Oil and Gas

Participants will learn to:

1. Discern the characteristics of carbonates from different depositional and diagenetic environments, and how they might be recognized in the geologic record.
2. Evaluate the different scales of heterogeneity in these carbonate depositional systems using field and remote sensing observations.
3. Characterize the controls on this heterogeneity, including geological, physical, chemical and biological oceanographic aspects.
4. Integrate these observations into a global (Holocene) and geological (deep-time) perspective.
5. Develop meaningful, predictive conceptual models of reservoir geometry and continuity and possible play relationships in subsurface analogs.

The Crooked-Acklins Platform (CAP) is an ideal location for learning many fundamentals of carbonate sedimentary systems. Located between the Great Bahama Bank and the Caicos Platform, the CAP includes all of the “classic” Holocene environments of both areas, including both wave- and tide- influenced  sedimentary systems. Importantly, these different environments all occur in close proximity, such that long boat rides are not necessary to see the entire spectrum of environments. Instead, participants focus on observing, discussing, and learning.

Each part of this system has been systematically studied, and participants will be exposed to novel data and new insights regarding sedimentary patterns and fundamental controls, including waves, tides, and geochemical and biological factors. Different Holocene environments that participants examine include:

• Shelf-margin barrier reef, the third longest in the Caribbean, and outboard drop-off and slope;
• Reef sand apron and back-reef shelf environments;
• Shelf-margin oolitic – skeletal shoal complex, shaped by tides;
• Grain-dominated platform interior, influenced by waves and tides;
• Progradational oolitic beach ridges;
• Tidal flat complex, including both a channeled belt and a progradational shoreline, with expansive hardgrounds;
• Evaporative ponds.

Likewise, outstanding exposures of Pleistocene strata we will visit include:

• Shelf-margin reef and associated patch reef deposits;
• Progradational, upward shoaling oolitic shoreline deposits.

In general, study of the Holocene offers several unique opportunities, including direct observation (and appreciation) of the scale of facies heterogeneity in plan view. Our observations will focus on: textures, grain types, organisms, sedimentary structures and early diagenetic alteration; and explicit and clear assessment of the influence of different variables (e.g., hydrodynamics, bathymetry, organisms) on these patterns. These will provide the basis for a deeper understanding of possible variability in reservoir analogs.

Our observations will focus on:

• textures, grain types, organisms, sedimentary structures and early diagenetic alteration; and
• explicit and clear assessment of the influence of different variables (e.g., hydrodynamics, bathymetry, organisms) on these patterns. These will provide the basis for a deeper understanding of possible variability in reservoir analogs.

Itinerary (Subject to Change)

Day 0:

• Arrive in Nassau

Day 1:

• Transfer to Crooked Island via Bahamasair.
• Lecture and field check.
• Coastal lagoon and island dynamics.
• Nearshore patch reefs.

Goals/learning objectives:

• Re-emphasize safety aspects; ensure participants are comfortable in the water.
• Hands-on review of Holocene biota, grains, and textures
• Introduce the geography, topography, climate, and oceanography of the area.
• Patch reef processes and dynamics.

Day 2:

Nearshore environments – tidal flats, shallow interior, tidal inlet and delta

Goals/learning objectives:

• Observe tidal flat processes, environments, and sediments.
• Study the vertical stratigraphic succession in core.
• Observe tidal deltas - their sedimentology, size, shape and geometry.
• Characterize variability and sedimentology of tidal flats and deltas (of the entire Bahamas and elsewhere).
• Review and critically discuss reservoir analogs.

Shoreface and Foreshore Environments

Goals/learning objectives:

• Observe present-day sediment distribution, ichnology, and dynamics across and along an extant carbonate shoreface and foreshore.
• Examine the late Holocene shoreface and stratigraphic succession.
• Study a Pleistocene shoreface succession.
• Discuss the nature, controls, and significance of early diagenesis (marine and meteoric).
• Characterize variability and sedimentology of carbonate shorefaces in the stratigraphic record and reservoir implications.

Day 3:

Platform interior, oolitic sand shoal, red algal flat, Pleistocene shoreface and reef outcrops

Goals/learning objectives:

• Observe the sedimentology, stratigraphy, and geometry of oolitic tidal sand shoal system.
• Characterize along-strike variability.
• Understand the roles of waves, tides, and currents on platform sedimentary systems.
• Explore an evaporative coastal lagoon with lacustrine microbialites.
• Summarize, review and provide perspectives on shoals throughout the Bahamas and in the geologic record.
• Examine a Pleistocene reef-oolitic succession in coastal outcrops; assess variability.
• Compare wave- and tide-dominated oolitic systems.

Day 4:

Reef, backreef, and slope; karst in Pleistocene; Pleistocene reef outcrops

Goals/learning objectives:

• Observe the nature of shelf margin reefs and shelf systems.
• Characterize their across- and along-strike variability.
• Review the roles of waves and tides on reefs, reef sand aprons, and backreef shelves.
• Summarize, review and provide perspectives on reefs and reef sand aprons globally.
• Observe a platform-margin drop-off with syn-depositional fracturing; discuss slope and basinal systems.
• Discuss concepts applicable to reservoir analogs.

Day 5

Overflight of Crooked-Acklins Platform to review facies belts.

Depart to Nassau and return home.

This course addresses the fundamental controls on carbonate systems with a global and a deep-time reservoir perspective and most concepts are broadly portable, beyond this platform. Thus the course is suitable for geologists, geophysicists, petrophysicists, reservoir engineers and managers assigned to carbonate evaluations.