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Achievements and Challenges in Sedimentary Basins Dynamics 203

a b

Major increase in the

DZW due to outward

migration of deformation

(no strain localisation)

Linear increase in

the DTW

(strain localisation)

CBr01 (WLC)

CBr02 (no WLC)

0

0

10

20

30

40

50

60

70

80

100 Time (sec) 300

Undeformed region

Undeformed region

Boundary effects

Boundary effects

Boundary effects

Boundary effects

DZW

DZW

CBr01 (WLC)

CBr02 (no WLC)

Deformed zone width (mm)

Fig. 43 Consequences of

presence or absence of lower

crustal weakness zones on

localization of deformation in

extended lithosphere. a)

Increase of width of deformed

zone during ongoing

extension; b) Planview of

extending lithosphere for two

end-member models: model

incorporating lower crustal

weakness zone (WLC), top;

model without crustal

weakness zone, bottom (from

Corti et al., 2003)

passive margins, foreland basins and foothills domains.

Geological processes operating in sedimentary basins

are too complex to be addressed by a single, multi￾process numerical tool. Therefore, it is quite important

to generate easy-access databases and to allow for the

import and export of files from one code to the other in

order to develop interactive workflows and more inte￾grated approaches. Moreover allowance must be made

for switching back and forth between basin-scale and

reservoir-scale studies.

In the following, we describe such an inte￾grated workflow, which couples analytical work and

Evolution through time on top views

Cross section in the << south >>

Volcanics Future SDRs

Future

break-up

Fig. 44 Application of rifted continental margin of Mid-Norway (from Sokoutis et al., 2007)

204 F. Roure et al.

modelling, and addresses the interactions between

selected but complex geological processes operating

at various temporal and spatial scales in sedimentary

basins.

Dynamic Controls on Reservoir Quality

in Foreland Fold-and-Thrust Belts

Integration of various datasets ranging from seismic

profiles to thin-sections, analytical work and mod￾elling is a prerequisite for the appraisal of sub-thrust

sandstone reservoirs, the porosity-permeability evo￾lution of which results from mechanical and chemi￾cal compaction, both processes interacting in response

to sedimentary burial, horizontal tectonic stress and

temperature.

First results of the SUBTRAP (SUB-Thrust Reser￾voir Appraisal) consortium studies have shown that in

the Sub-Andean basins of Venezuela and Colombia

the main episode of sandstone reservoirs deterioration

occurred in the footwall of frontal thrusts at the time

of their nucleation when the evolving thrust belt and

its foreland were mechanically strongly coupled. The

related build-up of horizontal tectonic stresses in the

foreland induced Layer Parallel Shortening (LPS) at

reservoir-scales, involving pressure-solution at detrital

grain contacts, causing the in-situ mobilization of sil￾ica, rapid reservoir cementation by quartz-overgrowth

and commensurate porosity and permeability reduc￾tions (Fig. 45; Roure et al., 2003, 2005). The age and

duration of such quartz-cementation episodes can be

roughly determined by combining microthermometric

fluid inclusion studies with 1D and 2D petroleum gen￾eration modelling.

In the case of the Oligocene El Furrial sandstone of

eastern Venezuela, homogenization temperatures (Th)

in quartz overgrowth reflect a very narrow temper￾ature range, averaging 110–130◦C, whereas the cur￾rent reservoir temperature exceeds 160◦C. When plot￾ted on burial/temperature versus time curves derived

from 1D or 2D basin models calibrated against bot￾tom hole temperatures (BHT) and the maturity rank

of organic matter, it becomes obvious that cementa￾tion occurred during a short time interval, no longer

than a few millions years, when the reservoir was not

yet incorporated into the orogenic wedge (Roure et al.,

2003, 2005).

The technique of combined microthermometry and

basin modelling can also be used for dating any other

diagenetic episodes, provided the reservoir was in ther￾mal equilibrium with the overburden at the time of

cementation (without advection of hot fluids). More￾over, forward diagenetic modelling at reservoir scales

can benefit from such output data from basin mod￾elling as e.g., reservoir temperature, length of the dia￾genetic episode and, in the case of diagenesis in an

open system, fluid velocities. For the quantification of

fluid-rocks interaction in the pore space of a reser￾voir or along open fractures transecting it, informa￾tion on these parameters is indeed required. Further￾more, the composition of the fluids involved and the

kinetic parameters, which control the growth or disso￾lution of various minerals present in the system, must

be known.

Pore Fluid Pressure, Fluid Flow

and Reactive Transport

When dewatering processes are slowed down by per￾meability barriers, which impede the vertical and lat￾eral escape of compaction fluids, pore fluid pressures

do not remain hydrostatic but can build up to geo￾static levels. The build-up of excess of pore fluid

pressure can impede mechanical compaction, stopping

pressure-solution at quartz grain contacts, but can also

cause hydraulic fracturing and failure of seals encasing

a reservoir.

New basin modelling tools have been implemented

for 2D simulation in tectonically complex areas of the

pore fluid pressure evolution and the migration veloc￾ity water and hydrocarbons circulating in such subsur￾face conduits as reservoir intervals and open fractures.

First tested in the Venezuelan and Canadian foothills

(Schneider et al., 2002; Schneider, 2003; Faure et al.,

2004, Roure et al., 2005), the CERES modelling tool

(a numerical prototype for HC potential evaluation in

complex areas) has now been applied in many fold￾and-thrust belts around the World. It is noteworthy that

the main results of fluid flow modelling in fold-and￾thrust belts accounts for long episodes during which

deep reservoirs behave as a closed system, whilst rela￾tively short episodes of fast fluid expulsion are directly

controlled by fold and thrust propagation (squeegee

episodes). Figure 46 documents the main results of

Achievements and Challenges in Sedimentary Basins Dynamics 205

El Furrial

0

1 0

3 0

4 0

2 0

90 100 110 120 130

Tt (C)

Frequency

Burial curve and thermal - diagenetic evolution of

the Oligocene Merecure reservoirs in subthrust wells ST

0

1

2

3

4

5

6

7

km

25 M.a. 0 M.a.

End Oligocene Present

B = onset of the tectonic

accretion of the El Furrial trend

= end of LPS and Q cements

= onset of oil accumulation

Increasing tectonic and

sedimentary burial comtemporaneous

with thrust - emplacement

Sedimentation

of the Middle - Upper

Carapita flexural sequence

20C

80 - 90C

120C

140C

A

B

A = onset of

the quartz cementation

B = end of the main

quartz cementation 5 to 7

M.a.

14 - 15

M.a. 8 - 9

M.a.

Frac t u ri ng

Cem e nt at i o n

Qua r t z -

L.P.S.

Middle-Late Miocene Hydrodynamism / Layer Parallel Shortening

Pliocene - Quaternary / Fracturing

rough topography

rough topography

Hydro dynamism

NEW

FOREDEEP

S1

S3

Meteoric

water

Long range migration

Orinoco

Tar

belt

Sedimentary

traps

Meteoric water

Hydrothermal brines

Short range

migration

Fracturing

E.F.

E. F. P. S1 S2

L.P.S.

Q overgrowth

low salinity

asphaltenes

Active kitchen

S2

a A

b

c

Fig. 45 Geodynamic control on quartz cementation in Sub￾Andean basins (Subtrap-Venezuelan transect, after Roure et al.,

2003, 2005): a) Thin-section evidencing various families of fluid

inclusions in a detrital quartz and its diagenetic overgrowth;

b) Diagram outlining the use of micro-thermometry (Th) and

1D thermal modelling to date the diagenetic event; c) Cartoon

depicting the development of LPS (Layer Parallel Shortening)

and quartz-cementation in the footwall of the frontal thrust

such combined kinematic and fluid flow modelling

applied to a case study in the Albanian foothills (Vilasi

et al., 2008).

The CERES modelling tool requires, however, mod￾ification to be able to handle the long term poros￾ity/permeability parameters for individual faults (faults

can change from non-sealing to sealing, depending

on regional stresses and compaction/cementation pro￾cesses), and to address these topics in 3D.

Numerical models require further improvement to

properly handle reactive transport at reservoir- and

basin-scales, since it probably controls the long-term

porosity/permeability evolution of the main subsurface

fluid circulation systems, such as porous and fractured

rock units and fracture and fault systems (including

hydrocarbon reservoirs).

Apart from serving the petroleum industry, new

societal challenges such as CO2 sequestration and

water management also require the implementation of

basin-scale reactive transport models. In such appli￾cations, basin geometries can be kept constant, whilst

the time resolution required is much smaller (months

or years instead of millions of years). Promising

results have already been obtained in the simulation

of thermo-haline circulations in the Northeast German

Basin, thus accounting for the advection of saline water

derived from Permian salt layers up to the surface (Fig.

47; Magri et al., 2005a, b, 2007; Magri et al., 2008).

206 F. Roure et al.

Depth (m)

Length (m)

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100000 102000 104000 106000 108000 110000 112000 114000 116000 118000 120000 122000 12400 126000 98000 96000 94000

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Fig. 46 Ceres fluid flow and pore fluid pressure modelling in the Albanian foreland fold-and-thrust belt (after Vilasi et al., 2009)