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A Four-Dimensional Petroleum System Model for the Vallecitos Syncline in the San Joaquin Basin Province, California, Combined with New Technologies of Organic Geochemistry

Meng He
Department of Geological and Environmental Sciences, Stanford University, Stanford, CA,
[email protected]

In a calibrated 3-D basin and petroleum system model through time (4D) for the San Joaquin Basin Province, California, developed by the USGS (2008), two major oil families were defined from geochemical and biomarker data. Surprisingly no mixed oils were identified. However, from our 1-D model of the Vallecitos area, we suspect a deep, high maturity source rock, which could contribute to mixed oils in parts of the San Joaquin basin. A lack of correlation between deep source rock and oils may indicate that traditional oil-oil and oil-source correlations using biomarkers are not applicable to a high mature source rock. In order to address this problem, provide a better understanding of the petroleum systems in Vallecitos area, and further improve the previous 3-D basin model, advanced methods are needed to correlate and distinguish the high maturity components.

The oil and rock samples will be collected from all over the Vallecitos area, and analyzed in Stanford’s organic geochemistry laboratory to establish oil-source and oil-oil genetic relationships, identify high maturity components and recognize the origin of high maturity oils and mixed oils by using diamondoid analysis. A detailed molecular study including biomarkers, and most importantly the application of diamondoids, has never been applied to this area. The results will provide improved input data for future 3D models of the basin. Particularly, the application of biomarkers and diamondoid concentration analysis will be extremely helpful for understanding the oil cracking process in the Vallecitos Syncline and the regional oil and gas distribution in this subbasin. Detailed maps of oil and gas distribution are critical for modeling the petroleum systems in the Vallecitos Syncline and also provide the possible flow-paths for the oil and gas migration. Moreover, these results could reduce the risk of future oil and gas exploration in the San Joaquin basin.


AAPG Search and Discovery Article #90094 © 2009 AAPG Foundation Grants in Aid