Warwel, Arne; Hübscher, Christian; Hartge, Matthias; Artschwager, Maike; Schäfer, Wiebke; Preine, Jonas; Häcker, Tobias; Strehse, Victoria; Karušs, Jānis; Lüdmann, Thomas (2023): 2D multichannel seismic reflection processed data (GI Gun working area dataset) of RV METEOR during cruise M177, Gotland Basin, Baltic Sea [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.957436

The Baltic Basin is known for its numerous Paleozoic hydrocarbon reservoirs. There is published evidence that hydrocarbons are leaking from the seafloor, however, little is known about the hydrocarbon migration pathways from Paleozoic source and reservoir rocks towards the seafloor and the escape structures. To investigate the processes involving the fluid migration pathways, we utilized 2D seismic reflection data from the eastern margin of the Gotland Deep. The data was acquired during the 2021 M177 Meteor expedition led by the University of Hamburg. Data acquisition was carried out using two GI guns (true GI-mode with 45 in3 generator and 105 in3 injector volume) and a 144-channel digital streamer with a channel spacing of 6.25 m and an active length of 600 m. Due to technical difficulties, only 72 channels - distributed over the whole streamer length – could be used for processing. Seismic data processing was divided into pre-processing, multiple attenuation and post-stack processing. Pre-processing consisted of geometry-setup (UTM zone 33N), filtering, despiking and spherical gaining. For multiple attenuation, we applied a predictive deconvolution in the τ-p domain, surface related multiple attenuation (SRME) and an f-k filtering attenuation scheme based on move-out differences between primary and multiple reflections. In between these steps we performed several iterations of manual velocity analysis. The post-stack processing included time migration, white noise suppression (4D-DEC), time-variant filtering and RMS scaling. The dominant frequency of the data is about 100 Hz and the vertical resolution of the final seismic images calculated with a velocity of 2000 m/s is about 5 m. The data is stored in SEGY-format with CMP No in header bytes 21-24, CMP x-coordinates in byte header 181-184 and CMP y-coordinates in byte header 185-188.