Physical Property Interpretation Using Log Data from the Ulleung Basin Sediments, East Sea of Korea

This research focuses on the physical properties of a drilled site (UBGH1-4) in the Ulleung Basin, East Sea of Korea. Based on seismic profile and core/log data, the upper 50m sediments of the drilled site are dominated by turbidite/hemipelagic sediments, whereas the sediments below the depth are characterized by thick debris-flow deposits. The physical properties data (velocity, density, porosity, resistivity, natural gamma, etc.) were acquired using Schlumberger's logging tools during Logging-While-Drilling (LWD). In-depth interval between 70 and 120 mbsf (meter below seafloor) corresponding to debris-flow deposits, is characterized by high resistivity, high velocity, high density, and low porosity. Physical properties seem mostly related to consolidation/compaction effects and the type of sediment, as occurs typically in unconsolidated marine sediments. The overall relationships among the physical properties have relatively good correlations, but some scattering and clustering of the data exist on the plot. This can be interpreted as the result of the difference of sediment properties caused by mass flow deposits (e.g., turbidite/hemipelagic and debris-flow deposit). Based on natural gamma response, seven electrofacies were identified throughout the logged depth. This may suggest that seven events were likely to have occurred during deposition and/or after deposition.