TITLE:
Paleogeomorphic Influence on Facies Characteristics of Braided Delta and Reservoir Prediction—An Example from L oilfield in Bohai Bay Basin
AUTHORS:
Longtao Cui, Xinwu Liao, Liye Zhou, Cheng Guo, Lan Zhang
KEYWORDS:
Slope Zone, Braided Delta, Reservoir Prediction, Forward Modeling
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.7 No.8,
August
23,
2019
ABSTRACT: Five wells of L oilfield in Bohai bay basin have
drilled 10 - 15 meters thick oil layer in the Paleogene delta. Due to the
deep-buried reservoir and the poor seismic performance, it is difficult to
identify the reservoir genesis, and predict reservoir
distribution. By analyzing core, well logging and seismic data, a stable
mudstone section is selected as the correlation marker to establish a
stratigraphic framework. The paleogeomorphology is reconstructed after
decompaction correction and paleobathymetric analysis. Based on the differences
of paleotopography and sedimentary facies, the study area mainly develops two
delta systems: low gradient coarse-grain delta system and steep gradient
delta-turbidite system. The favorable reservoir of low gradient coarse-grain
delta, which is thick and has good lateral connectivity, mainly locates in the
delta front. The favorable reservoir of steep gradient delta-turbidite system
locates in the delta front and turbidite facies, and the delta front deposits
are thin and have poor lateral connectivity. The boundary of delta front is
first depicted on the basis of paleotopography. In combination with reservoir
architecture and forward modeling analysis, the seismic attribute is then
optimized to predict the distribution of favorable reservoir. Using this
method, several sets of oil-bearing sandbodies have been drilled in L oilfield,
and the prediction accuracy of reservoir distribution is proved to be high.
This study demonstrates that the paleogeomorphology plays an important role in
controlling the genesis and distribution of the delta reservoir and provides
reference for the reservoir prediction in similar oilfields.