Frequency-Dependent Anisotropic Electromagnetic Responses of Fractured Reservoirs with Various Hydrate Distributions Based on Numerical Simulation

Geophysical methods detecting electromagnetic properties (e.g., conductivity, relative permittivity, and dielectric loss factor) have been developed into an important tool to accurately assess the hydrate-bearing reservoirs. The key to the satisfying inversion of the electromagnetic collected data i...

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Main Authors: Shengbiao Liu, Gaowei Hu, Qingtao Bu, Yapeng Zhao, Zhiwen Sun
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Journal of Marine Science and Engineering
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Online Access:https://www.mdpi.com/2077-1312/13/1/48
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author Shengbiao Liu
Gaowei Hu
Qingtao Bu
Yapeng Zhao
Zhiwen Sun
author_facet Shengbiao Liu
Gaowei Hu
Qingtao Bu
Yapeng Zhao
Zhiwen Sun
author_sort Shengbiao Liu
collection DOAJ
description Geophysical methods detecting electromagnetic properties (e.g., conductivity, relative permittivity, and dielectric loss factor) have been developed into an important tool to accurately assess the hydrate-bearing reservoirs. The key to the satisfying inversion of the electromagnetic collected data is the precise understanding of the electromagnetic responses in hydrate-bearing reservoirs. However, the frequency-dependent anisotropic electromagnetic responses in fracture-filling hydrate reservoirs remain poorly understood. To acquire the above understanding, we use a numerical simulation method to investigate the frequency-dependent anisotropic conductivities, relative permittivities, and dielectric loss factors of the constructed fracture-filling hydrate digital cores. The fractures in digital cores are aligned along a certain direction and contain the hydrate with various distributions and saturations. The simulated electromagnetic behaviors are comprehensively analyzed and explained by the effects of the electrical polarization, the aligned fractures, as well as the occurrence of hydrate with various distributions and saturation in fractures. The results show that the conductivities enhance while the relative permittivities reduce with increasing frequency, respectively, and their dispersion amplitudes at the frequency scope roughly between 100 MHz and 3000 MHz are more dramatic than that at other frequency ranges. The obtained dielectric loss factors increase first and then decrease with frequency and display peak value at the frequency of approximately 1000 MHz. The conductivities, relative permittivities, and loss factor peak values vertical to the fractures are lower than that in the other direction under the same conditions, respectively. It is found that these three parameters for all hydrate distributions and frequencies reduce with the enhancement of hydrate saturation, whereas the decreasing trends in conductivities and relative permittivities are distinct among the various hydrate distributions. The research results would be possible to pave a way for better identifying and evaluating hydrate resources of fractured reservoirs using the collected electromagnetic data.
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spelling doaj-art-bc8d8e43f6b44ccda9cdc7cfeb632b6c2025-01-24T13:36:40ZengMDPI AGJournal of Marine Science and Engineering2077-13122024-12-011314810.3390/jmse13010048Frequency-Dependent Anisotropic Electromagnetic Responses of Fractured Reservoirs with Various Hydrate Distributions Based on Numerical SimulationShengbiao Liu0Gaowei Hu1Qingtao Bu2Yapeng Zhao3Zhiwen Sun4Key Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, Qingdao 266237, ChinaKey Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, Qingdao 266237, ChinaKey Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, Qingdao 266237, ChinaKey Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, Qingdao 266237, ChinaKey Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, Qingdao 266237, ChinaGeophysical methods detecting electromagnetic properties (e.g., conductivity, relative permittivity, and dielectric loss factor) have been developed into an important tool to accurately assess the hydrate-bearing reservoirs. The key to the satisfying inversion of the electromagnetic collected data is the precise understanding of the electromagnetic responses in hydrate-bearing reservoirs. However, the frequency-dependent anisotropic electromagnetic responses in fracture-filling hydrate reservoirs remain poorly understood. To acquire the above understanding, we use a numerical simulation method to investigate the frequency-dependent anisotropic conductivities, relative permittivities, and dielectric loss factors of the constructed fracture-filling hydrate digital cores. The fractures in digital cores are aligned along a certain direction and contain the hydrate with various distributions and saturations. The simulated electromagnetic behaviors are comprehensively analyzed and explained by the effects of the electrical polarization, the aligned fractures, as well as the occurrence of hydrate with various distributions and saturation in fractures. The results show that the conductivities enhance while the relative permittivities reduce with increasing frequency, respectively, and their dispersion amplitudes at the frequency scope roughly between 100 MHz and 3000 MHz are more dramatic than that at other frequency ranges. The obtained dielectric loss factors increase first and then decrease with frequency and display peak value at the frequency of approximately 1000 MHz. The conductivities, relative permittivities, and loss factor peak values vertical to the fractures are lower than that in the other direction under the same conditions, respectively. It is found that these three parameters for all hydrate distributions and frequencies reduce with the enhancement of hydrate saturation, whereas the decreasing trends in conductivities and relative permittivities are distinct among the various hydrate distributions. The research results would be possible to pave a way for better identifying and evaluating hydrate resources of fractured reservoirs using the collected electromagnetic data.https://www.mdpi.com/2077-1312/13/1/48fracture-filling hydrate reservoirselectromagnetic propertiesfrequency-dependenceanisotropyhydrate distribution
spellingShingle Shengbiao Liu
Gaowei Hu
Qingtao Bu
Yapeng Zhao
Zhiwen Sun
Frequency-Dependent Anisotropic Electromagnetic Responses of Fractured Reservoirs with Various Hydrate Distributions Based on Numerical Simulation
Journal of Marine Science and Engineering
fracture-filling hydrate reservoirs
electromagnetic properties
frequency-dependence
anisotropy
hydrate distribution
title Frequency-Dependent Anisotropic Electromagnetic Responses of Fractured Reservoirs with Various Hydrate Distributions Based on Numerical Simulation
title_full Frequency-Dependent Anisotropic Electromagnetic Responses of Fractured Reservoirs with Various Hydrate Distributions Based on Numerical Simulation
title_fullStr Frequency-Dependent Anisotropic Electromagnetic Responses of Fractured Reservoirs with Various Hydrate Distributions Based on Numerical Simulation
title_full_unstemmed Frequency-Dependent Anisotropic Electromagnetic Responses of Fractured Reservoirs with Various Hydrate Distributions Based on Numerical Simulation
title_short Frequency-Dependent Anisotropic Electromagnetic Responses of Fractured Reservoirs with Various Hydrate Distributions Based on Numerical Simulation
title_sort frequency dependent anisotropic electromagnetic responses of fractured reservoirs with various hydrate distributions based on numerical simulation
topic fracture-filling hydrate reservoirs
electromagnetic properties
frequency-dependence
anisotropy
hydrate distribution
url https://www.mdpi.com/2077-1312/13/1/48
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