sedimentological processes modeling

Sedimentological Processes Modeling

Christopher G. St.C. Kendall

Outline of PresentationData - Outcrops, well log & seismic cross sections Sequence stratigraphy & modelingRelative sea level & 2D/3D sedimentary simulationsInverse conceptual simulation models versus numerical forward modelingShort-term, high-resolution, local versus long-term basin wideHolocene data particularly carbonatesSedimentary simulation movies & modeling.

Interconnected modules of numerical process simulations of sedimentary basins evolution - the future

Sequence Stratigraphy History

1791 - William Smith established relationship of sedimentary rocks to geologic time1962 - Hess proposed the theory of sea-floor spreading1963 - Vine & Matthews identified deep ocean paleomagnetic "stripes“1965 - Wilson began developing the theory of plate tectonics1977 - Vail proposed the discipline of sequence stratigraphy

Types of SimulationsSedimentary modeling:

Carbonates vs. clastics

Stochastic vs. deterministic

Fuzzy vs. empirical

Small vs large oceanic basins

Traditional Use of Sedimentary Simulations

Understand complexities of clastic or carbonate stratigraphy

Identify & model sedimentary systems.

Quantify models that explain & predict stratal geometries within sequences.

Used by specialized experts who design & build the simulations.

Sedimentary process models from outcrops, well log & seismic cross sections used to:

Sedimentological Processes Modeling

Inverse conceptual simulation models

Numerical forward modeling advanced.

Short-term, high-resolution local events vs a long-term regional events

2D & 3D sedimentary simulations, relative sea level, physical processes, & sedimentation & erosion:

Approaches to modeling Geometric models

Fixed depositional geometries are assumed Conservation of mass Simple computations through general nonlinear dynamic models Variations in depositional geometriesVariations in surface slope vs discharge More complex computationally

Chris Paola, 2002

Some sedimentary modelsShort-term local events

• SEDSIM (Tetzlaff and Harbaugh, 1989)• SEDFLUX (Syvitski et al., 1998a; Syvitski et al., 1998b)

Long-term regional events

• PHIL (Bowman et al 1999)• SEDPAK (Eberli, et al, 1994)• FUZZIM (Nordlund1999a&b)• CSM (Syvitski et al., 2002)• Robinson and Slingerland, 1998• Steckler et al., 1993.

Ross et al., 1995

Jervey, 1988

Perlmutter et al., 1998

Chris Paola

Geometric Model

Chris Paola

Geometric Models “Jurassic Tank”

Chris Paola, 2002.

Geometric Model

Eberli, et al, 1994

Uses by Specialized Users

John W. Harbaugh 3D sedimentary fillCarey et al., model high-resolution sequence stratigraphy Bowman & Vail empirical stratigraphic interpretion - stratigraphy of the Baltimore CanyonKendall et al., empirical stratigraphic simulator for BahamasSyvitski et al., model links fluvial discharge, suspended sediment plume, associated turbidites, the effects of slope stability, debris flow, and downslope diffusion

Approaches to modeling Geometric models

Aigner - Deterministic 2D

Bosence et al. - 3D Forward & Fieldwork

Bosscher - 2D Forward Model

Bowman - Forward Model

Cowell - Shoreface Model

Cross and Duan - 3D Forward Model

Demicco - Fuzzy Modeling

Some of the carbonate modelers

Aigner - Deterministic 2D

Bosence et al. - 3D Forward & Fieldwork

Bosscher - 2D Forward Model

Bowman - Forward Model

Cowell - Shoreface Model

Cross and Duan - 3D Forward Model

Demicco - Fuzzy Modeling

Flemmings - Meter-scale shaoling cycles

Goldhammer - High-frequency platform carbonate cycles

Granjeon - Diffusion-based stratigraphic model

Kendall – Deterministic forward model

Ulf Nordlund - Fuzzy logic

Read - Two-dimensional modeling

Rivanaes - Depth-dependent diffusion models of erosion, transport & sedimentation

Further carbonate modelers!

Why limited use of simulations

Software integrates seismic, well logs, outcrops & current depositional systems

On site interpretations & evalutation of data revealing origin of sediment depositional systems

Models explain sedimentary geometries displayed on interpreted seismic & well log sections

Historically sedimentary modeling derived from real data

Seismic

Wells.

Outcrop

But less from:

Holocene

Data Sources

Seismic

Outcrops

Outcrops

King 1954

Simulation Data NeedsModels are commonly based on subsurface

Input variables known but values are inferred from geologic record

Need to refine observations at deposition

Complexity needs to be handled by a team approach

Need to gather data from a Holocene setting like the “Arabian Gulf”

Restricted Entrance To Sea

Isolated linearBelt of interior

drainage

Regional

Drainage

Into Basin

Arid Tropics Air System

Wide Envelope of surrounding continents

United Arab Emirate CoastBarrierIslandCoast

Aeolian System

Arid Climate

CoastalEvaporiteSystem

ReefPlatform

United Arab Emirate CoastTidal

DeltasArid Climate

CoastalEvaporiteSystem Reef &

Lagoon

Power of Simulation Movies

Annotated movies of sedimentary simulation show evolution of sedimentary geometries in response to variations in rates of:SedimentationTectonic movementSea-level position

Movies involve hypothetical & real-life examples based on outcrops, well log & seismic cross sections.

Clastic Simulation

Geometric Effects of Sea Level Change

On-lap with rising sea level

Off-lap with falling sea level

By-pass at low stands of sea level

Erosion at low stands of sea level

Ravinement with sea level transgressions

Landward continental clastics at high stands

Seaward carbonates at high stands

Chronostratigraphic Chart

Venezuelan Example

P-10

LST : Avg. Width 6.6 kmAvg SS H 35.0 mAvg. W:T 220:1# of Valleys 9Valley Type (4) V-shaped

(3) Elongate-Straight(2) Elongate-Sl.-Sinuous

HST: Eroded-or not present

TST: Barrier Island sandsAvg. Width 1.75Avg. SS H 8.84 mAvg. W:T 143:1

Distance between sands 2.48 kmNumber of Sands 10

HST/LST TST

LST Chart

Example 1: Well Log Correlation

Venezuelan - Example

Sedimentary Simulations & Sequence Stratigraphy

Factors controlling sequence stratigraphic geometries

Efficient interpretations of data

Enhances biostratigraphy & infers ages

Quantifies models

Identifies & models ancient sedimentary systems

Sharing data with others

Potential use of sedimentary simulations

Stratal architecture - hydrocarbon explorationWater storage & geochemistry of hydrologic cycleNatural hazards assessment of risk Landscapes managementSedimentary basins as incubators of the deep biosphereControl carbon & other elemental cycles from sedimentary basins & eroded landscapes Tracking global & regional climate change

Sedimentary Simulations Conclusions

Earlier sedimentary simulation modelled large scale processes Will focus on smaller scale processes, to predict distribution of heterogeneous sedimentary facies from

a) 3D perspective b) Fluid flow c) Role of diagenesis

These models will probably involve combinations of fuzzy logic, empirical, stochastic & deterministic algorithms

Simulation Design

The design & use of sedimentary simulations involves:Complexity of stratigraphic geometries and sedimentation Changes in base level Data sources & qualityTypes of outputSensitivity of the results to errors in data input & model used

Simulations - which way?

Sedimentary models are a mix of deterministic and process driven Input variables are know but their value has to inferred from the geologic recordSedimentary models are going 3DSubsurface models are commonly oil field basedMovies are worth a thousand words

Sharpens & accelerates ability to observe & interpret complex sequence stratigraphic geometric relationships

Future Directions

Interconnected modules of numerical process simulations

Track the evolution of sedimentary basins & their associated landscapes

Time scales ranging from individual events to many millions of years

http://instaar.Colorado.EDU/deltaforce/workshop/csm.html).

Recently emphasis within the USA by US Government agencies & associated academic institutes:

Community Model

Conclusions – FutureEmphasis has been switched to whether:

One process should be coupled or uncoupled with respect to anotherA particular process is deterministic or stochasticAnalytical solutions have yet been formulated for a particular processProcesses can be scaled across time and spaceDeveloping adequate databases on key parameters from field or laboratory measurementLevels of simplification (1D, 2D, 3D)

Thus initially while over simple forward conceptual & empirical models were more widely used, lately computational process driven forward models have gained greater acceptance, & collective models may be the new wave

sedimentological processes modeling

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