3-D seismic exploration data and the study of shallow marine geology

摘要

High-resolution 2-D seismic site surveys are carried out routinely prior to the emplacement of exploration drilling rigs. The main purpose of these surveys is to identify hazards to drilling, such as shallow gas, shallow water flow sands, faulting and coarse channel deposits, within the top 1000 m or so below the seabed. Exploration 3-D data are made available by exploration and production companies to aid in planning these site surveys and it is from data such as these that the following example images have been assembled. Site survey data generally extend no farther than approximately 2000 m below the seabed. Within the Central and Northern North Sea, and the shelf and slope areas to the West of Shetland, the top 1000 m below the seabed are dominated by unconsolidated or poorly consolidated Late Tertiary to Quaternary sediments. These contain a record of the last 2.5 million years of geological history, covering the period from the onset of cold conditions at the end of the Tertiary to the present day.