Geochemical Solutions International Inc. (GSI) has conducted a series of geochemical studies of the Great Campos Basin based on data obtained from the detailed analysis of representative crude oils, source rocks and piston cores plus information from remote sensing and basin modeling. Results from these studies were used to identify and compare the petroleum systems that have contributed to accumulations in this important region. The sample set currently includes thirteen-hundred (1300) piston cores acquired in water depths ranging from 100 m up to 3,000 m and a collection of crude oils that exceeds six-hundred (600) fluids (see Great Campos 2020 prospectus). In addition, the source rock data set includes screen data for >15,000 potential source rock samples representing >140,000 m of section from >75 wells and was recently expanded to include key Kinetics Data for pre-salt sidewall core samples from five wells located in the pre-salt area (see Great Campos 2021 Kinetics prospectus).
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 migration, 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 provides 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 ensure that all findings are accessible to explorationists and research personnel. All geochemical data is provided in digital format in a database contained on CD that includes a proprietary data browser to facilitate access. 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.