Integrated Use of Marine Seismic Methods for Offshore Wind Farm Site Characterization and the Role of Air-gun MCS Streamer Data

Abstract

Offshore wind farm development requires reliable information on seabed and sub-seabed conditions because foundation type, installation risk, and long-term stability are strongly controlled by water depth, soft-sediment thickness, bedrock depth, and the distribution of faults, fracture zones, and shallow gas. Marine site investigations therefore integrate bathymetric mapping, seafloor imaging, magnetometry, sub-bottom profiling, marine seismic surveys, and geotechnical sampling to construct a ground model. Among these methods, marine seismic data provide laterally continuous images of sub-seabed stratigraphy and geological structures between borehole and cone penetration test locations. This study reviews the complementary roles of marine seismic methods used in offshore wind farm site characterization, with particular emphasis on air-gun multi-channel seismic (MCS) streamer data. High-frequency sub-bottom profile data and ultra-high-resolution seismic data are suitable for imaging shallow sedimentary structures at high vertical resolution, whereas lower-frequency, higher-energy air-gun seismic data provide complementary information on deeper structures at relatively lower resolution. As an illustrative field example, airgun streamer seismic data acquired along the margin of the Ulleung Basin were used to examine a candidate shallow stratigraphic boundary, fault/fracture zones, and shallow-gas-related acoustic blanking. The examples show that MCS data can complement shallow high-resolution datasets by tracing stratigraphic continuity and deeper structural features along a survey line. In addition, P-wave impedance sections derived from band-limited seismic inversion illustrate how relative impedance variations can serve as supplementary input for integrated ground-model construction. This study provides a reference for understanding the role, applicability, and limitations of marine seismic data in offshore wind farm site investigations.