Schlumberger 2011 Annual Report - page 16

address the degree of compartmentalization in defining
the potential of a newly found reservoir. In other words, if
geological faults are found through seismic imaging and
interpretation, do they form barriers? These and other
potential obstacles to fluid flow can divide reservoirs into
multiple compartments that have an impact on reservoir
To resolve the uncertainty posed by compartmental-
ization and gain better understanding of reservoir fluid
behavior, Schlumberger has directed considerable
research effort into the characterization of crude oils. The
work shows that compositional variations in an oil column
display systematic and predictable profiles that are robust
signatures of reservoir connectivity. This discovery led to
the introduction of Fluid Profiling* downhole fluid analy-
sis conducted with the latest-generation formation fluid
testing service, the InSitu Fluid Analyzer* tool, which was
commercialized in 2010. The ability of this tool to evalu-
ate the optical density of crude oil downhole, at reservoir
conditions, provides the means to establish the continu-
ity and connectivity of hydrocarbon accumulations much
more accurately than ever before.
The information generated by the InSitu Fluid Analyzer
service is critical to reservoir characterization in helping
determine the degree of compartmentalization. Downhole
fluid analysis does not, however, replace the need for well
testing, another Schlumberger leadership technology,
which provides information about reservoir-scale fluid
connectivity and boundaries for confirming reservoir
shape and size. This information is obtained by using
Testing Services technologies to bring the successful
exploration well into production for a sufficiently long
period of time to obtain representative pressure measure-
ments and reservoir fluid samples farther from the well-
bore. This helps confirm the volume of hydrocarbon
reserves in place.
The technologies that form the Reservoir
Characterization Group portfolio cover a wide range of
geological, geophysical, petrophysical, and reservoir engi-
neering measurements. The Schlumberger Data &
Consulting Services organization is integral in helping
customers interpret these measurements and use them
to build comprehensive static and dynamic models of the
Trap, Reservoir, Charge, and Seal
No matter how sophisticated the model used or the level
of detail of the data input, managing exploration risk
essentially comes down to understanding four factors—
trap, reservoir, charge, and seal. For over 30 years, opera-
tors have used these factors to define the degree of risk
that each exploration prospect presents. Trap concerns
the likelihood that the prospect contains a geological
mechanism to trap any hydrocarbons that have formed
over time. Reservoir refers to the presence of porous, per-
meable rock in which the hydrocarbons can accumulate.
Charge considers the presence of nearby source rock for
forming the hydrocarbons together with a path for hydro-
carbon migration to the reservoir rock. Finally, seal
expresses the degree to which the trap is strong enough
to keep the hydrocarbons in place.
Basin and petroleum system modeling assesses the
four risk factors of trap, reservoir, charge, and seal in a
systematic way. Advances in seismic technology have
made significant contributions to improving the evalua-
tion of trap and reservoir risks, but almost three-quarters
of exploration well failures result from an inadequate
understanding of charge and seal risks. Assessing charge
risk requires an understanding of how the source rock
matured relative to the timing of formation of the trap.
The key is that the trap—and seal—must be present
when the hydrocarbons migrate through the basin fill.
Seal risk has to do with whether the integrity of the seal
has remained uncompromised until penetrated by the
exploration well.
A full, integrated evaluation of exploration risk can
now be conducted on a single interpretation platform by
using Petrel software. Schlumberger Information
Solutions has introduced new functionality that comple-
ments existing Petrel geology and geophysics modules,
including a new geological structural framework tool, the
Petroleum Systems Quick Look module, and integration
with the Techlog* wellbore interpretation platform.
Techlog software, developed by Techsia, a Schlumberger
company acquired in May 2009, forms another comple-
ment to Petrel earth models through the integration of all
measurements made in the wellbore. Development of the
Petrel-based exploration system has also benefited from
the Schlumberger acquisitions of IGEOSS in April 2010 to
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