Canadian Patents Database / Patent 2287944 Summary

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(12) Patent: (11) CA 2287944
(54) English Title: COMMUNICATING HORIZONTAL WELL NETWORK
(54) French Title: RESEAU DE PUITS HORIZONTAUX COMMUNIQUANTS
(51) International Patent Classification (IPC):
  • E21B 43/30 (2006.01)
  • E21B 43/16 (2006.01)
(72) Inventors :
  • HASSAN, DAVID J. (Canada)
  • CHERNICHEN, MICHAEL D. (Canada)
  • JENSEN, EARL M. (Canada)
(73) Owners :
  • BP CORPORATION NORTH AMERICA INC. (United States of America)
(71) Applicants :
  • BP AMOCO CORPORATION (United States of America)
(74) Agent: GOWLING WLG (CANADA) LLP
(74) Associate agent: GOWLING WLG (CANADA) LLP
(45) Issued: 2006-03-21
(86) PCT Filing Date: 1997-05-01
(87) Open to Public Inspection: 1998-11-12
Examination requested: 2002-03-20
(30) Availability of licence: N/A
(30) Language of filing: English

English Abstract





A method of producing fluids from a subterranean formation (10) through a
single well (1) in a network of separate well-bores,
comprising the steps of forming a well (1) having a horizontal section (3)
located within the formation (10), completing and equipping such
well (1) to produce fluids from the formation (10), producing fluids from the
formation through such well (1); forming at least one additional
well (2) having a horizontal section (4) located within the formation (10)
such that such well (3) is in fluid communication with the first
well (1), without intersecting with the horizontal section (3) of the first
well (1), and using such additional well (2) as a conduit within
the formation to allow and cause fluids contained in the formation which drain
or flow into the horizontal section (4) of such additional
well-bore, to flow to and be produced through the first well-bore (1).


French Abstract

L'invention concerne un procédé d'extraction de fluides provenant d'une formation souterraine (10), à travers un puits (1) unique dans un réseau de puits de forage distincts, comprenant les opérations suivantes: formation d'un puits (1) à section horizontale (3) et situé dans la formation (10), finition et équipement de ce puits (1) pour permettre l'extraction de fluides provenant de la formation (10), extraction des fluides de la formation à travers ce puits (1); formation d'au moins un puits (2) additionnel à section horizontale (4) situé dans la formation (10), de manière que ce puits (3) se trouve en communication fluidique (3) avec le premier puits (1) et ne présentant pas d'intersection avec la section horizontale du premier puits (1), sans recouper la section horizontale (3) du premier puits (1), et utilisation de ce puits (2) additionnel comme conduit à l'intérieur de la formation, pour permettre ou provoquer l'écoulement des fluides contenus dans la formation et qui drainent ou s'écoulent dans la section horizontale (4) de ce puits additionnel, en direction du premier puits (1) pour en être extraits.


Note: Claims are shown in the official language in which they were submitted.




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CLAIMS

1. A method of producing fluids from a subterranean formation containing such
fluids, comprising
a network of conduits formed and operated according to the following steps:

(a) forming a well-bore having a horizontal section that is located within the
formation;
(b) completing and equipping the well-bore so that fluids contained in the
formation can
be produced from the formation through the well-bore;
(c) producing fluids from the formation through the well-bore characterised
by:
(d) forming at least one additional well-bore having a horizontal section that
is located
within the formation, such that the horizontal section of said at least one
additional
well-bore is oriented in the direction of the horizontal section of the well-
bore formed
pursuant to step (a), and is in fluid communication with the well-bore formed
pursuant
to step (a), without intersecting with such well-bore; and
e) at least completing the at least one additional well-bore to form a conduit
within the
formation to allow and cause fluids contained in the formation which drain or
flow into
such at least one additional well-bore to flow to and be produced from the
well-bore
formed pursuant to step (a) above.

2. The method as set forth in claim 1, where in performing step (d) fluid
communication between
the well-bore pursuant to step (a) occurs during the forming of said at least
one additional well-
bore.

3. The method as set forth in claim 1, where in performing step (d) the
production of substances
from the formation through the well-bore formed pursuant to step (a)
continues.

4. The method as set forth in claim 1, where in performing step (d) said fluid
communication is created by fracturing, perforation, washing away or removing
a portion
of the formation lying between the horizontal section of the at least one
additional well-
bore and the horizontal section of the well-bore formed pursuant to step (a).

5. The method as set forth in claim 1, where such fluid communication is
created by performing
step (c).

6. The method as set forth in claim 1, where in performing step (d) the
horizontal section of the
at least one additional well-bore is formed so that such section overlaps with
or crosses over




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the horizontal section of the well-bore formed pursuant to step (a), without
intersecting the
horizontal section such well-bore.

7. The method as set forth in claim 1, where in performing step (b) said well-
bore is also
equipped for injecting substances into the formation, and step (b) includes
the step of
injecting substances into the formation.

8. The method as set forth in claim 1, where in all well-bores formed pursuant
to steps (a) and
(d) are equipped to inject substances into the formation to conduct a cyclic
fluid injection and
production process to produce fluids from the formation, comprising the
following steps:

i) injecting a fluid into the formation, through the well-bore formed in step
(a), to
mobilize the fluids already contained in the formation;
ii) ceasing the injection of fluid and shutting the network of conduits in for
a period of
time;
iii) producing fluids from the formation through the well-bore formed in step
(a) of claim
1; and
iv) repeating steps (i), (ii) and (iii), in a continuous cycle until further
production of
fluids from the formation is no longer desirable.

9. The method as set forth in claim 8, where in performing step (i) said
injected fluid comprises
at least one of the group comprising a hydrocarbon, a solvent, water, steam,
carbon dioxide,
an acid, a base, a solution, a leaching fluid or a fluid containing a solid
held in suspension, a
liquid, a gas, a multiphase fluid or a mixture of two or more substances from
within such
group.

10. The method as set forth in claim 8, wherein the formation is characterized
by a temperature,
and wherein said injected fluid is heated and injected into the formation at a
temperature
higher than the temperature of the formation.

11. The method set forth in claim 8, wherein prior to performing step (i), the
at least one
additional well-bore is equipped to inject substances into the formation, and
wherein step (i)
comprises simultaneously injecting a fluid into the formation, through the
well-bore formed
in step (a) of claims 1 and the at least one additional well-bore, to mobilize
the fluids already
contained in the formation.

12. The method as set forth in claim 1, where in performing step (d) at least
two well-bores are
formed sequentially an immediately one after the other.





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13. The method as set forth in claim 1, where in performing step (d) at least
two well-bores are
formed sequentially one after the other.

14. A method of producing mineral substances from a subterranean formation
containing such
substances comprising the steps of:

a) forming a well-bore having a horizontal section that is located with the
formation
and completing and equipping the well-bore so that substances contained in the
formation
can be produced from the formation through the well-bore; characterized by:

b) sequentially or simultaneously forming further additional well-bores each
having a
horizontal section that is located within the formation, such that the
horizontal section of
each said further additional well-bores is in direct or indirect fluid
communication with the
well-bore formed pursuant to step (a), without intersecting with any other
well-bore, where
in such fluid communication is created by producing fluids from the formation
through the
well-bore formed pursuant to step (a) or by fracturing, perforation, washing
away or
removing a portion of the formation lying between the horizontal section of at
least one of
such additional well-bores and the horizontal section of the well-bore formed
pursuant to
step (a); and
c) at least completing the well-bores formed pursuant to step (b) and using
such well-
bores as conduits within the formation to allow and cause fluids contained in
the formation
which drain or flow into such well-bores to flow to and be produced through
the well-bore
formed pursuant to step (a) above, and producing fluids from the formation
through the
well-bore formed pursuant to step (a).

15. The method of claim 14, wherein at least one existing well-bore having a
horizontal section that
is located within the formation, that was previously formed and at least
completed, is used in
place of or in addition to a well-bore formed pursuant to at least one of
steps (a) and (b).

16. The method of claim 14, wherein at least two, but less than all of the
well-bores formed
pursuant to such claim are equipped and used to produce fluids from the
formation.

17. The method set forth in claim 14, including the additional step of
equipping all welt bores, for
the injection of one or more fluids into the formation and utilizing said well-
bores to
simultaneously inject one or more fluids from the group comprising a
hydrocarbon, a solvent,
water, steam, carbon dioxide, an acid, a base, a solution, a leaching fluid or
a fluid containing
a solid held in suspension, a liquid, a gas, a multiphase fluid or a mixture
of two or more
substances from within such group, into the formation, in order to mobilize
substances



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contained in the formation, in the conduct of a cyclic injection and
production process, using
only at least one but less than all such well-bores to produce fluids from the
formation in the
conduct of such process.

18. The method of claim 14 wherein the formation is characterized by a
temperature, and
wherein the injection fluid is heated above the temperature of the formation
prior to
injection into the formation.

19. The method of claim 17, wherein the substance contained in the formation
is a solid mineral
and the fluid being injected dissolves such mineral or carries such mineral in
suspension
through a wash or leaching process.


Note: Descriptions are shown in the official language in which they were submitted.


CA 02287944 1999-11-O1
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COMMUNICATING HORIZONTAL WELL NETWORK
Technical Field
This invention relates to the general subject of methods and devices for
recovering fluids from
subterranean formations, and, in particular, to processes and apparatus for
recovering bitumen, heavy
crude oil and other hydrocarbons by means of horizontal wells drilled from
surface locations.
Background of the Invention
It is well known that the use of horizontal wells drilled from surface
locations has improved the
economics and reduced the environmental impact of finding and recovering
hydrocarbons and other
substances from subterranean formations. A horizontal well is a well that is
formed with a section of the
l0 well being oriented relatively or approximately in a geometric plane that
is parallel to the surface of the
earth beneath which such section is located. In particular it is well known
that in appropriate applications,
a single horizontal well can expose and access as much of the mineral bearing
rock in a subterranean
formation as several vertical wells. A vertical well is a well which is not
comprised in whole or in part of a
horizontal section as described above, and includes a deviated or slant hole
well formed or drilled from the
surface of the earth.
The cost of drilling and completing a single horizontal well into a particular
formation, generally
exceeds the cost of drilling and completing a vertical welt into the same
formation. However substantial
economies of scale can be achieved where the use of horizontal wells
significantly reduces the number of
wells required to efficiently produce the hydrocarbons contained in a
subterranean reservoir. These
savings accrue as a result of reduced capital and operating costs for
developing and producing a mineral
bearing subterranean formation. For an excellent summary of the art and
advantages of producing a
subterranean reservoir using horizontal wells, see:
Butler, R.M., "The Potential for Horizontal wells for petroleum production",
Journal of Canadian
Petroleum Technology, May-June 1989, Volume 28, No. 3, pp.39-47;
Deskins, W.G, Reid, T. B. and McDonald, W.J., "Success of Horizontal Well
Technology in Heavy
Oil Applications", 6th UNITAR International Conference on Heavy Crude and Tar
Sands,
February 12-17, 1995, Houston Texas, USA, Volume 1, pp. 495 - 503; and
Thakur, G.C., "Horizontal Well Technology - A Key to Improving Reserves",
paper delivered at the
SPE/CIM 5th Annual One-day Conference on Improvement in Horizontal Well
Productivity and


CA 02287944 1999-11-O1
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Profitability, Calgary, Alberta, Canada, November 21, 1995.
A hydrocarbon bearing subterranean formation is usually developed and produced
through wells
formed from locations on the surface of the earth overlying such formation. It
is well known that the use of
horizontal wells can reduce the number of wells required to accomplish such
development and production
which in turn, can correspondingly reduce the number and areal extent of well
sites and access roads
required to form and support such wells. As a result the cost and
environmental impact of developing
and producing a hydrocarbon bearing subterranean formation can be reduced.
It is well known in the art that a subterranean reservoir containing
hydrocarbons or other valuable
substances which are fluid in nature or may be reduced to or carried in a
fluid, can be produced efficiently
through a network of horizontal well-bores. A means of exploiting and
producing substances contained in
a subterranean reservoir through a network of horizontal wells is disclosed in
U.S. 4,621,691 to Shuh.
However the method taught by Shuh requires that each horizontal well be
drilled from a separate well site,
and completed, equipped and operated as a separate individual well.
As improvements in technology have facilitated the drilling of horizontal
wells of increasing length
and at shallower depths, further reductions in the environmental impact and
economic cost of developing
a subterranean hydrocarbon reservoir have been achieved by drilling multiple
horizontal wells from the
same well site or drilling "pad" (see Sadler, K.W. and Houlihan, R.N. "An
Energy Resources Conservation
board Review of Oil Sands Development in Alberta, 6th UNITAR International
Conference on Heavy
Crude and Tar Sands, February 12-17, 1995, Houston Texas, USA, Volume 1, p. 95-
103, at pp.101 &
102). In these instance the well-bore of each well drilled from the pad is
characterized by having its own
vertical, build and horizontal sections. The vertical section lies
approximately perpendicular to the
surface of the earth from which the well is formed. The horizontal section
lies approximately parallel to the
surface of the earth. The build section is the portion of the well-bore which
connects the horizontal section
and the vertical section. Although multiple well-bores may be formed from a
single well site, frequently
each well-bore is completed, equipped and operated as a separate individual
well. By completing, it is
meant that steps are taken to prevent: (i) the collapse of the well-bore, (ii)
the infiltration of substances into
the well-bore from formations other the target formation, (iii) the ex-
filtration of substances from the well-
bore into formations other the target formation, and (iv) the uncontrolled
escape of substances from the
subterranean formations penetrated by the well-bore. By equipping, it is meant
that steps are taken to
prepare the well-bore to be used to inject or produce substances, into or from
the subterranean formation,
as the case may be. This includes the placing of pumps, production or
injection tubing and other
equipment into the well-bore and the installation and connection of tanks,
pumps, surface piping or other
equipment at surface on the well site and to the well-bore as the case may be.


CA 02287944 1999-11-O1
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To overcome the need to complete and equip each well formed from a pad site,
advances in the
art discloses the forming of multiple well-bores from a single vertical shaft
and the apparatus required to
form, operate and maintain such multiple well-bores. This allows more of the
reservoir to be accessed
from a single well site using a network of multiple horizontal well-bores that
share a common vertical
section. This further reduces the amount of surface disturbance. The size of
the well site required to
support multiple horizontal well-bores formed and operated in this fashion,
may be smaller than the well
site required to form and operate a similar number of horizontal well-bores
formed from individual vertical
sections . See:
Maurer, W.C., "Recent Advances in Horizontal Drilling", The Journal of
Canadian Petroleum
Technology, November 1995, Volume 34, No. 9, pp. 25-33.
Brockman, M. and Gann, C., "Multilateral Completions Prepare to Take Off',
Petroleum Engineer
International, January 1996, pp. 49-50.
Themig, D., "Planning And Evaluation Are Crucial To Multilateral Wells",
Petroleum Engineer
International, January 1996, pp. 53-57.
I S Collies, D., "Single-Size Reduction Offers Workover, Completion
Advantages" , Petroleum
Engineer International, January 1996, pp. 59-62.
Von Flatern, R., "Operators Are Ready For More Sophisticated Multilateral Well
Technology",
Petroleum Engineer International, January 1996, pp. 65-69.
Sperry-sun Drilling Services Brochure "Horizontal Drilling; Multilateral and
Twinned Wells",
copyright 1993, Sperry-Sun Drilling Services Inc..
U.S. 4,020,901 to Piso et al
U.S. 4,022,279 to Driver
U.S. 4,160,481 to Turk et al
U.S. 4,257,650 to Allen
U.S. 4,379,592 to Vakhnin et al
U.S. 4,434,849 to Allen
U.S. 4,442,896 to Reale et al

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U.S. 4,458,945 to Ayler et al
U.S. 4,463,988 to Bouck et al
U.S. 4,519,463 to Schuh
U.S. 4,595,239 to Ayler et al
U.S. 4,611,855 to Richards
U.S. 4,753,485 to Goddhart
U.S. 4,982,786 to Jennnings Jr.
U.S. 5,115,872 to Brunet et al
U.S. 5,123,488 to Jennings Jr.
U.S. 5,311,936 to McNair et al
U.S. 5,330,007 to Collins et al
U.S. 5,394,950 to Gardes
U.S. 5,425,429 to Thompson
U.S. 5,427,177 to Jordan Jr. et al
U.S. 5,435,392 to Kennedy et al
U.S. 5,458,199 to Collins et al
U.S. 5,458,209 to Hayes et al
U.S. 5,474,131 to Jordan, Jr. et al
U.S. 5,477,293 to Jordan, Jr. et al
U.S. 5,526,880 to Jordan, Jr. et al
U.S. 5,533,573 to Jordan, Jr. et al
However, practice of the methods and apparatus disclosed by the foregoing art
is expensive and


CA 02287944 1999-11-O1
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requires the employment of complicated mechanisms and procedures. The
construction of a network of
horizontal well-bores according to the foregoing art, requires that all well-
bores must communicate by
physically intersecting or connecting. By communicate, it is meant that
fluids, either gas or liquid, which
enter one well-bore in the network, may flow or drain to another well-bore in
the network. By intersecting
or connecting, it is meant that each well-bore is directly joined or coupled
to: (i) at least one other
horizontal well-bore to form a continuous bore hole composed of such joined or
coupled well-bores, or (ii)
a common shared vertical section.
Due to limitations in drilling technology, the area of the reservoir that can
be accessed and
produced through the practice of current multi-well technology is limited.
Also the efficient employment of
these technologies to form a network of communicating horizontal wells usually
requires that the entire
network be constructed before employing the network to produce substances from
the target reservoir. In
most cases the construction of the network in phases, while physically
possible, is usually not economic.
Other technologies disclosed by the art attempt to overcome these limitations
by disclosing
intersecting well-bores drilled separately from different locations. See:
U.S. 3,386,508 to Bielstein et al
U.S. 3,513,913 to Bruist
U.S. 3,892,270 to Lindquist
U.S. 3,986,557 to Striegler
U.S. 4,007,788 to Striegler
U.S. 4,016,942 to Wallis, Jr. et al
U.S. 4.037,658 to Anderson
U.S. 4,220,203 to Steeman
U.S. 4,368,781 to Anderson
U.S. 4,390,067 to Willman
U.S. 4,442,896 to Reale
U.S. 4,511,000 to Mims


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U.S. 4,532,986 to Mims et al
U.S. 5,016,710 to Renard et al
U.S. 5,074,360 to Guinn
U.S. 5,402,851 to Baiton
U.S. 5,450,902 to Mathews
This allows the network of wells to be formed in phases. However this still
requires that the well-
bores must connect or intersect. In practice, this has proven expensive and
difficult to implement. What is
required is an alternative method that will allow a large area of a
subterranean reservoir to be accessed
through and affected by a network of horizontal well-bores without:
(i) using complex and expensive drilling, completion and production equipment
and
techniques;
(ii) having to intersect or connect each well-bore with the other well-bores
in the network;
(iii) having to equip and operate each well-bore separately; and
(iv) having to construct the entire network immediately before being able to
utilize any portion
of the network.
U.S. 4,522,260 to Wolcott, Jr. teaches the formation of a network of
horizontal well-bores and the
use of explosives detonated in such well-bores in order to rubblize the solid
material comprising the
reservoir. Wolcott teaches that the rubblizing of the formation creates
improved permeability in the
reservoir, thereby allowing fluids to more readily flow or drain from the
reservoir into the wells. However,
the rendering of a solid or consolidated reservoir matrix into an
unconsolidated matrix, would not provide a
sufficient enhancement to the ability of liquids to flow through the
reservoir. Those skilled in the art will
realize that in order for liquids to flow efficiently through a subterranean
reservoir, a channel or conduit
must exist or be created.
Furthermore, much of the world's heavy crude oil and bitumen deposits are
found in reservoirs
comprised of unconsolidated materials, such as oil sands. The instability of
the reservoir matrix in these
situations makes the application of Wolcott impossible. Those skilled in the
art will also realize that the
method taught by Wolcott would be difficult to apply to a thin reservoir. For
example, in the Wabasca Area
of Alberta, Canada, heavy crude oil has been found and produced from
reservoirs less than 6 metres in


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thickness. The detonation of any significant amount of explosive in such a
thin reservoir would risk
rupturing the impermeable layers of rock which underlie and overlay the
reservoir.
The practice of Wolcott in a reservoir comprised of consolidated materials,
would result in the
collapse of substantial portions of the horizontal sections of the well-bores
comprising the network of wells
formed according to this method. This is a natural result of transforming the
consolidated reservoir matrix
into an unconsolidated matrix.
Finally Wolcott does not teach any method of reducing the cost and
environmental impact of
producing fluids from a reservoir through a network of wells. Wolcott does not
prescribe using less than
all wells in the network to produce fluids from the reservoir. Wolcott refers
to the application of methods
known in the art to accomplish such production of fluids.
It is well known in the art, that the use of vertical or horizontal wells to
produce fluids from
a subterranean formation comprised of unconsolidated material, will frequently
result in the production of
solid material from the formation with the fluid. In many instances this has
been observed to result in the
formation of conduits within the formation. It is believed that the formation
of such conduits can extend the
area of the formation affected by an individual well. By conduit, it is meant
that a channel or passage is
created within and relatively free of the solid material which comprises the
subterranean formation. See:
Smith, G. E., "Fluid Flow in Heavy Oil Reservoirs Under Primary Depletion and
Their Apparent
Enhanced Permeability", Presented at the SEGISIAM/SPE Conference entitled,
Mathematical and
Computations Methods In Seismic Exploration and Reservoir Modeling, held
January 21-24,
1985, in Houston Texas, USA
Smith, G. E., "Sand Production By Gross Formation Failure", Presented at the
CIM Lloydminster
Heavy Oil Seminar, held November 5, 1985, in Lloydminister, Alberta, Canada.
Squires, A., "Inter-well Tracer Results and Gel Blocking Program Clearwater
Reservoir, Elk Point,
Alberta", Presented at the Canadian Heavy Oil Association Tenth Annual Heavy
Oil & Oil Sands
Technical Symposium, March 9, 1993
The formation of such conduits can greatly extend the area of the reservoir
which can be accessed and
affected by the wells connected to such conduits. However, conduits formed in
the manner described in
the foregoing art are unreliable, as the direction, extent and stability of
such conduits cannot be controlled
or maintained. Furthermore, as disclosed in the foregoing articles, the
uncontrollable nature of such
naturally formed conduits can be detrimental to the production of hydrocarbons
from a reservoir.


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It is also well known in the art, that one of the major problems encountered
in drilling a horizontal
well, is the loss of circulation. This occurs when large volumes of drilling
fluid escape into the formation
being penetrated by the drill string. When drilling a horizontal well in the
vicinity of existing well-bores
which are being produced or have been produced, the loss of circulation is
common. Frequently the
production of fluids from existing offsetting wells must be temporarily
suspended while drilling operations
of the new well are under way, in order to mitigate the possibility of loss of
circulation occurring, or the
contamination of offsetting producing wells with drilling fluid.
It is an objective of the apparatus and process described herein to take
advantage of both of the
foregoing phenomena, by teaching the construction and operation a network of
communicating horizontal
wells without requiring the employment of complex equipment and processes, and
without the need for
such wells to intersect. Such a method and apparatus has particular
application in the production of
heavy viscous fluids such a bitumen and heavy crude oil. Such a method and
apparatus could also be
applied in the production of solid minerals using a wash or leaching process.
Summary of the Invention
In accordance with the present invention, a method and apparatus is provided
for producing fluids
from a large area of a subterranean formation through a network of individual
horizontal well-bores
without:
(i) using complex and expensive drilling, completion and production equipment
and
techniques to form, operate and maintain such network;
(ii) having to intersect or connect each well-bore with the other well-bores
in the network;
(iii) having to equip and operate each well-bore separately; and
(iv) having to construct the entire network immediately before being able to
utilize any portion
of the network.
The method comprises the steps of: (i) forming a main well-bore having a
horizontal section that
is located within the formation; (ii) completing and equipping the main well-
bore to produce fluids from the
formation; (ii) forming one or more additional and separate horizontal well-
bores such that the horizontal
section of each such additional well-bore is in fluid communication with the
horizontal section of the main
well-bore without intersecting or connecting with such main well. Only the
main well-bore is initially
completed and equipped to produce fluids. However the additional well-bores
may be completed to the


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extent required by government regulation, the art and conditions within the
formation. Initially, the
additional well-bores are not equipped. The well-bores of these additional or
conduit wells act as artificial
conduits within the reservoir facilitating the flow of fluids through the
reservoir to the well-bore of the main
well. By fluids it is meant to include gaseous or liquid substances contained
or introduced into a
subterranean reservoir or substances contained in the reservoir which can be
rendered into a gaseous or
liquid phase in-situ within the reservoir, including bitumen, crude oil, heavy
crude oil or natural gas.
If the main well-bore fails and can no longer be used to produce substances
from the formation,
one or more of the additional well-bores may be equipped to produce substances
from the formation. In
such event the additional well-bore so equipped replaces the main well-bore in
function and apparatus. It
to is also possible that in certain applications of the foregoing described
process and apparatus, that more
than one but not all wells comprising the network, may be completed, equipped
and operated in the
production of substances from the subterranean formation.
Once the main well-bore has been formed, additional well-bores are formed in
sequence. In one
embodiment, each additional well-bore is formed such that the horizontal
section of such additional well-
bore is formed towards or in the direction of the horizontal well-bore of the
main well-bore or the horizontal
section of an existing additional well-bore which is already in fluid
communication with the main well-bore.
Prior to and during the forming of an additional well-bore production of
fluids from the formation through
main well-bore commences and continues. Fluid communication with the main well-
bore is determined
when drilling fluid being used to form the additional well-bore appears in the
fluid being produced from the
main well-bore. When this happens loss of circulation in the additional well-
bore has or is occurring and
further construction of the additional well-bore ceases. To ensure that fluid
communication is achieved
between the main well-bore and the additional well-bore during the forming of
the additional well-bore, it is
advisable to produce fluids from the main well-bore for a period of time
before commencing to form the
additional well-bore.
Where fluid communication between the main well-bore and the additional well-
bore, cannot be
achieved during the forming of the additional well-bore, then the drilling of
the additional well-bore should
continue until the horizontal section of the additional well-bore, overlaps or
crosses over the horizontal
section of the main well-bore or the horizontal section of any existing
additional well-bore which is already
in fluid communication with the main well-bore. By crosses over, it is meant
that the well-bore of the
additional well crosses through the vertical plane in which the horizontal
section of the main well
approximately lies, without intersecting the horizontal section of the main
well. By overlaps, it is meant
that the well-bore of the additional well lies approximately in the vertical
plane in which the horizontal
section of the main well approximately lies, without intersecting the
horizontal section of the main well.


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Where such overlapping or crossing occurs without fluid communication
occurring during the
forming of the additional well-bore, then communication between the additional
well-bore and the main
well-bore must be established by the application of means know in the art.
This could include the use of
techniques such as hydraulic fracturing, perforation or jet washing of a
portion of the material comprising
the reservoir lying between the horizontal section of the additional well-bore
and horizontal section of
either the main well-bore or an existing additional well-bore which is already
in fluid communication with
the main well-bore.
In this manner a large area of the formation may be accessed and produced
through a single
horizontal well-bore, in communication with a network of horizontal wells,
which can be expanded over
to time or created at once in a shorter period of time. Similarly such a
network of communicating horizontal
well-bores formed in this manner, may be utilized to inject solvents, heat
bearing fluids, reactive fluids or
leaching fluids into a formation and produce back such fluids and substances
from the formation, through
the main well-bore. In this situation, the main well-bore is completed and
equipped to both inject and
produce fluids from the formation, although in some applications it may not be
desirable or necessary to
complete and equip such well-bore to inject fluids. The additional well-bores
when formed are initially
completed and equipped to inject fluids only. Conduct of the fluid injection
process can proceed
simultaneously through all well-bores or sequentially depending on the nature
of the injection fluid and
desired result of the fluid injection. The conduct of the injection/production
process is continuous until the
economic limit for production of fluids from the reservoir is reached. Where
the additional well-bores are
not initially equipped for the production of substances from the formation,
only a small permanent well site
may be required at the surface location of each additional well-bore. Where it
is not necessary or
desirable to access the horizontal section of the additional well-bores
subsequent to the forming of the
additional well-bores, it may be possible to complete the horizontal section
of each additional well-bore
and abandon the build and vertical sections of the additional well-bores. This
would eliminate the need to
construct or maintain a permanent well site for each additional well-bore.
Even where a permanent well
site is constructed and maintained for the additional well-bores, these wells
may n,ot require permanent all
weather access roads.
The elimination of permanent well sites and access roads and the reduction of
the size of the of
the permanent well site is of significant benefit to the environment. For
example, in northern muskeg or
tundra bearing terrain, the cost and environmental impact of producing heavy
crude oil and bitumen
through the drilling and operating of a network of wells, can be reduced by
drilling the additional well-bores
and accessing the wells sites for such well-bores, in the winter over frozen
ground. Only the main well-
bore, as it is the producing well-bore for the network, requires permanent
access and a large permanent
well site.


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Further environmental benefits can be achieved in terms of the reduction in
green house gas
emissions. For example in the production of heavy crude oils or bitumen, small
amounts of methane and
other gases are produced at the well site, in conjunction with the oil being
extracted from the reservoir.
These gases are frequently vented to the atmosphere, as they do not occur in
large enough quantities at
any individual well site to physically collect and recover. By producing a
heavy oil or bitumen bearing
reservoir utilizing a single producing well communicating with a network of
wells, the volume of gas
production, which is linked to the volume of oil production, can become
significant enough to enable the
recovery and conservation of the gas. Similarly well site production equipment
frequently incorporates
heaters and other devices which burn hydrocarbon fuel. The use of a single
well to produce a network of
communicating well bores, reduces the amount of C02 being emitted by reducing
the number of smaller
less efficient well site burners. Utilizing a single well site with larger
more energy efficient production
equipment should achieve greater fuel efficiency per barrel of heavy oil, or
bitumen produced. Additional
green house gas reductions can be achieved, where fluids produced from the
reservoir and collected on
the surface, such as heavy crude oil or bitumen, must be transported by truck
from the point of production,
to a remote facility for further processing or sale. Utilizing a single well
to produce and collect fluids from a
network of communicating wells reduces the distance and trucking time required
to gather and transport
fluids produced from the network
Therefore the application of this invention enables a large area of a
subterranean formation to be
accessed and produced at reduced capital, operating and environmental costs.
Brief Descrilation of the Drawings
FIG. 1 shows, by side view, the approximate geometry of a simple horizontal
well network formed
in accordance with the present invention, where the two horizontal well-bores
do not overlap;
FIG. 2 shows, by side view, the approximate geometry of a simple horizontal
well network formed
in accordance with the present invention, where the two horizontal well-bores
overlap but do not intersect;
FIG. 3 shows, by overhead view, the approximate geometry of a simple
horizontal well network
formed in accordance with the present invention, where two horizontal well-
bores communicate with the
main producing well-bore, but do not overlap or intersect with the main
producing horizontal well-bore;
FIG. 4 shows, by side view and cross section, the approximate geometry of a
simple horizontal
well network formed in accordance with khe present invention, where two
horizontal well-bores cross over
but do not intersect with a main producing horizontal well-bore;


CA 02287944 2004-12-03
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F1G. 5 shows, by overhead view, the approximate geometry of a horizontal nreti
network formed in
accordance with the present invention, where sixteen horizontal well-bores
communicate with the main
producing well=bore, but do not intersect with the main producing horizontal
well-bore;
FiG. 6 shows, by side view, the approximate geometry of a simple horizontal
well network formed
in.2ccordance with the present invention, where three horizontal well-bores
communicate with the main
producing well-bore, but do not intersect with the main producing horizontal
well-bore and one of the well-
bores communicates indirectly with the main producing well-bore through the
other well-bore;
FIG. 7 shows, by overhead view, the approximate geometry of the simple
horizontal well network
represented in FiG.,6; ~
t0 FIG. 8 shows, by side view, the approximate geometry of a simple ho~~zontal
well network formed
in accordance with.the present invention, where three horizontal well-bores
communicate with the main
producing well-bore, but do not intersect with the main producing horizontal
well-bore and one of the well-
bores communicates indirectly with, the main producing well-bore through the
other well-bore and all of the
welt-bores have been formed with the same approximate alignment;
FIG. 9 shows, ~by overhead view, the approximate geometry of the simple
horizontal well network
represented in FIG. 8;
F1G. 10 shows, by overhead view, the approximate geometry. of a horizontal
well. network formed
in accordance with the present invention, where one horizontal well-bore
communicates directly with the
main producing well-bore and there horizontal well-bores communicate
indirectly with the main producing
well-bore, and none of the well~bores intersect;
Vllhile this invention is susceptible of embodiment in many~different fomns,
there is shown in the
drawings, and will herein be described in detail, several specific embodiments
of the invention. It should
be understood, however, that the ,present disclosure is to be considered an
exemplification of the
principles of the invention and is not intended. to limit the invention to any
~ specific embodiment so
described.
Referring to FIG. 1 there is illustrated a single horizontal main well 1
("main wells) formed in
a subterranean reservoir 10 ("target reservoir") and having a wellhead 12. The
target reservoir is
bounded by relatively impermeable upper and lower boundaries 7 and 9 and is
composted of
permeable materials containing hydrocarbons.


' CA 02287944 2004-12-03
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-13-
The target reservoir shown is eicemplary for this process. Not off reservoirs
will have this exact structure.
Those skilled in the art know that reservoirs containing hydrocarbons can vary
significantly in depth,
location, nature, composition and structure. Neither is this-invention limited
to producing hydrocarbons
from a subterranean reservoir. Those skilled in the art will appreciate that
this invention could be applied
to produce a variety of fluids contained in.a subterranean reservoir. Also
this invention could be applied fo
produce solid subterranean occurring minerals which can be dissolved in a
solvent or carried in
suspension in a fluid, or rendered capa5le of flowing by the application of
heat. .
The main well is formed from the surface 8 using means known in the art. The
vertical depth and
horizontal length of the well is dependent upon the depth, location,
composition and nature of the target
reservoir. The, vertical depth of the main well should be sufficient to allow
for placement of the
approximately horizontal section 3 of the well-bore as described hereafter.
The main well is formed so that
the approximately horizontal section of the mail well is located above the
lower boundary 9 of the target
reservoir. However the exact location of the horizontal section of the main
well within the target reservoir
will depend on the nature, depth and composition of the target reservoir, the
type of hydrocarbons
contained in the target reservoir, and the type of production process to be
used to extract such
hydrocarbons from such reservoir.
The main well is completed and equipped using means known in the art to
produce fluids from
target reservoir. The main well may be formed specifically for the
impleriientation of the process and
apparatus described herein. _ The main weU.may also be an existing well which
was initially farmed and
used for other,purposes. However the main well must be completed and equipped
to produce fluids from
target reservoir, in order to, implement, the process and apparatus taught
herein. The manner and type of
completion and equipping wilt depend on the nature, depth~and composition of
the target reservoir, type of
hydrocarbons contained in the target reservoir, and the type of production
process to be used to extract
such hydrocarbons from such reservoir. In FIG. 1, the main well is completed
to produce fluids by means
of production tubing 5 and pump 6. Other methods and forms of completion and
equipping are possible in
the practice of this invention.
Subsequent to the formation of the main well, horizontal welt 2 ("conduit
weft') is' formed through
means known in the art. The conduit well is formed from the surface 8: The
conduit well has an
approximately horizontal section The vertical depth and horizontal length of
the well is dependent upon
the depth, location, composition and nature of the target reservoir. However,
a horizontal length in
excess of 300 feet is preferred. The vertical depth of the conduit well should
be Sufficient to allow for
placement of the approximately horizontal section 4 of the well-bore as
described hereafter. The conduit
well is formed so that the approximately horizontal section 4 of the conduit
well is located above the lower
boundary 9 of the target reservoir. The exact location of the approximately
horizontal section 4 within the
target


CA 02287944 1999-11-O1
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-14-
reservoir will depend on the nature, depth and composition of the target
reservoir, the hydrocarbons
contained in the target reservoir, and the production process being used to
extract such hydrocarbons
from such reservoir. However the approximately horizontal section of the
conduit well is formed in a
direction and depth such that it is oriented towards the approximately
horizontal section 3 of the main well.
In the practice of this invention, the approximately horizontal section of the
conduit well does not
physically come into contact with or intersect the approximately horizontal
section of the main well. While
the intersection of the approximately horizontal sections of each well does
not occur, it is desirable that the
distance between the approximately horizontal section of the main well and the
approximately horizontal
section of the conduit well, be as small as possible. The greater the distance
between the approximately
horizontal well-bores, the greater the difficulty of establishing and
maintaining fluid communication
between the wells. In actual practice, the maximum acceptable distance will
depend on the nature, depth
and composition of the target reservoir, the type of hydrocarbons contained in
the target reservoir, the
conduit substances, if any, associated with such hydrocarbons in the target
reservoir, the prior production
history of such reservoir and the type of production practices to be employed
in producing hydrocarbons
using the process and apparatus taught herein.
Before and during the forming of the conduit well, the production of fluids
from the target reservoir
through the main well commences and continues. In the forming of the conduit
well, the forming of the
approximately horizontal section 4 continues until circulation of drilling
fluid is lost and drilling fluid used to
form the conduit well is produced through the main well, or it is determined
that the horizontal section 4
overlaps or has crossed the horizontal section 3 of the main well. It is
preferred that the communication of
fluids from the conduit well .to the main well be confirmed by a portion of
the drilling fluid used to form the
conduit well, being produced through the main well. In many subterranean
reservoirs, fluid communication
will occur as a result of the natural permeability of the reservoir. In a
target reservoir comprised of
unconsolidated materials in order to establish and maintain substantial fluid
communication between the
main well and the conduit well, it is recommended, that fluids from the target
reservoir be produced
through the main well, for a period of time before the forming of the conduit
well commences.
Where fluid communication is not established through the production of
drilling fluids through the
main well, during the forming of the conduit well, such fluid communication
may occur over time by
producing fluids through the main well. In such event the communication of
fluids between the main well
and the conduit well can be determined and confirmed by careful monitoring of
fluid production volumes
and rates from the main well. Fluid communication between the main well and
the conduit well should be
detected as an increase in the volume of fluid produced from the main well,
beyond that which normally
occur by the production of fluids from the main well alone, prior to the
formation of the conduit well. As
an added measure to confirm interwell fluid communication, an appropriate
tracer fluid, such as a


CA 02287944 1999-11-O1
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-15-
fluorescent dye or fluid containing a mild radioactive source, may also be
placed in the well-bore of the
conduit well, thereby confirming fluid communication between the main well and
the conduit well when the
tracer fluid is produced though the main well.
The length of time required to establish fluid communication in this manner,
will vary, depending
upon the nature, depth and composition of the target reservoir, the type of
hydrocarbons contained in the
target reservoir, and the additional substances, if any, associated with such
hydrocarbons in the target
reservoir, the prior production history of such reservoir and the type of
production practices employed in
producing hydrocarbons using the process and apparatus taught herein.
In this situation, to expedite the establishment of fluid communication, it is
recommended that the
to approximately horizontal section 4 of the conduit well be formed so that it
overlaps or crosses the
approximately horizontal section 3 of the main well. If difficulty is
encountered in obtaining fluid
communication between the approximately horizontal section 3 of main well and
the approximately
. horizontal section 4 of the conduit well, means known in the art may be
employed to facilitate fluid
communication between the two well by fracturing, displacing or removing a
portion of the solid material
I S which comprises the target reservoir and lies between the approximately
horizontal sections of the two
wells. This could include the use of techniques such as hydraulic fracturing,
perforation or jet washing.
To further expedite the establishment of fluid communication it is recommended
that the
production of fluids from the target reservoir through the main well commence
before attempting to form
the conduit well, and should continue throughout the formation of such well.
The length of time that the
20 main well should be produced before attempting to form the conduit well,
depends upon the nature, depth
and composition of the target reservoir, the type of hydrocarbons contained in
the target reservoir, and the
additional substances, if any, associated with such hydrocarbons in the target
reservoir, the prior
production history of such reservoir and the type of production practices
employed in producing
hydrocarbons using the process and apparatus taught herein.
25 In the practice of this invention, the approximately horizontal section 4
of the conduit well acts as a
conduit, thereby extending the area of the target reservoir which may be
affected and produced from and
through the main well. Therefore, the conduit well is not initially completed
and equipped to produce
substances from target reservoir. Only minimal completion work should be
performed on the conduit well,
to comply with good production practice and government regulation, and to
prevent the well-bore from
30 collapsing. However, fluids contained in the target reservoir must be able
to flow or drain into the entire
length of the approximately horizontal section of the conduit well. Therefore
if possible, this section of
the conduit well should either be left as "open hole" with no liner or
completed with a perforated liner or
other method of completion which allows fluids from the target reservoir to
flow or drain into the entire


CA 02287944 2004-12-03
i
WO 98J50679 PCTIUS97J07368
_1g-
length of such section 4. At the surface 8 the conduit well 2 is completed by
the placement of a wellhead
12 at the surface outlet of the well.
Production tubing, pumps or other production equipment are not placed in the
conduit well or on
the well site of the conduit well at this time. As a result, a smaller
permanent weA site may be maintained
for the conduit well. As stated previously, in applications vuhere it is not
necessary or desirable to access
the horizontal section of the conduit well-bore subsequent to the forming of
the conduit well-bore, it may
be possible to complete the horizontal section of the conduit well-bore and
abandon the build and vertical
sections of the conduit well-bore. This would eliminate the. need to construct
or maintain a permanent
well site for the conduit welt-bore. Those skilled in the art wit! realize
that this situation could arise where
the prior production history of the target reservoir, the nature of the fluids
, contained therein, or the
processes intended' to be applied to produce substances from the target
reservoir, require the conduit
wells only as conduits.
If. the conduit well is formed in the manner described above and the build and
vertical sections of
the conduit well are .not abandoned, should at a later point in time, it
become desirable to convert the
conduit well, into either a production of injection well, the weU may be re-
entered and the necessary
equipment and tubing installed. In the practice of this invention, this should
not be required e~ccept as
specifically stated herein, or where the main well becomes unable to produce
fluids from the target
reservoir. Where the foregoing method is util'~zeit to construct a network .of
several communicating
horizontal wells, those skilled in the art will realize that this method and
apparatus may .be practiced by
completing and equipping more thin one but less than all of the wells in the
network to produce or inject
substances from or into the target reservoir.
in FIG. 1, main well and the conduit well are in fluid communication, without
the approximately
horizontal section 3 of main well crossing ovec or overlapping the
approximately horizontal sect'ron 4 of the
conduit well. Referring to FIG. 2, in this figure, the main well 1 and the
conduit well 2 are in fluid
communication,,with the approximately horizontal section 3 of the main well
crossing over or overlapping
the approximately ho~~zontat section 4 of the conduit well.
The orientation of the approximately horizontal section - of the main well to
the approximately
ho~~zontat section of the conduit well as illustrated in FIG. 1 and FIG. 2 is
an exemplification only: In the
practice of this invention, the actual orientation wilt vary according the
limitations and requirements
imposed or dictated by surface access for drilling locations; the nature,
location and characteristics of the
target reservoir; the equipment and methods employed to form each well; prior
production methods and
apparatus used to produce substances from the target reservoir; and the type
of production processes to
be employed using the network formed by the- main well and the conduit well.


CA 02287944 2004-12-03
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-17- ,
Furthermore,.t is not required that communication between the approximately
horizontal section of
ttie main~well to the approximately horizontal section of the conduit welt
occur at the terminal ends of such
horizontal sections, as illustrated in FIG. 1 and FIG. 2. Such illustrations
are an.exemplification only.
Neither is the apparatus comprising this invention limited to only two wells.
Referring to FIG.3, there is illustrated a network comprising three wells,
with the main well 1, first
conduit well 2a and second conduit well 2b ("the conduit wells"), each being
formed from the surface of the
earth, and comprised of a vertical and curved build angle sections 15a and
15b, respectively and an
approximately horizontal section 16a and 16b, respectively. The approximately
horizontal section of each
of the three wells in the network is located within the target reservoir. The
main well is completed and
equipped for the production of substances from the target reservoir. The
conduit wells are completed only
to the extent required by government regulation and good production practice.
The conduit wells are not
equipped for the injection or production of substances into or from the target
reservoir. Thus the
approximately horizontal sections of the conduit wells act as conduits,
thereby extending the area of the
reservoir which may be affected and produced from and through the,main well.
A permanent well site 17 is constructed and maintained at the surface outlet
of the main well. Only
a small permanent well site 18 is required for the conduit wells, which pierce
the surface of the earth at the
same approximate location. As stated previously, it may also be possible to
avoid constructing or
maintaining a permanent well site for the conduit wells.
The conduit weits'were formed subsequent to the formatioh, completion and
equipping of .the
main well. Prior to and during the formation of the conduit wells, fluids are
produced from the reservoir
through the main well. The.formation of the approximately horizontal section
of each of the conduit wells
ceases when drilling fluid used to form each such approximately horizontal
section is produced through
the main well, or such approximately horizontal section crosses over or
overlaps the approximately
horizontal section 3 of the main well, which ever event first occurs.
The conduit wells may be formed from a single welt site and may be formed
sequentially in any
order, with one well being formed through conventional means imivediately upon
completion of work to
farm the first well in the pair. However the additional wells, may be formed
from separate well sites. It is
recommended that such wells be formed sequentially. -This will help facilitate
'the confirmation of fluid
corrimunicafion between each of the conduit wells and the main well. Those
skilled in the art will realize
that it may be possible to form more than two conduit wells from the same well-
site:
In ~ the example illustrated in F1G. 3; the approximately horizontal sections-
of the welts do not
overlap or cross.


CA 02287944 2004-12-03
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_18~
Referring to FIG. 4, the approximately horizontal sections 16a and 16b of the
conduit wells 2a and
2b, cross over but do not intersect with the approximately horizontal section
3 of the main well. The
approximately horizontal sections of all three wells lie within the target
reservoir. In this example, the
approximately horizontal section 16a of conduit well 2a has been formed
between the upper boundary 7 of
the target reservoir and the approximately horizontal section 3 of the main
well. The approximately
horizontal section 16b of the conduit well 2b has been formed between the
lower boundary 9 of the target
reservoir and the approximately horizontal section of the main well. In this
example the approximately
horizontal sections of the conduit wells cross over the approximately
horizontal section of the main well, at
approximately right angels. The main well has a wellhead 11.
Referring to FIG. 5, the pattern illustrated in FIG. 3 could be extended to
form a network of conduits
constructed around the main well, with multiple conduit wells formed from
small well sites 18 ("the small
well-sites), with each such conduit well consisting of vertical and curved
build angle section 15a, 15b and
an approximately horizontal section 16a, 16b. The approximately horizontal
sections of all wells shown in
F1G. 5 lie substantially in the target reservoir. The approximately horizontal
sections of the conduit wells
are in fluid communication with the approximately horizontal section 3 of the
main well. However white the
approximately horizontal sections, of the conduit wells may, cross over or
overlap the approximately .
horizontal section of the main well, they do not physically intersect or
connect with the -approximately
hoW ontat section of the main well. The conduit wells are formed in sequence
after.the formation of the
main well. Prior to and during the forming of the conduit wells substances are
produced from the target
reservoir though main well: .
Ali of the conduit wells may be formed immediately in sequence or over a
period of time. The
sequerice and timing for forming each such conduit well will vary according to
the limitations and
requirements imposed or dictated by: (i) surface access for driifing
locations; (ii) the nature, location and
characteristics of the target reservoir; (iii) the equipment and methods
employed to form each well; (iv) the
prior production methods and the apparatus previously used to produce
substances from the target
reservoir, and, (v) the production processes to be employed using the network
formed by the main well
and the conduit wells. tt is recommended that the conduit wells, be formed in
order of the proximity that
the approximately horizontal section 16a, 16b of each of the conduit wells
will have to the vertical
section/build angle section of the main well, with those wells in closest
proximity thereto being formed first.
As before, only the main well is initially completed and equipped to produce
substances from the
target reservoir. A large permanent well site 17 is constructed and maintained
for the main well.
Permanent access is also constructed to this well site. The small well sites
may be smaller than well site
17, as the conduit wells, are not initially equipped for the production of
substances from the target reservoir.
As stated previously, it may be possible to avoid constructing or maintaining
a permanent well site for the


CA 02287944 2004-12-03
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-19-
conduit wells if it is not necessary or desirable to re-enter or access the
well-bores of the conduit wells
subsequent to the forming and completion of such well-bores.
The approximately horizontal section 16a, 18b of each of the conduit wells
acts only as conduit in
the reservoir facilitating the flow of fluids contained in the reservoir to
the well-bore of the main well. As
the approximately horizontal sections of the conduit wells are in fluid
communication with the
approximately horizontal section 3 of the main well, they extend the area of
the reservoir accessed and
affected by the main well.
Fig.'s 1 through to 5 illustrate a network of two or more wells where the
approximately horizontal
section of the main well communicates directly with the approximately
horizontal section of every other
~ 0 well in the network. The main well thus utilizes the approximately
horizontal sections of all other wells in
the network as conduits, to access and affect, a larger portion of the target
reservoir. .
Referring to FIG.'s 6 and 7, it is possible to construct a network of
communicating wells achieving
the same result, without having each conduit well communicating directly with
the main well which has
been equipped to produce substances from the target reservoir.' FIG.'s 6 and 7
illustrate a network
15 consisting of three horizontal wells, with the main well 1, being formed
first, from well site 20, and
consisting of a vertical section/build angle section 22 and an approximately
horizontal section 24 located
substantially in the target reservoir. The main well is completed and equipped
for the removal of
substances from the target reservoir. Except as stated below, the main well is
placed on production for a
period of time prior to and at substantially all times during the forming of
the other wells in the network.
20 Conduit well 2 is formed after the main well, from well site 26, and
consists of a vertical section/build
angle section 28 and an approximately horizontal section 11 located
substantially in the target reservoir.
Prior to the formation of conduit well 32, the well network comprised of the
main well and conduit well 2,
looks approximately as illustrated by FIG. 1 or FIG.2, depending on whether
the approximately horizontal
sections of these wells overlap.
25 Conduit well 32 is formed after conduit well 2, from well site 34, and
consists of a vertical
sectionlbuild angle section 36 and an approximately horizontal section 38
located substantially in the
target reservoir. The forming of conduit well 32 should not commence until
fluid communication between
the approximately horizontal sections of the main well and conduit well 2, has
been establish.
When formed, the approximately horizontal section of conduit well 32 is not in
direct fluid
30 communication with the approximately horizontal section of the main well.
Fluid contained in the target
reservoir which enters the approximately horizontal section of conduit well
32, passes through the
approximately horizontal section of conduit well 2 to reach the approximately
horizontal section of the


CA 02287944 2004-12-03
WO 98/50679 ~ PCTNS97/07368
-20-
main well. Therefore the approximately horizontal section of conduit well 32,
is formed such that it is in
fluid communication with the approximately horizontal section of conduit well
2. In forming conduit well 32,
if fluid communication with conduit well 2 occurs during the forming of
conduit well 32 through the loss of
drilling fluid circulation and the production of such fluid through the main
well, production ~f fluid from the
reservoir through main well must immediately cease, to allow the forming of
conduit well 32 to continue until
the approximately, horizontal section of conduitwell 32 is formed to the
length desired. Once the formation
of conduit well 32 is complete, production of fluids through the main well
recommences
The three well network represented in FIG. 6 and FIG. 7, could also be
constructed as illustrated
in FIG. 8 and FIG. 9, with conduit well 32 formed and oriented in the
approximate same direction as conduit
well 2. If the network is constructed to reflect the illustration in FIG. 8
and F1G.. 9, conduit well 32 would be
formed as prescribed for the network illustrated in FIG. 6 and FIG. 7, save
and except that the production
of s~stances from the reservoir through the main welt does not cease if
drilling fluid used to fame conduit
well 32 is communicated to and is produced through the main well, and the
forming of conduit well 32
ceases when such communication occurs.
Referring to F1G. 6, F1G. 7, FIG. 8 and FIG. 9, initially, conduit well 2 and
conduit well 32 are not
equipped to produce substances from the target reservoir. As in, the previous
examples these wells act
only as conduits allowing a larger portion of the targetreservoir to be
accessed and affected by the main
well. ~ The conduit wells are completed to the extent required by government
regulation, the art and good
production practice. Subject to government regulafion and the production
process to be employed to
20. remove substances from the target reservoir using the well network
comprised of the three wells
represented in FIG. 6, FIG:.7, FIG. 8 arid FIG. 9, it may be possible to avoid
having to maintain permanent
surface access to well sites 20 and 34. Also it may be possible to avoid
constructing or maintaining
permanent well sites for the conduit wells if it is not necessary or desirable
to re-enter or access the well-
bores of the conduit wells subsequent to the forming and completion of such
well-bores.
The network of wells represented by the illustrated in F1G. 8, FIG. 7, FIG. 8
and FIG. 9 can be
further extended subsequent to the forming of conduit well 32, by the forming
of additional wells in the
manner of conduit well 32, with each additional well indirectly communicating
with the main well, through
the approximately horizontal sections of the wells in the network formed
previously. The extension of the
network in this manner can take a variety of forms. Illustrated in FIG. 10 is
one hypothetical network of
wells formed in this manner. The main well 1 is formed from permanent well
site 40 and is equipped to
produce substances from the target reservoir. Conduit wells 42, 44, 46 and 48
are formed from well sites
50, 52, 54 and 56, respectively. The conduit wells are not initially equipped
to produce substances from the
target reservoir. The approximately horizontal section 58 of conduit well 42
is in fluid communication with
the approximately horizontal section 60 of the main well. The approximately
horizontal section 62 of conduit


CA 02287944 2004-12-03
WO 98/50679 ' PCT/US97/07368
-21 -
well 44 is in fluid communication with the approximately horizontal section of
conduit well 42 and
therefore in indirect fluid communication with the approximately horizontal
section of the main well. The
approximately horizontal section 64 of conduit well 46 is in fluid
communication with the approximately
horizontal section of conduit well 44 and therefore in indirect fluid
communication with the approximately
horizontal section of the main well through the approximately horizontal
sections of conduit wells 42 and
44 respectively. The approximately horizontal section 66 of conduit well 48 is
in fluid communication with
the approximately horizontal section of conduit well 46, and therefore in
indirect fluid communication with
the approximately horizontal section of the main well through the
approximately horizontal sections of
conduit wells 42, 44 and 46 respectively.
The well networks illustrated and described herein represent only a small
number of the possible
networks of communicating wells which may be constructed .and operated in the
manner described herein.
Those skilled in the art will realize that it is possible to construct a
significantly larger variety of patterns
and layouts using the foregoing described methods and apparatus.
. A network of communicating' wells constructed in the fashion described
herein may be used to
apply a variety of production processes known in the art. For example,
referring to all of the figures
attached hereto, in a target-reservoir containing crude oil which can be
produced only by the employment
of artificial lift technologies, the main well is the only well in the network
which is equipped with artificial lift
equipment. This invention may also be practiced by equipping and operating
more than one, but less than
all wells in the network.
In a .target reservoir containing heavy crude oil or bitumen which can only be
produced by the
injection of steam or other fluids into the reservoir in order to mobilize
the. viscous oil contained therein, the
main well may be completed and equipped to both inject and produce substances
from the target
reservoir. In the previous examples, all wells in the network other than main
well act merely conduits to
extend the area of the ,reservoir affected and accessed by the main welt:
Those skilled in the art will
realize the possible uses of a network of communicating horizontal well-bores
formed and operating in this
matter.
One of the unique advantages of this invention is the production of a large
area of a target
reservoir, using, a number of horizontal wells simultaneously as a network of
communicating well-bores,
without the necessity equipping each well to produce substances from the
reservoir. This can reduce the
cost of producing substances from the target reservoir. Further cost savings
can be achieved in
applications where it is, not necessary or desirable to access the
approximately ho~~zontat section of a
conduit well subsequent to the forming of such well. In these situations it
may be possible to complete the
approximately-horizontal section of such conduit well and abandon the build
and vertical section of such


CA 02287944 1999-11-O1
WO 98/50679 PCT/US97/07368
_22_
well. This would eliminate the need to construct or maintain a permanent well
site for such conduit well.
However if the build and vertical section of the conduit well are not
abandoned it may be possible
to quip the conduit well to inject or produce substances to or from the target
reservoir, at a future point in.
For example should the main well fail or become disabled beyond the point of
economic repair, one of the
conduit wells in the network could be equipped to replace the main well as the
well used to inject or
produce substances to or from the reservoir.
As a further embodiment of this invention, it is possible to employ a network
of communicating
horizontal wells formed in the manner described above, to produce substances
from a target reservoir
using any process that involves the injection of fluids into the reservoir,
and the production of fluids from
the reservoir, in a cyclic fashion. The first well formed is completed and
equipped as taught above, to both
inject substances into and produce substances from the target reservoir.
Additional wells formed as part
of the network are not initially equipped to produce substances from the
reservoir. However the
additional wells could also be equipped as injection wells as they are formed.
This would allow the
injection a larger amount of fluid into the reservoir over a larger area of
the reservoir, than could be
accessed by a single injection well.
The exact manner of operation of the well network constructed in this fashion
will vary, depending
on the limitations and requirements imposed or dictated by the composition,
location and characteristics of
the target reservoir; the type of substances contained in the target
reservoir; prior production methods and
apparatus used to produce substances from the target reservoir; and the type
of production processes to
be employed using the network. Many variations are possible. However as one
example to illustrate the
principles outlined in this regard, a network of communicating wells
constructed as represented in FIG. 5,
could be used to conduct a cyclic steam stimulation process to produce heavy
viscous fluids, such as
bitumen or heavy crude oil, from the target reservoir. To accomplish this, the
network would be
constructed in the manner described above, with the additional steps of: (i)
equipping the main well to both
inject substances inta and produce substances from the target reservoir; and
{ii) equipping the conduit
wells to inject substances into the target reservoir. In operating the
network, steam would be injected
through ail wells in the network simultaneously using means known in the art,
without any production of
fluids from the reservoir occurring during such injection phase. Upon
cessation of such steam injection,
with such period of injection and the point of cessation being determined in
accordance with injection
practices known in the art, all wells in the network would be shut in for a
period of time to allow heat from
the injected steam to be distributed through the reservoir and the previously
viscous fluids contained
therein. The length of this "soak" period would be determined according the
practice for this production
technique, as known in the art. Upon cessation of this "soak" period, the
production of fluids from the
reservoir, through the main well would commence and continue until it became
economically or physically


CA 02287944 1999-11-O1
WO 98/50679 PCT/US97/07368
-23-
impractical to continue such fluid production. This would be determined
according to the practices known
in the art for the conduct of cyclic steam injection processes. At this point
the cycle of injection, "soak"
and production would be repeated.
The practice of this invention in this manner allows for a larger area of the
target reservoir to be
affected and produced through a network of communicating wells, without all
wells in the network having
to be equipped to both inject and produce substances from the target
reservoir. Further, the wells in the
network which are equipped only to inject fluids into the reservoir, will
generally require a smaller
permanent well site than wells which are equipped to produce fluids as well.
The initial equipping of any
well in the network only as an injector, does not preclude re-equipping an
such well at a later point in time
as both a producer and injector.
This embodiment could be practiced with more than one but less than all wells
in the network
being equipped and operated to produce fluids from the target reservoir. Also
this embodiment could be
practiced by injecting fluids other than or in addition to steam.. This could
include fluids, at various
temperatures, in liquid, gaseous or multiphase form, such as a hydrocarbon, a
solvent, water, carbon
dioxide, an acid, a base, a solution, a leaching fluid or a fluid containing a
solid held in suspension, or a
mixture of two or more substances from within such group. The type,
temperature and state of the fluid
selected as the injection fluid will depend upon the nature, depth and
composition of the target reservoir,
and the type of substances contained in the target reservoir to be produced as
a result of such fluid
injection. Means of making such selection are well known in the art. With the
injection of a variety of
2o fluids being possible, those skilled in the art will realize that this
embodiment could be practiced to produce
a variety of hydrocarbons contained in a subterranean reservoir. Those skilled
in the art will also realize,
that it is possible to use a network of approximately horizontal well-bores
formed in the manner of this
invention, to produce solid minerals contained in a subterranean formation,
which can be dissolved or
reduced to solution or suspension.
In summary, this invention comprises a method of and apparatus for producing
fluids from a
subterranean formation containing such fluids comprising the steps of:
a) forming a well-bore having a horizontal section that is located within the
formation and
completing and equipping the well-bore so that fluids contained in the
formation can be produced from the
formation through the well-bore;
b) producing fluids from the formation through such well-bore and preferably
while producing
such fluids, forming at least one additional well-bore having a horizontal
section that is located within the
formation, such that the horizontal section of the said at least one
additional well-bore is in fluid


CA 02287944 1999-11-O1
WO 98/50679 PCT/US97/07368
-24-
communication with the well-bore formed pursuant to step (a) without
intersecting with such well-bore; and
c) at least completing but not equipping the at least one additional well-
bore, and
using such at least one additional well-bore as an conduit within the
formation to allow and cause fluids
contained in the formation which drain or flow into such at least one
additional well-bore to flow to and be
produced through the well-bore formed pursuant to step (a) above.
d) repeating steps (b) and (c) by forming, completing and utilizing further
additional
well-bores as conduits within the formation to allow and cause fluids
contained in the formation which
drain or flow into such further additional well-bores to flow to and be
produced formed the well-bore
formed pursuant to step (a) above.
This network of communicating horizontal well-bores can used to produce
substances
through a cyclic injection and production process, by including the additional
step of equipping all well-
bores, for the injection of fluids into the formation and utilizing said well-
bores to simultaneously inject
fluids into the formation, in order to mobilize fluids contained in the
formation. In the practice of this
invention more than one, but less than all wells, may be equipped to produce
fluids from the reservoir.
From the foregoing description, it will be observed that numerous variations,
alternatives and
modifications will be apparent to those skilled in the art. Accordingly, this
description is to be construed as
illustrative only and is for the purpose of teaching those skilled in the art
the manner of carrying out the
invention. Various changes may be made in the shape, materials, size and
arrangement of parts.
Moreover, equivalent techniques and steps (taken individually or together) may
be substituted for those
illustrated and described. Also certain features of the invention may be used
independently of other
features of the invention. For example, the present invention is not limited
to production of hydrocarbons
but could be used to produce any substance contained within a subterranean
formation which could
otherwise be produced from a bore-hole formed from the surtace of the earth.
The present invention
could be used to produce minerals which could be extracted using horizontal
wells and a wash or leaching
process. Also those embodiments of the present invention which facilitate the
injection of substances or
include the use of any injection fluid or substance suspended in a fluid which
would be desirable to use in
a process to produce substances from a subterranean formation. Reference to
any specific application of
the invention described above, is by way of example only. In applying the
process of the invention,
consideration must be given to: (i) the type, location and composition of the
target reservoir; (ii) the type
and composition the substances being sought, contained in such reservoir;
(iii) any prior production
methods and apparatus previously used to produce substances from the target
reservoir; and (iv) the type
of production processes to be employed using the network of wells. Thus, the
present invention should
not be limited by the details specified or by the specific embodiments chosen
to illustrate the invention or


CA 02287944 2004-12-03
-25-
the drawings attached hereto. Thus, it wilt be appreciated that such
modifications, alternatives, variations.
and changes maybe made withouf departing from the spirit and scope of the
invention as defined in the
appended claims.

A single figure which represents the drawing illustrating the invention.

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Admin Status

Title Date
Forecasted Issue Date 2006-03-21
(86) PCT Filing Date 1997-05-01
(87) PCT Publication Date 1998-11-12
(85) National Entry 1999-11-01
Examination Requested 2002-03-20
(45) Issued 2006-03-21
Lapsed 2016-05-02

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Filing $300.00 1999-11-01
Maintenance Fee - Application - New Act 2 1999-05-03 $100.00 1999-11-01
Maintenance Fee - Application - New Act 3 2000-05-01 $100.00 2000-03-23
Maintenance Fee - Application - New Act 4 2001-05-01 $100.00 2001-05-01
Request for Examination $400.00 2002-03-20
Maintenance Fee - Application - New Act 5 2002-05-01 $150.00 2002-04-12
Maintenance Fee - Application - New Act 6 2003-05-01 $150.00 2003-04-24
Maintenance Fee - Application - New Act 7 2004-05-03 $200.00 2004-04-23
Maintenance Fee - Application - New Act 8 2005-05-02 $200.00 2005-04-25
Registration of Documents $100.00 2005-12-16
Final Fee $300.00 2005-12-16
Maintenance Fee - Patent - New Act 9 2006-05-01 $200.00 2006-04-18
Maintenance Fee - Patent - New Act 10 2007-05-01 $250.00 2007-04-17
Maintenance Fee - Patent - New Act 11 2008-05-01 $250.00 2008-04-17
Maintenance Fee - Patent - New Act 12 2009-05-01 $250.00 2009-04-17
Maintenance Fee - Patent - New Act 13 2010-05-03 $250.00 2010-04-19
Maintenance Fee - Patent - New Act 14 2011-05-02 $250.00 2011-04-18
Maintenance Fee - Patent - New Act 15 2012-05-01 $450.00 2012-04-17
Maintenance Fee - Patent - New Act 16 2013-05-01 $450.00 2013-04-17
Maintenance Fee - Patent - New Act 17 2014-05-01 $450.00 2014-04-28
Current owners on record shown in alphabetical order.
Current Owners on Record
BP CORPORATION NORTH AMERICA INC.
Past owners on record shown in alphabetical order.
Past Owners on Record
AMOCO CORPORATION
BP AMOCO CORPORATION
CHERNICHEN, MICHAEL D.
HASSAN, DAVID J.
JENSEN, EARL M.
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.

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Cover Page 2006-02-22 1 53
Representative Drawing 1999-12-23 1 12
Description 1999-11-01 25 1,384
Abstract 1999-11-01 1 57
Cover Page 1999-12-23 1 62
Claims 1999-11-01 4 156
Drawings 1999-11-01 8 146
Description 2004-12-03 25 1,421
Claims 2004-12-03 4 174
Drawings 2004-12-03 8 140
Representative Drawing 2005-06-08 1 17
Correspondence 1999-12-01 1 2
Assignment 1999-11-01 4 141
PCT 1999-11-01 19 767
Correspondence 1999-12-16 1 2
Assignment 2000-01-20 3 154
Correspondence 2000-02-25 1 1
Prosecution-Amendment 2002-03-20 1 31
Prosecution-Amendment 2002-06-05 1 23
Correspondence 2003-04-10 18 571
Prosecution-Amendment 2004-07-08 2 63
Prosecution-Amendment 2004-12-03 21 861
Correspondence 2005-12-16 1 39
Assignment 2005-12-16 2 42
Correspondence 2006-01-16 1 16