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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.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California