Forward Seismic Modeling: A Case Study from the Froan Basin and the Frøya High Area

Abstract

An extensive two-dimensional geological model was created to represent an offshore area in the mid-Norwegian Sea. The geological model was built based on a seismic line from the Froan Basin and the Frøya High area. Forward seismic modeling followed by a basic processing flow was applied to the geological model to generate a synthetic seismic section that could be used to investigate the seismic expression of the area. The final step in the processing flow consisted of a 2D Kirchoff Pre-Stack Time Migration (PSTM). To further study the seismic nature, a second model was created where a volcanic layer replaced the Shetland Group. To carry out the forward seismic modeling, a supercomputer was used.Since criterias related to the grid size of the geological model had to be fulfilled, a low frequency was used in the seismic acquisition. Some parts of the synthetic sections are contaminated by numerical noise that is related to the modeling algorithm. The unmigrated synthetic sections provide a clearer image with more visible layers than the migrated synthetic sections. The master fault between the Froan Basin and the Frøya High has been imaged better on the migrated sections compared to the unmigrated sections. The basement reflector and the reflector from the volcanic layer can easily be seen because of the high contrasts in acoustic impedance. The volcanic layer was modeled as a homogenous layer and did therefore not give a realistic image of how a volcanic layer will affect the imaging of the subsurface.