Abstract: Geological Interpretation and Reservoir Geometry of Submarine Fan and Channel Deposits
Lambertini, Roberto; Pedro Ivo De Assis; Steven M. Hansen and Roy Nurmi - Schlumberger
Structural interpretation and high-resolution
sequence analysis of offshore deep water deposits encountered by drilling
are optimally and cost-effectively done using borehole
imagery on a geological
workstation. Precise geometrical analysis of depositional facies, erosional
channels and sedimentary structures as well as tectonic features is critical
in assessing both wildcats and development wells. This assessment usually
includes fault characteristics slumping and channel orientations that are
extrapolated three dimensionally by integration with the seismic data on
a workstation.
Borehole
imagery, including electrical, a variety of acoustic
imagery techniques and new density/lithology imagery, is routinely providing
new insights into reservoir geometry. In addition, recent breakthroughs
in sonic
imaging
allows geometrical definition of features away from the
borehole
which is invaluable for assessing attic oil left behind because
of faulting and/or erosional channels.
Detailed reservoir bedding characteristics has
been found to be a function of the processes forming modem submarine fans,
(i.e. such as bed thickness variations in the Amazon fan. In addition,
other, high-resolution data can be used to improve the geological interpretation
of borehole
imagery, as does an integration of nuclear magnetic resonance
data, which helps to define reservoir texture, the presence of authigenic
clays and permeability profiles. Early testing of imagery logging and coring
in Brazil revealed that some of the offshore submarine channel, turbidite
and fan reservoirs are texturally complex and include coarse-grained facies.
These data are compared to detailed studies which include outcrop, seismic,
borehole
imagery, core, pressure and production data from similar complex
reservoirs in other parts of the world.
AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil