Nanopore Structure and Fractal Characteristics of Lacustrine Shale: Implications for Shale Gas Storage and Production Potential

Chen, Lei; Jiang, Zhenxue; Jiang, Shu; Liu, Keyu; Yang, Wei; Tan, Jingqiang; Gao, Fei

doi:10.3390/nano9030390

Cited by 26 publications

(21 citation statements)

References 71 publications

(157 reference statements)

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“…In addition to organic type and thermal maturity, pore structures of the shale matrix are also key factors for gas adsorption. To better understand the nature of pore structures of shale formations, researchers applied many techniques, such as small-angle neutron scattering (SANS), field-emission scanning electron microscopy (FE-SEM), microcomputed tomography (µ-CT), mercury intrusion porosimetry (MIP), and low-pressure N 2 /CO 2 adsorption experiments, to obtain the pore size distribution (PSD) of shale reservoirs [14][15][16][17][18]. It was found that shale formations have multiscale pore size distribution with numerous micropores (<2 nm), mesopores (2-50 nm), and macropores (>50 nm).…”

Section: Introductionmentioning

confidence: 99%

Molecular Investigation of CO2/CH4 Competitive Adsorption and Confinement in Realistic Shale Kerogen

et al. 2019

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The adsorption behavior and the mechanism of a CO2/CH4 mixture in shale organic matter play significant roles to predict the carbon dioxide sequestration with enhanced gas recovery (CS-EGR) in shale reservoirs. In the present work, the adsorption performance and the mechanism of a CO2/CH4 binary mixture in realistic shale kerogen were explored by employing grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. Specifically, the effects of shale organic type and maturity, temperature, pressure, and moisture content on pure CH4 and the competitive adsorption performance of a CO2/CH4 mixture were investigated. It was found that pressure and temperature have a significant influence on both the adsorption capacity and the selectivity of CO2/CH4. The simulated results also show that the adsorption capacities of CO2/CH4 increase with the maturity level of kerogen. Type II-D kerogen exhibits an obvious superiority in the adsorption capacity of CH4 and CO2 compared with other type II kerogen. In addition, the adsorption capacities of CO2 and CH4 are significantly suppressed in moist kerogen due to the strong adsorption strength of H2O molecules on the kerogen surface. Furthermore, to characterize realistic kerogen pore structure, a slit-like kerogen nanopore was constructed. It was observed that the kerogen nanopore plays an important role in determining the potential of CO2 subsurface sequestration in shale reservoirs. With the increase in nanopore size, a transition of the dominated gas adsorption mechanism from micropore filling to monolayer adsorption on the surface due to confinement effects was found. The results obtained in this study could be helpful to estimate original gas-in-place and evaluate carbon dioxide sequestration capacity in a shale matrix.

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Section: Introductionmentioning

confidence: 99%

Molecular Investigation of CO2/CH4 Competitive Adsorption and Confinement in Realistic Shale Kerogen

et al. 2019

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“…9). The available pore structures (D 2 ) in shales are heterogeneous and complex (Jiang et al, 2016;Hazra et al, 2018c;Chen et al, 2019). The plot of D 1 shows similar trend to that of D 2 in shales, indicating that the ruggedness of the pore surface is interrelated to the complexity of pore structure (Fig.…”

Section: Discussionmentioning

confidence: 92%

Pore structures and fractal dimensions in Early Permian Barakar shales of Rajmahal Basin, Jharkhand, India

et al. 2021

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The proximate, low-pressure N 2 sorption, X-ray diffraction, and organic petrography parameters have been used to delineate the pore structures and fractal dimensions in the Barakar shales of Rajmahal Basin, India. The information has been utilized for the assessment of shale gas reservoir and to know about the mode of occurrence and storage capacity of shales for the entrapment of methane (CH 4 ). The studied shales are characterized by high fixed carbon contents (10.14-46.09 wt.%) and contain significant abundance of brittle minerals, like quartz (6.0-51.6%) and mica (1.0-41.2%). The petrographic observations show that the studied samples comprise of numerous laths of vitrinite (collotelinite and vitrodetrinite) and semifusinite macerals and quartz grains. The data of low-pressure N 2 sorption analysis indicates the shales encompass mainly meso-to macropores and microfractures. The total pore volume, average pore size, and multipoint BET surface area of the studied shales vary from 0.012 to 0.023 cc/g, 8.295 to 10.840 nm, and 5.752 to 10.390 m 2 /g respectively. Two types of fractal dimensions (D 1 and D 2 ) have been calculated by using FHH (Frankel-Halsey-Hill) method from the N 2 adsorption isotherm. The high values of fractal dimensions (2.1949 < D 1 < 2.4837 and 2.6668 < D 2 < 2.7247) are indicating the highly rugged pore surface or complexity in the pore structures.

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“…Figure 6: ln V vs. ln ðln ðP 0 /PÞÞ from LP-N 2 GA analyses of samples soaked in slick water for different times. 5 Geofluids…”

Section: Y-8dmentioning

confidence: 99%

“…The shale gas resources in China are abundant, and the recoverable volume is estimated to be about 261012 cubic meters [1][2][3]. Shale gas refers to the gas in shale pores and adsorbed in the matrix [4][5][6]; thus, understanding the characteristics of shale gas reservoirs is very important for efficient exploitation. Pores in shale gas reservoirs are dominated by nanopores, resulting in lower porosity and permeability [7][8][9], which necessitates the use of advanced fracturing technology during the exploitation.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation into the Effects of Fracturing Fluid-Shale Interaction on Pore Structure and Wettability

Zhang

Lai

et al. 2021

Geofluids

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One of the main techniques for the exploitation of shale oil and gas is hydraulic fracturing, and the fracturing fluid (slick water) may interact with minerals during the fracturing process, which has a significant effect on the shale pore structure. In this study, the pore structure and fluid distribution of shale samples were analyzed by utilizing low-pressure liquid nitrogen adsorption (LP-N2GA) and nuclear magnetic resonance (NMR). The fractal analysis showed that the pore structure of the sample was strongly heterogeneous. It was also found that the effect of slick water on pore structure can be attributed to two phenomena: the swelling of clay minerals and the dissolution of carbonate minerals. The swelling and dissolution of minerals can exist at the same time, and the strength of them at different soaking times is different, leading to the changes in specific surface area and pore size. After the samples were soaked in the slick water for two days, the contact angle reached the minimum value (below 8°), which means the sample is strongly hydrophilic; then the contact angle increased to above 38° with longer soaking times. The connected pore space in the shale matrix is enlarged by the soaking processing. Therefore, an in-depth understanding of the interaction between the fracking fluid and shale is essential to deepen our understanding of changes in the pore structure in the reservoir and the long-term productivity of shale gas.

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Nanopore Structure and Fractal Characteristics of Lacustrine Shale: Implications for Shale Gas Storage and Production Potential

Cited by 26 publications

References 71 publications

Molecular Investigation of CO2/CH4 Competitive Adsorption and Confinement in Realistic Shale Kerogen

Molecular Investigation of CO2/CH4 Competitive Adsorption and Confinement in Realistic Shale Kerogen

Pore structures and fractal dimensions in Early Permian Barakar shales of Rajmahal Basin, Jharkhand, India

Experimental Investigation into the Effects of Fracturing Fluid-Shale Interaction on Pore Structure and Wettability

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