3-D Reservoir
Characterization of a Point-Sourced Deepwater Carbonate Reservoir Analog, Upper
Miocene, Agua Amarga Basin, SE Spain
Dvoretsky, Rachel1,
Evan Franseen2, Robert Goldstein1, Alan Byrnes2
(1) University of Kansas, Lawrence, KS (2) Kansas Geological Survey, Lawrence, KS
Excellent exposures of Upper Miocene
carbonates of the Agua Amarga
basin, SE
Spain,
reveal a point-sourced wedge of sediment gravity-flow deposits that contrast
with the semi-continuous, line-sourced aprons of many carbonate basin margins.
The basin (~8 x 4 km; ~200 m relief) formed on earlier Miocene volcanic rocks
that had been faulted, exposed subaerially, and
eroded prior to carbonate deposition. Updip of the
basin margin, the Tortonian/Messinian section
includes a reef complex along a west- and north-facing escarpment. A flooded paleovalley in the southwest corner of the basin focused
shedding of carbonate shelf sediment and reef debris, creating a point-sourced,
basin-floor succession of laterally restricted sediment gravity-flow wedges and
other deepwater deposits. Proximal deposits are approximately 50-meters thick
and consist of at least 40 gravity-flow stratigraphic
units. Coarse debrites, coarse turbidites,
coarse-grained wackestone/packstone, and fine-grained
wackestone/packstone exhibit a complex distribution
of facies that display internal erosion surfaces, backstepping, progradation and onlap. Distally, grain coarseness decreases as low-density
sediment gravity-flows and hemi-pelagic deposition become dominant.
Detailed stratigraphic
and facies relationships, integrated with outcrop
spectral gamma ray data and core petrophysical data,
are being utilized to build a 3-D reservoir model. Reservoir facies include coarse-grained turbidites
and debris units (25-40% porosity, 10-300 md
permeability), whereas hemi-pelagic deposits and fine-grained turbidites exhibit poorer properties and may constrain flow
(30-60%, 1-10 md).
The reservoir model explores the effects
of paleotopography and sea-level history on dynamics
of sediment deposition, and assesses reservoir analog potential of these
deepwater carbonate deposits for future subsurface hydrocarbon exploration.