TITLE:
Fine Characterization and Residual Oil Exploitation of Shallow-Water Delta Sand in Oilfield B of Bohai Bay Basin
AUTHORS:
Junshou Zhao, Qiang Sun, Yanan Xu, Quanlin Wang, Junliang Zhou
KEYWORDS:
Shallow Water Delta Front, Fine Characterization of Sand Body, Sand Body Contact Style, Residual Oil Prediction, Bohai Bay Basin
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.13 No.11,
November
26,
2025
ABSTRACT: In Oilfield B of the Bohai Bay Basin, the shallow-water delta sandbody reservoirs are thin and exhibit rapid lateral changes. Local incised superposition results in complex oil-water relationships within the sandbodies and uneven plane injection-production response, which restricts the efficient tapping of remaining oil. Based on data such as drilling cores, geochemical analysis, well logging, and seismic data, the sedimentary characteristics of the lobate shallow-water delta are determined. Through seismic forward modeling, the seismic waveform characteristics of different sand body stacking patterns are summarized to guide the fine description of composite sand body stacking patterns and single-stage sand body plane distribution patterns. The results show that: by using identification markers such as the discontinuous, superimposed, and elevation difference characteristics of event axes on inverted seismic profiles, as well as the variation zones of planar seismic attributes, 2 phases of composite channels can be divided. Five types of sandbody contact patterns were summarized, including discrete contact, lateral cutting contact, natural levee connection, vertical aggradation superimposition, and composite superimposition. Combined with the results of fine characterization of sand bodies, based on the single-phase channel and river-bar lobes, the remaining oil distribution law is summarized, the oil-water relationship and remaining oil distribution of the river-bar composite sand body are jointly controlled by the cutting interface of the sand body and the rhythm pattern of the composite sand body, and the potential tapping strategies such as improving the single-phase channel well pattern, river-bar lobes well pattern reconstruction and local encryption are proposed. The successful implementation of 24 adjustment wells and the successful production of 100 m3/d from 9 new adjustment wells demonstrates that the fine characterization method and resulting residual oil predictions are reasonable and credible, and provide reference for the development, production and potential mining of similar oilfields.