D343 Depositional Evolution of the GOM Sedimentary Basin

1. Introduction

• Setting and physiography
  
• Crustal structure and basin origin
  
• Structural framework
  
• Gravity tectonics, growth structures, salt tectonics

Exercise: Seismic interpretation of the Gulf of Mexico structural margin

• Correlate from onshore to deep offshore basin, crossing multiple depositional margins, growth fault zones, carbonate margins and slope
  
• Use stratal terminations to identify low-order sequence boundaries and maximum flooding events
  
• Understand how to use seismic character, within calibrated, well-defined intervals to discriminate sand-prone intervals versus shale-prone sections. Compare to
• basin-scale paleogeography
  
• Understand architectural controls on where faults detach and become listric

2. Depositional Framework

• Application of lithostratigraphy and chronostratigraphy
  
• Cenozoic framework
  - Depositional episodes versus sequences
  - Key tectonostratigraphic events
  
• Mesozoic framework
  - Rift to divergent margin transition
  - Key tectonostratigraphic events
  - Interplay of carbonates, evaporites, and siliciclastics
  - Unconventional reservoirs: Haynesville, Eagle Ford, and Tuscaloosa Marine Shale

Exercise: Use of biostratigraphy and CDS (Chronostratigraphic Designation System) in deepwater Gulf of Mexico

• Use well-based biostratigraphy and CDS to calculate average sedimentation rates
  
• Match calculated sedimentation rates and age/depth trends to the most likely structural geometry in particular wells

3. Mesozoic Depositional History

• Middle Jurassic to Earliest Cretaceous (Bathonian-Berriasian, Louann to Cotton Valley-Bossier)
  
• Early Cretaceous (Valanginian to Cenomanian, Hosston to Washita)
  
• Late Cretaceous (Cenomanian to Maastrichtian, Tuscaloosa-Eagle Ford to KPg Boundary mass flows)

Exercise: Recognition of unconventional plays from well logs

• Correlate logs and create cross-sections of Tuscaloosa Marine Shale
  
• Key Parameters justifying entry into specific shale plays
  
• ID key TOC-enriched intervals from delta LogR plots
  
• Understand how local paleogeography enhances shale reservoirs’ prospectivity
  
• Compare to global distribution of discrete organic enrichment events

4. Cenozoic Depositional History

• Paleocene to Middle Eocene (Laramide compression)
  
• Middle Cenozoic thermal phase
  
• Appalachian rejuvenation sub-phase
  
• Late Neogene glacial cycles and final salt canopy emplacement

Exercise: Onshore to offshore Mesozoic and Cenozoic stratigraphy in Gulf of Mexico based on 2D seismic, well logs, and biostratigraphic data

• Correlate via wells and seismic data from onshore Mesozoic to deepwater subsalt
  
• Recognize how salt carapaces provide key insights into Mesozoic source rocks of deep basin
  
• Discriminate between suprasalt plays, deep shelf sub-weld plays, and subsalt plays of the ultra-deepwater

5. Established and Emerging GOM Plays

• Established and Emerging Mesozoic Plays (Norphlet eolian, Jurassic forereef, Valanginian and Cenomanian deepwater sandstones)
  
• Emerging and Established Cenozoic Plays (Subsalt Paleogene and Miocene, inboard lower Tertiary)
  
• Exploration Play Analysis