Development of a portable 3D seismic survey system for nearshore surveys and the first case study offshore Pohang, South Korea

Abstract

The utilization of sea areas adjacent to land has rapidly increased in recent years due to the expansion of economic activities from the land to the ocean. To secure the economic feasibility and safety of coastal development, technologies are required that can be used to image the seafloor and shallow subsurface structures at high resolution. For example, ultra-high-resolution (UHR) seismic surveys have improved the spatiotemporal resolution of seismic surveys. Since 2014, the Korea Institute of Geoscience and Mineral Resources has been working on the development of a three-dimensional (3D) UHR seismic survey system that can be operated with a small 10-ton vessel (EOS-Streamer). In this study, the composition of the EOS-Streamer and its individual components are described in detail. To validate the system, the first field demonstration was conducted offshore Pohang in southeastern Korea in 2019. A 9.77-ton small vessel and two 10 in 3 air guns were used for the acquisition of field data and a 3D cube with a bin size of 2.5 m was obtained at the postprocessing stage. Continuity was maintained in the 3D cube in both the inline and crossline directions. Various geological structures and fault planes were observed close to the seafloor. The results of this study confirm that economical 3D seismic surveys in coastal areas, which are difficult to conduct using large vessels, can be carried out with the EOS-Streamer system.