Geochemical Solutions International Inc. (GSI) has completed a geochemical study of oils from the basins along the Equatorial margin of Brazil designed to identify and compare the petroleum systems that have contributed to accumulations in this important area. The studied basins include Foz do Amazonas, Pará Maranhão, Barreirinhas, Ceará and Potiguar. Approximately 150 crude oils representing the major fields and producing horizons have been analyzed using state-of-the-art oil fingerprinting techniques to 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.
Oil geochemistry is a fundamental component of any regional exploration and production program. It can be used to determine the number of discrete sources in a basin and their respective stratigraphic and areal distribution, source age, lithology, depositional environment (marine, non-marine, lacustrine) and thermal maturity. Areas with overlapping petroleum systems can be identified in relation to possible oil mixing from two or more sources. Mapping source-related oil families is the first step toward understanding and predicting the lateral extent of oil fields and regional oil quality variations in different parts of the Equatorial Margin.
The extent of processes that act to modify the original composition of oils, such as biodegradation and oil mixing, can also be assessed. This is a fundamental issue in Brazil because the effect of these processes can be widespread and can significantly degrade oil quality. Because oil quality can impact exploration economics at both the prospect and basin-wide scale, it is imperative to gain a firm understanding of the factors that govern it prior to acquiring acreage or drilling a well.
Deliverables for this study consist of printed data volumes summarizing the analytical results in addition to an interpretative final report. The final report contains a synthesis and interpretation of all information provided including oil-oil and oil-source rock correlations, thermal maturity, and oil quality. All geochemical data is also provided in digital format in a database contained on CD, which includes a proprietary data browser to facilitate access.
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