Clastic Sequence Stratigraphy and Sedimentation

Evert van de Graaff 
Mark Bouman 
5 days

Business context

A good understanding of how depositional processes control the distribution of clastic reservoir and non-reservoir rocks in the subsurface is of fundamental importance to sound EP decision making. This applies throughout a field's life-cycle, all the way from the exploration phase, through appraisal, field development and finally field abandonment.

Who should attend

Petroleum geoscientists. petroleum engineers and members of integrated asset teams, who are responsible for defining and evaluating subsurface geological risks and uncertainties. The course targets EP professionals in the initial phase of their career.

Course content

Overview of clastic stratigraphic analysis and sequence stratigraphy. Course focuses on how geological characteristics of a reservoir impact on EP decision making during all phases of a field's life cycle.

  • Clastic depositional systems &reservoir characteristics
    • Fluviatile systems
    • Deltaic systems
    • Non-deltaic coastal systems
    • Deepwater ("turbidite") systems
  • Sequence stratigraphy
    • Controls on sea level changes
    • Fundamental concepts & terminology
    • Fluviatile, deltaic and turbidite systems in a sequence stratigraphic context
  • Fundamentals of clastic reservoir architecture and subsurface fluid flow
    • Clastic reservoir architecture
    • Reservoir rock typing
    • Recovery mechanisms and subsurface fluid flow
    • Static reservoir modelling workflow

Learning, methods and tools

The course uses a combination of lectures and paper exercises. The exercises are mostly built around correlation problems to highlight the importance of using sound sedimentological and stratigraphic concepts for building fit-for-purpose subsurface models.

The PPT viewgraphs used and a set of short briefing notes are provided as a hard-copy hand-out, as well as the text book 'Sedimentology and Stratigraphy' [Nichols, G., (2009), Wiley-Blackwell, (2nd Ed.) pp. 419 (subject to availability)].

Subject to prior agreement a ½ to 1-day workshop / demo on how to build a static reservoir model [using a Client's own data set] may be incorporated in the programme. Including such a workshop / demo in the course will be at the expense of the time available for one or more of the lecturing modules.

Day by day programme

Day 1

Clastic stratigraphy & sedimentation - basis for subsurface modeling

  • Correlation - key to subsurface modeling
  • Fundamentals of clastic reservoir architecture and subsurface fluid flow

Sea level change - the fundamentals

  • Temporal and spatial scales of sea level change
  • Relative vs eustatic sea level change
  • 'Haq' sea level curve: test case Australia
  • Mechanisms of sea level change (Milankovitch cyclicity)
  • 'Ice house' vs 'Green house' periods
  • Allocyclicity vs Autocyclicity
  • Seismic stratigraphy: basis for 'Haq' sea level curve

Day 2

Sequence stratigraphy

  • Why sequence stratigraphy matters
  • Sediment supply vs accommodation space (Sea level change + subsidence = accommodation space)
  • Sea level change and stratal patterns (Coastal progradation / aggradation / retrogradation; Transgression / regression; Deepwater sands)
  • Accommodation space and sequence development (Stratal surfaces & terminology)
  • Wheeler diagrams
  • Depositional sequences & systems tracts
  • Parasequences & (maximum) flooding surfaces
  • Forced regressions & incised valleys
  • Expression of sea levels changes in fluvial realm
  • Sequence stratigraphy vs Genetic stratigraphy

Day 3    

Fluvial systems & reservoir characteristics of fluviatile deposits

  • Processes and main facies
  • Alluvial fans
  • Alluvial valleys
  • Braided streams
  • Meandering streams
  • Anastomosing rivers
  • Fluvial distributary channels in deltas
  • Fluvial architecture and reservoir geometry

Deltaic coastal systems & reservoir characteristics of deltaic deposits

  • Processes and main facies
  • River-dominated deltas
  • Wave-dominated deltas
  • Tide-dominated deltas

Non-deltaic coastal systems and continental shelves

  • Processes and main facies
  • Shoreline architecture
  • High-energy shelf systems
  • Shelf edge and slope
  • Log correlation exercise

Lacustrine systems

  • Main controls on lake formation
  • Processes and main facies
  • Preservation potential of lacustrine deposits
  • Source rock potential

Day 4

Deep water mass-flow sediment transport:

  • Sediment supply to deep water (Rock falls / slumps / debris flows / grain flows / liquefied flows / turbidity currents)
  • Deepwater fan models & prediction of reservoir quality
  • Dimensions of deep-water depositional systems

Deepwater mass-flow sedimentary systems

  • Sea level low-stand as a control on deep water sedimentation
  • Deep-water fan models (Autocyclicity in deep water fans; 'Shaley sands' in turbidite deposits)

Megaturbidites

  • Channel / levee / basin plain deposits
  • Seismic characterisation of deep-water clastics (Reservoir architecture: descriptive terminology)

Gulf of Mexico deep-water clastics

  • Salt structures as a control on sea floor topography (Mini-basin sedimentation)

North Sea deep-water clastics

  • Subsurface uncertainty (Commercial discovery instead of 'dry hole')

Day 5     

Clastics vs Carbonates

  • Poroperm characteristics of clastics
  • Biology: key control on carbonate deposition
  • Poroperm characteristics of carbonates (Extreme pore systems: karst reservoirs)
  • Carbonate depositional systems (Tropical / cool-water / mud mound carbonate factories)

Clastic stratigraphy & sedimentation - impact on field and reservoir development:

  • Reservoir architecture
  • Subsurface fluid flow and field development implications

Optional workshop part of course

  • Review of participants' data sets / case studies

Course assessment: multiple choice test