3D Seismic Sedimentology of Nearshore Subaqueous Fans – A Case Study from Dongying Depression, Eastern China - Advances in Data, Methods, Models and Their Applications in Geoscience - page 126

2007; Liu, B.G. & Liu, L.H., 2008; Nordfjord et al., 2005; Posamentier & Killa, 2003; Prather,
2003; Sullivan et al., 2007; Schwab et al., 2007; Wang et al , 2004; Wu et al, 2005; Zeng et al.,
2003, 2004, 2007; Zhang et al., 2007), but rarely used to study nearshore subaqueous fans. In
this paper, we took the nearshore subaqueous fan in the Dongying Depression as a case, and
used the pseudo-acoustic 3D seismic inversion method on characteristic logs to reconstruct
3D seismic sedimentological structures of the nearshore subaqueous fans including the
distribution of the effective sand-conglomerate reservoirs and the temporospatial evolution
of individual nearshore subaqueous fan system.
Over the years, six exploratory wells were drilled into the lower Es4 Formation in the
northern Dongying Depression and four of them encountered commercial oil and gas. The
logging data from all six wells yield good coverage with 0.125 m or 0.25 m sampling
spacing. An industry- standard 3D seismic data of 600 km 2 acquired in 2005 was processed
using high-fidelity prestack time migration technique with 25m × 25m track spacing, 1ms
sampling interval, 25HZ dominant frequency and 10-60Hz effective frequency bandwidth in
the target formation.
2. Characteristics of the nearshore subaqueous fan in the northern Dongying
Depression
The Dongying Depression is a typical sub-structural unit in the Bohai Bay Basin, Eastern
China, surrounded by a series of uplifts, including the Luxi Massif in the south,
Chenjiazhuang Uplift in the north, Qingtuozi Uplift in the east, Binxian Uplift and
Qingcheng Uplift in the west (Fig.1). As a rift basin, the Dongying Depression is
Fig. 1. Location and distribution of sedimentary facies of the lower Es4 Formation in the
northern Dongying Depression, Bohai Bay Basin, Eastern China. 3D seismic area is marked
by Red box.