This Petroleum System study is a quantitative investigation of the Campos Basin, based on detailed geological, geophysical and geochemical information of all its systems, but mainly on its exceptional well-recognized overcharged system: the Lagoa Feia-Carapebus (!). It was sourced from lacustrine-saline organic shales and predominantly preserved in widespread turbidite reservoirs of the Carapebus Formation.

In this study High-Resolution Geochemical Technology (HRGT) was applied in 228 selected oil samples and 39 wells (for source rocks) aiming to identify and characterize the petroleum systems of the Campos Basin. The integration of all data allowed the distinction and mapping of oil families and their respective source rock distributions. In addition, source-rock age and depositional environment, thermal evolution, degree of thermal oil-to-gas cracking and biodegradation were also characterized. Also, parameters controlling oil quality and possible migration pathways from source rock to trap were discussed by means of 2D basin modeling of two regional cross-sections representing the main tectonic-sedimentary aspects of the geologic evolution of Campos Basin.

A substantial part of this study contains a detailed section on electrofacies and lithofacies characteristics of Oligocene and Miocene deep-water reservoirs, which required a large set of core samples, logs and seismic sections from some production fields and data from adjacent wells. It is a very useful geophysical and sedimentological framework to address some of the most important reservoirs of the basin.

Full references of all images are listed in the reports

1. Executive summary
2. Geological and geochemical modeling
3. Introduction
4. Regional geology and tectonic framework
5. Exploratory history
6. Elements of the petroleum systems
   1. Source rocks and hydrocarbons
      1. Lagoa feia formation
      2. Macaé formation
   2. Reservoirs, seals and traps
      1. Cabiunas formation
      2. Lagoa feia formation
      3. Macaé formation
      4. Carapebus member/ubatuba formation
      5. The roncador field reservoirs
      6. Carapebus paleocene and eocene reservoirs
7. Processes of the petroleum systems (generation and migration)
8. Petroleum systems of the campos basin
   1. Lagoa feia-carapebus (!)
9. Exploratory implications and risks
10. 2D Basin Modeling in the Campos Basin (Line CS-1)
    1. Geological Characteristics of the Cross Section
    2. Source Rock Characteristics
    3. Maturity Analysis
    4. Migration Analysis
    5. Analysis of the Fluid System
    6. Biodegradation Risk
    7. Conclusions
11. 2D Basin Modeling in the Campos Basin (Line CS-2)
    1. Geological Characteristics of the Cross Section
    2. Source Rock Characteristics
    3. Maturity Analysis
    4. Migration Analysis
    5. Analysis of the Fluid System
    6. Biodegradation Risk
    7. Conclusions
12. 2D Basin Modeling in the Campos Basin (Line CS-3)
    1. Geological Characteristics of the Cross Section
    2. Source Rock Characteristics
    3. Maturity Analysis
    4. Migration Analysis
    5. Analysis of the Fluid System
    6. Biodegradation Risk
    7. Conclusions
13. Appendix
    1. Reservoir eletrofacies and lithofacies summary

1. Location of the Campos Basin with its limits, main structural features and oil fields (Guardado et.al., 1989).
2. Schematic Structural map of Campos Basin showing the main oil fields location.
3. Generalized tectonic framework of Campos Basin (modified from Guardado et al., 1990).
4. Schematic dip cross-section in Campos Basin (for location, see the map above – after Guardado et al., 1990).
5. Generalized stratigraphic chart of Campos Basin (modified from Guardado, 1989).
6. Distribution of oil fields in Campos Basin by reservoir ages (modified from Guardado et al., 1989).
7. Map of Campos Basin showing location of all the wells in which oil samples were studied. The red wells represent the initially studied wells, whereas the green wells represent new oil samples that were made available.
8. Map of Campos Basin showing location of the wells (yellow) in which organic-rich rock samples were studied. The orange wells represent new wells where TOC and rock Eval data have been performed.
9. Stratigraphic column of Campos Basin showing the source rocks and main reservoirs intervals (modified from Rangel & Martins, 1998). The oil accumulations occur widespread in reservoirs ranging from Neocomian to Miocene.
10. Geochemical log of a well from Campos Basin showing the stratigraphic position of lacustrine saline water organic-rich sedimentary succession for samples from the Upper Neocomian and Barremian section. Total organic carbon can reach up to 10% mainly composed of organic matter type I (algal kerogen).
11. Geochemical log of a well from Campos Basin showing the stratigraphic position of two lacustrine saline water organic-rich sedimentary succession for samples from the Upper Neocomian (3966m) and Barremian section (3837m).
12. Natural series of the organic-rich sediments of the Lagoa Feia Formation showing two separate organic intervals of the potential source rocks of the Campos Basin. As can be noted, only after 4800 to 5000 meters the kerogen started to be transformed in hydrocarbons.
13. Schematic sedimentary column of the Lagoa Feia Formation (Modified from Dias et al., 1988). The best organic-rich sections of the Lagoa Feia Formation are the Coquinas and the Talc-Stivensitic sequences.
14. Distribution of TOC and Rock-Eval data for organic rich sediments of the Coquinas and Talc-Stevensitic Sequence (Trindade et al., 1995). As can be noted the Coquina sequence is a much better source than the Talc-Stivensitic one.
15. Map of maximum Total Organic Carbon contents of the organic-rich sediments from the Lagoa Feia Formation. (Table 4 in Appendix). Note that the lack of control wells in the structural lows located at the shallow (São Tomé and Curvina-Parati Lows , and the deep and ultra-deepwater depocenters (Eastern area). In this areas the Lagoa Feia Formation was not sampled and analyzed.
16. Map of maximum of Hydrocarbon source potential – S2 from Pyrolysis Rock-eval of the organic-rich sediments from the Lagoa Feia Formation. (Table 4 in Appendix). Also here, the organic-rich sections of the Lagoa Feia Formation in the Northeastern part of the basin have not been reported due to the lack of control wells.
17. Map of the thickness of the sediments from the Lagoa Feia Formation analyzed in this study (Table 4 in Appendix). Note that the thickest intervals are located at the São Tomé and Curvina-Parati lows, and in the northern east areas of the basin.
18. Geochemical log showing TOC and Rock Eval data of selected sediment samples from Macaé Formation. These sections occur in most wells drilled in the Central and Eastern part of the basin, and is known as the Bota sequence. Generally, its thickness reaches up to 200 meters, most of them organic-rich.
19. Natural series of organic rich sediments of the Albian-Turonian, Macaé Formation analyzed in this study. As can be noted, the sediments of the Lower part of the Macaé Formation (Bota Section) presents a very good hydrocarbon source potential, but still immature.
20. Gas chromatograms of oils of the Campos Basin showing differences in the n-alkanes envelop related to biodegradation and oil mixing. As can be noted, the presence of light n-alkanes in the Marlim biodegraded oils indicate the arrival of fresh oil very recently.
21. M/Z 191 Fragmentograms of oils from Campos Basin, showing identical distributions of the terpanes biomarkers, therefore implying a common source for Albacora and Marlim Fields.
22. M/Z 217 Fragmentograms of oils from Campos Basin showing identical steranes distributions, therefore implying a common source. Also, it can be noted the same thermal evolution for both oils suggesting that their active pod have a similar burial depth.
23. M/Z 259 Fragmentograms of oils from Campos Basin showing high abundance of TPP relative to the C27 regular steranes. Such data are diagnostic of lacustrine environments, therefore implying a common lacustrine source rock sequence.
24. M/Z 231 and M/Z 245 Fragmentograms of two lacustrine oils from Campos. Note that lacustrine oils present high abundances of C29 triaromatics related to the marine oils. On the other hand, the marine oils tend to present higher abundances of 3 Methyl/ 4 Methyl compounds.
25. Mass chromatograms from metastable ion monitoring of C30 steranes compounds of oils from Campos basin. Note the absence of C30 steranes confirming the lacustrine character of Campos oils.
26. Gas chromatograms of Campos Basin oils, showing the presence of carotenoids and a bimodal n-alkane distribution related to biodegradation in the Roncador oil sample. As can be observed, the Badejo oil presents a slight different oil type when compared with Roncador, Marlim and Albacora oils. The presence of high molecular n-alkanes and the carotenoids in the Badejo oil field and in the oils from the São Tome low area suggest a different organic facies (Lacustrine Brackish to hypersaline) for the Lagoa Feia organic-rich sediments.
27. M/Z 217 Fragmentograms (steranes) of oils from Campos Basin, showing the differences between the oil from a Badejo well, suggesting a lower thermal evolution for the source of this oil compared to the Roncador oil sample. Note, also, that the Badejo oil presents low amounts of 4-methysterane suggesting an increased salinity.
28. M/Z 259 Fragmentograms of oils from Roncador and Badejo fields indicating their lacustrine origin.
29. Gas chromatograms of Campos Basin oils showing different stages of biodegradation and oil mixing.
30. M/Z 191 Fragmentograms (terpanes)of oils from Campos Basin, showing identical biomarker distribution, despite different stages of biodegradation.
31. M/Z 217 Fragmentograms (steranes) of oils from Campos basin showing identical thermal maturity profiles, despite the different stages of biodegradation. Such data suggest that biodegradation and oil mixing controls the oil quality in Campos Basin (note the differences in % in Sulphur and API gravity).
32. M/Z 259 Fragmentograms of oils from Campos Basin indicating their lacustrine origin.
33. Gas chromatograms of oils of the Campos Basin showing different stages of biodegradation and oil mixing. Note that the oil from1-RJS-150 well shows an increase in abundance of -carotane, suggesting a more saline than brackish water character.
34. M/Z 191 Fragmentograms (terpanes) of oils from Campos Basin showing small facies variations for the Lagoa Feia source rocks that contribute for the oils associated to the Badejo low (area of the 1-RJS-150). As can be observed, they are richer in Gammacerane. Such feature could be caused by a small variation in the Lagoa Feia depositional environmental. The presence of 25 norhopane in the 1-RJS 150 and 267 oils suggest oil mixing.
35. M/Z 217 Fragmentograms (steranes) of oils from Campos Basin. As can be observed, the oil samples from the 1-RJS-150 well area show lower maturity ratios than the other oils. Such feature can only be explained by oil mixing and not by thermal alteration (Mello, 1988).
36. M/Z 259 Fragmentograms of oils from Campos Basin showing identical biomarker distribution indicating their lacustrine common origin.
37. Map of the API gravity values for the oils analyzed in Campos Basin.
38. Map of the Sulfur contents values for the oils analyzed in Campos Basin.
39. Carbon isotope correlation plot for oils from Campos Basin.
40. Plot of Gammacerane index versus Hopano/sterane ratio for oils from Campos Basin.
41. Plot of pristane/phytane ratios versus whole oil carbon isotope values for oils from Campos Basin.
42. C29 steranes versus Ts/(Ts+Tm) ratios of oils from, Campos Basin.
43. Map of the Ts / (Ts+Tm) for the oils analyzed in Campos Basin.
44. C29 versusC29 20S/(20S + 20R).steranes for oils from Campos Basin. Another important maturity parameter is the Ts/(Ts+Tm) ratio, although it is affected by source and mineral matrix (Mello., 1988).
45. Map of the C29 /(+) sterane ratio for the oils analyzed in Campos Basin.
46. Map of 25-norhopanes values for the oils from Campos Basin suggesting the presence of oil mixing in almost all oils of the Campos Basin.
47. Gas chromatograms and M/Z 191 mass fragmentograms for oils from Campos Basin showing different stages of biodegradation. The presence of 25-norhopane, together with n-alkanes suggest a complex history of oil accumulations with mixture of biodegraded and non-biodegraded oils.
48. Plot of oil cracking data from Campos Basin showing that the majority of the Campos oils analyzed were sourced at a stage before peak to peak of oil generation. However, the oils from 1-RJS-433 and 7-AB-7DA-RJS are mixtures of low cracked oil with a highly cracked one, indicating that deep reservoir/source rock is charging pre-existing reservoirs.
49. Macroscopic view of the coquina, the principal Linguado field productive rock (Horschutz et al., 1992).
50. Microscopic view of the productive coquina from Linguado field (Horschutz et al., 1992).:
51. Microscopic view of the productive coquina from Linguado field (Horschutz et al., 1992).
52. Intensive carbonate and silica cementation causing diagenetic trapping in the coquinas (Horschutz et al., 1992).
53. Restored section across the Cherne and Namorado fields showing the evolution of the tectono-sedimentation at the area (Modified from Fernandes, 2002).
54. Restored section across the Cherne and Namorado fields showing the evolution of the tectono-sedimentation at the area (Modified from Fernandes, 2002).
55. Restored section across the Cherne and Namorado fields showing the evolution of the tectono-sedimentation at the area (Modified from Fernandes, 2002).
56. Restored section across the Cherne and Namorado fields showing the evolution of the tectono-sedimentation at the area (Modified from Fernandes, 2002). The extension diagram shows the variations of the extension with time.
57. Macroscopic view of the productive sandstones from Marimbá field (Horschutz et al., 1992).
58. Microscopic view of the productive sandstone from Marimbá field (Horschutz et al., 1992).
59. Macroscopic views of the productive sandstones from the Carapeba field (from Cândido, 1998).
60. Microscopic view of the productive sandstone from the Carapeba field (Horschutz et al., 1992).
61. Amplitude seismic map on the top of a Cretaceous reservoir from Marimbá field (Horschutz et al., 1992).
62. Trapping styles at the Piraúna and Marimbá fields (Horschutz et al., 1992).
63. Microscopic view of the productive sandstone from Vermelho field (Horschutz et al., 1992).
64. Location of the Oligocene and Miocene turbidite systems (Guardado et al., 1990).
65. Location of the Oligocene and Miocene turbidite systems controlled by salt movements (Peres, 1993).
66. Location of the Oligocene and Miocene turbidite systems controlled by salt movements.
67. Main petroleum fields of Campos Basin and their respective reservoirs (modified from Guardado et. al., 1990).
68. Schematic cross section along Cherne and Namorado fields. Mixed entrapments of oil and gas within the sandstone turbidites of the Macaé (Albian/Cenomanian) and Carapebus (Eocene) formations (after Figueiredo, 1985).
69. Schematic cross section showing the structural entrapment of oil within basalt and coquinas reservoirs in the Pampo field (after Figueiredo, 1985).
70. Schematic cross section along the Albacora field, showing the mixed entrapment of oil and gas within the sandstone turbidites of the Macaé (Albian) and Carapebus (Oligo/Miocene) formations (Candido & Corá, 1992).
71. W-E cross section showing the stratigraphic/paleogeomorphic entrapment of oil and gas in the Bonito and Enchova fields (after Guardado et.al., 1990).
72. Kerogen transformation ratio of the Lagoa Feia Formation source rocks through time in two wells of the Campos Basin (modified from Soldan et al., 1994).
73. Schematic dip cross section (not to scale) of the Campos Basin showing the main hydrocarbon migration pathways of the Lagoa Feia-Carapebus (!) petroleum system (after Guardado et al., 1990).
74. Distribution of the petroleum occurrences and the inferred location of the main pods of source rock of the Lagoa Feia-Carapebus petroleum system (modified from Mello et al., 1994 and Rangel & Martins, 1998).
75. Timing of the elements and processes of the Lagoa Feia-Carapebus (!) Petroleum System.
76. Petroleum system event chart of the Macaé Source rocks showing the elements and processes that controlled the habitat of Petroleum, in the Campos Basin, during the Lower Cretaceous time.
77. Summary of the exploratory characteristics of the petroleum systems of the Campos basin
78. Gravelly Sandstone Electrofacies (GvS). Composite log (1a) and corresponding cored interval (core 5) in 1b (A) and (C).
79. Explanation for the lithology and sedimentary structures symbols used in the composite logs.
80. Gravelly-Sandstone with Mudclasts Electrofacies (GvSm). Composite log (2a) and the corresponding cored interval, cores 1 and 2 (2b). (At the based of box 02/02 the coiled object is foam for core protection).
81. Diamictite Electrofacies (DMT). Composite log (3a) and its corresponding cored interval, core 4 (3b). The photomicrograph C shows the composition and the textural characteristics of a rock of this electrofacies.
82. Grain size distribution of a sample from the very coarse sandstone lithofacies VcS.
83. Very Coarse Sandstone Lithofacies VcS of the Amalgamated Sandstone Electrofacies (AmS). Composite log (4a) and corresponding cored interval, cores 1, 2 (4b). Observe the poor normal grading at photo B.
84. Grain size distribution of a sample from the Amalgamated Sandstone Lithofacies AmS..
85. Amalgamated Sandstone Lithofacies of the Electrofacies (AmS). Composite log (5a) and corresponding cored interval, cores 1 and 2 (5b).
86. Grain size distribution of a sample from the Medium/fine-normal graded Sandstone Lithofacies FTab.
87. Lithofacies FTab of the Thick-bedded Sandstone Electrofacies (FTab). Core 1 shows a transition downward and upward respectively to the AmS and FTb-e Lithofacies (6a and 6b). The close ups show Tabc (B) and Ta part of the Bouma sequence with an erosional contact over a Tb (C).
88. Grain size distribution of a sample from the Parallel-laminated Fine/very fine Sandstone Lithofacies.
89. Lithofacies FTb of the Thick-bedded Sandstone Electrofacies (FTab). Composite log (7a) of this Electrofacies with its corresponding cored interval showing Tb and some Tbc of Bouma sequences in A, B and C (7b).
90. Muddy Thin-bedded Sand-Mud Couplet Electrofacies (FTb-e). Composite log (8a) with its corresponding cored interval (8b).
91. Muddy Thin-bedded Sand-Mud Couplet Electrofacies (FTb-e). Composite log (9a) and its corresponding cored interval (9b). Observe the high frequency of millimetric intercalations (photo A) of very fine-grained sandstones and mudstones. Thicker sandstone beds show well developed Tbc Bouma sequence (B and C).
92. Grain size distribution of a sample from the Thin-bedded Very fine-Sandstone with Flaser-bedding Lithofacies Fla.
93. Thin-bedded Fine-sandstone with Flaser-bedding Lithofacies Fla of the Electrofacies (E). Composite log (10a) and its corresponding cored interval (10b). The high degree of amalgamation, small thicknesses of individual beds, and discontinuous muddy laminae have characteristics that resemble flaser-bedding in this example (10b).
94. Thin-bedded Fine-Sandstone with Wavy-bedding Lithofacies Wav of Electrofacies (E). Composite log (11a) and its corresponding cored interval (11b).
95. Very thin-bedded Fine/very Fine-grained Sandstone Lithofacies Rip of Electrofacies (E). Composite log (12a) and its corresponding cored interval (12b).
96. ‘Chaotic’ Electrofacies (F). Composite log (13a) and its corresponding sampled interval (13b). Observe the brecciation features, the texture and composition of these rocks (photos A, B, C). Additionally, in photo C can be seen a spine of an echinoid (E).
97. Chalk Lithofacies G1. Composite log (14) and its corresponding cored interval (14b). Oil stained fractures can be seen in box 2/6 (photo A). The burrows are difficult to identify because of the lack of siliciclastic mud (photo B). An example of the commonly found coccolith Braarudosphaera sp. is shown in the S.E.I. photomicrograph C.
98. Marlstone Lithofacies G2. Composite log (15) and its corresponding cored interval (15b). Observe the rhythmic characteristic of this lithofacies (photo A). Planolites (P), Chondrites (Ch) and Zoophycos (Z) are the most common observed trace fossils (photos B and C).
99. Siliciclastic Mudstones Lithofacies G4. Composite log (92a) and corresponding cored interval (92b). Darker grey/black color, very high porosity and characteristic clay chips in core samples. Compare the differences in the composition of dolomitized marlstones (G2 Lithofacies) with the one of this lithofacies, respectively shown in the S.E.M (B.S.I.) photomicrographs B and C.
100. Mottled Mudstones Electrofacies (MM/MS). Composite log (93a) and corresponding cored interval (93b). A typical arrangement of contourite facies in Plate 93b, C (from Stow and Piper, 1984; after Gonthier et al., 1984) is also shown for comparison.
101. Mottled Mudstone Electrofacies (MM/MS). Composite log (94a) and corresponding cored interval (94b). Close-ups B and C show burrows infilled with sand-sized grains and cemented by calcite, lighter areas.
102. Mottled Sandstone Lithofacies MS of the (MM/MS) Electrofacies. Composite log (19a) and corresponding cored interval (95b). The B.S.I. photomicrograph (C) shows the high amounts of heavy minerals (brighter grains).
103. Bioturbated Sandy Siltstone Electrofacies (BSl). Composite log (26a) and corresponding cored interval (26b). Close-up (B) shows burrows infilled with sand.
104. Explanation for the stratigraphic sections.
105. Stratigraphic section A-B.
106. Stratigraphic section C-D.
107. Stratigraphic section E-F.
108. Stratigraphic section G-H.
109. Stratigraphic section I-J.
110. Stratigraphic section K-L.