U.S. patent application number 12/327547 was filed with the patent office on 2009-06-04 for method of recovering bitumen from a tunnel or shaft with heating elements and recovery wells.
This patent application is currently assigned to OSUM OIL SANDS CORP.. Invention is credited to Dana Brock, Henry Gil, Andrew Squires.
Application Number | 20090139716 12/327547 |
Document ID | / |
Family ID | 40674561 |
Filed Date | 2009-06-04 |
United States Patent
Application |
20090139716 |
Kind Code |
A1 |
Brock; Dana ; et
al. |
June 4, 2009 |
METHOD OF RECOVERING BITUMEN FROM A TUNNEL OR SHAFT WITH HEATING
ELEMENTS AND RECOVERY WELLS
Abstract
The present invention is directed to the operation of heating
elements from wells emanating from an underground excavation to
heat and mobilize hydrocarbons, such as bitumen, heavy oil and oil
shale.
Inventors: |
Brock; Dana; (Sebastopol,
CA) ; Squires; Andrew; (Calgary, CA) ; Gil;
Henry; (Calgary, CA) |
Correspondence
Address: |
SHERIDAN ROSS PC
1560 BROADWAY, SUITE 1200
DENVER
CO
80202
US
|
Assignee: |
; OSUM OIL SANDS CORP.
Calgary
CA
|
Family ID: |
40674561 |
Appl. No.: |
12/327547 |
Filed: |
December 3, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60992001 |
Dec 3, 2007 |
|
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Current U.S.
Class: |
166/272.1 ;
166/52 |
Current CPC
Class: |
E21B 43/24 20130101;
E21B 43/305 20130101; E21B 43/2401 20130101 |
Class at
Publication: |
166/272.1 ;
166/52 |
International
Class: |
E21B 43/24 20060101
E21B043/24; E21B 43/00 20060101 E21B043/00; E21B 36/00 20060101
E21B036/00 |
Claims
1. A method, comprising: (a) forming a manned underground
excavation at least one of in proximity to and in a
hydrocarbon-containing deposit; (b) forming, from the underground
excavation, a plurality of mobilizing wells extending into the
hydrocarbon-containing deposit, each mobilizing well containing at
least one of a heating element, steam injector, and diluent
injector; and (c) forming, from the underground excavation, at
least one recovery well extending into the hydrocarbon-containing
deposit and positioned in proximity to at least some of the
plurality of mobilizing wells, wherein the mobilizing wells and
recovery wells define a drainage volume and wherein the mobilizing
wells mobilize hydrocarbons contained within the drainage volume
and the recovery wells collect the mobilized hydrocarbons.
2. The method of claim 1, wherein the hydrocarbon is bitumen or
heavy oil, wherein the underground excavation has an inner diameter
ranging from about 3 to about 15 meters, wherein the mobilizing
wells have a diameter ranging from about 0.1 to about 1 meters,
wherein the distance between adjacent mobilizing wells ranges from
about 10 to about 30 meters and wherein the mobilizing wells each
have a length of at least about 100 meters.
3. The method of claim 1, wherein the hydrocarbon is bitumen or
heavy oil, wherein a selected mobilizing well is to contain a
plurality of heating elements, wherein each of the heating elements
is shorter than a diameter of the underground excavation adjacent
to the selected mobilizing well, and wherein the heating elements
are inserted one-at-a-time into the mobilizing well.
4. The method of claim 1, wherein the hydrocarbon is bitumen or
heavy oil, wherein the drainage volume has a height ranging from
about 20 to about 100 meters and a width ranging from about 30 to
about 150 meters.
5. The method of claim 1 wherein the hydrocarbon is oil shale.
6. A method, comprising: (a) providing a manned underground
excavation in proximity to and/or in a hydrocarbon-containing
deposit, the manned underground excavation comprising: (i) a
plurality of heating wells extending into the
hydrocarbon-containing deposit, each heating well containing one or
more heating elements; and (ii) at least one recovery well in fluid
communication with the hydrocarbon-containing deposit and
positioned in proximity to at least some of the plurality of
heating wells, wherein the heating wells and recovery wells define
a drainage volume; and (b) generating thermal energy from the
heating wells to heat and mobilize the hydrocarbons for collection
by the recovery wells.
7. The method of claim 6, wherein the hydrocarbon is bitumen or
heavy oil, wherein the underground excavation has an inner diameter
ranging from about 3 to about 15 meters, wherein the heating wells
have a diameter ranging from about 0.1 to about 1 meters, and
wherein the heating wells each have a length of at least about 100
meters.
8. The method of claim 6, wherein the hydrocarbon is bitumen or
heavy oil, wherein a selected heating well is to contain a
plurality of heating elements, wherein each of the heating elements
is shorter than a diameter of the underground excavation adjacent
to the selected heating well, and wherein the heating elements are
inserted one-at-a-time into the heating well.
9. The method of claim 6, wherein the hydrocarbon is bitumen or
heavy oil, wherein the drainage volume has a height ranging from
about 20 to about 100 meters and a width ranging from about 30 to
about 150 meters.
10. The method of claim 6, wherein the heating wells are located
above the recovery wells, wherein substantial lengths of each of
the heating wells and recovery wells are substantially parallel to
one another and wherein the distance between adjacent heating wells
ranges from about 10 to about 30 meters.
11. The method of claim 6, wherein step (b) comprises the substeps:
(B1) in an electrode mode, energizing the heating elements in the
heating wells to heat hydrocarbons contained in the drainage
volume; and (B2) when the temperature of the hydrocarbons reaches a
selected level, operating the heating elements as thermal
conduction heaters.
12. The method of claim 6, wherein the heating wells nearest the
recovery wells are energized before the heating wells farthest from
the recovery wells to produce a flow path for hydrocarbons to the
recovery wells.
13. The method of claim 6, wherein, during a first time interval,
the heating wells are energized to heat the hydrocarbons and,
during a second time interval, at least one of steam and diluent is
injected through the heating wells into the hydrocarbon-containing
deposit and wherein the first and second time intervals are
discrete.
14. The method of claim 6 wherein the hydrocarbon is oil shale.
15. The method of claim 6, further comprising: (c) installing
equipment in proximity to and/or in the hydrocarbon-containing
deposit that is adapted to inject at least one of steam and diluent
into the hydrocarbon-containing deposit.
16. A system, comprising: (a) a manned underground excavation in
proximity to and/or in a hydrocarbon-containing deposit; (b) at
least one heating well extending from the underground excavation
into the hydrocarbon-containing deposit, the at least one heating
well containing one or more heating elements; and (c) at least one
recovery well in fluid communication with the
hydrocarbon-containing deposit and positioned in proximity to the
at least one heating well, wherein the at least one heating well
and the at least one recovery well define a drainage volume,
whereby thermal energy is generated from the at least one heating
well to heat and mobilize hydrocarbons in the drainage volume for
collection by the recovery wells.
17. The system of claim 16, wherein the hydrocarbon is bitumen or
heavy oil, wherein the underground excavation has an inner diameter
ranging from about 3 to about 15 meters, wherein the at least one
heating well has a diameter ranging from about 0.1 to about 1
meters, and wherein the at least one heating well has a length of
at least about 100 meters.
18. The system of claim 16, wherein the hydrocarbon is bitumen or
heavy oil, wherein the at least one heating well comprises a
plurality of heating elements, wherein each of the heating elements
is shorter than a diameter of the underground excavation adjacent
to the at least one heating well, and wherein the heating elements
are inserted one-at-a-time into the at least one heating well.
19. The system of claim 16, wherein the hydrocarbon is bitumen or
heavy oil, wherein the drainage volume has a height ranging from
about 20 to about 100 meters and a width ranging from about 30 to
about 150 meters.
20. The system of claim 16, wherein the at least one heating well
comprises a plurality of heating wells which are located above the
recovery wells, wherein substantial lengths of each of the heating
wells and recovery wells are substantially parallel to one another
and wherein the distance between adjacent heating wells ranges from
about 10 to about 30 meters.
21. The system of claim 16, wherein the heating elements operate in
the following operating modes: in an electrode mode, the heating
elements operate as electrodes to heat hydrocarbons contained in
the drainage volume; and in a thermal conduction mode, the heating
elements operate as thermal conduction heaters to heat hydrocarbons
contained in the drainage volume.
22. The system of claim 20, wherein the heating wells nearest the
recovery wells are energized before the heating wells farthest from
the recovery well to produce a flow path for hydrocarbons to the
recovery well.
23. The system of claim 20, wherein, during a first time interval,
the heating wells are energized to heat the hydrocarbons and,
during a second time interval, at least one of steam and diluent is
injected through the heating wells into the hydrocarbon-containing
deposit.
24. The method of claim 16 wherein the hydrocarbon is oil
shale.
25. The method of claim 16, further comprising: (d) equipment that
is adapted to inject at least one of steam and diluent into the
hydrocarbon-containing deposit.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application claims the benefits, under 35 U.S.C.
.sctn.119(e), of U.S. Provisional Application Ser. No. 60/992,001,
filed Dec. 3, 2007, entitled "Method of Recovering Bitumen from
Tunnel and Shaft With Electrodes, Heating Elements and Recovery
Wells" to Brock et al, which is incorporated herein by this
reference.
FIELD
[0002] The present invention relates generally to a lined tunnel-
and shaft-based method and system for installing, operating and
servicing electrodes, heating elements and recovery wells for
recovery of hydrocarbons.
BACKGROUND
[0003] Oil is a nonrenewable natural resource having great
importance to the industrialized world. The increased demand for
and decreasing supplies of conventional oil has led to the
development of alternative sources of crude oil such as oil sands,
oil shales, and carbonate deposits containing bitumen or heavy oil;
and to a search for new techniques for continued recovery from both
conventional and unconventional oil deposits. The development of
the Athabasca oil sands in particular has resulted in increased
proven world reserves of over 170 billion barrels from the
application of surface mining and in-situ technologies. The
anticipated development of carbonate deposits in Alberta and
elsewhere represents many billions of additional barrels. Further,
there are immense deposits of oil shales in the United States that
can be recovered by the methods described herein. There are also
large untapped reserves in the form of stranded oil deposits from
known reservoirs. Estimates as high as 300 billion barrels of
recoverable light and heavy oil have been made for North America.
Recovery of stranded oil requires new recovery techniques that can
overcome, for example, the loss of drive pressure required to move
the oil to nearby wells where it can be pumped to the surface.
These sources of oil, oil sands, oil shales, oil carbonates and
stranded oil, are more than enough to eliminate dependence on
outside sources of oil and, in addition, require no substantial
exploration.
[0004] In the Athabasca oil sands, when the deposits are too deep
for economical surface mining, in-situ recovery methods have been
used wherein the viscosity of the bitumen in the oil sand is first
reduced so that it can flow. These bitumen mobilization techniques
include steam injection, diluent flooding, gas injection, and the
like. The principal method currently being implemented on a large
scale is Steam Assisted Gravity Drain ("SAGD"). Typically, SAGD
wells or well pairs are drilled from the earth's surface down to
the bottom of the oil sand deposit and then horizontally along the
bottom of the deposit and then used to inject steam and collect
mobilized bitumen.
[0005] In the US oil shales, one recovery method being implemented
in pilot projects involves the use of resistance heaters and
heating elements to raise the temperature of the oil shales so that
oil is produced. These methods are being considered for application
to both oil sand and carbonate deposits in Alberta. These methods
are designed to heat heavy oil and bitumen deposits to mobilize
these hydrocarbons for production.
[0006] Pilot phase projects currently underway include:
1. Heating of oil sands by electrodes, often referred to as a form
of Heat Assisted Gravity Drain ("HAGD"). 2. Direct heating of oil
sands by electrically-powered heating elements which is another
form of HAGD.
[0007] One electrode pilot project in the Athabasca oil sands
utilizes an array of vertically placed cathodes, anodes and
recovery wells. A voltage difference is applied across anodes and
cathodes, causing electrical flow through the brackish, connate,
interstitial water that typically adheres to each oil sand grain.
The electrical flow generates heat within the formation which
lowers the viscosity of the heavy oil so that it will flow to the
vertical recovery well. Examples of this approach are described in
"Electromagnetic Heating Methods for Heavy Oil Reservoirs" by A.
Sahni, M. Kumar and R. B. Knapp, UCRL-JC-138802, May 1, 2000 (this
article was submitted to 2000 Society of Petroleum Engineers,
SPE/AAPG Western Regional Meeting, Long Beach, Calif., Jun. 19-23,
2000).
[0008] Another pilot in the U.S. utilizes electrodes (similar in
function the above-described Canadian oil sands project) to heat
oil shales to a temperature below the boiling point of the water in
the formation. The electrodes are then converted to direct heating
elements to further increase the formation temperature so that
mobile oil will be liberated from the oil shale. The direct heating
elements can increase formation temperatures so that in-situ
refining takes place prior to production, for example, kerogens,
which are typically not produced from the formation, are converted
to producible, synthetic oil at temperatures on the order of
400-600.degree. C. Examples of this approach are described in
"E-ICP Project Plan of Operations" (Shell Frontier Oil and Gas
Inc., E-ICP Test Project, Oil Shale Research and Development
Project, prepared for the Bureau of Land Management, Feb. 15,
2006.
[0009] There remains a need for a method of installing a large
number of densely spaced heating elements in a reservoir without
having to drill through substantial overburden for every placement.
Dense spacing of heating elements in a reservoir can increase the
control and efficiency of a thermal recovery method including
utilizing gravity drain to remove melted bitumen from the
reservoir.
SUMMARY
[0010] The present invention is directed generally to mobilizing
and recovering hydrocarbons in an underground deposit, such as a
bitumen, heavy oil or oil shale deposit.
[0011] In a first embodiment, a method is provided that includes
the steps:
[0012] (a) forming a manned underground excavation in proximity to
and/or in a hydrocarbon-containing deposit;
[0013] (b) forming, from the manned underground excavation, a
plurality of mobilizing wells extending into the
hydrocarbon-containing deposit, each mobilizing well containing at
least one of a heating element, steam injector, and diluent
injector; and
[0014] (c) forming, from the manned underground excavation, at
least one recovery well in fluid communication with the
hydrocarbon-containing deposit and positioned in proximity to at
least some of the plurality of mobilizing wells, wherein the
mobilizing wells and recovery wells define a drainage volume and
wherein the mobilizing wells mobilize hydrocarbons contained within
the drainage volume and the recovery wells collect the mobilized
hydrocarbons.
[0015] In a second embodiment, a method comprising:
[0016] (a) providing a manned underground excavation in proximity
to and/or in a hydrocarbon-containing deposit, the manned
underground excavation comprising: [0017] (i) a plurality of
heating wells extending into the hydrocarbon-containing deposit,
each heating well containing one or more heating elements; and
[0018] (ii) at least one recovery well in fluid communication with
the hydrocarbon-containing deposit and positioned in proximity to
at least some of the plurality of heating wells, wherein the
heating wells and recovery wells define a drainage volume; and
[0019] (b) generating thermal energy from the heating wells to heat
and mobilize the hydrocarbons in the drainage volume for collection
by the recovery wells.
[0020] In a third embodiment, a system comprising:
[0021] (a) a manned underground excavation in proximity to and/or
in a hydrocarbon-containing deposit;
[0022] (b) at least one heating well extending from the underground
excavation into the hydrocarbon-containing deposit, the at least
one heating well containing one or more heating elements; and
[0023] (c) at least one recovery well in fluid communication with
the hydrocarbon-containing deposit and positioned in proximity to
the at least one heating well, wherein the at least one heating
well and the at least one recovery well define a drainage volume,
whereby thermal energy is generated from the at least one heating
well to heat and mobilize hydrocarbons in the drainage volume for
collection by the recovery wells.
[0024] The present invention can provide a method and means of
installing and servicing substantially horizontal heating elements
and recovery wells in a hydrocarbon deposit from a tunnel or shaft
that is driven into, above or under the hydrocarbon deposit. It has
the potential to increase hydrocarbon recovery factors, lower
costs, increase safety, decrease emissions at the site from the
heating process and result in less surface disturbance. It can
provide another means of assisting the extraction of hydrocarbons
and be used as needed in conjunction with other technologies such
as steaming, solvent and diluents, gas or water flooding and
hydraulic mining.
[0025] In some configurations, the invention can combine shaft and
tunneling, in-tunnel and in-shaft drilling, heating element
technologies to access, mobilize and produce heavy hydrocarbons
from oil sands, oil shales and oil carbonate reservoirs. Production
can be accomplished while providing full isolation for workers and
operators from formation fluids and gases. The invention can be
initiated, for example, from within the hydrocarbon formation or
from the underlying rock below the formation.
[0026] In one configuration, the invention discloses a method and
system for installing a lined shaft and tunnel from which heating
elements are installed substantially horizontally into the
formation in an array that approximates shape and function of a
steam chamber resulting from the SAGD process using horizontal
directional well pairs drilled from the surface. To begin, a
horizontal recovery well of several hundred meters in length is
installed from the tunnel into the bottom of the producing
interval. Then horizontal heating elements of several hundred
meters in length are installed above the recovery well in a pattern
that promotes uniform heating of the bitumen. Once the recovery
well is completed, the path of each heating elements is guided
while drilling by staying a fixed distance from a ranging
transmitter traveling up the recovery well. The chamber heating
would be initiated by passing current between the electrodes and
uniformly heating the chamber to near the boiling point of water at
chamber pressure. At this temperature, since boiling would disrupt
the flow of electricity, each heating element would be converted
from an electrode to a thermal conduction heater. The thermal
conduction heater would then continue to increase chamber
temperature until oil flows to the recovery well or wells. The
pattern of heating would begin with the center elements so that
downward flow along the shortest path to the recovery well or wells
is quickly established, followed by heating of the outside elements
to produce a flow path down and then sloping toward the recovery
well or wells (typically on the order of a 15.degree. slope
downward toward the recovery well or wells).
[0027] Other configurations of heating elements and recovery wells
are contemplated. Heating elements can be installed from the tunnel
by drilling equipment that can drill directly upward or at any
angle from vertical to horizontal and to below horizontal (if
necessary), depending on the target reserves, geology and tunnel
configuration.
[0028] In some configurations, lateral spacing of the heating
elements will depend also on site-specific conditions and
accumulated experience. Pilot spacing will be on the order of 15 to
20 meters between heating elements. A heating element would be
located directly adjacent to each recovery well to encourage flow
into and down to the recovery well. The recovery well may be
drained by gravity or with pump assistance.
[0029] Although the present invention is discussed with reference
to electrodes and thermal conduction heaters, it is understood that
other types of heating methods may be employed such as RF
antennas.
[0030] Another embodiment of the invention is the installation of
ohmic or induction electrodes in some situations, thermal
conduction heaters in some situations, RF antennas in some
situations and various combinations of these elements in other
situations.
[0031] Another aspect of the present invention is the energy source
for the heating elements. Electrical power will most likely be used
for all necessary energy for the Heating elements, although some
heating elements could be heated by combusting fuel or circulation
of a heated working fluid (e.g., molten salt, heated oil or
water).
[0032] Another aspect of this invention is the design of the
heating elements. Steel in its various forms (carbon, high tensile,
stainless) casing is a prime candidate as the heating elements must
withstand the torque and axial loads during drilling.
[0033] Another aspect of this invention is the drilling system,
which preferably includes a surface casing installation rig, drill
rig and possibly a completion rig, as well as drill pipe, mud
system and downhole tools. The drill bit may consist of a rotary,
percussive or jetting bit, depending on formation characteristics.
The mud composition may be water or oil, bentonite and/or polymer
based. The mud system would include facility for mud cleaning.
Pressure control may be necessary and wellhead, blow-out prevention
("BOP") can be adapted from standard oil field equipment in
accordance with regulatory agency requirements, such as, for
example, the regulations imposed by the Alberta Energy Utilities
Board. Drilling is anticipated to be underbalanced, but could be
overbalanced or balanced. Guidance for the recovery well may be by
Measurement While Drilling ("MWD") or other guidance systems that
are known in the art. Guidance for the heating elements may be by
paralleling a ranging tool advancing up the recovery well while
drilling the guidance hole.
[0034] Another aspect of this invention is the tunnel liner which
serves a number of purposes. These include protecting the interior
of the tunnel from the formation fluids and vapors, protecting the
formation from activities in the tunnel including sparks and the
like which can create fires; serving as a base for attaching fluid
cutting and control assemblies used for drilling, logging,
operating and servicing wells drilled through the liner; and
serving as a base for drains for oil collected around the tunnel
itself. Oil field wellhead and blow-out prevention equipment would
be modified to compact form suitable for regulatory approval.
[0035] Another aspect of this invention is that the use of heating
elements could be combined with other extraction technologies
advanced from the tunnel or shaft. For example, the heating
elements could be used as a formation pre-heater in electrode mode
or thermal conduction heater mode, then the formation could be
steamed, diluent injected or other method advanced from the
underground workings or the ground surface.
[0036] The following definitions are used herein:
[0037] Kerogen is a mixture of organic chemical compounds that make
up a portion of the organic matter in sedimentary rocks such as oil
shales. When heated to the right temperatures, some types of
kerogen release oil or gas.
[0038] A mobilized hydrocarbon is a hydrocarbon that has been made
flowable by some means. For example, some heavy oils and bitumen
may be mobilized by heating them or mixing them with a diluent to
reduce their viscosities and allow them to flow under the
prevailing drive pressure. Most liquid hydrocarbons may be
mobilized by increasing the drive pressure on them, for example by
water or gas floods, so that they can overcome interfacial and/or
surface tensions and begin to flow.
[0039] A mobilizing well as used herein is a well whose function is
to cause bitumen, heavy oil or another hydrocarbon which does not
readily flow, to be mobilized and able to flow to a recovery well.
A well containing heating elements is an example of a mobilizing
well. A well from which steam or diluent may be injected into a
producing formation is another example of a mobilizing well. A well
that can be used to operate a combination of heating elements,
steam and diluent injection either simultaneously or at different
times is, in general, defined herein as a mobilizing well. A
mobilizing well may also be converted to a recovery well.
[0040] Primary production or recovery is the first stage of
hydrocarbon production, in which natural reservoir energy, such as
gasdrive, waterdrive or gravity drainage, displaces hydrocarbons
from the reservoir, into the wellbore and up to surface. Production
using an artificial lift system, such as a rod pump, an electrical
submersible pump or a gas-lift installation is considered primary
recovery. Secondary production or recovery methods frequently
involve an artificial-lift system and/or reservoir injection for
pressure maintenance. The purpose of secondary recovery is to
maintain reservoir pressure and to displace hydrocarbons toward the
wellbore. Tertiary production or recovery is the third stage of
hydrocarbon production during which sophisticated techniques that
alter the original properties of the oil are used. Enhanced oil
recovery can begin after a secondary recovery process or at any
time during the productive life of an oil reservoir. Its purpose is
not only to restore formation pressure, but also to improve oil
displacement or fluid flow in the reservoir. The three major types
of enhanced oil recovery operations are chemical flooding, miscible
displacement and thermal recovery.
[0041] A recovery well is a well from which a mobilized hydrocarbon
such, as for example, bitumen or heavy oil may be recovered.
[0042] A shaft is a long approximately vertical underground opening
commonly having a circular cross-section that is large enough for
personnel and/or large equipment. A shaft typically connects one
underground level with another underground level or the ground
surface.
[0043] A tunnel is a long approximately horizontal underground
opening having a circular, elliptical or horseshoe-shaped
cross-section that is large enough for personnel and/or vehicles. A
tunnel typically connects one underground location with
another.
[0044] An underground workspace as used in the present invention is
any excavated opening that is effectively sealed from the formation
pressure and/or fluids and has a connection to at least one entry
point to the ground surface.
[0045] A well is a long underground opening commonly having a
circular cross-section that is typically not large enough for
personnel and/or vehicles and is commonly used to collect and
transport liquids, gases or slurries from a ground formation to an
accessible location and to inject liquids, gases or slurries into a
ground formation from an accessible location.
[0046] Well drilling is the activity of collaring and drilling a
well to a desired length or depth.
[0047] Well completion refers to any activity or operation that is
used to place the drilled well in condition for production. Well
completion, for example, includes the activities of open-hole well
logging, casing, cementing the casing, cased hole logging,
perforating the casing, measuring shut-in pressures and production
rates, gas or hydraulic fracturing and other well and well bore
treatments and any other commonly applied techniques to prepare a
well for production.
[0048] It is to be understood that a reference to oil herein is
intended to include low API hydrocarbons such as bitumen (API less
than .about.10.degree.) and heavy crude oils (API from
.about.10.degree. to .about.20.degree.) as well as higher API
hydrocarbons such as medium crude oils (API from .about.20.degree.
to .about.35.degree.) and light crude oils (API higher than
.about.35.degree.). A reference to bitumen is also taken to mean a
reference to low API heavy oils.
[0049] As used herein, "at least one", "one or more", and "and/or"
are open-ended expressions that are both conjunctive and
disjunctive in operation. For example, each of the expressions "at
least one of A, B and C", "at least one of A, B, or C", "one or
more of A, B, and C", "one or more of A, B, or C" and "A, B, and/or
C" means A alone, B alone, C alone, A and B together, A and C
together, B and C together, or A, B and C together.
BRIEF DESCRIPTION OF THE DRAWINGS
[0050] FIG. 1 is a schematic of a prior art surface-based SAGD
recovery operation.
[0051] FIG. 2 is a schematic side view of a prior art well setup as
applied to the present invention.
[0052] FIG. 3 is a schematic showing drilling a well into a
formation from a lined tunnel which is prior art.
[0053] FIG. 4 is an end view of a HAGD installation of the present
invention.
[0054] FIG. 5 is an isometric view of a HAGD installation of the
present invention with heating elements.
[0055] FIG. 6 is an end view of a HAGD installation of the present
invention in resistance pre-heating mode.
[0056] FIG. 7 is an end view of a HAGD installation of the present
invention during start-up of production.
[0057] FIG. 8 is an end view of a HAGD installation of the present
invention during an intermediate stage of production.
[0058] FIG. 9 is an end view of a HAGD installation of the present
invention during a later stage of production.
DETAILED DESCRIPTION
[0059] Mobilizing hydrocarbons such as bitumen or heavy oil, for
example from oil sands, may be accomplished using steam to heat the
bitumen or heavy oil, or by injecting diluents to increase the API
rating of the bitumen or heavy oil. Other heating methods besides
steam may also be used. These include, for example: [0060]
electrodes for AC or DC ohmic heating of the reservoir material
between adjacent electrodes; [0061] thermal conduction heaters that
heat the surrounding reservoir material by thermal conduction;
[0062] electrodes for inductive heating of the surrounding
reservoir material; [0063] high frequency RF, including microwave,
heating of the surrounding reservoir material in which the heating
element is typically called an RF antenna.
[0064] Where any of these heating methods may be used, they are
referred to herein generally as heating elements. When a specific
type of heating method is intended, it will be referred to by its
specific name (i.e., ohmic electrode, thermal conduction heater,
induction electrode, RF antenna).
[0065] A mobilizing well as used herein is a well whose function is
to cause bitumen, heavy oil or another hydrocarbon which does not
readily flow, to be mobilized and able to flow to a recovery well.
A well containing heating elements is an example of a mobilizing
well. A well from which steam or diluent may be injected into a
producing formation is another example of a mobilizing well. A well
that can be used to operate a combination of heating elements,
steam and diluent injection either simultaneously or at different
times is, in general, defined herein as a mobilizing well. A
mobilizing well may also be converted to a recovery well.
[0066] A recovery well as used herein is a well from which a
mobilized hydrocarbon such, as for example, bitumen or heavy oil
may be recovered.
[0067] A heating well as used herein is a well containing any of
the heating elements described above.
PRIOR ART USED IN THE PRESENT INVENTION
[0068] A number of technologies proposed for recovery of
hydrocarbons, including heavy oil and bitumen, are based on mining
for access. For example, a system of underground lined shafts and
lined tunnels has been proposed to allow wells to be installed from
under or from within a reservoir. This approach overcomes a number
of problems such as surface access, product lifting difficulties
and reliability of downhole pumps. In these mining for access
technologies, the wellhead and its associated equipment is readily
accessible and is typically only a few meters from the formation.
Also, the wells are installed from the underground workspace either
horizontally or inclined upwards. A discussion of these mining for
access methods can be found in U.S. patent application Ser. No.
11/441,929 entitled "Method for Underground Recovery of
Hydrocarbons" and U.S. patent application Ser. No. 11/737,578
entitled "Method of Drilling from a Shaft", both of which are
incorporated herein by reference.
[0069] Installing wells from an underground workspace, rather than
drilling the wells from the surface, opens up possibilities for
improving the economics of, for example, SAGD and HAGD by reducing
the cost of installing wells, minimizing steam transmission losses
and enabling more accurate placement of well pairs. This approach
also allows deposits that have surface restrictions to be
exploited.
[0070] When drilling is carried out from inside a lined tunnel, the
tunnel liner serves a number of purposes. These include protecting
the interior of the tunnel from the formation fluids and vapors,
protecting the formation from activities in the tunnel including
sparks and the like which can create fires; serving as a base for
attaching fluid cutting and control assemblies used for drilling,
logging, operating and servicing wells drilled through the liner;
serving as a base for blow-out prevention equipment; and serving as
a base for drains for oil collected around the tunnel itself. Some
of these techniques are discussed in U.S. patent application Ser.
No. 11/441,929 entitled "Method for Underground Recovery of
Hydrocarbons" and U.S. patent application Ser. No. 11/737,578
entitled "Method of Drilling from a Shaft".
[0071] FIG. 1, which is prior art, shows a schematic representation
of a well pair as installed from the surface for a SAGD operation
as currently practiced. Typically, the well pair is drilled from a
surface pad 103 through the overburden 101 and into an oil sand
deposit 102 using directional drilling techniques. The lower well
105 is the collector or producer well and is generally located near
the bottom of the oil sand deposit 102 just above the underlying
bedrock. The upper well 104 is the injector well and is generally
located just above the producer well 105. The injector well 104 is
typically drilled to be parallel to the producer well but offset 1
to 5 meters above the producer well 104. This well pair geometry
has been field tested and has confirmed the basic operation of the
SAGD process. Steam is injected along the horizontal portion of
injector 104 and rises into the oil sand deposit, heating the oil
sand and mobilizing the bitumen in the pore space (mobilizing means
reducing the viscosity to where the bitumen becomes fluid and will
flow). As more bitumen is collected, the steam chamber represented
by its expanding condensation front 106, grows. The steam rises and
the mobilized bitumen along with condensed steam falls under
gravity typically around the periphery of the condensation front
106 and is collected in the producer well 105. The placement of the
well pairs horizontally not only allows the bitumen to flow
downward for collection but also presents a long length of
collector well to the formation so that commercially viable
production rates are achieved. In practice, an oil sands deposit
might be thermally produced by a number of SAGD well pairs ranging
from about 5 well pairs to about 200 well pairs. The SAGD process
has been successfully applied to some but not all of bitumen and
heavy oil deposits.
[0072] FIG. 2 is a schematic side view of the well setup of the
present invention showing an end view of a lined tunnel 204
installed in an oil sands deposit 202. This figure was derived from
U.S. patent application Ser. No. 11/944,013 entitled "Recovery of
Bitumen by Hydraulic Excavation" filed Nov. 21, 2007 and is prior
art and which is incorporated herein by reference. The oil sands
deposit 202 is typically overlain by an overburden layer 201 and
the oil sands deposit 202 typically overlies a basement zone 203
such as for example a limestone strata. Lower wells 205 are drilled
approximately horizontally out through the tunnel liner 204 for a
distance in the range of about 100 to 1,200 meters. These wells are
typically positioned near the bottom of the oil sands deposit 202.
Wells 206 may also drilled out from the tunnel liner 204 and then
upwards into the oil sands deposit 202 also for a distance in the
range of about 100 to 1,200 meters out to the approximately the
same distance from the tunnel 204 as the lower wells 205. The
tunnel 204 has a diameter in the range of about 3 meters to about
12 meters but can be as large as 15 meters in diameter. The tunnel
liner thicknesses are typically in the range of about 75
millimeters to about 600 millimeters. The well lengths are limited
by the drilling technology employed but are at least in the range
of about 100 to 1,200 meters. The well diameters are in the range
of about 50 millimeters to about 1,500 millimeters, depending on
the instructions of the reservoir engineer. The methods of drilling
from within tunnel 204 may include, for example, conventional soft
ground drilling methods using rotary or auger bits attached to
lengths of drill pipe which are lengthened by adding additional
drill pipe sections as drilling proceeds. Drilling methods may also
include, for example, water jet drilling methods. Drilling methods
may also include, for example, micro-tunneling techniques where a
slurry excavation head is used and is advanced into the deposit by
pipe-jacking methods. Directional drilling methods may be used from
within tunnel 204 allowing the wells 206, for example, to be
drilled upwards at an inclination and then be directionally changed
to be a horizontal well at a new elevation within the
formation.
[0073] FIG. 3 is a schematic showing drilling a well into a
formation from a lined tunnel which is prior art. FIG. 3 is a
cutaway side view of a well-head recess 306 with well-head
equipment 305 installed. Also shown is drilling equipment 302
drilling a well 304 through blow-out preventer apparatus 305
located in recess 306. Both recesses shown are located in tunnel
301. As can be seen, the well-head equipment, once installed as
shown by 305, does not interfere with on-going drilling operations
in other recesses. This means, for example, that not all wells need
be drilled at the same time. With the recess configuration,
additional recesses can be installed and additional wells can be
completed while the original wells continue to be operated. This
technique of installing and operating wells from a lined tunnel or
shaft is described fully in U.S. patent application Ser. No.
11/737,578 entitled "Method of Drilling from a Shaft". By isolating
the inside of lined tunnel 301 from the formation pressure, vapors,
gases and other fluids, the hydrocarbon removal and collection
methods of the present invention can be practiced in safety in the
deeper oil sands formations which are often pressurized by
formation gases such as methane and carbon dioxide and often
contain mobile water aquifers.
Recovering Bitumen from Tunnel and Shaft with Heating Elements
[0074] FIG. 4 is an end view of a HAGD installation according to an
embodiment of the present invention. The HAGD-containing wells and
recovery wells are drilled, and the heating elements installed
from, a manned underground excavation, such as a shaft, tunnel,
drift, stope, incline, decline, or winze. The underground
excavation preferably has an inner diameter ranging from about 3 to
about 15 meters and an outer diameter ranging from about 3.5 to
about 16 meter. The excavation is typically lined to inhibit
ingress or egress of vapors, gases, and other fluids. It is to be
appreciated that the HAGD installation method will use, in part,
the teachings of FIGS. 1 through 3.
[0075] FIG. 4 illustrates an example of a spacing of horizontal
heating elements 403 and an example of a recovery well 402 in a
bitumen deposit. This array of heating elements 403 is designed to
form a melt chamber 401 in which mobilized bitumen will tend to
flow toward recovery well 402. Preferably, the diameter of the
recovery well 402 is in the range of about 0.1 to about 1 meters.
Preferably, the diameter of the heating elements 403 is also in the
range of about 0.1 to about 1 meters. Preferably, the height 412 of
the melt chamber 401 is in the range of about 20 meters to about
100 meters, with the example of FIG. 4 shown to be about 60 meters.
Preferably, the width 411 of the melt chamber 401 is in the range
of about 30 meters to about 150 meters, with the example of FIG. 4
shown to be about 100 meters. Preferably, the lengths of the
heating elements 403, the heating element wells, and the recovery
well 402 are in the range of about 100 to about 3,000 meters and
even more preferably in the range of about 1,500 meters but
typically in the range of about 800 to about 1,200 meters. As can
be appreciated, the dimensions of the melt chamber 401 are
determined by the geology of the deposit and the horizontal
directional drilling technology available.
[0076] The heating elements 403 are installed into the formation in
an array to form a melt chamber 401 that approximates shape and
function of a steam chamber resulting from the SAGD process using
horizontal directional well pairs drilled from the surface. To
begin, a horizontal recovery well 402 several hundred meters in
length is installed from a tunnel or shaft into the bottom of the
producing interval. Then horizontal heating elements 403 are
installed above the recovery well 402 in a pattern that promotes
uniform heating of the bitumen once the bitumen is mobilized and
flow is established. Once the recovery well 403 is completed, the
path of each heating element 402 is guided while drilling by
staying a fixed distance from a ranging transmitter traveling up
the recovery well. The melt chamber heating may be initiated by
passing current between electrodes 403 and uniformly heating the
chamber 401 to near the boiling point of water at chamber pressure.
At this temperature, since boiling would disrupt the flow of
electricity, each electrode 403 would be converted from an
electrode to a thermal conduction heater. The thermal conduction
heaters 403 would then continue to increase melt chamber 401
temperature until oil flows to the recovery well 402. As will be
described in FIGS. 7, 8 and 9, the pattern of heating with
electrodes and thermal conduction heaters would begin with the
center elements so that downward flow along the shortest path to
the recovery well 402 is quickly established, followed by heating
of the outside elements to produce a flow path down and then
sloping toward the recovery well 402 (typically on approximately a
15.degree. slope downward toward the recovery well 402).
[0077] Other configurations of heating elements 403 and recovery
wells 402 are contemplated. Heating elements can be installed from
a tunnel (not shown) by drilling equipment (similar to that shown
in FIG. 3) that can drill directly upward or at any angle from
vertical to horizontal and to below horizontal (if necessary),
depending on the target reserves, geology and tunnel configuration.
Spacing of the heating elements 403 will depend also on
site-specific conditions and accumulated experience. Pilot spacing
between heating elements will be in the range of about 10 to 30
meters but is expected to be typically in the range of about 15 to
20 meters. At least one heating element would be located directly
adjacent to each recovery well to encourage flow into and down the
recovery well 402. The recovery well 402 could be drained by
gravity or with pump assistance. Another embodiment of the
invention is the installation of ohmic or inductive electrodes in
some situations, thermal conduction heaters in some situations, RF
antennas in some situations or combinations of these in other
situations. Another aspect of this invention is the use of heating
elements combined with other extraction technologies advanced from
the tunnel or shaft. For example, the heating elements could be
used as a formation pre-heater in electrode mode, then the
formation could be steamed, diluent injected or other method
advanced from the underground workings or the ground surface.
Steaming, diluent injection, and the like may be done from other
wells or through the same wells occupied by the heating elements.
In the latter case, the heating elements are removed from the wells
followed by installation of a well head. Alternatively, the well
head is already in position and the heating elements are inserted
and removed through the well head.
[0078] FIG. 5 is an isometric view of a HAGD installation of the
present invention with heating elements. This figure illustrates
another perspective of the heating element and recovery well
geometry illustrated in FIG. 4 and shows heating elements 503 and a
recovery well 502 in a bitumen deposit. This array of heating
elements 503 is designed to form a melt chamber 501 in which
mobilized bitumen will tend to flow toward recovery well 502. The
length of the heating elements 503 and the recovery well 502 is in
the range of about 100 to about 1,000 meters. As can be
appreciated, the dimensions of the melt chamber 501 such as its
width 511 and height 512, are determined by the geology of the
deposit and the horizontal directional drilling technology
available.
[0079] FIG. 6 is an end view of a HAGD installation of the present
invention in electrode resistance pre-heating mode. This figure
illustrates the example of FIGS. 4 and 5 in resistance pre-heating
mode showing electrodes 603 and a recovery well 602 in a bitumen
deposit. This array of electrodes 603 is designed to form a melt
chamber 601 in which mobilized bitumen will tend to flow toward
recovery well 602. The melt chamber heating would be initiated by
passing current between adjacent electrodes 603 (current paths
represented as wiggly lines between adjacent electrodes) and
uniformly heating the chamber 601 to near the boiling point of
water at chamber formation pressure. At this temperature, boiling
will tend to disrupt the flow of electricity and each electrode 603
would be converted from an electrode to a thermal conduction
heater.
[0080] FIG. 7 is an end view of a HAGD installation of the present
invention during start-up. As shown in FIG. 6, the melt chamber
heating would be initiated by passing current between adjacent
electrodes 703 and uniformly heating the chamber 701 to near the
boiling point of water at chamber formation pressure. At this
temperature, boiling will tend to disrupt the flow of electricity
and each electrode would be converted from electrode to a thermal
conduction heater. The initial pattern of heating by thermal
conduction heaters would begin with the center elements (those
above recovery well 702) followed by heating by the outside
elements to produce a flow path down and then sloping toward the
recovery well 702 (typically on approximately a 15.degree. slope
downward toward the recovery well 702). The center elements are
shown forming melting zones of bitumen around each heating
element.
[0081] FIG. 8 is an end view of a HAGD installation of the present
invention during an intermediate stage. Here the melting zones of
bitumen around each of the center heating elements are shown
coalesced 506 and forming a melt zone now connected with the
recovery well 802 and allowing the mobilized bitumen recovery
process to begin.
[0082] FIG. 9 is an end view of a HAGD installation of the present
invention during a later stage where the heating elements outside
the center heating elements are shown forming melting zones of
bitumen 905 around each heating element outside the center heating
elements. As described in FIG. 8, the melting zones of bitumen
around each of the center heating elements have coalesced 906,
forming a melt zone connected with the recovery well 902, which
continues to drain mobilized bitumen toward recovery well 902. The
melting zones of bitumen 905 around each of the heating elements
outside the center heating elements will eventually coalesce and
allow the rest of the deposit to begin draining toward the recovery
well 902 until the bitumen in the entire melt chamber 901 becomes
mobilized and drains toward recovery well 902.
[0083] In the foregoing examples as described in FIGS. 4 through 9,
the electrode mode is used to pre-heat the entire projected melt
chamber. Once pre-heated, thermal conduction heaters would be used
to melt the zone above the recovery well. Once recovery begins from
this initial melted zone, the other thermal conduction heaters
would be activated to melt the bitumen progressing from the center
zone out towards the edges of the projected melt chamber.
[0084] As can be appreciated, other pre-heating and melting
scenarios are possible. For example, preheating can be carried out
sequentially from the center zone out towards the edges of the
projected melt chamber while direct heating could follow a similar
pattern but delayed in time so that melting always progresses into
a preheated zone. This illustrates an advantage of HAGD over SAGD.
SAGD uses steam which convects heat into pore space from which
bitumen has been mobilized and drained. The growth of a SAGD steam
chamber thus is constrained to an expanding chamber emanating from
the injector/collector well pair. In a HAGD recovery operation, the
preheating and melting phases can be carried out in a different
pattern by choreographing either or both the placement and the
timing of the heating elements. This capability could be used for
example, to form a melt chamber around a thief zone in such a way
as to isolate the thief zone and prevent a precipitous loss of
heating energy. As can be appreciated, pre-heating can be
accomplished, for example, using RF antenna heaters or induction
electrodes instead of ohmic electrodes.
[0085] A number of variations and modifications of the invention
can be used. As will be appreciated, it would be possible to
provide for some features of the invention without providing
others. For example, the use of horizontal heating elements could
be combined with other extraction technologies advanced from the
tunnel or shaft. For example, the heating elements could be used as
a formation pre-heater in electrode mode, then the formation could
be steamed, diluent injected or other method advanced from the
underground workings or the ground surface.
[0086] The present invention, in various embodiments, includes
components, methods, processes, systems and/or apparatus
substantially as depicted and described herein, including various
embodiments, sub-combinations, and subsets thereof. Those of skill
in the art will understand how to make and use the present
invention after understanding the present disclosure. The present
invention, in various embodiments, includes providing devices and
processes in the absence of items not depicted and/or described
herein or in various embodiments hereof, including in the absence
of such items as may have been used in previous devices or
processes, for example for improving performance, achieving ease
and\or reducing cost of implementation.
[0087] The foregoing discussion of the invention has been presented
for purposes of illustration and description. The foregoing is not
intended to limit the invention to the form or forms disclosed
herein. In the foregoing Detailed Description for example, various
features of the invention are grouped together in one or more
embodiments for the purpose of streamlining the disclosure. This
method of disclosure is not to be interpreted as reflecting an
intention that the claimed invention requires more features than
are expressly recited in each claim. Rather, as the following
claims reflect, inventive aspects lie in less than all features of
a single foregoing disclosed embodiment. Thus, the following claims
are hereby incorporated into this Detailed Description, with each
claim standing on its own as a separate preferred embodiment of the
invention.
[0088] Moreover though the description of the invention has
included description of one or more embodiments and certain
variations and modifications, other variations and modifications
are within the scope of the invention, e.g., as may be within the
skill and knowledge of those in the art, after understanding the
present disclosure. It is intended to obtain rights which include
alternative embodiments to the extent permitted, including
alternate, interchangeable and/or equivalent structures, functions,
ranges or steps to those claimed, whether or not such alternate,
interchangeable and/or equivalent structures, functions, ranges or
steps are disclosed herein, and without intending to publicly
dedicate any patentable subject matter.
* * * * *