6 | Halliburton Landmark
Exploration Insights | 7
CO 2
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Arabian
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S h i e l d Wa
PDEM
Drainage
(S2S)
Sequence
Stratigraphic
model
Paleoclimate model
300 km
Topographic
control
Data
Modeling (conceptual + numerical)
Figure 2> All the geological information, from both models and geological data, that are integrated to produce Neftex ® Paleo Digital
Elevation Models (PDEMs), which are then used to generate global drainage models. From these outputs, paleoclimate models are
produced.
and source-to-sink models, which provide insight
into the quality and distribution of reservoir
and source rocks through geological time.
The prediction of siliciclastic reservoirs can be
particularly enhanced using ESM, since the
factors that impact the effectiveness of such
reservoirs, for example, the reservoir quartz
content, are largely dictated by the mineralogy
of the hinterland. Source-to-sink analysis
provides information on hinterland composition.
When combined with drainage models and an
understanding of paleoclimate, it can be used
to predict sediment flux and fan extents into
basins.
Paleoclimate modeling requires the integration and
analysis of a wide range of data types. At Neftex ® ,
many different types of empirical geological
data (e.g. geochronology and thermochronology)
and integrated models (e.g. the Neftex Plate
Model) are used to produce robust paleo-digital
elevation models (PDEMs). These are used to
generate global paleo-drainage networks (Figure
2). The powerful combination of these geological
disciplines and ESM facilitates the development of
paleoclimatic outputs that are particularly insightful
for specific geological time slices.
We run numerous paleoclimate models
for each time slice at several different CO 2
concentrations. The paleoclimate models are
then independently tested against more than
60 climate-sensitive proxies. These proxies
range from sedimentological proxies, such
as the location of evaporites indicative of arid
environments, to paleontological proxies, such as
climate- dependent reef-building organisms. This
process validates the paleoclimate models. By
utilizing insights gained from ESM the possibility
of deep-water siliciclastic lowstand plays in the
northern Arabian Gulf can be assessed in a holistic
fashion.
LOCATING LOWSTAND FANS IN
THE NORTHERN ARABIAN GULF
The late Valanginian–Barremian Zubair Formation
is marked by a major unconformity at its base,
related to extension in the Levant, which caused
uplift of the Arabian Shield and the Hamad High.
This was coincident with a high amplitude, glacio-
eustatic sea-level drop of up to 65 m (Ray et al.,
2019 and Ray et al., 2020, next article).
During this time of lower sea level, vast expanses
of the Arabian Plate were exposed. In the most
proximal parts of this depositional system,
numerous, stacked incised valleys can be
observed in Saudi Arabia, Kuwait, and southern
Iraq (Figure 3). These incised valleys are close to
Figure 3> The late Valanginian combined Neftex ® Paleo
Digital Elevation Model and Palinspastic Gross Depositional
Environment map. Incised valleys and deep-water siliciclastics
have been identified in proximity to major basement
lineaments (black lines) across the Middle East.
major East-West trending basin lineaments, such
as Wadi al Buteen, which can be seen on the
Neftex Tectonic Elements map. They likely acted
as sediment pathways into the deeper water of
the northern Arabian Gulf.
Further down-dip, well correlations in southern
Iraq and seismic data in offshore Kuwait have
been used to identify deep-water, coarse-
grained siliciclastic lowstand fans, deposited in
the northern Arabian Gulf (Figure 3). Integrating
regional well correlations and seismic data
(available to Neftex Core subscribers) with ESM
provided a greater understanding of the climate
and source-to-sink relationships, enabling an
assessment of reservoir quality to be made.
A
ASSESSING CLIMATE AND
DRAINAGE PATTERNS IN THE
NORTHERN ARABIAN GULF
By combining the late Valanginian PDEM with
regional insights into potential drainage pathways
(e.g. Wadi al Buteen), a drainage model was
developed for the Middle East. This helped
predict the course of sediment transportation
from the hinterland to the sink; in this case, from
the Arabian Shield and the Hamad High to the
northern Arabian Gulf (Figure 4a).
However, without sufficient rainfall, little erosion
takes place in the hinterland, and sediment flux
into the sink is limited. The late Valanginian global
climate humidity map (part of Neftex PRIME)
(Figure 4b) highlights the relative amounts of
rainfall pre-dicted across the Arabian Plate. Apart
from the far northwest and the southernmost
areas of the Arabian plate, which are arid
(indicated in yellow), vast areas of the Arabian
Plate are likely to have experienced significant
rainfall (indicated in blue) during the late
Valanginian. This predicted rainfall would have
provided the mechanism to erode and transport
sediment from the Arabian Shield and Hamad
High into the northern Arabian Gulf.
Sediment flux predictions calculate the volume
of sediment shed into a basin at river mouths,
and are a useful tool to gauge the amount of
sediment deposited. By combining the PDEM,
drainage model, and paleoclimate simulations for
the late Valanginian, sediment flux predictions
and corresponding drainage catchment areas
were assessed (Figure 4c).
C
B
Northern
Arabian Gulf
300 km
GDE map
Neftex data
Plate model
Solar
radiation
Earth Systems
Tectonic
Elements
Incised
valleys
location
ad
m
h
a
H Hig
Figure 4> A) The late Valanginian simplified Neftex ® Paleo Gross Depositional Environment map superimposed on the Paleo Digital
Elevation Model to highlight the source-to-sink relationships across the Arabian Plate; B) the corresponding global climate humidity map
for aridity; and C) the drainage catchment areas and predicted sediment flux into the northern Arabian Gulf.