--> Interpretation and Modeling of Structurally Complex Eocene La Paz and Oligocene Mugrosa Fluvial Sandstone Reservoirs, Yarigui-Cantagallo Field, Middle Magdalena Basin, Colombia, SA, May, Michael; Brinton, Lise; Arestad, John; McKamey, Keith; Keay, James; Kisselman, David; Lara, Aurelio, #90100 (2009)

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Interpretation and Modeling of Structurally Complex Eocene La Paz and Oligocene Mugrosa Fluvial Sandstone Reservoirs, Yarigui-Cantagallo Field, Middle Magdalena Basin, Colombia, SA

May, Michael1
 Brinton, Lise1
 Arestad, John2
 McKamey, Keith1
 Keay, James1
 Kisselman, David1
 Lara, Aurelio3

1International Reservoir Technologies, Lakewood, CO.
2
ExplorTech, Centennial, CO.
3
Ecopetrol,
Bogota, Colombia.

Integration of reprocessed 3D seismic data with well logs, digital core descriptions, FMI and dip meter data, resulted in extensive revisions to existing structural and stratigraphic interpretations used in a new reservoir model of the Yarigui-Cantagallo Field, Middle Magdalena Basin, Colombia. The structural and stratigraphic complexity of the field has presented modeling and development challenges reflected in a current recovery factor <25%; similar less complex fields have recoveries >30%. This new model has the potential to positively impact water flood strategies.

Stratigraphic and reservoir intervals of interest include the Eocene La Paz CG and C, and the Oligocene Mugrosa B3. The CG interval is composed of stacked, amalgamated alluvial/fluvial sands and interbedded floodplain silt and clay. The La Paz C and Mugrosa are dominated by floodplain deposits with thinner, isolated and laterally discontinuous, reservoir sands.

A significant unconformity resulting from structural uplift, possibly related to a major compressional/transpressional event, was identified on 3D seismic and well logs near the top of the CG stratigraphic interval. Over 1000 feet of uplifted section was removed on the west side of the field adjacent to the bounding Cantagallo fault; most of the Cantagallo section is absent in several fault blocks in the field. The previously unrecognized erosional unconformity is most dramatic at the south end of the field where Cretaceous sediments are in contact with the La Paz C. Near the Cantagallo fault the CG units are steeply upturned and truncate against the unconformity. Preservation of the CG increases away from and to the east of the fault. Significant thinning of the overlying Oligocene Mugrosa formation indicates continued post unconformity uplift. Movement continued in the field area throughout deposition of the overlying La Cira Formation.

The thick section of alluvial fan and braided stream deposits comprising the principle CG reservoir interval is located below the recently recognized Cantagallo unconformity. This reservoir interval overlies fluvial and floodplain deposits and a major flooding event marked by a widely correlative silt and clay unit. The section below the flooding event is also characterized by cyclically deposited flood plain muds and fluvial sands. The upper CG, C and B3 units deposited above the Cantagallo unconformity record return to relative quiescence and a low energy flood-plain dominated system.


AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil