U.S. patent application number 13/971893 was filed with the patent office on 2014-02-27 for bitumen recovery process.
This patent application is currently assigned to KEMEX LTD.. The applicant listed for this patent is Kenneth James, Laureen Little, Bob Nabata. Invention is credited to Kenneth James, Laureen Little, Bob Nabata.
Application Number | 20140054028 13/971893 |
Document ID | / |
Family ID | 50146985 |
Filed Date | 2014-02-27 |
United States Patent
Application |
20140054028 |
Kind Code |
A1 |
Little; Laureen ; et
al. |
February 27, 2014 |
BITUMEN RECOVERY PROCESS
Abstract
1. A bitumen recovery process where the process includes the
following steps: a) Drilling a single well into a bitumen deposit;
b) Equipping the well with a heating element, a solvent injecting
member, and a bitumen recovering member; c) Injecting the well with
a solvent; d) Heating the solvent with the heating element to a
vapor state; e) Mixing the solvent vapour with bitumen in the
deposit; f) Draining the bitumen to the bottom of the well; g)
Heating the bitumen to keep its viscosity low; h) Evaporating part
of solvent entrapped in the bitumen by the heating element; i)
Recovering the bitumen and traces of water from the well; j)
Condensing the solvent inside the well for further mixing with the
bitumen in the deposit; k) Repeating steps h through j, where the
majority of the solvent does not leave the well during the
process.
Inventors: |
Little; Laureen; (Calgary,
CA) ; James; Kenneth; (Calgary, CA) ; Nabata;
Bob; (Calgary, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Little; Laureen
James; Kenneth
Nabata; Bob |
Calgary
Calgary
Calgary |
|
CA
CA
CA |
|
|
Assignee: |
KEMEX LTD.
Calgary
CA
|
Family ID: |
50146985 |
Appl. No.: |
13/971893 |
Filed: |
August 21, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61691484 |
Aug 21, 2012 |
|
|
|
Current U.S.
Class: |
166/248 ;
166/303 |
Current CPC
Class: |
E21B 43/2401 20130101;
E21B 43/24 20130101 |
Class at
Publication: |
166/248 ;
166/303 |
International
Class: |
E21B 43/24 20060101
E21B043/24 |
Claims
1. A bitumen recovery process comprising the following steps: a)
Drilling a single well into a bitumen deposit; b) Equipping said
well with a heating element, a solvent injecting member, and a
bitumen recovering member; c) Injecting said well with a solvent
having a low flash point through said solvent injecting member; d)
Heating said solvent with the said heating element to a vapor state
while keeping the temperature and pressure in the well at a
predetermined condition; e) Mixing said solvent vapour with bitumen
in the deposit thus reducing said bitumen viscosity; f) Draining
said bitumen to the bottom of the well proximate the heating
element; g) Heating the bitumen to keep its viscosity low, enabling
recovery of the bitumen by bitumen recovering member; h)
Evaporating at least part of solvent entrapped in the bitumen at
the bottom of the well by the heating element; i) Recovering said
bitumen and traces of water from the well by said bitumen
recovering member; j) Condensing said solvent inside the well for
further mixing with the bitumen in the deposit; k) Repeating steps
h through j, wherein the majority of said solvent does not leave
the well during the bitumen recovery process.
2. The process of claim 1 wherein the heating element utilizes
electricity, steam, or a hot fluid circulating through the
well.
3. The process of claim 2 where said electricity, steam, or hot
fluid circulate through the well in a tube.
4. The process of claim 3 where the tube is insulated or partially
insulated.
5. The process of claim 2 where the electricity, steam, or hot
fluid are reheated at the surface.
6. The process of claim 2 where the electricity, steam, or hot
fluid are reheated in the bore of the well.
7. The process of claim 1 wherein the solvent is pure light
hydrocarbon solvent.
8. The process of claim 6 where the pure hydrocarbon solvent
comprises propane, butane (normal, iso & mixed), pentane
(normal, iso & mixed), or hexane (normal, iso & mixed).
9. The process of claim 1 wherein the solvent is a mixed solvent
with composition from C3 to C8.
10. The process of claim 1 wherein the solvent is a mixed solvent
with composition from C5 to C7.
11. The method of claims 8 and 9 where the solvent composition is a
heavier C7 in the initial recovery process and is progressively
replaced with lighter hydrocarbons as the process continues.
12. The process of claim 1 wherein there is steam injected into the
well along with the solvent.
13. The process of claim 1 wherein the produced fluids recovered
from the well are primarily bitumen or heavy oil with a small
amount of miscible contained solvent and some connate water.
14. The method of claim 9 where the solvent composition is a
heavier C7 in the initial recovery process and is progressively
replaced with lighter hydrocarbons as the process continues.
Description
BACKGROUND OF THE INVENTION
[0001] There are several known techniques for enhanced oil recovery
from underground formations. Some of those techniques use heating
of the formation in order to increase the flow of bitumen and allow
easier recovery. One of these techniques is known as steam assisted
gravity drainage (SAGD).
[0002] Other enhanced oil recovery technologies include introducing
a heating element to the underground formation. The heating element
can be any type known in the art, including the following: 1) a
continuous tube having an electric heating element or 2) a
continuous tube permitting circulation of a heated fluid such as
steam, gas, superheated liquid, molten salts, or other heated
fluids known in the art. These heating elements are typically
utilized to preheat the underground formation prior to injection of
the steam into the formation.
[0003] Further enhanced oil recovery technologies utilize a solvent
assisted technique. The solvent assisted technique includes the
following steps: 1) the solvent is injected into the formation; 2)
the solvent is mixed with the bitumen; 3) the solvent/bitumen
mixture is recovered from the bitumen formation; and 4) the solvent
is separated from the bitumen, recycled and then used in the
formation again.
[0004] Recent developments in enhanced oil recovery technologies
include US 2011/0303423. US 2011/0303423 teaches recovering in situ
viscous oil from an underground reservoir. Electricity is conducted
through the underground reservoir by at least two electrodes in an
amount that would, in the absence of solvent injection, cause water
in the reservoir to vaporize adjacent to the electrodes. Solvent is
injected into the reservoir to mitigate water vaporization adjacent
to the electrodes by vaporizing solvent in this region. Oil and
solvent are produced through one or more production wells. However,
the method disclosed in US 2011/0303423 does not contemplate an
energy efficient process that reduces both solvent usage and water
treatment procedures.
[0005] The known enhanced oil recovery technologies are heavily
investigated, but still require improvements at every stage. The
required improvements include 1) simplifying oil recovery the
process; 2) reducing the need for materials such as steam and
solvents thereby reducing energy consumption for steam generation;
3) reducing water treatment procedures; and 4) improving the
process solvent recovery from the bitumen mixture.
SUMMARY OF THE INVENTION
[0006] Disclosed herein is a process for recovering hydrocarbons
such as bitumen from an underground formation which is designed to
increase energy efficiency by reducing I) surface water treatment
and 2) solvent usage.
[0007] In one aspect, the bitumen recovery process comprises the
following steps: [0008] a) Drilling a single well into a bitumen
deposit; [0009] b) Equipping said well with a heating element, a
solvent injecting member, and a bitumen recovering member; [0010]
c) Injecting said well with a solvent having a low flash point
through said solvent injecting member; [0011] d) Heating said
solvent with the said heating element to a vapor state while
keeping the temperature and pressure in the well at a predetermined
condition; [0012] e) Mixing said solvent vapor with bitumen in the
deposit thus reducing said bitumen viscosity; [0013] f) Draining
said bitumen to the bottom of the well proximate the heating
element; [0014] g) Heating the bitumen to keep its viscosity low,
enabling recovery of the bitumen by bitumen recovering member;
[0015] h) Evaporating at least part of solvent entrapped in the
bitumen at the bottom of the well by the heating element; [0016] i)
Recovering said bitumen and traces of water from the well by said
bitumen recovering member; [0017] j) Condensing said solvent inside
the well for further reaction with the bitumen in the deposit;
[0018] k) Repeating steps h through j, wherein the majority of said
solvent does not leave the well during the bitumen recovery
process.
[0019] In one embodiment, the heating element utilizes electricity,
steam, or a hot fluid circulating through the well. In a further
embodiment, the heating element utilizes electricity, steam, or a
hot fluid circulating through the well in a tube. In yet another
embodiment, the electricity, steam, or hot fluid is reheated at the
surface or in the bore of the well.
[0020] In one embodiment, the solvent used in the process comprises
propane, butane (normal, iso & mixed), pentane (normal, iso
& mixed), or hexane (normal, iso & mixed). In a further
embodiment, the solvent is a mixed solvent with a composition from
C3 to C8. In yet another embodiment, the solvent is a mixed solvent
with a composition from C5 to C7. Even further, the solvent
composition is a heavier C7 in the initial recovery process and is
progressively replaced with lighter hydrocarbons as the process
continues In one embodiment, steam is injected into the well along
with the solvent.
[0021] In one embodiment, the produced fluids recovered from the
well are primarily bitumen or heavy oil with a small amount of
miscible contained solvent and some connate water.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a cross-sectional view of single well heating.
[0023] FIG. 2 is a cross-sectional view of the end of pre-heating
the single well.
[0024] FIG. 3 is an alternative view of the end of pre-heating the
single well.
[0025] FIG. 4 is a cross-sectional view of the single well near
abandonment.
[0026] FIG. 5 is a production profile of single well heating.
[0027] FIG. 6 is a graph showing the production profile of single
well heating.
[0028] FIG. 7 is a cross-sectional view of solvent recovery in
single well heating.
DETAILED DESCRIPTION
[0029] A well is drilled into the target formation. The entire
operation may be achieved in a vertical well, slant well,
horizontal well or an irregular well having a combination of
vertical, horizontal and tilted portions to adapt to the geometry
of the formation. Even further, the horizontal well can be extended
from the vertical well.
[0030] A single well is used to achieve a gravity driven bitumen or
heavy oil production process. However, multiple wells may be heated
and produced simultaneously or sequentially, each with their own
heat string. The well is cased to the bottom of an intermediate
casing, where the horizontal section includes a thermal casing and
thermal cement. In the horizontal section, the well has a liner
with either slotting or screens to control any sand influx.
[0031] As shown in FIG. 1, a string of tubing 2 is placed into the
hole down through the vertical section and out into the horizontal
section to a desired length. Then, the tube 2 subsequently curls
back to return along the horizontal run and back to the surface 4.
The tubing can be fully insulated, partially insulated, or
non-insulated.
[0032] The tubing contains a heating medium 6 which could be
electricity, steam, or another fluid with high-heat transfer
characteristics. At the surface 4, the electricity, steam, or fluid
is reheated to the target temperature and then returned to the
portion of tubing string 2 in the well. The electricity, steam, or
fluid is at super-heated or saturated steam condition as it enters
the well bore so that it transfers heat to the horizontal section.
This initial preheating of the formation creates and initiates a
depletion chamber. Condensing may take place and, because of the
phase change and fixed volume, a thermo-siphon effect will be
created.
[0033] After the preheating step, a solvent is introduced into the
well. Preferably, in the horizontal section of the well, the
solvent is added through an additional tubing string. Preferably,
the solvent is a straight chain hydrocarbon which is easily
vaporized at the well temperature and is miscible with the
reservoir bitumen/oil. More preferably, the solvent is a light
hydrocarbon such as butane, iso-butane, pentane, hexane or a mixed
solvent with similar commercial diluents with a composition from C3
to C8, but the bulk of the solvent volume in the C5-C7 range.
Experiments have shown that xylene and natural citric acid may also
be used as solvents. Varying the solvent composition over time may
be helpful from heavier C7 to lighter C3 over the production cycle.
It should be kept in mind that the solvent composition must be
matched to the specific reservoir operating conditions, ensuring a
good vaporization and condensation temperature that matches the
down hole temperature.
[0034] As shown in FIGS. 2 and 3, an initial fill of solvent in the
horizontal well bore should be sufficient to maintain the process.
When the liquid solvent reaches the tube heated by steam, the heat
of condensation is released to the solvent. The solvent quickly
heats to its boiling point and vaporizes. Since vapor is lighter
and has a lower density than the liquid phase, solvent vapor will
rise in the well bore filling the depletion chamber. The vapor will
rise until it reaches a surface that is cool enough to condense it.
Generally, the cooling surface will be the bitumen above the cased
well. Once the vapor is condensed onto or with the bitumen, a
hydrocarbon mixture is created and the viscosity and density of the
mixture are much lower than bitumen alone but higher than pure
solvent. The hydrocarbon mixture will flow by gravity down to the
horizontal section of the well, creating a void space above in the
reservoir. The lighter hydrocarbon mixture falls into the
horizontal section of the well bore and meets with the heat of the
steam tubing again. This causes the solvent portion of the mixture
to evaporate and rise into the void space in a new cycle. At the
same time, the bitumen in the well bore is maintained at a warm
temperature, which keeps it mobile.
[0035] As shown in FIG. 4, the mobile bitumen can be recovered from
the horizontal well by means known in the art. For example, a gas
lift or electric submersible pump system 12 can be used to lift the
hot bitumen to surface. Preferably, the heat source is positioned
at ground level. However, it may be also positioned down hole, as
when using a standard ESP (electric submersible pump) which
generates a significant amount of heat in the pumping action.
Furthermore, an electric heating source can be used alone or in
combination with other heating sources.
[0036] Based on the reservoir characteristics, if the proper
solvent composition and operating conditions are used, the solvent
will stay in the reservoir throughout the process without the need
to top up the solvent. This results in little or no solvent in the
production fluid because the solvent remains a working fluid within
the reservoir. The solvent has a repeating cycle consisting of
being warm liquid in the horizontal section to hot vapor rising
through the reservoir to a bitumen/solvent mixture flow back to the
horizontal section. Because the solvent remains a working fluid in
the reservoir, there is no solvent recovery until the end of the
process resulting in less solvent used in the overall process.
[0037] Because there is minimal solvent injection in the process,
energy is conserved because solvent recovery at the surface isn't
typically needed. Even if the bitumen recovered contains trace or
small amounts of solvent, the solvent remaining in the bitumen
results in a slightly reduced viscosity and density, lowering any
requirement for diluent additions prior to sales or pipelining.
[0038] As depicted in FIGS. 5 and 6, the bitumen produced from this
process will still contain some water, since there is connate water
entrapped around the sand grains in the reservoir along with the
bitumen. However, the volume of water in the well will be
substantially lower. In fact, the 300% volume of water in the
bitumen volume experienced in typical SAGD operation is reduced to
15-30% volume of water in the bitumen volume.
[0039] Shown in FIG. 7, upon depletion of the bitumen formation,
the solvent remaining inside the formation can be cooled, drained
to the bottom of the well, and recovered from the well for future
reuse.
[0040] As is seen from above, important advantages of this process
include the following: [0041] 1) Production costs will be
significantly lower than traditional CSS or SAGD processes. Because
there is no added water, the water doesn't have be lifted to
surface, cleaned, and reused or disposed. Likewise, there is no
need to vapourize water for the steam injection into the reservoir.
[0042] 2) The environmental impact of the operation will be much
lower than traditional CSS or SAGD since there is no heavy water
usage. [0043] 3) Using and cycling a contained heated fluid can
maintain the well bore at very low pressures. This feature allows
recovery of deposits which are very close to the surface and too
complicated or even dangerous (in terms of potential steam release
to the surface) for SAGD or CSS processes. The amount of resources
suitable for this specific technology is huge in the Athabasca
region alone, and is almost unexplored internationally. [0044] 4)
The process described above can be equipped with additional
machinery and equipment used in the enhanced oil recovery such as
an oil treating facility, water treating facility, heaters, oil
storage, power generating and pumping equipment known in the
art.
[0045] As many changes therefore may be made to the preferred
embodiment of the invention without departing from the scope
thereof. It is considered that all matter contained herein be
considered illustrative of the invention and not in a limiting
sense.
* * * * *