Quantitative
Estimate of Residual and Palaeo Oil Columns to Trace Oil Migration and
Accumulation: Case Studies from Panyu Uplift in the Pearl River Mouth Basin,
South China Sea
Wang, Feiyu1, Yulei SHi2,
Huasen Zeng1, Keyu Liu3, Hesheng Shi4 (1)
China University of Petroleum (CUP), Beijing, China (2) China University of
Petroleum (CUP), Beijing, Colombia (3) CSIRO Petroleum, Bentley, WA, Australia
(4) CNOOC Limited, Guangzhou, China
Only some commercial gas fields were
discovered in the Panyu uplift Pearl River Mouth Basin, South China Sea, which
is southwardly abut upon deep water area Baiyun petroleum generative
depression. The existence of commercial oil migration and accumulated in Panyu
uplift is still controversial, although many geologists presumed that Eocene
Wenchang Formation oil-prone lacustrine source rocks and Oligocene Enping
Formation gas-prone humic-type source rocks were co-existed in the Baiyun
depression. Quantitative estimation of the residual or palaeo oil columns are
critical to the accurate calculation of the size of the original reserve and
may have important implications for predictive drilling in the surrounding
areas. Quantitative grain fluorescence (QGF) and quantitative grain
fluorescence on Extract (QGF-E) screen analysis, Molecular Composition of oil
inclusion(MCI) were applied to detect the size and putative sources of
palaeo-oil zones and current residual oil zones in main carrier beds (T5
sandstones) of 14 wells, Palaeo-oil zones have distinct fluorescence spectra
with spectral peaks between 375 and 440 nm and elevated fluorescence
intensities compared with spectra for rocks that have always been water
saturated. QGF-E and QGF intensities parameter increase upwards from near the
current residual oil¨Cwater contact (ROWC) or palaeo oil¨Cwater contact (POWC)
to the crest of trap. QGF-E and QGF parameter profiles compared with wireline
log data Oil Migration Intervals (OMI) algorithms analysis to determine the
cumulative thickness of palaeo-oil zones in T5 sandstones ranging from ca 30m
to 100m. Biomarker assemblages of oil inclusions from MCI data indicated oil
were originateµÄ from lacustrine source rocks. Those result confirmed that
early oil migration and accumulation event and size, later gas displaced the
original oils in the Panyu uplift.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California