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Seismic-Scale Integrated Reservoir Characterization of a Permian Fluvio-Aeolian
Gas Reservoir, Waqar Field,
Sprague, Ronald
Allan, Saudi Aramco,
An integrated geological model of the Permian ‘Unayzah A fluvio-eolian g
as reservoir, Waqar Field, core,
core plug porosity and permeability, thin section, SEM, image log, and wireline
log data were utilized. These were integrated with seismic structural and
stratigraphic interpretations of amplitude and impedance. The geologic model
includes analysis of fluid characteristics, drillstem tests and production
pressure data.
Lineation analysis of seismic structure maps tied to wells
suggests the existence of minor faulting that may create either reservoir
baffles or potential reservoir compartments. The existing seismic structural
interpretation was reexamined for subtle faults; subsequent image log
interpretation and whole core description confirmed their existence. Facies
analysis from whole core description tied to image log interpretation
demonstrates a range of “arid” continental facies across the field, from
lacustrine to fluvial to eolian, with paleosols possibly acting as reservoir
baffles or barriers. Thin section, SEM, and core plug porosity and permeability
data correlated to these environments suggest a strong facies control on
reservoir porosity and permeability. Seismic amplitude and impedance data tied
to whole core
indicate a similar facies influence on the seismic expression of
the distribution of reservoir and non-reservoir intervals.
The resultant
geological model explains existing gas well drillstem test and production
pressure behavior, and demonstrates the necessity for a multi-scalar,
multi-disciplinary modeling approach.