Abstract: This proposal requests the 3nd year support of the 4-year gas hydrate project entitled “Geological Exploration of Gas Hydrate Prospects Offshore Southwestern Taiwan – Geophysical Investigation”. Various marine geophysical exploration techniques will be used to map the gas hydrate distribution in the study area, to understand the regional structures and deposition environment, to investigate the characteristics of the gas hydrate bearing sediment, and to estimate the amount of gas hydrate in place and its energy potential. Gas hydrate prospects will be selected for detailed investigation, all the preparation work for drilling should be carried out in the 4th year. So, that we are ready for the drilling investigation to be conducted in the 2nd phase of the gashydrate program. During the first 2 years of this project, regional geophysical reconnaissance surveys and densely space 2.5D seismic survey plus OBS experient were conducted to map the regional gas hydrate distribution. Compilation and analysis of geophysical and geological data have been performed to establish the regional geophysical characters, geological structures, and sedimentary patterns of both the accretionary wedge province and the passive China continent slope regions of the study area. Special geophysical investigation techniques, such as ocean bottom seismometers, heat flow measuring devices, etc., have been established and tested, seismic data analysis and interpretation system has also been purchased and installed. Regional sedimentary deposition history and structural patterns have been proposed.
In the 3rd year of this project, integrated approach on analyzing all the geophysical, geological and geochemistical data is emphasized. Detailed geophysical investigations will be carried out in the selected prospects in order to understand how the gas hydrate distribution relates to regional structures and stratigraphy, physical characteristics of the hydrate bearing sediment, possible generation and migration paths of the gas hydrate, and to have a better estimation of the amount of gas hydrate in place. Selection and site preparation of a few drilling sites will be the prime objectives of the 4th year investigations.
Major investigation work proposed for the 3rd year will include:
1.Integrations of geophysical data collected during the first 2 years.
2.2.5D seismic reflection survey and ocean bottom seismometer experiment for 2D wide-angle reflection/refraction data acquisition and analyses in a selected small area for detailed investigation.
3.Using new heat flow devices to conduct heat flow measurement while collecting piston core samples, also to analyze regional heat flow data.
4.Regional structure and seismic stratigraphy studies.
5.Establish the structural and sedimentary characters of the hydrate bearing sedimentary layers.
6.Collect magnetic data using deep-towed magnetometer in the 2.5D seismic reflection and OBS survey area, perform data analyses and modeling
Offshore southwestern Taiwan