Exploration Insights March 2020 | Page 4

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Lessons Learned from Established
Unconventional Plays: Application to
the Middle–Late Jurassic Resource
Interval of the Middle East
Legend
Simplified Resource Play Extent
Jurassic Resource Interval
Play Concept Diagram
Jurassic Resource Interval
Hydrocarbon fields charged by
Jurassic source rocks
Oil
Gas
by: Alex Bromhead, David Weeks, and Owen Sutcliffe
Line of section
for Figure 3
250 km
© 2020 Halliburton
Tuwaiq Escarpment Source: https://ca.m.wikipedia.org/wiki/Fitxer:Tuwaiq_Escarpment-14h38m25s-k.jpg
Unconventional resource plays are firmly
established as an integral component of global
hydrocarbon production. In 2018, resource plays
accounted for 59% of total U.S. oil production and
enabled the U.S. to overtake Russia and Saudi
Arabia as the largest producer of crude oil (EIA,
2018). The development of resource plays within
North America has sparked interest in exploring
similar unconventional play concepts globally.
There is a great deal of uncertainty associated
with the development of frontier and
emerging unconventional resource plays.
While technological aspects of developing
unconventional plays have been proven,
developing these plays economically within
a volatile energy market has been extremely
challenging. In most instances, developing
unconventional plays in the U.S. has been
inefficient, with factory drilling outside the
geological sweet spots commonplace during the
initial development phase.
Understanding the geological controls that
influence production rates, and predicting the
distribution of geological sweet spots, is integral
to efficient and cost-effective development. There
has been more than a decade of experience
gained during the development of North
American resource plays. Valuable insight can be
gained by comparison with pertinent analogues,
and can be leveraged to drive efficiency in the
development of Middle East resource plays.
This article focuses on the Middle–Late Jurassic
(J60–J110) resource interval of the Middle East,
and discusses the lessons learned from these
analogues.
RESOURCE PLAY OPPORTUNITIES
IN THE MIDDLE EAST
The Middle East contains the most prolific
conventional petroleum systems in the world.
Source rocks within the Silurian (S02–S20)
and Middle–Late Jurassic (J60–J110) have
generated a large proportion of the conventional
hydrocarbon, and are obvious contenders for
resource play development. The Middle–Late
Jurassic (Tuwaiq Mountain and Hanifa formations
and equivalents) resource interval is arguably the
most prolific source rock in the world, and has
considerable unconventional potential. Note that
Figure 1> Location map with simplified play extent for the Middle–Late Jurassic resource interval. The play extent was derived using the
Neftex ® Insights unconventional screening workflow, which applies cut-offs for the presence of organic-rich facies, thermal maturity,
thickness, and depth. Note the close association between the resource interval extent and conventional hydrocarbon fields charged by
Jurassic source rocks.
the potential of the Silurian (Qusaiba Member
and equivalents) resource interval has been
discussed previously by Sutcliffe and Cousins, in
the July 2018 edition of the Exploration Insights
magazine.
The Middle–Late Jurassic resource interval
is widespread across the Middle East (Figure
1). However, its prospectively is likely to vary
considerably across the play extent. This is
because unconventional plays in general are
inherently heterogeneous, and typically only a
small proportion of the play contains the ideal
combination of geological criteria that classify it
as a sweet spot.
RESOURCE PLAY CLASSIFICATION
Given the range of stratigraphic heterogeneity
observed within resource plays, it is necessary to
systematically classify this variability in order to
identify pertinent analogues. We have developed
a comprehensive classification scheme that
characterizes a wide range of geological aspects
within unconventional resource plays. At a basic
level, unconventional plays can be classified
based on play type and stratigraphic organization
(Figure 2). This classification scheme is applied
to conceptualize a variety of unconventional play
opportunities within the Middle–Late Jurassic of
the Middle East and to identify analogues.
UNCONVENTIONAL PLAY
CONCEPTS
Stratigraphic heterogeneity within the Middle–
Late Jurassic resource interval facilitates a variety
of shale play (S) and tight play (T) concepts.
These play concepts are represented along
a schematic stratigraphic cross-section that
transects the Jafurah and Khaleej Al-Bahrain
basins (Figure 3).
The basal shale play (S1) (J60–J80) corresponds
to the Tuwaiq Mountain Formation (and regional
equivalents) and comprises an interbedded
source, calcareous mudstone shale play. This
play type is under development in the Jafurah
Basin, Saudi Arabia, following encouraging results
from more than 40 wells tested during the pilot
phase (Almubarak et al., 2017). The play has
recently undergone a high-profile stimulation test
in the Khaleej al-Bahrain Basin, offshore Bahrain,
following which a resource in-place of 80 billion