1994 年 59 巻 1 号 p. 30-42
A sequence stratigraphic study in conjunction with a quantitative basin subsidence analysis was undertaken in the northern part of Ishikari plain of Hokkaido to clarify the depositional history, recognize the tectonic influences and predict the sandstone reservoir distribution.
An interpretation based on seismic data, well logs and biostratigraphic data indicates that the Miocene strata in the basin are composed of eight 3rd order depositional sequences which can be further subdivided into component systems tracts. In the Miocene depositional history of the basin, three stages of sedimentation are recognized by variations in the development of systems tracts and basin architecture.
A quantitative basin subsidence analysis from well data indicates that each sequence boundary was resulted from a relative sea level fall and the stages of sedimentation were strongly influenced by the rate of total basin subsidence.
Tectonic activity influenced the development of sequences and their component systems tracts by masking the sea level fall with periods of rapid subsidence, by exaggerating relative sea level fall and by shifts in sediment source direction as well as sediment accumulation rate as a result of regional uplift.
This study indicates potentials of new stratigraphic types of plays in the basin by predicting sandstone reservoirs basinward, although the previous exploration activities have been focused on anticline-structural traps.