ABSTRACT

The observed maturity trends determined from 481 northern Gulf of Mexico oils and offshore seeps follow the major geological trends of the basin in a manner consistent with published heatflow measurements. Onshore the Luling-Mexia-Gilbertown-Pickens-Pollard fault zones appear to act as areas of enhanced heatflow, as indicated by the high maturity of nearby oils (near base of oil window). To the north and south of these fault lines, oils of reduced maturity are encountered.

Offshore Louisiana, oils of lower maturity, comparable to the middle to early oil window, are found; the low maturity of these oils appears to be linked to salt diapirism. By contrast, the mature condensates offshore Texas appear to link, in part, with shale diapirism and growth faulting.

Analyses of oils and seepage from the Flexure Trend area indicates that hydrocarbon maturity is reduced towards the south where the Tertiary overburden thins.