Preliminary
interpretation in a 16,700-acre 3-D seismic survey (Figure 2) in
the southern portion of Fullerton field and 35 2-D seismic lines
over the northern portion of the field indicate numerous deep-seated
E-W and SW-NW-striking faults. These faults bound many present-day
structures and appear to have influenced reservoir facies distribution.
Faults display
major offsets through Devonian and older strata and appear to be
the cause of subtle displacements in Wolfcampian- to Leonardian-age
strata and/or changes in stratigraphic architecture and facies (Figure
16). In areas underlain by unfaulted horst blocks, for example,
seismic data generally display flat, continuous reflections and
cores display predictable facies and cycle development patterns
indicating typically flat platform depositional environments. In
areas of deep-seated faults, in contrast, seismic data display a
more chaotic signature and cores exhibit features indicative of
deeper water, slump, and downslope transport. These relationships
suggest steepened slopes caused by ongoing tectonic instability
in these areas.
Whereas most
structural interpretations of the Central Basin Platform region
suggest that the area became tectonically quiescent after the Wolfcampian,
seismic and core data from Fullerton field indicate continued activity
along structural features well into Leonardian time. Our data further
suggest that this activity locally had significant impact on depositional
processes and thus may play a profound role in the distribution
of porosity and permeability in these reservoirs. |