Reservoir characterization of gas hydrate in the Northwestern part of the Ulleung Basin,East Sea |
| |
| Authors: | Kyoung-Jin Kim Bo-Yeon Yi Nyeon-Keon Kang |
| |
| Institution: | 1. Department of Petroleum Resources Technology, University of Science and Technology, Daejeon, Korea;2. Petroleum and Marine Research Division, Korea Institute of Geoscience and Mineral Resources, Daejeon, Korea |
| |
| Abstract: | An analysis of 3D seismic data from the northwestern part of the Ulleung Basin, East Sea, revealed that the gas hydrate stability zone (GHSZ) consists of five seismic units separated by regional reflectors. An anticline is present that documents activity of many faults. The seismic indicators of gas hydrate occurrence included bottom simulating reflector (BSR) and acoustic blanking in the gas hydrate occurrence zone (GHOZ). By the analysis of the seismic characteristics and the gradient of the sedimentary strata, the GHOZ was divided into four classes: (1) dipping strata upon strong BSR, (2) dipping strata below strong BSR, (3) parallel strata with acoustic blanking, and (4) parallel strata below weak BSR. Seismic attributes such as reflection strength and instantaneous frequency were computed along the GHOZ. Low reflection strength and high instantaneous frequency were identified above the BSR, indicating the occurrence of gas hydrate. A remarkably high reflection strength and low instantaneous frequency indicated the presence of free gas below the BSR. Considering the distribution of the gas hydrate and free gas, two gas migration processes are suggested: (1) stratigraphic migration through the dipping, permeable strata and (2) structural migration from below the GHSZ along faults. |
| |
| Keywords: | Gas-hydrate gas hydrate stability zone gas migration seismic attribute Ulleung Basin |
|
|
