Abstract:
Sandbody distribution patterns and controls are the most important foundation for
petroleum exploration and development, particularly in a lacustrine basin with rapid changes
in the sedimentary environment. To provide sedimentologists and petroleum geologists around
the world with an analogue for sandstone reservoir prediction, the sedimentary facies of the fourth
member of the Shahejie Formation (Sha-4 Member) in the Huimin Depression of the Bohai Bay Basin
were analyzed, and the sequence stratigraphic framework was established based on characteristics of
spontaneous potential logs and lithology. According to the findings of this study, the Sha-4 Member’s
sedimentary environment was dominated by delta front and shallow lake facies. Delta front sandbodies
were discovered to retrograde before prograding again throughout the established profile.
The Sha-4 Member in the Huimin Depression is divided into a third-order sequence (LSC1), which
can be further divided into four fourth-order sequences (MSC1 to MSC4), corresponding to the four
sub-members (S4-1 to S4-4). During the development of the MSC1 to MSC4 sequences, the delta
depositional scale first decreased and then increased with the changing base level. The maximum
flooding surface developed within the MSC3 sequence. The Sha-4 Member sequence model reveals
that the deltas in the study area exhibit self-similarity, and delta sandbodies are primarily developed
in the MSC1, MSC2, and MSC4, whereas mudstone is largely developed in the MSC3.
