As a part of Korean National Gas Hydrate Program, the Second Ulleung Basin Gas Hydrate Drilling Expedition (UBGH2) was successfully performed by using the D/V Fugro Synergy to establish 13 research drill sites in the period of time from July 8 to September 30, 2010. The first leg of this expedition focused on logging-while-drilling operations, while the second leg focused on both conventional and pressure coring. The primary objectives of UBGH2 were: (1) to confirm the occurrence of gas hydrate-bearing sediments in the Ulleung Basin, East Sea of Korea (2) to obtain scientific information on the distribution of gas hydrate-bearing structures as needed to conduct gas hydrate resource assessment, and (3) to identify the suitable sites for an initial gas hydrate production test from sand reservoirs containing gas hydrate in the Ulleung Basin. It is important to highlight that there is currently a broad consensus among the major international R&D efforts that the subset of gas hydrate resources that are housed in sand reservoirs are the most favorable targets for initial evaluation of production potential.
During the UBGH2, downhole logging-while-drilling (LWD), wireline logging and vertical-seismic-profiling (WL/VSP), conventional and pressurized coring, seafloor visual surveys, and seafloor methane surveys using remotely operated vehicles (ROV), laboratory analysis of recovered cores including physical property, sedimentology, and geochemistry were conducted at sea for the drill sites established during this expedition. LWD data were collected at all thirteen sites. Coring was conducted at 10 of the sites, which were selected onboard by the analysis of the UBGH2 collected LWD data. WL/VSP logging was conducted at two sites.
Integrated seismic, well log, and core analysis indicate at least four different types of gas hydrate accumulations in the Ulleung Basin. Probably the most striking feature in the basin is the existence of numerous vertical chimney structures. Downhole logging and coring activities at four of the UBGH2 sites have confirmed the chimney structures in the Ulleung Basin contain a relatively large volume of fracture-filling gas hydrate. Another type of gas hydrate accumulation appears to be associated with the presence of diatomaceous clay-rich sediments. Two of the UBGH2 sites are characterized by a thick section of very uniform diatomaceousc clay-rich sediments, the top of this section often contains numerous gas hydrate filled strata-bound fractures. It is possible, that these strata-bound gas-hydrate-bearing fractures may be related to differential compaction associated with dewatering of the diatom-rich hemipelagic muds in this section. Seismic data from the Ullung Basin also clearly shows the development of a thick, potential basin wide, sedimentary sections characterized by mostly debris flows. The downhole LWD logs and core data from at least one site suggests the presence of gas hydrate at relatively low concentrations in basal silt-sand sections associated with debris flow units. It is important to highlight that this is the first time a debris flow hosted gas hydrate accumulation has been described in nature. In support of the main goal of this research drilling project, the UBGH2 LWD and coring program have also confirmed the occurrence of numerous volcaniclastic and siliciclastic sand reservoirs that were deposited as part of local to basin-wide turbidite events, which probably hold the greatest promise for substantial gas hydrate occurrence and production in the Ulleung Basin.
Scientific results of the Second Gas Hydrate Drilling Expedition in the Ulleung Basin, Korea
Journal of Marine and Petroleum Geology: Volume 47, Pages 1-302 (November 2013)
Scientific Results of the Second Gas Hydrate Drilling Expedition in the Ulleung Basin (UBGH2), East Sea of Korea
SCIENTIFIC RESULTS REPORT
The scientific results of the 2010 Second Ulleung Basin Gas Hydrate Drilling Expedition (UBGH2) have been published as a special issue of the Journal of Marine and Petroleum Geology (Volume 47, November 2013). This special issue, co-edited by Timothy S. Collett (USGS), Byong-Jae Ryu (KIGAM), and Michael Riedel (NRCan) contains 24 papers that detail the operation and scientific results of the UBGH2 expedition.
Ryu, Byong-Jae, Collett, T.S., Riedel, M., Kim, Gil Young, Chun, Jong-Hwa, Bahk, Jang-Jun, Lee, Joo Yong, Kim, Ji-Hoon, and Yoo, Dong-Geun, Scientific results of the Second Gas Hydrate Drilling Expedition in the Ulleung Basin (UBGH2)
J.-J. Bahk, D.-H. Kim, J.-H. Chun, B.-K. Son, J.-H. Kim, B.-J. Ryu, M.E. Torres, M. Riedel, P. Schultheiss, Gas hydrate occurrences and their relation to host sediment properties: Results from Second Ulleung Basin Gas Hydrate Drilling Expedition, East Sea
J.-J. Bahk, G.-Y. Kim, J.-H. Chun, J.-H. Kim, J.Y. Lee, B.-J. Ryu, J.-H. Lee, B.-K. Son, T.S. Collett, Characterization of gas hydrate reservoirs by integration of core and log data in the Ulleung Basin, East Sea
J.Y. Lee, G.-Y. Kim, N.K. Kang, B.-Y. Yi, J.W. Jung, J.-H. Im, B.-K. Son, J.-J. Bahk, J.-H. Chun, B.-J. Ryu, D.S. Kim, Physical properties of sediments from the Ulleung Basin, East Sea: Results from Second Ulleung Basin Gas Hydrate Drilling Expedition, East Sea (Korea)
Hak-Sung Kim, Gye-Chun Cho, Joo Yong Lee, Se-Joon Kim, Geotechnical and geophysical properties of deep marine fine-grained sediments recovered during the second Ulleung Basin Gas Hydrate expedition, East Sea, Korea
Jong-Sub Lee, Joo Yong Lee, Young Moon Kim, Changho Lee, Stress-dependent and strength properties of gas hydrate-bearing marine sediments from the Ulleung Basin, East Sea, Korea
Young, Jin-Kim, Tae-Sup Yun, Thermal conductivity of methane hydrate-bearing Ulleung Basin marine sediments: Laboratory testing and numerical evaluation
J.Y. Lee, J.W. Jung, M.H. Lee, J.-J. Bahk, J. Choi, B.-J. Ryu, P. Schultheiss, Pressure core based study of gas hydrates in the Ulleung Basin and implication for geomechanical controls on gas hydrate occurrence
Ji-Hoon Kim, Marta E. Torres, Wei-Li Hong, Jiyoung Choi, Michael Riedel, Jang-Jun Bahk, Sung-Han Kim, Pore fluid chemistry from the Second Gas Hydrate Drilling Expedition in the Ulleung Basin (UBGH2): Source, mechanisms and consequences of fluid freshening in the central part of the Ulleung Basin, East Sea
Jiyoung Choi, Ji-Hoon Kim, Marta E. Torres, Wei-Li Hong, Jin-Woo Lee, Bo Yeon Yi, Jang-Jun Bahk, Kyung Eun Lee, Gas origin and migration in the Ulleung Basin, East Sea: Results from the Second Ulleung Basin Gas Hydrate Drilling Expedition (UBGH2)
Dong-Hun Lee, Ji-Hoon Kim, Jang-Jun Bahk, Hye-Youn Cho, Jung-Ho Hyun, Kyung-Hoon Shin, Geochemical signature related to lipid biomarkers of ANMEs in gas hydrate-bearing sediments in the Ulleung Basin, East Sea (Korea)
Jin-Woo Lee, Kae Kyoung Kwon, Aqil Azizi, Hyun-Myung Oh, Wonduck Kim, Jang-Jun Bahk, Dong-Hun Lee, Jung-Hyun Lee, Microbial community structures of methane hydrate-bearing sediments in the Ulleung Basin, East Sea of Korea
Brandon R. Briggs, Michael Graw, Eoin L. Brodie, Jang-Jun Bahk, Sung-Han Kim, Jung-Ho Hyun, Ji-Hoon Kim, Marta Torres, Frederick S. Colwell, Microbial distributions detected by an oligonucleotide microarray across geochemical zones associated with methane in marine sediments from the Ulleung Basin
H.-S. Kim, M. Riedel, B.-J. Ryu, G.-Y. Kim, J.-J. Bahk, Improving gas hydrate saturation estimates using P-wave velocity log data by incorporating XRD-data for detailed matrix-mineralogy definition
M.W. Lee, T.S. Collett, Characteristics and interpretation of fracture-filled gas hydrate – An example from the Ulleung Basin, East Sea of Korea
Gil Young Kim, B. Narantsetseg, B.-J. Ryu, D.-G. Yoo, J.Y. Lee, H.S. Kim, M. Riedel, Fracture orientation and induced anisotropy of gas hydrate-bearing sediments in seismic chimney-like-structures of the Ulleung Basin, East Sea
M.W. Lee, T.S. Collett, Scale-dependent gas hydrate saturation estimates in sand reservoirs in the Ulleung Basin, East Sea of Korea
Heewon Tak, Joongmoo Byun, Soon Jee Seol, Dong Geun Yoo, Zero-offset vertical seismic profiling survey and estimation of gas hydrate concentration from borehole data from the Ulleung Basin, Korea
Han-Joon Kim, Hyeong-Tae Jou, Seung-Goo Kang, Gwang Hoon Lee, Bo Yeon Yi, Dong-Geun Yoo, Byong-Jae Ryu, Changsoo Shin, Seismic characterization and imaging of a gas hydrate deposit in the western part of the Ulleung Basin, the East Sea (Japan Sea)
Michael Riedel, T.S. Collett, H.-S. Kim, J.-J. Bahk, J.-H. Kim, B.-J. Ryu, G.Y. Kim, Large-scale depositional characteristics of the Ulleung Basin and its impact on electrical resistivity and Archie-parameters for gas hydrate saturation estimates
Dong G. Yoo, Nyeon K. Kang, Bo Y. Yi, Gil Y. Kim, Byong J. Ryu, Keumsuk Lee, Gwang H. Lee, M. Riedel, Occurrence and seismic characteristics of gas hydrate in the Ulleung Basin, East Sea
Michael Riedel, J.-J. Bahk, H.-S. Kim, D.-G. Yoo, W.-S. Kim, B.-J. Ryu, Seismic facies analyses as aid in regional gas hydrate assessments. Part-I: Classification analyses
Michael Riedel, J.-J. Bahk, H.-S. Kim, N.A. Scholz, D.G. Yoo, W.-S. Kim, B.-J. Ryu, S.R. Lee, Seismic facies analyses as aid in regional gas hydrate assessments. Part-II: Prediction of reservoir properties, gas hydrate petroleum system analysis, and Monte Carlo simulation
Gwang H. Lee, Bo Y. Yi, Dong G. Yoo, Byong J. Ryu, Han J. Kim, Estimation of the gas-hydrate resource volume in a small area of the Ulleung Basin, East Sea using seismic inversion and multi-attribute transform techniques