Using grain size analysis to study facies distribution and paleo-environment in the Southern North Sea delta of the Dutch offshore

The Neogene paleo-delta of the Southern North Sea (SNS) also known as the Eridanos delta consists mainly of Plio- to Pleistocene sequences that have been deposited from various westward flowing rivers. As part of TNO’s effort to map the area to locate shallow gas occurrences and to determine their reservoir and sealing properties, grain size and litho-facies distributions were analyzed in the Early Pleistocene s5 unit. The s5 unit is identified with seismic imaging as a unit of succeeding glacial and interglacial intervals and contains an important depositional record that can be identified by studying the lithology of rock samples. This information was also used to calculate petrophysical properties. Silt-rich sediments can be attributed to cyclic glacial and interglacial events throughout the s5 unit. In addition, the presence of sand in the E and SE margin of the northernmost part of the Dutch offshore hints towards a source area of these Eridanos delta deposits to the east of the Dutch offshore.