So, if I remember correctly, the Anahuac is the shale that sits on top of the Frio. The Frio is a major producer in the Gulf Coast, primarily from structural traps. Do you know of any geochemical work that has been done to prove that the Anahuac is a source rock, i.e. total organic carbon, vitrinite reflectance, and the like? Throughout my career, I have been charged with searching for these source rock-type resource plays. I could never find a source rock in the Gulf Coast that wasn’t out in the bowels of the Gulf. From what I remember, the Anahuac had generative capacity but it had too high of a clay content to be a reservoir, like what we would call a rubber mat instead of a pane of glass. You couldn’t frac it. Oh well, I am rambling now.
There was some work done back in the mid 70s. IIRC, the Anahuac is sandstone as well as mud shale. You are correct that some of it sits on top of the Frio but there are plunges that reach through the Frio heading toward the Upper Wilcox and is mostly mud shale.
Again, this from memory that is 50 years old. Dang, can not believe it has been that long.
We had two wells in SW Goliad county where the log showed there was NO separation between the U and L Wilcox. There was over 800’ of zone. Of course the oil company (small grave digger) did not know what they had and tried to straight hole produce it instead of directiknal and fracking it Of course it plugged off and the axid fracked it and screwed it up. They are both plugged now but man oh man I was counting the dollars