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Peshkov G.1, Ibragimov I.1, Yarushina V.2, Wangen M. 2,
Myasnikov A.3
Basin modelling as a predictive tool for
potential zones of chimney presence
1 Skolkovo Institute of Science & Technology (Skoltech), Moscow, Russia
2 Institute for Energy Technology (IFE), Kjeller, Norway
3 Moscow State University (MSU), Moscow, Russia
EGU General Assembly 2020 Online 4-8,
May
• Focused fluid-flow is associated with excess pore-fluid pressure which
can be attributed to varying processes:
• rapid sediment loading,
• uplift and erosion
• dissociation of gas hydrate
• polygonal faulting
• leakage from source and reservoir
• While the origin of focused fluid flow is still under debate, its practical
significance is two-fold:
• It is an indicator of hydrocarbon presence,
• It is a potential location CO2 leakage pathway.
The aim of this work is to use basin modelling to identify precursors of
chimney formation in the geological history.
In this work:
• High-quality 3D seismic data are used to analyze the location of
hydrocarbon leakage in the Snøhvit Field, Southwestern Barents Sea
• Two different basin modelling approaches complement each other
EGU General Assembly 2020 Online 4-8 May 2
Focused Fluid Flow and Chimney Phenomena
(Panieri et al., 2017)
Dataset
EGU General Assembly 2020 Online 4-8 May 3
Distribution of gas chimneys and
leakage in SW Barents Sea
location of modelled geological section
Snøhvit
Gas Field
Hammerfest
Basin
(Vadakkepuliyambatta et al, 2013)
location of gas chimney
Hammerfest Basin
discovered gas fields
(based on Ostanin et al., 2017)
Structural map of the SW Barents Sea
Stratigraphy
A
Б
A Б
(Ostanin et al., 2017)
Chimney Location
EGU General Assembly 2020 Online 4-8 May 4
7120/5-1 7120/6-1 7121/4-1 7121/5-1
A B
In Geological Section
Chimney 1Chimney 2 Chimney 3
location of geological section
On Base Map
A
B7120/5-1
7120/6-1
7121/4-1 7121/5-1
In Probe of Seismic Cube
(Ostanin et al., 2017)
(Duran et al., 2013)01 1 km(Mohammedyasin et al., 2016)
Chimney 1
Chimney 2
Chimney 3
Migrating Fluid
Wellbore
EGU General Assembly 2020 Online 4-8 May 5
Plot of Porosity distribution
• Gas chimneys tend to reservoir thickened flanks,
with the best petrophysical characteristics:• the highest porosity
• maximum vertical thickness
• This might indicate the role of gas/liquid dynamics
in chimney formation
Focus on Reservoir Zone with Chimney
Reservoir
without chimneys
Reservoir
with chimneys
Porosity, %
Chimney 1 Chimney 2 Chimney 3
Reservoir
flanks
Basin Model I: Porosity modelling with Tecmod2D cont.
EGU General Assembly 2020 Online 4-8 May 6
Basin Model I: Temperature modelling with Tecmod2D cont.
• In reservoir area with chimneys we observe the local maximum of heat flow density in temporary and today, and
hence temperature values, that contributes the source rock formations to produce more hydrocarbons and increase
the overpressure within the overlaying reservoir in the most buried part od the basin
• Area without chimney locates in less conducive thermic conditions for their formation
mW/m2
Horizontal section at -3.2 km
Heat Flow at 0 Ma
Heat Flow through the Basement/Basin boundary
mW/m2
Basement
Basin
(tim
e s
ca
le)
T, oCTemperature at 0 Ma
Basement
Basin
Reservoir
with chimneys
Zone of temperature
maximum
Zone of temperature
minimum
Reservoir
without chimneys
Reservoir
with chimneysReservoir
without chimneys
Present day temperature and porosity
• The basin appears to be at maximal burial towards
Mid Oligocene before the basin was uplifted and
eroded. Thermal maximum coincides with maximum
burial.
• Therefore, rates of hydrocarbon generation reach
maximum during Oligocene.
• Quartz cementation of the sandstone units also
reaches maximum rates during Oligocene.
Burial histories at x=50km and x=100km
Basin Model II: Temperature modelling with Bas14
• The hiatus during Tertiary is uncertain. Different representations of the hiatus can produce quite different thermal
maximum during Mid Oligocene.
EGU General Assembly 2020 Online 4-8 May 7
Overpressure at 56 Ma
• Compaction is modelled by assuming
porosity as a function of depth
• Only a small fraction of the porosity that is
lost during compaction is recovered during
unloading by erosion
• Maximum overpressure build-up takes place
when burial rates are at maximum
• Maximum burial rates are during Triassic,
Early Jurassic and during Paleocene.
• Burial rates during the Tertiary hiatus are
uncertain
• The timing of maximum overpressure build-
up is therefore uncertain during the Tertiary.
• Erosion and unloading during Eocene and
Miocene may have removed high
overpressure from before the erosion
process
• Conditions for chimney formation appear to
be prior to the last erosion process.
• We have not studied pressure build-up by
glacial loading which could also be a cause
for chimney formation.
Basin Model II: Overpressure modelling with Bas14
EGU General Assembly 2020 Online 4-8 May 8
Overpressure histories at x=50km and x=100km
• Detailed seismic analysis facilitated the location of chimneys on our basin model
• Petrophysical and geological characteristics of the reservoirare described in the location of chimneys
• Two examples of the neighbor reservoir are shown and characterized by the presence or absence of chimneys, that justified by the different thermobaric history of the underlying source rock formations
• This explanation are proved by two different approaches of basin modelling
• An additional study is needed of the effects of glaciation periods on the formation of over-solders and winter trees
EGU General Assembly 2020 Online 4-8 May 9
Conclusion