Analysis of the environmental history of sedimentary rock and its relation to the accumulation of oil and gas is the primary responsibility of petroleum geologists today. Environmental analysis includes all the normal tools of exploration (structure, isopach maps, lithology) plus imagination--imagination based on a comprehensive knowledge of the sedimentary rocks in the subsurface coupled with an insight into contemporary environments.

Samples and cores from approximately 100 wells dispersed evenly throughout East Texas were examined to provide the data necessary for environmental analysis of the Lower Cretaceous interval.

Lithologic characteristics of time-stratigraphic units from the Hosston-Pettet through the Ferry Lake indicate an overall transgression of environments, the upper Hosston-Pettet showing the most rapid transgression. Ferry Lake sediments are the most widespread because of continual eustatic rise of sea level. Well-defined continental, transitional, and marine environments can be mapped regionally and related to lithology and hydrocarbon production for each time-stratigraphic unit.

Environments and imagination can lead to new exploration ideas, even in a mature oil province like East Texas.

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