國立成功大學 地球科學系 地球物理探勘研究室
Geophysical Exploration Laboratory (GEL), Department of Earth Sciences, National Cheng Kung University
Executive Summary
My work uses geophysical techniques, including seafloor mapping, exploration seismology, ground penetrating radar (GPR), and resistivity, to examine land and offshore Earth processes related to sediment transports, deformation, resources, and geohazards. I am most enthralled by integrating seismic data with all other geophysical, geological, and geochemical data because seismic reveals an overall picture with high resolutions. It can then be compared with boreholes or surface samples. Sustainable energy, geoengineering, and geohazards are among the most engaging topics for me because earth scientists can play a decisive role in protecting the environment and human life. Taiwan heavily relies on imported resources; thus it is urgent to explore natural resources and plan for sustainable development.
Research Topic I: Developing Geophysical Technologies for Renewable Energies and CC
●Research Achievements
(1) Geophysical-based soil prediction for offshore wind farms (Han et al., 2020)
We developed a neural network suitable for soil prediction up to 60 m below the seafloor in the Taiwan Strait. The prediction results reveal detailed lithological variations tested by independent in-situ borehole measurements (Figs. 1a and 1b). This approach could effectively obtain the soil distribution and thus reduce the costs in offshore
engineering applications.
(2) 3D seismic processing and seismic attribute analysis (Han et al., 2019)
We developed a 3D seismic data processing technique, which significantly improves the quality and resolution of the
seismic images (Figs. 1c and 1d), using streamer feathering information from closely spaced 2D seismic profiles. After that, small-scale geological features were analyzed using seismic attributes and neural networks (Fig. 1e), which
gives insights into the subsurface fluid flow processes.
Fig. 1. (a) Conventional seismic display and (b) soil prediction (probability of clay) compared to an independent borehole; (c) utilizing streamer feathering effect to generate the high-resolution 3D seismic cube from densely spaced 2D seismic data; (d) and (e) detailed geological features revealed from the 3D seismic cube.
Research Topic II: Natural Resources and Subsurface Fluid Flow
●Research Achievements
(1) Natural gas hydrate systems with active fluid flow (Han et al., 2016; 2019; 2021)
Subsurface fluid conduits and potential gas hydrate reservoirs were analyzed to understand the dynamic gas hydrate system. Reduced overburden leads to more active fluid flow in the erosional environment than the depositional one (Fig. 2a). The sedimentary processes and fluid accumulation significantly control the development of gas chimneys
in the study area (Fig. 2b).
(2) Groundwater exploration using the geoelectrical method (Han et al., 2022)
To explore potential groundwater aquifers, we have conducted geoelectrical surveying. By integrating the
geoelectrical results and existing borehole data, we have proposed several hydrogeological models in the western
foothills of Taiwan.
Fig. 2. (a) co-blending of time slices of the seismic and chimney cubes showing the more active fluid flow in the footwall (erosional) compared to the hanging wall (depositional) of the major fault; (b) conceptual model illustrating the stratigraphy and gas hydrate system in the Pointer Ridge offshore SW Taiwan
Research Topic III: Active Tectonics and Geohazards
●Research Achievements
(1) Westward advance of the deformation front and development of the foreland basin (Han et al., 2017; Yang et al., 2021)
By analyzing seismic and bathymetric data, our results reveal that the migration of the deformation front might have
shaped the canyon paths offshore SW Taiwan (Fig. 3a). The interactions of down-slope processes and active tectonics
control the canyon paths offshore SW Taiwan. For the region offshore northern Taiwan, we proposed a five-stage
evolutionary model presenting the foreland basin evolution (Fig. 3b).
(2) Active structures and seafloor dynamics (Han et al., 2018; Chen et al., 2021; Lo et al., 2018)
Through the integrated analysis of seismic, bathymetric, and borehole data, we established a 3D geological model for
the Chang-Bin offshore wind farm in the Taiwan Strait (Fig. 3c). Our results show five types of sand waves coexisting in
the western Changyun Sand Ridge (Fig. 3d) and several large landslides offshore Taiwan.
Fig. 3. (a) Conceptual model illustrates processes affecting the canyon paths near the deformation front offshore SW Taiwan; (b) cartoons showing present regional structures offshore northern Taiwan.; (c) a 3D geological model showing geometries of unconformities and structures in the Chang-Bin OWF; (d) bathymetry overlaid by the sand wave crests in the Chang-Bin OWF; (e) a large submarine landslide identified from seismic data.
Related Publications
Chen, L., Lu, Y., Han, W., Lo, S. 2021. Characteristics of Sand Waves of the Changyun Sand Ridge and Taiwan Shoal in the Taiwan Strait. Marine Research, 1(1), 1-23.
Han, W., Chen, L.*, Liu, C., Berndt, C., Chi, W. 2019. Seismic analysis of the gas hydrate system at Pointer Ridge offshore SW Taiwan. Marine and Petroleum Geology, 105,
158- 167. (SCIE)
Han, W.*, Chen, L., Liu, C. 2021. Distribution and characteristics of gas chimneys in the passive margin offshore SW Taiwan. Marine Geophysical Research, 42(3), 1-16. (SCIE)
Han, W., Liu, C.*, Chi, W., Chen, L., Lin, C., Chen, S. 2017. Westward advance of the deformation front and evolution of submarine canyons offshore of southwestern Taiwan.
Journal of Asian Earth Sciences, 149, 6–19. (SCIE)
Han, W.*, Liu, C., Hsu, H., Lin, L., Chen, T., Chen, S. 2016. Gas hydrate system in the South China Sea continental slope offshore SW Taiwan, Special Publication of the
Central Geological Survey, 30, 43-57.
Han, W., Lo, S., Weng, T., Shen, J., Huang, J., Liu, C. 2018. 3D Geologic Model Building and Visualization in a Wind Energy Prospect Offshore Western Taiwan, 9th Chinese-
German Joint Symposium on Hydraulic and Ocean Engineering; Tainan, Taiwan. (Young Scientist Award)
Han, W.*, Lu, Y., Lo, S. 2020. Seismic prediction of soil distribution for the Chang-Bin offshore wind farm in the Taiwan Strait. Interpretation, 8(4), T727-T737. (SCIE)
Han, W., Shen, H., Chung, C., Lee, C., Liu, H. 2022. Deep groundwater resource exploration using resistivity imaging. Taiwan Geosciences Assembly; Taipei, Taiwan.
Lo, S., Weng, T.*, Huang, J., Han, W. 2019. Marine Environmental Database and 3D Geological Model Construction for Offshore Wind Farm. Mining & Metallurgy, 63(3), 9-17.
Yang, E., Chang, J., Hsu, H., Han, W., Liu, C., Su, C. 2021. Middle Miocene-Pleistocene Foreland Basin Offshore Northern Taiwan. Petroleum Geology of Taiwan, 45, 29-54