Reservoir Characterization and 3-D Static Modeling of In Situ Shallow-Water and Resedimented Deepwater Carbonate Deposits, Agua Amarga Basin, SE Spain
Reservoir-analog characterization of late Miocene carbonates of the Agua Amarga basin, southeast Spain, documents an important outcrop analog for assessing reservoir potential of subsurface in situ shallow-water and resedimented deepwater carbonate systems. 3-D exposures allow for characterization using measured sections, photomosaics, and core plug petrophysical data. Integration of field and lab data into 2-D and 3-D models (PetraTM and PetrelTM) facilitated the creation of a full-field reservoir-analog model.
Pore volumes calculated from the 3-D model reveal three reservoir analogs: (1) in situ skeletal packstone-grainstones (shallow-water play); (2) focused-flow sediment-gravity flows (deepwater play); and (3) dispersed-flow sediment-gravity flows (deepwater play). Reservoir facies (with porosity -2 to +2 standard deviations; corresponding permeability) comprise volcaniclastic skeletal packstone-grainstones (10-43%; 0.1-1750md) and skeletal grainstones (14-38%; 1.5-1150md) within the shallow-water play, and graded skeletal packstones (17-44%; 1-2700md) and breccias (13-47%; 0.03-4150md) within the deepwater plays. Nonreservoir baffle facies include foraminiferal, volcaniclastic-foraminiferal, and skeletal-foraminiferal wacke-packstones (16-56%; 0.05-250md) within the deepwater plays. The model reveals different exploration strategies for each target using an approach that integrates paleotopography with sequence stratigraphy.
Paleotopography in the accumulation of volumetrically significant reservoir bodies is particularly relevant for the deepwater plays. Focused-flow deposits have a significantly higher volume ratio of reservoir-to-baffle facies (0.70) compared to dispersed-flow deposits (0.09), indicating that paleotopographic focus of sediment-gravity flows improves reservoir character in a predictable way. The ratio of deepwater reservoir volume to linear distance of shelf margin is 9200m3/m for the focused-flow play (~5km of shelf margin) and 8700 m3/m for the dispersed-flow play (~2km of shelf margin). The similarity of these ratios indicates that linear dimension of shelf margin sourcing a deepwater play might predict total volume of reservoir rock.
This study shows that where topographic features that focus flows are located in close proximity, and oriented approximately parallel to a long linear distance of carbonate platform margin, high-volume focused-flow deepwater carbonates with excellent reservoir characteristics will occur.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009