Thursday, September 15, 2011

Tuscaloosa Hydrocarbon Source

The Tuscaloosa Marine Shale is a known source rock in the Tuscaloosa Trend.  During my Amoco years working the Tuscaloosa in the early 90's, our research group performed hydrocarbon source analysis on several wells in the deep Tuscaloosa Trend.  Hydrocarbon source was determined to be from three intervals: Lower Cretaceous, Tuscaloosa shales, and the Eutaw (Tusc Marine Shale).  In one unique case, Austin Chalk oil sourced Tuscaloosa sands in Lockhart Crossing Field due to juxtaposition across the large growth fault that divides the field.

The maps below present the outline of the higher resistivities in the TMS (blue dashes) along with the cumulative production from all of the fields in the deep Tuscaloosa Trend.  An interesting correlation exists between the termination points of deep Tuscaloosa production on both the east and west sides with a decrease in resistivities in the TMS.  Coincidence? A similar geological environment exists in the TMS in Washington, St. Tammany, and southern Tangipahoa Parishes, but TMS resistivities are much lower than the area to the west and northwest.  Does the alignment of the east/west TMS resistivities and the borders of the deep Tuscaloosa production indicate a hydrocarbon migration story?  Is it a coincidence that Port Hudson Field (1.3 TCFE) is located directly in the center of the high resistivity outline when projected updip?   Join the discussion and post a comment.

Tuscaloosa Producing Fields: Cumulative Production; Tuscaloosa Marine Shale Higher Resistivity Outline
Tuscaloosa Producing Fields; Tuscaloosa Marine Shale Higher Resistivity Outline


  1. Please define dip. What is the significance of downdip vs. middip vs. updip in the TMS? Can you suggest a reference for me to read up on this? Thanks Kirk for your very educational posts.

  2. FM,
    Dip refers to the orientation of the geological strata. The TMS dips or "tilts" to the south. The terms "updip", "middip", and "downdip" refer to the depth of the TMS. Updip is the shallowest. More depth means increased costs and possible risks. Downdip will have more gas.