Geochemical Solutions International Inc. (GSI) has conducted a geochemical study of crude oils from the Central Basin area of eastern Brazil designed to identify and compare the petroleum systems that have contributed to accumulations in this important area. The studied basins include Sergipe-Alagoas, Reconcavo, Camamu-Almada, Jequitinhonha, Cumuruxatiba, Mucuri and Espirito Santo. Information in this study include:

Detailed compositional data have been acquired for one hundred fifteen (115) crude oils from ninety-nine wells distributed throughout the basins along the central margin of eastern Brazil. Oils were analyzed for physical properties, whole oil gas chromatography, gross composition, deuterium, and carbon isotopic compositions and quantitative GCMS analysis of saturate and aromatic hydrocarbons. Data were used to identify petroleum systems, establish genetic relationships and evaluate the major factors governing oil quality and quantity including: (1) source facies, (2) thermal maturity, (3) distance of migration from source to trap, (4) extent and timing of biodegradation, and (5) degree of oil mixing.

Key source rock data (%TOC and Rock-Eval pyrolysis) from 4,500 samples representing 72,000+ m of section from thirty-seven (37) wells were statistically evaluated in terms of organic richness, hydrocarbon-generating potential, oil proneness, and thermal maturity level of all potential source rock intervals in the Camamu-Almada, Jequitinhonha, Cumuruxatiba and Mucuri basins. Detailed GC, isotope and biomarker data for a subset of source rock samples were used to establish maturity trends and, where possible, source to oil correlation. 

Piston core data were obtained from the screen and detailed analysis of one hundred (100) piston cores acquired in offshore blocks (BM-SEAL-4 and BM-SEAL-5) in the Sergipe basin and fifty (50) cores in Camamu (block BM-CAL-4) basin. Collection sites were selected through the analysis of regular seismic lines in which near surface faults, erosional outcrops, and fluid-related features were chosen for sampling. The results of this study have been documented in an interpretative final report, which describes the presence/absence of petroleum hydrocarbons and their geochemical characteristics. The report contains maps showing distributions of key geochemical properties, highlighting sites of geochemical anomalies in the Central Basin.

Surface geochemical data were acquired for eight hundred forty (840) samples in Sergipe-Alagoas Basin (Block BT-SEAL-1, BT-SEAL-2, and BT-SEAL-3) and six hundred thirty-six (636) samples from Recôncavo (Block BT-REC-1, BT-REC-2 and BT-REC-3) in separate studies designed to detect anomalous concentrations of deep subsurface light (C1-C4) hydrocarbons in surface samples. The studies are based on the fundamental premise that light hydrocarbons generated from deep subsurface sources can migrate vertically to surface and near-surface soils. 

All geochemical data are provided in digital format in a database contained on CD that includes a proprietary data browser to facilitate access. The analytical data and an interpretive report are available for immediate delivery. For interested companies, basin-specific quantitative modeling studies can be performed as a supplementary product.

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