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Seminars and Colloquia

Earth and Climate Science

Predicting Future Sea-Level Rise and Subsurface Reservoir Heterogeneities: Clues from Ancient and Modern Carbonate Outcrop Analogues 
Thu, Dec 12, 2019,   11:00 AM at ECS Seminar Room no. 32, Second floor, Main Building

Dr. Pankaj Khanna
King Abdullah University of Science and Technology, ANPERC, Thuwal, Saudi Arabia

Coral Reefs form a primary basis for reconstructing sea level fluctuations over Earth’s
history and have been used to establish that, since the Last Glacial Maximum, sea level did not
always rise gradually, but was instead characterized by three periods of rapid inundation occurring
over several centuries. Recognizing the nature of past sea level rises (i.e., gradual or stepwise)
during deglaciation is critical for informing models that predict future vertical behavior of global
oceans, and thus this science benefits society’s welfare. Further, the change from hydrocarbons to
renewable energy will not be a quick transition. Hence, based on the current energy needs, better
secondary and tertiary recovery will be required. Future production, therefore, will require better
reservoir models to improve sweep and recovery from complex and heterogeneous carbonate
reservoirs (approx. 50% of all reservoirs) while keeping development costs at bay. Hence, modern
and ancient carbonate outcrop analogues are interrogated to create comprehensive data sets on
morphological evolution and depositional heterogeneities of carbonates.
Modern reefs are studied from south Texas shelf, Maldives, and Red Sea to understand the
sea-level fluctuations in the recent past, and Late Cambrian microbial reefs, central Texas, and
Late Jurassic Arabian carbonates in Saudi Arabia to characterize and understand depositional
heterogeneities. Datasets including multibeam bathymetric mapping, CHIRP sub-bottomprofiling, 3D drone surveys, GPR, and seismic are collected. These high-end techniques are
paired with tried and tested standard geological techniques of measuring (several) stratigraphic
sections anchored by outcrop spectral gamma ray logs, analysis of sediment samples (texture, grain
size, mineralogy) and fracture/fault surveys all integrated with full cores drilled in the outcrops.
Utilizing these datasets sea-level fluctuations in the recent past reveals that there were
episodes of catastrophic sea-level rise leading to a few m of sea level rise within few decades.
Additionally, during Holocene, Arabian Peninsula had a contemporaneous sea-level highstand
where sea-level was a few m higher than today, followed by a sea-level regression until recent
renewed rise. The ancient outcrops are statistically analyzed and reveal scaling relationships and
preferential growth directions owing to paleogeography, paleoclimatology, and paleoceanography,
which usually are never mapped or identified. The rules identified from these datasets can be used
as input for static analogue models and dynamic simulations to test sensitivities and determine
optimum development scenarios for improving ultimate recovery.