Three data bases were developed for a regional survey of reservoir quality in Tertiary sandstones along the Texas Gulf Coast.

1. Core analyses from 252 wells (10,900 datum points) are the basis of plots which indicate that porosity and permeability do not simply decrease with depth but commonly increase at depth by development of secondary leached porosity.

2. Point count analyses of 535 thin sections from 169 wells for mineralogy, diagenetic features, and porosity types indicate, within formations, regional mineralogic trends that affect reservoir quality, especially at depth. The average Tertiary sandstone is a moderately sorted, very fine-grained quartzose lithic arkose. Each Tertiary formation shows a similar general diagenetic history; primary porosity is dominant in the shallow subsurface, and secondary leached porosity is dominant in the moderate and deep subsurface.

3. Plots of interval transit time versus depth for 87 acoustic logs indicate general compaction and consolidation histories of complete stratigraphic sections, and they are useful for comparing compaction and consolidation histories among different areas. Both the Wilcox and Frio trends exhibit a general pattern of more rapid compaction and greater degree of consolidation in the lower Texas Gulf Coast than in the upper Texas Gulf Coast.

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