that as the fracturing process progressed, the total porosity increased sharply and formed pore channels .…”

Section: Introductionmentioning

confidence: 99%

Effects of Shale Pore Size and Connectivity on scCO₂ Enhanced Oil Recovery: A Molecular Dynamics Simulation Investigation

et al. 2023

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The differences in pore width distributions and connectivity of shale reservoirs have significant influences on supercritical carbon dioxide (scCO 2 )-enhanced oil recovery (CO 2 EOR) in shale. Herein, the molecular dynamics simulation was adopted to investigate the microscopic mechanism of CO 2 EOR in the shale nanopores with different pore size width distributions and pore connectivity. The results show that the pore connectivity has significant effects on the oil displacement, and the recovery efficiency is ordered as: connected pore > double pore > single pore for the 3 nm pore, which are 91.32, 74.43, and 65.93%, respectively. Therefore, the increase in pore connectivity can significantly improve the recovery efficiency of the small pore of the connected pore system. For the shale reservoirs with different pore width distributions, the oil recovery rate of large pores is generally higher than that of small pores. In addition, the displacement of oil in the small pore of the double pore system is accelerated due to the pushing effect of the discharge fluid from the large pore. The results furnish a certain theoretical support for the research of the microscopic mechanism of CO 2 EOR in the shale pore with different pore width distributions and connectivity and the exploit of shale oil.

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“…Tectonically deformed coals (TDCs) formed under the action of tectonic stress have significantly altered structures, including physical, optical, and even chemical structures (Hou et al, 2012;Niu et al, 2017;Zhang et al, 2019;Pan et al, 2022;Yu et al, 2022). The structural variation of TDCs directly affects the gas occurrence state (Ju and Li, 2009;Jiang et al, 2010;Zhang et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulation of shear friction process in tectonically deformed coal

Liu

Song²,

Du³

2023

Front. Earth Sci.

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Shear friction is an important deformation process in tectonically deformed coals (TDCs) and is closely related to the dynamic metamorphism of coal. In the current study, we perform a molecular dynamics (MD) simulation of the shear friction process on primary structure coal. The simulation results show that coal friction is a process of energy transformation. The mechanical energy of shear friction work can lead to temperature increases and chain motion. Chain diffusion and reorientation are the two main chain motion modes during friction. Chain diffusion behavior is regular in the initial friction stage and becomes irregular in the later friction stage. The orientation change is different for various fused aromatic chains. The orientation changes of pentacenes and naphthacenes are more significant than those of the other fused aromatic chains, indicating that fused aromatic chains with a higher aspect ratio are preferentially reorientated by shear friction. It is also demonstrated that the C-O and C-N bonds in coal are more easily disassociated by shear friction. The research results directly confirm the molecular evolution during coal friction caused by shear stress.

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Micro-nano-scale pore stimulation of coalbed methane reservoirs caused by hydraulic fracturing experiments

Cited by 22 publications

References 55 publications

Geochemical reactions altering the mineralogical and multiscale pore characteristics of uranium-bearing reservoirs during CO2 + O2in situ leaching

Geochemical reactions altering the mineralogical and multiscale pore characteristics of uranium-bearing reservoirs during CO2 + O2in situ leaching

Effects of Shale Pore Size and Connectivity on scCO₂ Enhanced Oil Recovery: A Molecular Dynamics Simulation Investigation

Molecular dynamics simulation of shear friction process in tectonically deformed coal

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Micro-nano-scale pore stimulation of coalbed methane reservoirs caused by hydraulic fracturing experiments

Cited by 22 publications

References 55 publications

Geochemical reactions altering the mineralogical and multiscale pore characteristics of uranium-bearing reservoirs during CO2 + O2in situ leaching

Geochemical reactions altering the mineralogical and multiscale pore characteristics of uranium-bearing reservoirs during CO2 + O2in situ leaching

Effects of Shale Pore Size and Connectivity on scCO2 Enhanced Oil Recovery: A Molecular Dynamics Simulation Investigation

Molecular dynamics simulation of shear friction process in tectonically deformed coal

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Effects of Shale Pore Size and Connectivity on scCO₂ Enhanced Oil Recovery: A Molecular Dynamics Simulation Investigation