1.What is SAGD? 2.What does “pore scale” mean? 3.What are the aspects of “SAGD process at pore scale”? 4.conclusion.

2. SAGD PROCESS AT PORE SCALE:
1.What is SAGD?
2.What does “pore scale” mean?
3.What are the aspects of “SAGD process at pore scale”?
4.conclusion.

3. SAGD PROCESS
Steam Assisted Gravity Drainage (SAGD) is an enhanced oil recovery
technology for producing heavy crude oil and bitumen by steam injection. The concept of
SAGD was initially proposed by Butler and his colleagues (Butler et al., 1981; Butler and
Stephens, 1981). In this process, two horizontal wells are placed close to the bottom of a
formation, with one above the other at a short vertical distance. Steam is continuously
injected into the upper injection well with slightly above reservoir pressure. As the steam
rises, moving both upward and sideward, it conducts its latent heat to the cold heavy oil
and bitumen. As the reduction of the bitumen viscosity continues due to heat conduction,
the heated oil together with the condensed steam drains into the lower production well.

5. WHAT DOES “PORE SCALE” MEAN?
Pore=An opening or channelway in rock or soil.
Scale= in weights and measures

6. MICROMODELS RELATED TO PORE SCALE:

7. HINTS:
1.The glass micromodels were initially saturated with heavy oil.
2.All the pore-level SAGD experiments were carried out in a vacuum
chamber in order to reduce the excessive heat loss to the surrounding
environment while steam was injected under different superheating levels.
3.Local temperatures along the model's height and width were recorded on
a real time basis.
4.The pore-scale events were recorded using digital photo capturing techniques.

8. MECHANISTIC INVESTIGATION
OF THE SAGD PROCESS USING PORE-SCALE EXPERIMENTAL STUDIES:
The interplay between gravity and capillarity forces results in the
drainage of the
mobile oil near this pore-scale mobilized region.
Mobilization of the bitumen was found to be as a result of both conductive
and
convective elements of the local heat transfer

9. PORE-SCALE EVENTS ANALYSIS WITHIN THE
MOBILIZED REGION
The mobilized region contains thermally-mobilized oil, droplets of water condensate,
and also steam phase which are flowing simultaneously parallel to the apparent
interface.
Different acting forces are contributing to the simultaneous fluid flow within this
mobilized region, namely gravity, capillarity, and buoyancy forces in the absence of
excessive viscous force. This region is formed due to the presence of temperature
gradient at the pore-scale and it clearly has an oriented structure, in which three
different fluid phases are flowing parallel to the apparent SAGD interface.
The mobile oil, as well as the water condensate within the mobilized region, would
drain by the action of gravity when gravity forces overcome the capillary and possible
viscous forces.

10. This phenomenon, which is supported by the temperature gradient, could be seen
in
two successive pictures shown as Figures. Mobile oil drained out of these pores
and
steam invaded through them following the sequential behaviour of pore drainage
during an immiscible displacement process .

13. MICRO-SCALE CHALLENGES OF THE SAGD PROCESS :
a) Local fluid mixing at the pore bodies,
b) Snap-off mechanism of the invading fluids,
c) Local conduction-convection heat transfer,
d) Steam Fingering Phenomenon
f) Micro-scale emulsion formation and flow along the drainage path.

14. STEAM FINGERING PHENOMENON
The conceptualized Butler’s theory of rising steam fingers during the vertical
encroachment of the steam chamber is schematically shown in Figures. It is
believed
that the steam fingering phenomenon during the vertical encroachment of the
steam
chamber happens as a result of buoyancy forces. Although the steam chamber is
stable at its bottom part near the injection well due to continuous nature of the
steam
injection, buoyant steam phase near the topside of the steam chamber has an
inherently
unstable interface with the thick, cold, and stagnant continuum of oil on the top..
It is likely
that the topside of the chamber would be dome-shaped, having a lot of steam
fingers in it.
According to the literature, there is still doubt about the possibility of steam
fingering in the
outward direction, i.e. spreading phase of the steam chamber.

16. EMULSIFICATION AT THE PORE-SCALE
presence of a gas phase, local enclosure of water droplets within the continuum of
the mobile oil behind the apparent SAGD interface would form the localized water in
oil emulsification. In Figure , three snapshots are shown regarding the state of in-
situ emulsification in the SAGD process. Figure a shows the local entrapment of
a large number of water micro-droplets within the continuum of the mobile oil at the
pore-scale. The selected area is one pore-body-dimension distance away from the
apparent SAGD interface. Figure b presents the engulfment of two individual
water droplets inside the pool of oil with a distance equivalent to three-pore-
dimensions from the apparent SAGD interface. Figure .c also demonstrates the
microscopic enclosure process of a number of small condensate droplets at the left side of
the picture which were detached from the bulk column of the condensate phase formed at
the top of the oil-filled pores.

18. + condensate droplets would be trapped within the reduced-viscosity oil continuum. In
addition, they should overcome the associated film pressure of the tiny mobile oil
films in between in order to be able to coalesce to each other. Due to the convective
nature of the drainage process within the mobilized region, it was observed that both
condensate droplets and also small steam bubbles become entrapped within the
continuum of the mobile oil just behind the apparent SAGD interface. One of the
mechanisms responsible for small steam bubbles being trapped within the bulk of the
mobile oil is the snap-off phenomenon at the pore-scale.

20. REFERENCES:
1. A thesis presented to the University of Waterloo in fulfilment of the
Thesis requirement for the degree of Doctor of Philosophy in Chemical
Engineering
Waterloo, Ontario, Canada, 2012,Omidreza Mohammadzadeh Shanehsaz
2. Pore-Level Investigation of Heavy Oil and Bitumen Recovery Using
Solvent –Aided
Steam Assisted Gravity Drainage (SA-SAGD) ProcessO.
Mohammadzadeh,* N.
Rezaei, and I. Chatzis
3.My own efforts(saman mohammadi)
4. Pengrowth Energy Corporation Lindbergh SAGD Project .