| dc.description.abstract | Nowadays, EOR methods such as thermal techniques are widely used to recover the
viscous hydrocarbons from heavy oils and bitumen reservoirs. One of the thermal methods is
the Steam-Assisted Gravity Drainage (also called SAGD) consists in injecting steam through
the injector well into the reservoir to melt the viscous oil and allow its mobility. The melted
oil falls by gravity and is produced by the production well. The hot steam injected, in contact
with heavy oils/bitumen, creates chemical reactions called aquathermolysis reactions. These
reactions generate gases such as the hydrogen sulfide (H2S) or carbon dioxide (CO2). The H2S
is known to be a highly toxic and corrosive, therefore, it needs to be given a particular
attention when it is produced at the surface. Reservoir models have been built to simulate
thermal effects during a SAGD but only few publications in the literature deal with the
aquathermolysis reactions occurring in the reservoir where steam is injected.
This report will focus on building a reservoir simulation model in order to forecast the H2S
production. This model is built based on a PVT description of the heavy oil/bitumen and on a
new sulfur-based kinetic model. A literature study was performed to build up the general
understanding of the physical and chemical mechanisms occurring during a steam injection
process. A description of the heaviest components found in heavy oils/bitumen is made
through a SARA analysis. A new sulfur-based kinetic model recently developed was
presented and used in the reservoir model to reproduce the aquathermolysis reactions.
A large part of this thesis is dedicated to the topic of building a PVT model for heavy oils.
Throughout this chapter, the PVT (Pressure-Volume-Temperature) model is built based on
correlations specific for heavy oils. This PVT describes the behavior of the fluid (oil) used
during reservoir simulations.
Then, a chapter presents the reservoir models used for the simulations. Reservoir simulations
were run using both the 2D and 3D models in order to compare the simulation results. A 3D
reservoir model is presented to get to know the main characteristics of this heterogeneous
reservoir. This model reproduces the Hangingstone heavy oil field in Canada.
Finally, these simulations results are then presented, such as the oil and gas productions, the
steam injection, the Steam-Oil Ratio as well as the H2S production. A sensitivity analysis was
also performed in order to see how some parameters, such as the pressure/temperature (at the
saturation conditions) of the steam injected or the rock conductivity, would affect the H2S
production or the oil production.
The different simulations presented in this report show consistent results in terms of H2S
production at surface for different steam injection pressures. This shows that the fluid
description and the kinetic model used in the study are relevant for acid gases prediction in
the context of steam injection reservoir simulations. | en |
