Structural, stratigraphic and thermal basin modelling

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Structural, stratigraphic and thermal basin
modelling

• In collaboration with Prof. Nick Kusznir
• Liverpool University

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Structural, stratigraphic thermal basin
modelling

• Background and history
• Since the late 1980s we have worked with Prof.
  Nick Kusznir to develop a set of software tools
  and workflow practices which use state-of-the-art
  academic research to produce geodynamic models
  with a direct application and relevance to
  predictive exploration of rifts and continental
  margins
• No-one else in the UK or overseas can offer these
  services or facilities, they are unique to
  Badleys
• Past and present customers include
• BP, Shell, Conoco, Phillips, Anadarko, KMG, Norsk
  Hydro, Statoil
• We are constantly keeping these services at the
  leading edge by collaborating in new research,
  such as the government and industry-funded iSIMM
  Atlantic Margin project, running from 2001-2005.

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Structural, stratigraphic thermal basin
modelling

• What do we offer ?
• 2D modelling of cross-sections and structural
  profiles
• FlexDecomp for backstripping through the
  thermal-subsidence history of rifts and
  continental margins, using 2D flexural
  backstripping
• Stretch for forward modelling the structure and
  subsidence history of rifts and continental
  margins, using the flexural cantilever model
• 3D modelling of maps and grids
• FlexDecomp 3D for backstripping and restoration
  of maps and grids, using 3D flexural
  backstripping. Powerful palaeobathymetric
  prediction.
• Thermal modelling of wells and transects
• Heat for whole-lithosphere thermal modelling,
  works in conjunction with structural predictions
  from Stretch or FlexDecomp
• 2DHeat and 3DHeat for modelling thermal transfer
  in 2D profiles or 3D volumes, includes igneous
  and oceanic heating

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Structural, stratigraphic thermal basin
modelling

• What are the applications ?
• Interpretation QC Constrain and help the seismic
  interpretation of difficult-to-interpret faulted
  structure in basins. An alternative to
  traditional section balancing.
• Understanding basin dynamics Understand and
  predict the large-scale process driving
  extension, subsidence, uplift and heat-flow in a
  basin.
• Palinspastic Restoration Produce sequential
  isostatically-balanced cross-sections or maps,
  depicting stratigraphic, fault and basin
  geometries. Palaeostructure.
• Palaeobathymetry Predict variation of
  bathymetry, basin-floor slope and depocentre
  location through time. Applicable both to 2D
  cross-sections and 3D maps grids
• Cont

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Structural, stratigraphic thermal basin
modelling

• What are the applications ?
• Depositional Erosional Analysis Model syn-rift
  elevation (footwall uplift) highlighting sediment
  source areas and predict amounts of erosion of
  fault blocks. Quantify the effects of sediment
  loading and compaction on stratigraphy. Generate
  burial history plots across a basin.
• Thermal History Evaluate a basin's temperature
  history by generating beta factor and heat-flow
  profiles from both forward and reverse models.
  Predict top basement and top sediment heat-flow
  and horizon temperatures through time. Calibrate
  vitrinite and downhole temperature against a
  tectonic/thermal model. Other specialised
  applications also.
• Gravity modelling Compare structurally-derived
  predictions of gravity anomaly with measured
  gravity data.

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Structural, stratigraphic thermal basin
modelling

• Who can benefit ?
• Almost anyone in the exploration team
• Seismic interpreter, wanting to check the
  validity of a fault interpretation
• Sedimentologist, wanting to know whether a
  depositional model is tenable
• Biostratigrapher, wanting to know whether their
  bathymetric estimates are reasonable
• Structural geologist, wanting to know the
  morphology of the syn-rift basin
• Stratigrapher, wanting to investigate the
  generation of unconformities in the basin
• Geophysicist, wanting to know the magnitude of
  stretching (beta) in the basin
• Geochemist, wanting a constrained estimates of
  heat-flow and temperature through time
• Team leader, wanting his staff better trained in
  understanding fundamental processes

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FlexDecomp 2D backstripping of cross-sections
Section validation, palaeobathymetry,
depocentres, topography, beta factors, burial
history

• The modelling involves
• Layer-by-layer removal of the stratigraphic
  sequence, accompanied by sediment decompaction
  and incorporating long-term eustasy
• Isostatic unloading, applying flexural isostasy
  in 2D. Key to the methodology and much more
  robust than applying Airy isostasy
• Reverse thermal-subsidence modelling of one or
  two rift events
• Regional uplift/subsidence related, for example,
  to the plume dynamics
• Calibration against geological data, bathymetry,
  emergence, erosion
• The main sensitivities, which can be iterated or
  tested
• Rift ages and rift magnitudes (beta factors)
• Flexural isostatic parameters
• Decompaction parameters, overpressure, location
  of basement

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FlexDecomp 2D backstripping of cross-sections
Regional 2D model

• Backstrip from present to near syn-rift
• Acknowledge two rift events
• Jurassic (150Ma) beta profile from Stretch
• Constant value for Triassic (250Ma) beta
• Allow for Palaeocene uplift by Iceland plume

Northern Viking Graben Magnus Basin, across
Snorre horst to Sogn Graben
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FlexDecomp 2D backstripping of cross-sections
Backstripped to Top Cretaceous
Top Lower Cretaceous
Base Cretaceous
Northern Viking Graben Magnus Basin, across
Snorre horst to Sogn Graben
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FlexDecomp 2D backstripping of cross-sections
More detailed 2D model
Present-day section
Top Palaeocene With plume support

• Backstrip from present to near syn-rift
• Acknowledge two rift events
• Constant values for Jurassic and Triassic beta

Top Cretaceous No plume support

• Allow for Palaeocene uplift by Iceland plume

Northern Viking Graben More detail over Dunlin,
Statfjord, Gullfaks
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FlexDecomp 2D backstripping of cross-sections
Top Lower Cretaceous
Base Cretaceous

• Backstrip from present to near syn-rift
• Acknowledge two rift events
• Constant values for Jurassic and Triassic beta

Upper Jurassic Syn-rift
Note the variable timing and amount of footwall
emergence for the three fault blocks
Northern Viking Graben More detail over Dunlin,
Statfjord, Gullfaks
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FlexDecomp 2D backstripping of cross-sections
Passive margin model
Present-day section
Base Tertiary With plume uplift Syn-rift Near
breakup
Large beta values
Vøring Basin, Norwegian Atlantic margin Nyk
High and Hel Graben
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FlexDecomp 2D backstripping of cross-sections
Mapping beta factor
Multiple 2D models produce constrained maps of
beta factor, which are a proxy for maps of heat
flow
Published map of beta stretching factor for the
Vøring basin, Norway Roberts et al 1997 JGS
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Stretch forward modelling of cross-sections
Section validation, fault geometry, footwall
uplift erosion, beta factors, heat flow,
gravity model

• The modelling involves
• Application of the Flexural-cantilever model of
  continental lithosphere extension, an established
  model for investigating rift geometries.
• Flexural isostasy in 2D applied to all faulting
  and loading processes. Key to the methodology,
  much more robust than applying Airy isostasy.
• Multiple rifting and re-faulting capability.
• Forward thermal-subsidence modelling of one or
  two rift events.
• Calibration against the results of flexural
  backstripping.
• The main sensitivities, which can be iterated or
  tested
• Fault extension, fault position, fault dip.
• Erosion of topography and deposition in basinal
  areas
• Flexural isostatic parameters

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Stretch forward modelling of cross-sections
Regional model
Whole crustal model of Late Jurassic rift
basin. Single rift model. 11
Beta stretching-factor and corresponding syn-rift
heat-flow anomaly for Late Jurassic rift
Upper-crustal detail view of Late Jurassic rift
basin. Note repeated and varied footwall uplift.
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Northern Viking Graben Magnus Basin, across
Snorre horst to Sogn Graben
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Stretch forward modelling of cross-sections
50 erosion at syn-rift stage
50 further erosion at Base Cretaceous, 15Ma
Base Cretaceous forward model with corresponding
backstripped template
Northern Viking Graben Magnus Basin, across
Snorre horst to Sogn Graben
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Stretch forward modelling of cross-sections
Multiple rifting
Triassic-rift template re-rifted on the same
faults during the Late Jurassic. Note the
variable thickness of pre-rift
Model of Triassic early rift basin after 100Ma
thermal subsidence, prior to re-rifting in the
Late Jurassic
Northern Viking Graben Magnus Basin, across
Snorre horst to Sogn Graben
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Stretch forward modelling of cross-sections
Beta profiles, Late Jurassic and combined
Combined heat-flow anomaly, in Late Jurassic
Gravity anomaly associated with syn-rift multiple
rift model, gravity highs associated with
structural highs and vice versa
Multiple rift model 150Ma thermal subsidence
after Jurassic rift
Northern Viking Graben Magnus Basin, across
Snorre horst to Sogn Graben
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Stretch forward modelling of cross-sections
Detail of syn-rift model template
More focussed local model
Detail of base Cret model template
Detailed whole-crustal model, includes small
faults within the major structures
Maximum erosion from the syn-rift model
Northern Viking Graben More detail over Dunlin,
Statfjord, Gullfaks
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FlexDecomp 3D backstripping of maps grids
Palaeobathymetry, depocentres, topography,
palaeostructure, decompacted isochores, beta
factors,

• The modelling involves
• Layer-by-layer removal of the stratigraphic
  sequence, accompanied by sediment decompaction
  and incorporating long-term eustasy
• Isostatic unloading, applying flexural isostasy
  in 3D, allowing 3D variations in stratigraphic
  and structural geometry to be acknowledged
• Reverse thermal-subsidence modelling of one or
  two rift events
• Regional uplift/subsidence related, for example,
  to the plume dynamics
• Calibration against geological data, bathymetry,
  emergence, erosion
• The main sensitivities, which can be iterated or
  tested
• Rift ages and rift magnitudes (beta factors)
• Flexural isostatic parameters
• Decompaction parameters, overpressure, location
  of basement

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FlexDecomp 3D backstripping of maps grids
QC agaist 2D sections
Input
Output
Load removal
Map-based restorations
Palaeobathymetric maps to aid depositional
modelling
Neogene uplift
3D-backstripping method and iterations
Sea-level variation
Palaeostructure maps to aid structural
understanding and migration modelling
Model of the uncertainty arising from the
interpretation range
Thermal balance McKenzie model
Beta map
Beta map
Iterations to match well and seismic
paleobathymetric markers
Illustration courtesy of Richard Corfield, BP
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FlexDecomp 3D backstripping of maps grids
Input requirements example present-day depth
maps and grids
Seabed Accurate seabed topography is essential
for deeper restoration
Intermediate horizons With folds, compaction
features and bathymetric markers
Deep horizons With fault-block structure and rift
bathymetry
Norwegian Atlantic margin
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FlexDecomp 3D backstripping of maps grids
Reverse thermal-subsidence modelling is
constrained either by applying constant values of
beta stretching-factor, or more rigorously by
applying a map of stretching factor, typically
constrained by multiple 2D sections
Published map of beta stretching factor for the
Vøring basin, Norway Roberts et al 1997 JGS
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FlexDecomp 3D backstripping of maps grids
Base Cretaceous deep structure present day
B
Restoration and bathymetric calibration
Base Cretaceous at seabed
B
Lower Tertiary present day
Base Cretaceous fault-blocks restored to sea-level
Extrusive basalts (B) restored to sea-level
Lower Tertiary at seabed
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FlexDecomp 3D backstripping of maps grids
Subsurface palaeostructural restorations Basal
Tertiary back to seabed
Preferred geodynamic model sequentially restoring
the Basal Tertiary back in time from the present
day to contemporary seabed. Full 3D model and N-S
serial sections
Norwegian Atlantic margin
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FlexDecomp 3D backstripping of maps grids
Subsurface palaeostructure below Lower Tertiary
Multiple subsurface Cretaceous horizons below
Base Eocene at seabed
Base Cretaceous palaeostructure structure below
Base Eocene palaeobathymetry
Palaeostructure section between horizon surfaces
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FlexDecomp 3D backstripping of maps grids
Decompacted isochores highlight structural growth
and sediment depocentres

• Stratigraphic sequence sufficiently thick to
  avoid differential compaction over basement highs

• Isochore variation in Tertiary and Upper
  Cretaceous reflects structure or relict seabed
  topography

Upper Tertiary
Basal Tertiary

• Upper isochores show Tertiary domes

• Deeper isochores show Vøring fault-blocks and
  basins

Upper Cretaceous
Lower Tertiary
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Heat whole-lithosphere thermal modelling
Heat is a 1D forward modelling program for
predicting heat-flow, maturation and horizon
temperature histories from well or cross-section
data.

• The modelling is very fast and incorporates
• Whole-lithosphere thermal perturbation, with
  adjustable lithosphere parameters
• Burial history, defined by input stratigraphy and
  lithology, incorporating compaction
• Tectonic thermal history, the ability to model
  the thermal perturbation from multiple rift
  events and their subsequent relaxation.
  Calibrated by Stretch and FlexDecomp
• Crustal and lithosphere thinning, defined by the
  tectonic history. Lithosphere thinning can be
  considered as uniform with depth or
  depth-dependent
• Crustal and sediment radiogenic heat input
• The thermal consequences of igneous intrusion
  into the sediment pile
• Calibration against downhole temperature and VR
  data
• The main sensitivities, which can be iterated or
  tested
• Rift ages and rift magnitudes (beta factors)
• Background radiogenic parameters, particularly
  crustal Rad Gen
• Lithological parameters

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Heat whole-lithosphere thermal modelling
Heat 2D and Heat 3D are new bespoke applications
for modelling heat transfer and temperature
profiles across continental margins

• The modelling is computationally intensive and
  incorporates
• Whole-lithosphere thermal perturbation, with
  adjustable lithosphere parameters
• Lateral thermal input into the basin or margin
  from new oceanic crust or igneous intrusion, 2D
  or 3D model
• Tectonic thermal history, the thermal
  perturbation from tectonic rift events and their
  subsequent relaxation. Calibrated by Stretch and
  FlexDecomp
• Crustal radiogenic heat input
• Lithological control
• The main sensitivities, which can be iterated or
  tested
• Oceanic spreading rate, thermal passage of hot
  ridge
• Thickness of igneous intrusion
• Lithological and Rad Gen parameters

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Heat whole-lithosphere thermal modelling
Heat is a 1D forward modelling program for
predicting heat-flow, maturation and horizon
temperature histories, incorporating tectonic
thermal input
Heat-flow and temperature history
Heat basic output for model QC, model with
multiple rift events
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Heat whole-lithosphere thermal modelling
Heat is a 1D forward modelling program for
predicting heat-flow, maturation and horizon
temperature histories, incorporating tectonic
thermal input
Maturation and burial history
Heat basic output for model QC, model with
multiple rift events
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Heat whole-lithosphere thermal modelling
Heat is a 1D forward modelling program for
predicting heat-flow, maturation and horizon
temperature histories, incorporating tectonic
thermal input
Detailed heat-flow history and multi-model
sensitivity tests
Large rift 3 55Ma
Small rift 1 250Ma
Large rift 2 140Ma
Small rift 1 250Ma
Large rift 3 55Ma
Large rift 2 140Ma
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Heat whole-lithosphere thermal modelling
Heat is a 1D forward modelling program for
predicting heat-flow, maturation and horizon
temperature histories, incorporating tectonic
thermal input
Burial and temperature history and multi-model
sensitivity tests
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Heat whole-lithosphere thermal modelling
Heat 2D and Heat 3D are new bespoke applications
for modelling heat transfer and temperature
profiles across continental margins

• 2D and 3D Thermal Models
• Whole lithosphere thermal model
• Includes sediments, basement, lithospheric mantle
• Steady state initial continental temperature
• Oceanic lithosphere emplaced at t 0 Ma
• 2D or 3D (vertical and horizontal) conductive
  heat transfer
• Compaction dependent sediment conductivity (kr
  km1-f.kwf) for shale, sand or shaly sand
• Upper crustal radiogenic heat productivity
• Lithosphere thickness 125 km
• To 1333oC
• Transform margin at X0 km

• Sensitivities
• ridge duration time
• continental crustal thickness
• oceanic crustal thickness
• continental sediment thickness
• oceanic sediment thickness
• continental sediment composition
• oceanic sediment composition

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Structural, stratigraphic thermal basin
modelling

• Resumé
• At Badleys we offer a range of basin-modelling
  products and services integrated across the
  following disciplines
• Structural geology
• Stratigraphy
• Geophysics
• Thermal modelling
• In this way we draw upon our own expertise in
  tectonic analysis and collaborate with Prof. Nick
  Kusznir on the application of quantitative
  geophysical and thermal modelling techniques to
  provide a unique portfolio of experience.
• This capability distinguishes us very clearly
  from both traditional structural analysis and
  traditional geochemical basin modelling, and
  provides the logical bridge between these two
  normally-separate areas of study.