Deposition & diagenesis (applied studies)

(2 days total for all listed modules)

Great Barrier Reef Province, Australia

What defines carbonate sediment?

Limestone constituents at deposition construct distinctive textures that in part imply original depositional setting, ocean chemistry and water depth. But this sediment is biochemical and so is reactive from the time of deposition. Assumptions in terms of textures as indicators of simple responses to physical energy at the time of deposition are wrong.

         Code #    Topic

  • 3000.01    Carbonate grains
  • 3000.02    Depositional textures
  • 3000.03    Altered textures
  • 3000.04    Mud in carbonates
  • 3000.05    Classification of carbonates
  • 3000.06    Why carbonates are complex

Diagenetic evolution

Carbonate texture and rock chemistry preserve evidence of as the various diagenetic fluids it was exposed to during burial, re-equilibration and uplift. Unlike a sandstone, which tends to preserve most primary textures and structures, ancient carbonates are generally dominated by textures and cements indicative of post-depositional alteration.

         Code #    Topic

  • 3025.01     Marine cements
  • 3025.02     Meteoric alteration
  • 3025.03     The burial environment
  • 3025.04     Uplift and alteration
  • 3025.05     Isotopes and other tracers

Great Blue Hole, Belize

Porosity and permeability

Unlike sandstones, porosity and permeability distributions in ancient carbonates are rarely directly related to the depositional setting. Understanding and reliably predicting carbonate poroperm distribution requires a level of textural understanding and diagenetic timings not needed in siliciclastics.

         Code #    Topic

  • 3050.00    Ø & k textural variation
  • 3050.01    Choquette and Pray Ø types
  • 3050.02    Lucia classes & k prediction
  • 3050.03    Classes & reservoir quality
  • 3050.04    Poroperm trends & burial
  • 3050.05    Diagenetic geometries

Dolomite, Carboniferous

Carbonate geosystems across time

The modern gives a limited sampling of ancient epeiric and saline basins. This reflects the limited climatic and tectonic spectrum of today. Past systems were more extensive and variable.

         Code #    Topic

  • 3075.01     Eustasy, greenhouse, icehouse
  • 3075.02     Epeiric seaways and giants
  • 3075.03     Eustacy, karst, present & past
  • 3075.04     Are carbonates different?
  • 3075.05     Are all carbonates fractured?

By-pass reef wall, Pacific


Most dolomite is a diagenetic mineral phase. Sometimes dolomitization enhances reservoir quality, other times it destroys it. There are many types and styles of dolomite, some are economically significant and can have recognizable criteria at both the local  (wireline) and regional scales. Some sequences maintain economic levels of dolomite-induced or enhanced poroperm at greater depths and pressures compared to limestones.


         Code #    Topic

  • 3125.01     Chemistry and physics of dolomite
  • 3125.02     Models & geobodies
  • 3125.03     Permeability contrasts
  • 3125.04     Predicting overdolomitization
  • 3125.05     Reservoir linkages



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