Seismic Modeling of Entire Outcropping Basin-Fill Successions: A Novel Approach to Resolving and Ground-Truthing Seismic Stratigraphy

Bakke, Kristina¹, Trond Lien¹, Ole Martinsen¹, Steen Petersen¹ (1) Hydro Oil and Energy Research Center, Bergen, Norway

Seismic models of outcrops is essential for qualifying petroleum targets, because they provide an important scale-link between the architectural geometries observed in outcrops and in seismic. Traditionally, such modeling is carried out at the scale of individual reservoir elements, such as for deep-water channels or sheets. Generating outcrop-based seismic models at basin scale is unusual, mainly because of outcrop limitations, but has significant advances for calibrating seismic stratigraphy to lithology.

A 2D seismic model of the deep-water fill of the late Mississippian-early Pennsylvanian Shannon Basin in western Ireland (100 km wide and 1400 m thick) has been constructed based on detailed field data, reconstruction of the basin geometry and conditioned by analogue well data from the Gulf of Mexico. The Shannon Basin represents an extensional deep basin with a basin fill succession comparable to several hydrocarbon-bearing basins around the world and is a widely used analogue. The basin fill is an overall deepening to shallowing-upwards succession from shallow and deep-water carbonates through a source-rock quality deep basinal shale succession (Clare Shales), through a 460m thick turbidite accumulation (the Ross Formation), further through a 550m thick overall fine-grained, very complex slope succession (the Gull Island Formation) to a thick succession of deltaic cyclothems on the top.

This study not only increases the understanding of the anticipated seismic character and imaging of the fill of the Shannon Basin. More importantly, it reveals the expected seismic architecture and character of similar deep-water basin fills and increases the predictive ability in hydrocarbon-bearing basins.