Correction of water column height variation on 2D grid high-resolution seismic data using dGPS based methodology

Abstract

Variations in the physical properties of water column usually impede exact water column height correction on high-resolution seismic data, especially when the data are collected in shallow marine environments. Changes in water column properties can be attributed to variation in tides and currents, wind-generated swells, long and short amplitude wave-fronts, or variation in salinity and water temperature. Likewise, the proper motion of the vessel complicates the determinability of the water column height. This study provides a less time-consuming and precise differential Global Positioning System based methodology that can be applied to most types of high-resolution seismic data in order to significantly improve the tracking and quality of deduced geological interpretations on smaller depth scales. The methodology was tested on geophysical profiles obtained from the German sector of the North Sea. The focus here was to identify, distinguish and classify various sub-surface sedimentary structures in a stratigraphically highly complex shallow marine environment on decimeter small-scale. After applying the correction to the profiles, the sea floor, in general, occurs 1.1 to 3.4 m (mean of 2.2 m) deeper than the uncorrected profiles and is consistent with the sea floor from published tide corrected bathymetry data. The corrected seismic profiles were used in plotting the depth of the base of Holocene channel structures and to define their gradients. The applied correction methodology was also crucial in glacial and post-glacial valley features distinction, across profile correlation and establishing structural and stratigraphic framework of the study area.

The submerged Palaeo-Ems River in the Quaternary stratigraphic context of the German North Sea

“…Conventional seismic processing procedures were carried out specifically to meet the needs of high-resolution shallow-water SBP data with special emphasis on water-column static correction. Where applicable, water-column height variations caused by tides, weather and current were accounted for using procedures outlined by Abegunrin et al (2020) prior to interpretation.…”

Formation of the Figge Maar Seafloor Crater During the 1964 B1 Blowout in the German North Sea

“…against fluidization. Examples are pockmarks in the Barents Sea (Andreassen et al, 2017;Waage et al, 2020) or the 22/ 4b blowout in the British North Sea (Figure 7B; Leifer and Judd, 2015;Schneider von Deimling et al, 2015).…”

“…The released gas may also include carbon dioxide or methane sourced from e.g., Holocene peat deposits surrounding the blowout (McGinnis et al, 2011;Hepp et al, 2012;Coughlan et al, 2018). The present-day lower-intensity gas emissions occur predominantly during low tide, indicating the gas reservoir's sensitivity to hydrostatic pressure variations induced by tides and storms (Schneider von Deimling et al, 2010;Abegunrin et al, 2020). These low-intensity present-day emissions are unlikely to contribute significantly to greenhouse gas budgets.…”