The Austin Chalk formation has produced a significant amount of oil across Texas so the oil and gas windows are well defined. Much less production in Louisiana presents some unknowns with regards to oil gravity in the new exploratory areas of the play.
The maps below were constructed from thousands of completions in Texas. The western portion of Louisiana has sufficient control to confirm the trends. These maps have been "clipped" where little data control exists. The "blue" outlines on the maps define Austin Chalk field boundaries. In Texas, Giddings Field has a broad range of oil gravity from 30-63 API. Active drilling today at Giddings Field in Washington County is focused in the range of 45-60 API gravity. EOG's recent "monster" wells in the Karnes Trough range from 38-47 API gravity. Pearsall Field ranges from 32-35 API. Brookeland Field in East Texas ranges from 37-60 API. Masters Creek in LA-West ranges from 39-59 API. ConocoPhillips' first two wells in Louisiana produced 36-37 API from their initial production. A historical producer from 1996 north of the ConocoPhillips Hebert #1 produced 43 API from 12970'.