An open access carbonate reservoir model
Abstract
This thesis presents a new open-source carbonate reservoir benchmarking case study, the
COSTA model, that uniquely considers major uncertainties inherent to carbonate
reservoirs, providing a far more challenging and realistic benchmarking test for a range
of geo-energy applications. The COSTA model is large (1,600 km2
), with many wells
(447) and large associated hydrocarbon volumes (109
bbls). The dataset embeds many
interacting geological and petrophysical uncertainties in an ensemble of model concepts
with realistic geological and model complexity levels and varying production profiles.
The large number of models and long-run times creates a harder computational challenge
than older benchmarking models.
The COSTA model takes inspiration from the shelf-to-basin geological setting of the
Upper Kharaib Member (Early Cretaceous), one of the most prolific aggradational
parasequence carbonate formations sets in the world. The dataset to build the model uses
43 wells from fully anonymized published data from the north-eastern part of the Rub Al
Khali basin, a sub-basin of the wider Arabian Basin. My model encapsulates both the
large-scale geological setting and reservoir heterogeneities found across the shelf-tobasin profile (~36,000 km2
), into one single model (~8,300 km2
), for geological
modelling and reservoir simulation studies.
The result of this research is a semi-synthetic but geologically realistic suite of carbonate
reservoir models that capture a wide range of geological, petrophysical, and geomodelling
uncertainties and that can be history-matched against an undisclosed, synthetic truth case.
The models and dataset are made available as open-source to analyse several issues
related to testing new numerical algorithms for reservoir characterisation, uncertainty
quantification, reservoir simulation, history matching, robust optimisation, and machine
learning. The novelty of my work is the provision of a unique and realistic open-access
dataset that enables reproducible science in the field of reservoir characterisation and
simulation and offers new training opportunities in the areas of reservoir characterisation
simulation and prediction of the reservoir performance of carbonate reservoirs. The
model(s) can also be used to study geological sequestration of CO2, the feasibility of
EOR processes, geothermal and groundwater studies.