The use of Radarsat and Envisat Asar images processed together with meteorological and oceanographic data in the offshore of Rio Grande do Norte and Ceará states showed the presence of many oil slicks, widespread in water depth areas ranging from 5 m to 3576 m. Most of the identified oil slicks are considered indications of 100% of probability to occur as a result of the convergence of the optimum tectonic, temporal and environmental scenarios, and confirms the presence a prolific and active petroleum system in the subsurface of the investigated area.

The geochemical gas and oil results – headspace gas and GC-MS of saturate and aromatic biomarkers – from piston core data collected in the Mundaú sub-basin (in the Ceará Basin) revealed the presence of liquid biomarkers in some cores and in several other cores, the study detected very consistent thermogenic oil and gas signatures.

The occurrence of oil slicks detected hydrocarbon at levels of micro seepages indicating that .hydrocarbons migrated and reached the sea bottom sediments. These data provide valuable information and allows a positive assessment of lease areas aiming hydrocarbon exploration activities in this frontier offshore area.

Full references of all images are listed in the reports

1. Introduction
2. Area Location
3. Geological Framework
   1. Tectonic and Stratigraphic Framework
4. Laboratory Procedures
5. Geochemical Results and Discussions
   1. Gas Chromatography (GC) Analysis of Cans for Interstitial Gases
   2. Total Scanning Fluorescence (TSF)
   3. Gas Chromatography of C15+ Hydrocarbons
   4. High Resolution Geochemical Technologies (HRGT)
   5. Quality Assurance and Quality Control (QA/QC) Samples
6. Synthetic Aperture RADAR (SAR) Data and Meteorological and Oceanographic Ancillary Data AnalysIs
   1. SAR Systems and data
   2. Textural classification of SAR data
   3. Meteorological and oceanographic ancillary data
      1. Sea surface temperature maps
      2. Top of clouds temperature maps
      3. Wind field intensity maps
      4. Chorophyll-a concentration maps
7. Oil Seep Interpretation
8. Oil Seeps and Regional Geology
9. Conclusions and Recommendations
10. References

1. ocation map of the Potiguar basin with the seabed piston core samples
2. Location map of the Potiguar basin and its main geological boundaries.
3. Simplified tectonic framework and main petroleum accumulations of the Potiguar Basin is also shown here (modified from Bertani et al., 1990).
4. Stratigraphic chart of the Potiguar Basin (modified from Caixeta et al, 2007).
5. Schematic cross-section in the Potiguar Basin (modified from Bertani et al., 1990).
6. Schematic representation of the sedimentation model and structural style of the Neocomian rift in the Onshore portion of Potiguar Basin. This model is considered valid for all the basins in offshore areas.
7. Depositional models associated to the diverse system tracts of the Drift Phase of Potiguar Basin (Modified from Bertani & Costa, 1988).
8. Diamondoid concentrations in extractable liquids from source rocks and coals reveal an exponential increase in the gas window (Ro ~1.1% to 4%; Wei et al., 2006).
9. Example of a GC trace of headspace analysis of a sediment sample.
10. Correlation between the ratios ethane/ethene and the ratios propane/propene.
11. Correlation between the ethane and methane concentrations.
12. Correlation between the propane and methane concentrations.
13. Correlation between the isomerization ratio iso-butane/normal-butane and the ethane concentrations.
14. Ratios ethane/propane versus ethane concentrations.
15. Correlation between the ethane and propane concentrations.
16. Map of iso-values of ethane concentrations.
17. Map of iso-values of propane concentrations.
18. Map of iso-values of ethane/ethene concentrations.
19. Map of iso-values of propane/propene concentrations.
20. Location of all the studied piston core, and of the ones presenting evidence of thermogenic gas genetically associated with oil.
21. TSF MI versus R1 values for all sediment extracts from Potiguar basin.
22. TSF MI versus UCM values for all sediment extracts from Potiguar basin.
23. UCM versus R1 values for all sediment extracts from Potiguar basin.
24. Map of the total scanning fluorescence, TSF, maximum fluorescence intensity, MFI, of the piston core extracts from top, middle and bottom sections of the core.
25. GC chromatograms of the organic extracts obtained from (A) top, (B) middle and (C) bottom sections of core POT420 showing high relative abundance of the recent organic matter.
26. UCM versus summation of n-alkanes values for all sediment extracts from Potiguar basin.
27. UCM versus thermogenic hydrocarbons/ diagenetic hydrocarbons ratio, T/D, values for all sediment extracts from Potiguar basin.
28. GC chromatogram of the organic extract obtained from sample CBR0272 recovered from bottom section of core POT308.
29. GC chromatogram of the organic extract obtained from sample CBR0152 recovered from bottom section of core POT421.
30. GC chromatogram of the organic extract obtained from sample CBR0102 recovered from middle section of core POT010A.
31. Map of concentration of n-alkanes (ng/g) of the piston core extracts from top (A), middle (B), and bottom (C) core sections.
32. Map of the UCM content (ug/g) of the piston core extracts from top (A), middle (B), and bottom (C) core sections.
33. Chromatogram, and mass chromatograms m/z 191 and 217 of sample CBR0272 from the bottom section of core POT308 showing the distribution of (A) alkanes, (B) terpanes and (C) steranes.
34. Mass chromatograms m/z 231 and 245 of sample CBR0272 from the bottom section of core POT308 showing the distribution of (A) triaromatic steranes and (B) triaromatic methylsteranes.
35. Chromatogram, and mass chromatograms m/z 191 and 217 of sample CBR0152 from the bottom section of core POT421 showing distribution of (A) alkanes, (B) terpanes and (C) steranes.
36. Mass chromatograms m/z 231 and 245 of sample CBR0152 from the bottom section of core POT421 showing the distribution of (A) triaromatic steranes and (B) triaromatic methylsteranes.
37. Chromatogram, and mass chromatograms m/z 191 and 217 of sample CBR0102 from the bottom section of core POT010A showing the distribution of (A) alkanes, (B) terpanes and (C) steranes.
38. Mass chromatograms m/z 231 and 245 of sample CBR0102 from the bottom section of core POT010A showing the distribution of (A) triaromatic steranes and (B) triaromatic methylsteranes.
39. Map showing the hydrocarbon classification based on saturate and aromatic biomarker analysis.
40. The classical diamondoid-biomarker cross-plot applied to gas/ oil seep detection.
41. The classical diamondoid-biomarker cross-plot applied to gas/ oil seep detection (detail from Figure 40).
42. GC chromatogram of the quality assurance and quality control (QA/QC) sample CBD0038 (lubricant oil).
43. GC chromatogram of the quality assurance and quality control (QA/QC) sample CBD0040 hydraulic oil).
44. GC chromatogram of the quality assurance and quality control (QA/QC) sample CBD0040 fuel oil).
45. GC chromatogram of the quality assurance and quality control (QA/QC) sample CBD0015 (interior do liner).
46. GC chromatogram of the quality assurance and quality control (QA/QC) sample CBD0035 (interior do liner).