Application of frequency division inversion in the prediction of heterogeneous natural gas hydrates reservoirs in the Shenhu Area, South China Sea

ABSTRACT: Drilling results suggest that the thickness of natural gas hydrates (NGHs) in the Shenhu Area, South China Sea (SCS) are spatially heterogenous, making it difficult to accurately assess the NGHs resources in this area. In the case that free gas exists beneath hydrate deposits, the frequenc...

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Main Authors: Shu-yu Wu, Jun Liu, Hua-ning Xu, Chang-ling Liu, Fu-long Ning, Hong-xian Chu, Hao-ran Wu, Kai Wang
Format: Article
Language:English
Published: KeAi Communications Co., Ltd. 2022-04-01
Series:China Geology
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S209651922200115X
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author Shu-yu Wu
Jun Liu
Hua-ning Xu
Chang-ling Liu
Fu-long Ning
Hong-xian Chu
Hao-ran Wu
Kai Wang
author_facet Shu-yu Wu
Jun Liu
Hua-ning Xu
Chang-ling Liu
Fu-long Ning
Hong-xian Chu
Hao-ran Wu
Kai Wang
author_sort Shu-yu Wu
collection DOAJ
description ABSTRACT: Drilling results suggest that the thickness of natural gas hydrates (NGHs) in the Shenhu Area, South China Sea (SCS) are spatially heterogenous, making it difficult to accurately assess the NGHs resources in this area. In the case that free gas exists beneath hydrate deposits, the frequency of the hydrate deposits will be noticeably attenuated, with the attenuation degree mainly affected by pore development and free gas content. Therefore, the frequency can be used as an important attribute to identify hydrate reservoirs. Based on the time-frequency characteristics of deposits, this study predicted the spatial distribution of hydrates in this area using the frequency division inversion method as follows. Firstly, the support vector machine (SVM) method was employed to study the amplitude versus frequency (AVF) response based on seismic and well logging data. Afterward, the AVF response was introduced as independent information to establish the nonlinear relationship between logging data and seismic waveform. Then, the full frequency band information of the seismic data was fully utilized to obtain the results of frequency division inversion. The inversion results can effectively broaden the frequency band, reflect the NGHs distribution, and reveal the NGHs reservoirs of two types, namely the fluid migration pathway type and the in situ self-generation self-storage diffusion type. Moreover, the inversion results well coincide with the drilling results. Therefore, it is feasible to use the frequency division inversion to predict the spatial distribution of heterogeneous NGHs reservoirs, which facilitates the optimization of favorable drilling targets and is crucial to the resource potential assessment of NGHs.©2022 China Geology Editorial Office.
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spelling doaj.art-96ced0218b8842a6a13c447a34d0661f2023-02-07T04:22:53ZengKeAi Communications Co., Ltd.China Geology2096-51922022-04-0152251266Application of frequency division inversion in the prediction of heterogeneous natural gas hydrates reservoirs in the Shenhu Area, South China SeaShu-yu Wu0Jun Liu1Hua-ning Xu2Chang-ling Liu3Fu-long Ning4Hong-xian Chu5Hao-ran Wu6Kai Wang7School of Engineering, China University of Geosciences, Wuhan 430074, China; Yantai Coastal Zone Geological Survey Center, China Geological Survey, Yantai 264001, China; Chinese Academy of Geological Sciences, Beijing 100037, China; Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China; First author: E-mail address: hnwushuyu@163.com (Shu-yu Wu).Yantai Coastal Zone Geological Survey Center, China Geological Survey, Yantai 264001, China; Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China; Corresponding author: E-mail address: vnlj@163.com (Jun Liu).Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China; The Key Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, Qingdao 266071, ChinaLaboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China; The Key Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, Qingdao 266071, ChinaSchool of Engineering, China University of Geosciences, Wuhan 430074, ChinaYantai Coastal Zone Geological Survey Center, China Geological Survey, Yantai 264001, ChinaYantai Coastal Zone Geological Survey Center, China Geological Survey, Yantai 264001, ChinaYantai Coastal Zone Geological Survey Center, China Geological Survey, Yantai 264001, ChinaABSTRACT: Drilling results suggest that the thickness of natural gas hydrates (NGHs) in the Shenhu Area, South China Sea (SCS) are spatially heterogenous, making it difficult to accurately assess the NGHs resources in this area. In the case that free gas exists beneath hydrate deposits, the frequency of the hydrate deposits will be noticeably attenuated, with the attenuation degree mainly affected by pore development and free gas content. Therefore, the frequency can be used as an important attribute to identify hydrate reservoirs. Based on the time-frequency characteristics of deposits, this study predicted the spatial distribution of hydrates in this area using the frequency division inversion method as follows. Firstly, the support vector machine (SVM) method was employed to study the amplitude versus frequency (AVF) response based on seismic and well logging data. Afterward, the AVF response was introduced as independent information to establish the nonlinear relationship between logging data and seismic waveform. Then, the full frequency band information of the seismic data was fully utilized to obtain the results of frequency division inversion. The inversion results can effectively broaden the frequency band, reflect the NGHs distribution, and reveal the NGHs reservoirs of two types, namely the fluid migration pathway type and the in situ self-generation self-storage diffusion type. Moreover, the inversion results well coincide with the drilling results. Therefore, it is feasible to use the frequency division inversion to predict the spatial distribution of heterogeneous NGHs reservoirs, which facilitates the optimization of favorable drilling targets and is crucial to the resource potential assessment of NGHs.©2022 China Geology Editorial Office.http://www.sciencedirect.com/science/article/pii/S209651922200115XGas hydratesHeterogeneityFrequency division inversionSelf-generation and self-storage diffusion typeNGHs exploration trial engineeringOil and gas exploration engineering
spellingShingle Shu-yu Wu
Jun Liu
Hua-ning Xu
Chang-ling Liu
Fu-long Ning
Hong-xian Chu
Hao-ran Wu
Kai Wang
Application of frequency division inversion in the prediction of heterogeneous natural gas hydrates reservoirs in the Shenhu Area, South China Sea
China Geology
Gas hydrates
Heterogeneity
Frequency division inversion
Self-generation and self-storage diffusion type
NGHs exploration trial engineering
Oil and gas exploration engineering
title Application of frequency division inversion in the prediction of heterogeneous natural gas hydrates reservoirs in the Shenhu Area, South China Sea
title_full Application of frequency division inversion in the prediction of heterogeneous natural gas hydrates reservoirs in the Shenhu Area, South China Sea
title_fullStr Application of frequency division inversion in the prediction of heterogeneous natural gas hydrates reservoirs in the Shenhu Area, South China Sea
title_full_unstemmed Application of frequency division inversion in the prediction of heterogeneous natural gas hydrates reservoirs in the Shenhu Area, South China Sea
title_short Application of frequency division inversion in the prediction of heterogeneous natural gas hydrates reservoirs in the Shenhu Area, South China Sea
title_sort application of frequency division inversion in the prediction of heterogeneous natural gas hydrates reservoirs in the shenhu area south china sea
topic Gas hydrates
Heterogeneity
Frequency division inversion
Self-generation and self-storage diffusion type
NGHs exploration trial engineering
Oil and gas exploration engineering
url http://www.sciencedirect.com/science/article/pii/S209651922200115X
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