Integrated
Interpretation
of North Sea Turbidite Play
Combining Elastic Inversion, Sedimentology and
Seismic
Geomodelling Technology
Schmidt, Ingelise 1; Stanbrook, David A.1;
Hansen, Hans P.2; Kiely, James M.1
(1)Exploration,
Maersk Oil, Copenhagen, Denmark. (2) Cooperate Petroleum Engineering, Maersk
Oil, Copenhagen, Denmark.
In mature areas such as the North Sea, identification of new plays
is challenging but essential as readily identified prospects and plays have
already been drilled. Thorough integration of geophysical, geological data
and
the use of new methods become increasingly important to identify new plays and
prospects. This study demonstrates how new tools combined with traditional
analysis can provide detailed information supporting a geological model in a
new play.
A potentially large turbidite system was identified from seismic
using conventional
interpretation
methods and attribute extractions showed this
to be seismically anomalous. Firm evidence supporting reservoir potential was
lacking however and a key concern was that the system could be mud dominated.
Various geological and geophysical approaches were utilized and new
seismic
geomodelling technology proved a powerful aid to investigate attributes derived
from
seismic
elastic inversion, extract maps of subtle geometries indicating
channelization and for
interpretation
of environments of deposition. The
outputs were thus used for volumetric calculations and to support the
interpretation
of basin filling and seal hypothesis.
The elastic inversion was performed integrating local well control
to establish a shale rock-physics model, combined with data
from a nearby
analogue well for sand attributes. Relative impedance, relative Vp/Vs, and
transforms of these volumes were produced. The
seismic
geomodelling tool
allowed these attribute volumes together with
seismic
envelope attributes to be
extracted along a great number of surfaces/horizons throughout the
seismic
volume - far more than feasible with conventional
seismic
interpretation
. The
surfaces, also called 'surface stacks' were derived using
seismic
geomodelling
technology and the “scanning” using these surfaces revealed details of the
depositional system supporting a sand dominated turbidite system.
A thickness attribute derived from the seimic geomodel was also
“scanned” and used to identify channelized geometries. Importantly, this
particular attribute also revealed information on basin filling history and
seal risk. Sedimentological interpretation
of core
data
from wells that were
drilled proximal and distal to the areas of interest provided evidence for an
active turbidite environment, supporting the
interpretation
of the
seismic
anomalies. The paleo-environmental and geographical
interpretation
of these
wells also supported the proposed model.
AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.