1. Estimation and destination of some of the eroded Post Mid-Miocene sediments using a classic method- Vitrinite Reflectance (VR). 28 TH of February, 2013

2. Why do this study? Why do this study? What is Vitrinite Reflectance? What is Vitrinite Reflectance? Location of wells Location of wells VR – depth plots VR – depth plots VR – temperature plots VR – temperature plots Summary Summary Why do this study? Why do this study? What is Vitrinite Reflectance? What is Vitrinite Reflectance? Location of wells Location of wells VR – depth plots VR – depth plots VR – temperature plots VR – temperature plots Summary Summary 2 Presentation Outline

3. 3 Why this study? Unconformities. (Higgs. 1997) Convergent margin phase: encroachment of Caribbean plate Passive margin phase Where is the missing sediment and can it be potential reservoirs?

4. MACERAL (from Latin: “macerare”, to soften) Stopes, 1935 “ Macerals are constituents of coals, occurring naturally in the sedimentary, metamorphic, and igneous materials of the earth ” Spackman, (1958) What is a Maceral?

5. 5 What is Vitrinite?

6. Organic Matter Fractionation

7. Dispersed Vitrinite

8. 8 What is Vitrinite Reflectance- VR Vitrinite Reflectance (%Ro) is a measurement of the percentage of light reflected off the vitrinite maceral at oil immersion Vitrinite reflectance Ro as a thermal indicator Thermodynamic record are preserved in rock and such records are irreversible. Increase in burial causes progressive increase in temperature; thus maturity increases with depth.

9. Dispersed Vitrinite Ro Histograms should be based on 40-100 Measurements

10. Note the lg scale on the x axis Can be used to estimate eroded sediment, Dow (1977) VR vs Depth plots. Moolenaar, 1996 1400 m

11. Dow (1977) The 0.2 estimate has limitations 1) No significant unconformities 2) Heating rate of 1- 10 degrees C/ Myrs (no igneous intrusions 3) No large variations in the geothermal gradient 4) Depends on whether or not the studied section is in Tropical or Temperate climate. 5) Indicates the depth of diagenesis Erosion estimation based on Dow (1977) ; using 0.2 as a near surface VR estimate

12. VRo valued tied to a maximum palaeo- temperature Indicates the oil window for Type 1 and Type 2 kerogens VR values used in thermal history reconstruction

13. Maximum Palaeotemperature vs VR values 1)Saxony Basin, Germany 2)North Sea 3)Kearl Lake, Alberta 4)Santos Basin, Brasil 5)Mahakam Delta, Indonesia 6)Gulf Of Mexico

14. 14 Well locations Well A Well B Well C Well E Well D

15. Ro from Well A with an estimated 4552’ to 1300’ of missing sediment. Ro from Well A with an estimated 4552’ to 1300’ of missing sediment. Depth (ft) Cretaceous Oligocene Miocene Early Pliocene Eocene 0.5 Missing Late Pliocene to E. Pleistocene, Early Miocene and Palaeocene L. Cretaceous source rock is in the main oil window

16. Depth (ft)Age Estimated Reflectance value Maximum calculated palaeotemperatures/ 0 C Present day temperatures / 0 C Difference / 0 C 6000Miocene0.41 72 5121 8000Miocene0.48 87 6522 10000Oligocene0.55 99 7920 12000Eocene0.62 112 9418 14000Cretaceous0.71 123 10023 Difference between the maximum palaeotemperature and the present day temperature- Well A Average difference in temperatures is 21C

17. Ro from Well B with an estimated 5851’ to 2956’ of missing sediment? Ro from Well B with an estimated 5851’ to 2956’ of missing sediment? Cretaceous Late Miocene to Early Pliocene Early Miocene to Oligocene Oligocene to Cretaceous Missing Mid-Miocene and Late Pliocene- Present sediment 0.5 Depth (ft) Missing Late Pliocene to E. Pleistocene, Early Miocene L. Cretaceous source rock is in the main oil window

18. Difference between the maximum palaeotemperature and the present day temperature- Well B Depth (ft)Age Estimated Reflectance value Maximum calculated palaeotemperatures / 0 C Present day temperatures / 0 C Difference / 0 C 2000 L Miocene to E. Pliocene 0.36 602238 3000E. Miocene0.39 682939 4000 Oligocene to Palaeocene 0.41 7236 5400Cretaceous0.47 854639 7000Cretaceous0.52 945836 Average difference in temperatures is 38C

19. Ro from Well C with an estimated 4970’ to 2689’ of missing sediment?. Ro from Well C with an estimated 4970’ to 2689’ of missing sediment?. Depth (ft) Eocene Early-Miocene 0.5 Oligocene Late Pliocene to Pleistocene Missing Mid to Late Miocene

20. Depth (ft) Age Estimated Reflectance value Maximum calculated palaeotemperatures /C Present day temperatures /C Difference 2800 E.Miocene0.41722745 3500 E.Miocene0.47853352 4000 Oligocene0.49893653 4500 Oligocene0.5914051 5000Oligocene/ Eocene 0.51924349 Difference between the maximum palaeotemperature and the present day temperature- Well C Average difference in temperatures is 50C

21. Ro from Well D with an estimated 6000’ of missing sediment. Ro from Well D with an estimated 6000’ of missing sediment. Early Cretaceous Pliocene Pleistocene Y= -10854ln(x)-9148 Depth (ft) Late Miocene Missing the Late Cretaceous to Mid Miocene 0.5 Any possible L. Cretaceous source rock maybe in the oil to gas phase

22. Difference between the maximum palaeotemperature and the present day temperature- Well D Depth (ft)Age Estimated Reflectance value Maximum calculated palaeotemperatures / C Present day temperatures Difference 2350L Pliocene0.343 403 5750Early Pliocene 0.470 682 7240Early Pliocene0.4581801 9300Late Miocene0.5599981 9800E. Cretaceous1.05159 10257 12200Early Cretaceous 1.317812157 Average Pre Miocene difference in temperatures is 57

23. 23 Well locations Well A Well B Well C Well E Well D

24. Ro from Well E with an estimated 300’ to 2740’ of extra sediment Ro from Well E with an estimated 300’ to 2740’ of extra sediment Late Pliocene to Early Pleistocene? Late Pliocene Approximately 5,000’ of reworked or recycled vitrinite. Possible MLE equivalent The VR data was backed up with pore maturity data 0.5 Y= -13881(lnx)-24272 Sediment reached approximately 92 C Uplift has to be quick in E.Pleistocene Vitrinite in deep water

25. Depth (ft)Age Estimated Reflectance value Maximum expected palaeotemperatures Present day temperatures /C Difference 4325 L Pliocene to E Pleistocene 0.29 402911 6305 L Pliocene to E Pleistocene 0.54 984058 8315 L Pliocene to E Pleistocene 0.3968 5216 10315Late Pliocene0.3763 0 12305Late Pliocene0.4172 73 14320Late Pliocene0.4887 0 15567Late Pliocene0.5294 931 Difference between the maximum palaeotemperature and the present day temperature- Well E Average Late Pliocene difference in temperatures is 1

26. Trinidad and Tobago AssetDD Month YearPage 26 Columbus Basin Upper Tertiary Depocenter Caroni Basin Upper Tertiary Depocenter Non Deposition/Erosion Eastern Offshore Ties? Cruse-Forest- Morne L’Enfer Depocenter Gros Morne- Mayora Depocenter Late Tertiary Summary Plio-Pleistocene tectonics

27. Top Cretaceous, Gibson et al. 2005 Onshore Cretaceous is at 4000’ to 6000’. Pleistocene Southern Range transpressional uplift at about 1.6 Ma – regional Southern Anticline Inversion of Caroni Basin

28. 28 Where is the reworked sediment coming from? Well A Well B Well C Well E Well D Seismic indicates a strong NE-SW bias

29. Irreversible Insensitive to rock composition Covers wide temperature range Present in most sedimentary rocks (Silurian to present) Advantages of Vitrinite Reflectance (Ro)

30. Issues with VRo: Sample Preparation Affects Vitrinite Reflectance Values

31. Effect on Ro Caving Lower Rough vitrinite Lower Suppression Lower Mud contamination Usually Lower Oxidized vitrinite Usually Higher Recycled/reworked Higher Incorrect maceral identification Both Statistical errors (few measurements) Both Vitrinite Reflectance of Ditch Cuttings Has Pitfalls

32. So what have we learned?

33. Vitrinite is a coal maceral derived from wood. Vitrinite reflectance cannot tell you whether or not a rock generated oil or gas It may be difficult to accurately estimate the amount of missing sediment due to differences in thermal gradients and thermal conductivities of the sediment. The deep water area has some definitive reworked sediment (the origin and final site of deposition is difficult to determine) Are there potential MLE equivalent reservoirs in the deep water? There exists different maturities for sediment of the same age onshore Trinidad. Can reworked sediment be reservoirs for the deep water area? Summary

36. Trinidad and Tobago AssetDD Month YearPage 36 Structural Domains, Trinidad and Tobago