Great Campos

Petroleum System Evaluation of The Great Campos Basin Offshore Southeastern Brazil
Focused on Areas Offered During ANP Bid Rounds

GEOCHEMICAL SOLUTIONS INTERNATIONAL INC. (GSI) has conducted a series of studies based on geochemical data obtained from remote sensing and basin modeling and from the analysis of representative crude oils, source rocks, and piston cores collected from the Espírito Santo, Campos and Santos sub-basins. Results from these studies, which were originally designed to identify and compare the petroleum systems that have contributed to accumulations in this region, have been used to evaluate cells included in the upcoming ANP bid Round 9. The sample set includes thirteen-hundred (1300) piston cores acquired in water depths ranging from 100 m up to 3,000 m and more than three-hundred (300) crude oils. In addition, more than 9,000 potential source rock samples representing more than 135,000 m of section from more than 60 wells were screened and based on total organic carbon (TOC) data approximately two hundred and fifty (250) well cuttings and/or core samples were selected for detailed bitumen and kerogen analyses.

Several attributes of the Great Campos Basin favor the use of piston coring for regional hydrocarbon charge risk-assessment and source evaluation: (1) The existence of prolific source rocks (Lagoa Feia and age equivalents), (2) Ongoing oil and gas generation and migrationn, and (3) The widespread occurrence of salt diapirs and faults that can act as vertical conduits for hydrocarbons from the subsurface to the seafloor.

Crude oils were characterized in detail and results were used to develop an understanding of how generative petroleum systems, maturity, and biodegradation affect oil quantity and quality. This information together with available source rock data has been used to 1) Determine the number of distinct oil families within each basin, and determine the age and paleoenvironment of the associated source rocks, 2) Map the stratigraphic and geographic distribution of the oil families and distinguish areas where oil mixing has occurred, 3) Assess oil quality with respect to alteration by bacteria or water washing, 4) Identify distinct kitchen areas and estimate migration directions by comparing oil family distributions with the location of known source rocks, and 5) Utilize the geographic, stratigraphic and structural distribution of the oil families to identify and map active petroleum systems.

Basin modeling has become an essential tool for petroleum exploration. It allows the explorationist an integrated, dynamic means by which to simulate basin evolution and petroleum generation, expulsion and migration. It also provides insights into fundamental questions such as: 1) where are the source rock “kitchens”? 2) what is the timing of petroleum generation, expulsion and migration for each source rock interval? 3) what are possible migration pathways from source rocks to reservoirs? 4) what is the significance of faults as migration pathways? 5) how effective must drains and seals be in order to have commercial accumulations? and 6) what are the expected oil and gas compositions in a hydrocarbon trap?

Results of these studies are presented in both analytical and interpretive formats to insure that all findings are accessible to explorationists and research personnel. All geochemical data is provided in hard copy and in digital format in a database contained on CD, which includes a proprietary data browser to facilitate access. A synthesis and interpretation of all information is presented in a series of comprehensive final reports including oil-oil and oil-source rock correlations, oil quality, hydrocarbon source potential, oil proneness and thermal maturity.