Geology of linear seismic anomalies of Frolovskaya formation

As 3D seismic is becoming more widespread in exploration projects, interpreters begin observing anomalies of varying genesis. It is not always obvious what geological processes cause their formation. This article considers the possible causes of amplitude anomalies in the Frolovskaya Formation. The main attention is paid to linear anomalies which are not typical of Neocomian time interval and rarely found in seismic data. The authors put forward two hypotheses about the origin of these anomalies. Since the study interval is attributed to the shallow-marine depositional environment, the first hypothesis is based on visual analysis and associates linear anomalies with wave-dominated delta activity. In this case linear anomalies can be interpreted as alongshore bars and adjacent lagoons. However, the direction of the coastline in the Neocomian did not coincide with that of the anomalies in this area. Therefore, there is a contradiction here. The second hypothesis is the most probable. It is based on tectonic activity and associated with the secondary lithological changes or diapirism. It is suggested that under the influence of seismic vibration and anomalous strata pressure clays of the Frolovskaya Formation became plastic and filled cavities or voids along weakened or fractured zones. The study of possible reasons for formation of such anomalies plays an important role in seismic data interpretation, as the accuracy of the conceptual geological model depends on it