Oil&Gas Thought-Leader Webinar - New Plays for Old Ideas - Dr. Rob Forkner
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Transcript of Oil&Gas Thought-Leader Webinar - New Plays for Old Ideas - Dr. Rob Forkner
Why we must consider OAEs whenexploring Mesozoic systemsRob Forkner, Statoil Exploration Research Center Austin 13 March 2017Classification: Internal
© Statoil ASA
Why should industry care about OAE?• Source Rock: Improving 2D/3D facies mapping within SR intervals. OAE and
unique biomarker/diamondoid fingerprinting?
• Reservoir: Improving understanding and predictability of unique reservoir facies
that occur in association with OAE. Are recovery trends global or do they relate to
palaeoceanographic positions?
• Stratigraphy: Shift in understanding of tectono-eustasy to eco-tectono-eustasy,
especially for Mesozoic carbonate platforms. Is it becoming increasingly
appropriate to move away from the accommodation-control model?
• Predictability/variability: Marked variability exists within OAE systems as well as
between OAE systems. How do we better approach predictability in order to affect
exploration efforts?
Classification: Internal
Livello Bonarelli: 1m
60
m
13 March 20172 Classification: Internal © Statoil ASA
World’s effective SR through time. Klemme and Ulmishek (1991)
Neocomian
3%
Aptian-Turonian
29%
Coniacian-Eocene
3%
Oligo-Miocene
13%
Cambro-Ordovician
1%Silurian
9%U. Devonian-Tournaisian
8%
Penn.-L. Perm
8%
M/U. Permian
1%
Jurassic
25%
Jenkyns, 2010
Importance of considering OAE in exploring hydrocarbon systemsCa. 50% of SR are interpreted as related to known OAE
Source Rock: Stratigraphic association between OAE and major SR intervals
Reservoir: Stratigraphic association between OAE and unique reservoir facies
that may favor eutrophic/heterozoan organisms. These tend to be very grainy
systems.
Stratigraphy: Association between OAE and seismically-resolvable
stratigraphic breaks that can be mapped over hundreds of km2, especially on
Mesozoic carbonate shelves. They can also serve as markers for finer-scale
correlation.
13 March 20173 Classification: Internal © Statoil ASA
• Bu Hasa Field (Abu Dhabi, UAE): Discovered 1962
− Avg porosity: 5-27%; Avg perm: 0.1-120 mD
− Pay thickness 70-100m
Production:
− Oil (BBL) reserves: 6.52 BBL
− Oil production: 600K bl/day
Example: Reservoir- Cretaceous OAE 1A Recovery, Shuaiba Lithocodium boundstones and grainstones
Rameil et al., 2010
Strohmenger et al., 2006
13 March 20174 Classification: Internal © Statoil ASA
OAE 1A/B
OAE 2
OAE 1A/B
OAE 2
Example: Packaged play OAE 1A, Mesozoic of N. GoM
Goldhammer (1999)
OAE form seismically-resolvable stratigraphic
breaks that can be mapped over hundreds of
km2. Event recovery reefs with grainstone
aprons are also easily imaged.
Comanche Shelf, Texas
Example: James Production in Houston County to Shelby
county (1983)
Oil (BBL): 172,895,647
Gas (MCF): 32,864,000
James Limestone, OAE 1A recovery
13 March 20175 Classification: Internal © Statoil ASA
Towards a predictive facies model: OAE 1A/B Northern GoM
• Highlight role of repeated OAE’s in shaping Cretaceous platform in NW
Gulf of Mexico
• Carbonates are very good recorders of environmental change. This allows
us to outline the sequence of events associated with OAE-driven demise
and recovery of carbonate platforms
• Provide examples of OAE-linked stratigraphic signals
• Example of OAE-driven backstepped platforms and intrashelf basins. May
be a characteristic of greenhouse platforms (ex, Devonian, Cretaceous)
• Consider the differential response of the NW GOM platform relative to
eastern Tethys
13 March 20176 Classification: Internal © Statoil ASA
Gulf of Mexico Paleogeography - Albian
Kerans et al., 201413 March 20178 Classification: Internal © Statoil ASA
?
Purpose: Address unknowns in correlation,
depositional architecture, and stratigraphic
response to environmental forcing to better
affect subsurface predictability
- Conceptual depositional models affect the
way we correlate.
- How we correlate affects how we map
- How we map affects how we make lateral
facies predictions
13 March 20179 Classification: Internal © Statoil ASA
Sycamore ConglomerateSycamore Ss.
and conglom.Hammett
Shale
Pine Island
Shale
13 March 201710 Classification: Internal © Statoil ASA
Broader Conclusions• Development of the Cretaceous platform of NW GOM was impacted by the OAE1A,
OAE1B, OAE1D, and OAE2 events. OAE 1A and OAE 2 were major events that
affected platform arcitechture.
• The pre-OAE1A mixed mineralogy flat-topped platform was reduced to a slowly
accumulating calcitic ramp and eventually drowned. This situation repeats at OAE2
• Eco-accommodation-driven OAE cycles operate at a range of scales and are the
main driver of Cretaceous platform architecture in the Western Tethys and GoM.
These events occur regardless of eustatic position. However, not all OAE have the
same affect on platform architecture.
• Demise of benthic carbonate producers and lack of major siliciclastic input may
provde an environment well suited for SR accumulation and preservation.
• OAEs provide a global framework for correlation coupled with biostratigraphic and
chemostratigraphic constraints
13 March 201713 Classification: Internal © Statoil ASA
What’s new?
• While many Mesozoic stratigraphic intervals are known working hydrocarbon
systems in the subsurface, the link between the those systems and the OAE have
only recently been established. This is especially true for OAE-related reservoir
and OAE-related packaged plays. In other words, many OAE related hydrocarbon
systems were discovered without the realization that they formed as a result of
OAE.
• Predictive stratigraphy around OAE systems- both as source rocks and as reservoir
is a very new topic. We in research should improve our understanding of these
systems, including better understanding both source rock and reservoir variability,
and how to better geochemically recognize fingerprints of specific events.
• Exploration should apply these concepts to any region under evaluation. This is of
particular importance in Mesozoic and/or carbonate systems.