25th International Meeting on Organic Geochemistry IMOG 2011

O-72
Compositional kinetic model for thermal evolution of extra heavy
oils and tar sands
François Gelin 1 , Luc Fusetti 1 , Yongchun Tang 2 , Françoise Behar 3 , Tuong-Van Ledoan 1 ,
Paul-Marie Marquaire 4 , Roda Bounaceur 4 ,
1 TOTAL, Pau, France, 2 PEERI, Los Angeles, United States of America, 3 IFP, Paris, France, 4 ENSIC, France,
France (corresponding author:luc.fusetti@total.com)
The production of extra heavy oils and tar sands
resources faces the challenge to mobilize
hydrocarbon fluids of extremely high viscosities due to
the extended alterations (e.g. biodegradation) these
resources have overcome through geological time.
When such unconventional hydrocarbons plays are
too deep to enable pit mining, flow assurance
becomes a serious issue and, in addition to the use of
high efficiency pumps, its improvements often passes
through the application of enhanced thermal recovery
techniques.
Among thermal EOR techniques:
(i) Steam Injection has become very popular to
decrease the viscosity of hydrocarbon fluids in place
by increasing the formation temperature with steam
In Situ Upgrading (IUP) via Subsurface Pyrolysis is
debated in order to pre-upgrade the oil in situ by
substantial heating of its environment, theoretically
inducing the production of higher quality oil.
(ii) Both steam injection and IUP processes imply
chemical modifications within the OIP which cannot
be correctly predicted without an accurate kinetic
model that would account for the compositional
changes related to a given thermal history.
The present study proposes the development of a
compositional kinetic model that has been optimized
in order to predict the compositional evolution of extra
heavy oils and bitumen when submitted to thermal
stress. The model is based on 11 lumped chemical
classes and chemical 22 equations. It also includes
32 stoichiometric coefficients and 30 activation
energies/frequency factors.
On a range of several hundred degrees centigrade, it
is able to predict the evolution of cumulated (Figure
1) and instantaneous yields for the whole range of
molecular weights i.e.:
� The decrease of aromatics and polar
compounds (heavy cuts),
� The generation of hydrocarbon gases and
acid gases,
� The generation and potential destruction of
light cuts,
� The generation of pyrobitumen.
Figure 1: Evolution of various reactivity lumps of
an heavy oil under isothermal stress
Such prediction, either under isothermal or nonisothermal
heating conditions, provides key
arguments in the discussion to determine the most
appropriate (temperature-time) conditions needed to:
� Enhance the generation of light cuts,
� Minimize the generation of pyrobitumen than
could seriously damage formation porosity
and permeability,
� Reduce acid gases generation to manage
HSE and corrosion issues.
In a near future, it is expected to couple such kinetic
model with a thermal propagation model and a
polyphasic thermodynamic model to improve reservoir
simulation of thermal EOR processes using various
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