High resolution seq stra applied to field development

1. Sequence Stratigraphic Evolution of the Oficina Formation, Eastern Venezuela Basin: Depositional Systems and Sand Body Geometry in a Non-Marine to Estuarine Environment A. T. Picarelli 1 , R.R. Savini 1 , V. Abreu 2 , S. Grosso 1 , J. Arguello 1 and D. Salas 1 (1) Perez Companc de Venezuela (2) Exxon-Mobil URC

3. Geotectonics and Paleophysiography Llanos Basin Barinas Basin Maturin Basin Guyana Craton

4. Paleophisiographical Setting Mod. from Parnauld et al. (1995) Orinoco River Mata/Acema S N Oficina/Merecure fms (Oligocene/Miocene) Mesa and Las Piedras fms (Late Mioc./Pliocene) 100 km 4 km 0 km 4 km 8 km 12 km 16 km La Pica fm (Late Miocene) Freites/Carapita fms (Late Mioceno) Collision Front Serranía del Interior Oritupano/Leona Maturin Sub - basin Shallow marine Shelf Break

7. Foredeep Cycles and Paleobatimetry

8. Seismic Expression - 2nd Order Events

9. Foredeep Cycles and High-Frequency Stacking Patterns

11. Seismic Expression - Sequence Boundaries 30 Km Mata Oritupano -Leona Acema

14. Fluvial-dominated Incised Valley Fills Example from High-Frequency Sequence Merecure I 11471’ 11480’ 11550’ 11541’ 11520’ SB SB 11511’ 11500’ TS 11490’

16. High-Frequency Sequence Architecture within 3rd Order LST: Sequence Boundary and LST SB MFS SB 10589’ 10579’ 10569’ 10559’ TS/PS 10549’ 10539’ 30 ‘ PS PS PS PS Cross stratified, medium to coarse grained tidal channel sandstone, fining upward (individual sets 2 - 3 ft), water escape related structures and mud drapes eroding offshore mud.

17. High-Frequency Sequence Architecture within 3rd Order LST: Transgressive Surface SB MFS SB 10589’ 10579’ 10569’ 10559’ TS/PS 10549’ 10539’ 30 ‘ PS PS PS PS Siltstone to very fine sandstone layer strongly bioturbated (Planolites isp and Teichichnus isp), ripple cross lamination, siderite nodules overlaid by offshore mud.

18. High-Frequency Sequence Architecture within 3rd Order LST: HST Deposits/Sequence Boundary SB MFS SB 10589’ 10579’ 10569’ 10559’ TS/PS 10549’ 10539’ 30 ‘ PS PS PS PS Offshore mud bioturbated by Thallassinoides isp, with pipes filled by coarse grained sands from the overlying unit.

19. High-Frequency Sequence Architecture within 3rd Order LST: HST Deposits and Sequence Boundary Expression SB MFS SB 10589’ 10579’ 10569’ 10559’ TS/PS 10549’ 10539’ 30 ‘ PS PS PS PS Coarse grained sandstone, massive to horizontal/low angle lamination, bioturbated. Interpreted as a fluvial distributary channels, marine influenced, with sharp contact with offshore mud.

21. TST and MFS - Seismic Expression 30 Km Mata Oritupano -Leona Acema

24. TST/(HST) Deposits and Sequence Boundary Expression: Core data 30 ‘ Medium to fine grained sandstone, massive strongly bioturbated, overlying offshore mud with Thallassinoides isp. 3rd order Sequence Boundary High frequency SB and TS PS 10599’

25. HST - Seismic Expression 30 Km Mata Oritupano -Leona Acema

26. HST - Deltaic Sedimentation

27. Stratigraphical and sedimentological Model - LST Deep Incised valley fills, fluvial-dominated Distributary channels tidally influenced Distributary channels Tidal bars Overbank 2 Hydraulic Communication W E SB SB S E 1 2 4 3 N SB SB TS 1 2 3 4 5th Order Events 1 4 3

28. Stratigraphical and sedimentological Model - LST tidal-dominated Shallow incised valley fills W E S N 1 2 4 3 5 6 7 1 2 4 3 5 6 1 2 4 3 5 6 2 3 5 6 7 4 Distributary channels tidally influenced Tidal channels Tidal bars Tidal bars (distal) Transgressive surface Sand ridges 7 Offshore SB TS SB SB/TS SB/TS SB SB Hydraulic Communication 5th Order Events

29. High-resolution Sequence Architecture and Base level Change Fluvial channels Paleosoils and Crevasse splay Paleosoils, swamp and tidal flats Tidal and Channel bars or fluvial channels tidal influenced Pedogenic Profiles, swamps and tidal flats Internal and External Platform Muds and Storm Related Sands W/NW E/SE Paleosoils, swamps and tidal flats Tidal and Channel bars or fluvial channels tidal influenced Hydraulic isolated Incised valley fills Pedogenic Profiles, swamps and tidal flats

31. Stratigraphical and sedimentological Model TST/(HST) Littoral Sand Ridges (tidal- and wave-dominated) W E N S Transgressive sands (medium to fine grained sandstone, bioturbated) Offshore shale with Thallassinoides isp (Glossifungites ichnofacies) Offshore shale 1 2 3 1 2 2 SB/TS SB TS SB/TS Hydraulic Communication 5th Order Events 1 SB/TS 3 Snedden and Dalrymple, 1999 1 2 2

33. Foreland Setting and Base Level Evolution in the Mata, Acema and Oritupano Areas T Foreland Basin (Forebulge) Main Sediment Source Zona A Zona B T T S S Shallow marine Ramp-like Basin Foreland Basin - Distal Zone Zona A Zona B

34. Paleogeographical Model Atmospheric Circulation Pattern Miocene Gulf Main source of sediment supply (Guyanna Craton)