U.S. patent application number 14/837495 was filed with the patent office on 2016-03-03 for hydraulically unitary well system and recovery process (huwsrp).
The applicant listed for this patent is CENOVUS ENERGY INC.. Invention is credited to Arun SOOD, Alvin WINESTOCK.
Application Number | 20160061014 14/837495 |
Document ID | / |
Family ID | 55401928 |
Filed Date | 2016-03-03 |
United States Patent
Application |
20160061014 |
Kind Code |
A1 |
SOOD; Arun ; et al. |
March 3, 2016 |
HYDRAULICALLY UNITARY WELL SYSTEM AND RECOVERY PROCESS (HUWSRP)
Abstract
The present disclosure describes a method of recovering viscous
hydrocarbons from a subterranean formation using a gravity
dominated recovery process with a group of wells, the recovery
process incorporating an interwell recovery phase. The group of
wells is initially operated independently to establish hydraulic
communication between two or more wells in the group. Once
hydraulic communication is established, injection of mobilizing
fluid and production of hydrocarbons continues in at least one well
within the group with an excess amount of mobilizing fluid being
injected into the well. At the same time, production only continues
in at least one well within the group, without any injection of
mobilizing fluid. The wells in the group are spaced closer together
than in conventional recovery processes. The recovery process may
be SAGD.
Inventors: |
SOOD; Arun; (Calgary,
CA) ; WINESTOCK; Alvin; (Calgary, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CENOVUS ENERGY INC. |
Calgary |
|
CA |
|
|
Family ID: |
55401928 |
Appl. No.: |
14/837495 |
Filed: |
August 27, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62043170 |
Aug 28, 2014 |
|
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|
Current U.S.
Class: |
166/270.1 ;
166/268; 166/272.3 |
Current CPC
Class: |
E21B 43/2408 20130101;
E21B 43/30 20130101; E21B 43/16 20130101 |
International
Class: |
E21B 43/16 20060101
E21B043/16; E21B 43/30 20060101 E21B043/30; E21B 43/24 20060101
E21B043/24 |
Claims
1. A method of producing viscous hydrocarbons from a subterranean
formation using a group of wells, comprising the steps of: i.
providing two or more wells within a formation, each well having an
injection means and a production means; ii. independently operating
a predominantly gravity-dominated recovery process at each of the
two or more wells, the recovery process comprising injecting a
first amount of a mobilizing fluid through the injection means into
the formation, to mobilize the viscous hydrocarbons in the
formation, and substantially concurrently producing the mobilized
hydrocarbons through the production means; iii. forming fluid
chambers adjacent each of the two or more wells in the reservoir as
the mobilized hydrocarbons are produced; iv. establishing hydraulic
communication between the fluid chambers for at least two of the
two or more wells to form a cluster of wells; v. continuing
injection and production from at least one of the two or more wells
in the cluster and ceasing injection and continuing production from
at least one of the two or more wells in the cluster, wherein the
injection of mobilizing fluid in the at least one well in the
cluster is a second amount of mobilizing fluid, greater than the
first amount of mobilizing fluid; and wherein the two or more wells
are spaced sufficiently close to establish fluid communication
between the two or more wells.
2. The method of claim 1 further comprising ceasing injection and
continuing production at the at least one well within the cluster
in step (v) that continued both injection and production, and
reinitiating injection of the mobilizing fluid and continuing
production at the at least one well within the cluster in step (v)
that ceased injection of the mobilizing fluid.
3. The method of claim 1 further comprising the step of ceasing
injection of a mobilizing fluid into the at least one well in the
cluster, and injecting a non-condensable gas through the at least
one well in the cluster while continuing production at the at least
one other well in the cluster.
4. The method of claim 1 wherein the cluster of wells is operated
as a hydraulic unit.
5. The method of claim 1 wherein the wells in the cluster are
spaced so that infill wells are not required.
6. The method of claim 1 wherein the recovery process is steam
assisted gravity drainage (SAGD) and the two or more wells within
the formation are selected from the group consisting of SAGD well
pairs or single vertical, inclined, or horizontal SAGD wells.
7. The method of claim 1, wherein the mobilizing fluid is steam,
hot water, light hydrocarbon, solvent, surfactant, non-condensing
gas, or mixtures thereof.
8. The method of claim 7 wherein the solvent is one or more of a C3
to C10 solvent or hexane, or wherein the non-condensing gas is a
light hydrocarbon or an oxygen containing gas.
9. The method of claim 1 wherein the injecting and/or producing is
done on a continuous or interrupted basis.
10. The method of claim 1 wherein the viscous hydrocarbons are
selected from the group consisting of bitumen, heavy oil, and
unmobilized hydrocarbons.
11. A method of producing viscous hydrocarbons from a subterranean
formation using a group of wells, comprising the steps of: i.
providing two or more wells within a formation, each well having an
injection means and a production means, the injection means being
positioned in the well closer to the surface than the production
means; ii. independently operating a predominantly
gravity-dominated recovery method in the two or more wells
comprising the steps of injecting a first amount of a mobilizing
fluid through the injection means into the formation, to mobilize
the viscous hydrocarbons; and substantially concurrently producing
the mobilized hydrocarbons through the production means, wherein
producing the mobilized hydrocarbons forms fluid chambers in the
formation adjacent each of the two or or more wells; iii.
establishing hydraulic communication between the fluid chambers
formed adjacent at least two of the two or more wells to form a
cluster of wells; and iv. continuing injection and production from
at least one of the two or more wells in the cluster and ceasing
injection and continuing production from at least one of the two or
more wells in the cluster, wherein the injection of mobilizing
fluid in the at least one of the two or more wells in the cluster
is a second amount of mobilizing fluid greater than the first
amount of mobilizing fluid; wherein the two or more wells are
spaced sufficiently close to establish fluid communication between
the two or more wells.
12. The method of claim 11 further comprising ceasing injection and
continuing production at the at least one well within the cluster
in step (v) that continued both injection and production, and
reinitiating injection of the mobilizing fluid and continuing
production at the at least one well within the cluster in step (v)
that ceased injection of the mobilizing fluid.
13. The method of claim 11 further comprising the step of ceasing
injection of a mobilizing fluid, and injecting a non-condensable
gas through the at least one well in the cluster while continuing
production at the at least one other well in the cluster.
14. The method of claim 11 wherein the cluster of wells is operated
as a hydraulic unit.
15. The method of claim 11 wherein the wells in the cluster are
spaced so that infill wells are not required.
16. The method of claim 11 wherein the recovery process is steam
assisted gravity drainage (SAGD) and the two or more wells within
the formation are selected from the group consisting or SAGD well
pairs or single vertical, inclined, or horizontal SAGD wells.
17. The method of claim 11 wherein the mobilizing fluid is steam,
hot water, light hydrocarbon, solvent, surfactant, non-condensing
gas, or mixtures thereof.
18. The method of claim 17 wherein the solvent is one or more of a
C3 to C10 solvent or hexane, or the non-condensing gas is a light
hydrocarbon or an oxygen containing gas.
19. The method of claim 11 wherein the injecting and/or producing
is done on a continuous or interrupted basis.
20. The method of claim 11 wherein the viscous hydrocarbons are
selected from the group consisting of bitumen, heavy oil, and
unmobilized hydrocarbons.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority of U.S.
Provisional Patent Application No. 62/043,170 filed Aug. 28, 2014,
which is incorporated herein by reference in its entirety.
FIELD
[0002] The present disclosure relates generally to efficient
hydrocarbon recovery from subterranean reservoirs using recovery
processes and, in particular, to operating wells as a hydraulically
connected cluster in an efficient hydrocarbon recovery process.
BACKGROUND
[0003] Recovery of hydrocarbons such as bitumen and heavy oil from
reservoirs presents significant challenges due to their high
viscosities. Examples of in situ recovery methods for bitumen or
heavy oil include steam assisted gravity drainage (SAGD) or cyclic
steam stimulation (CSS). These recovery methods involve drilling
wells into the reservoir, injecting mobilizing fluids into the
reservoir to mobilize the bitumen or heavy oil, and recovering the
mobilized bitumen or heavy oil from the reservoir. These recovery
processes may include a number of phases. In the case of SAGD, the
first phase is a start-up phase where a mobilizing fluid is
circulated to mobilized bitumen or heavy oil in the near wellbore
region to expedite communication between the wells in a well pair.
The second phase of the SAGD recovery process is an operational
phase where mobilized fluid is injected into the reservoir and the
mobilized bitumen or heavy oil is produced and recovered from the
reservoir. The third phase is initiated once operation is no longer
economical and the chamber is mature. This phase is referred to as
a blowdown phase where fluid such as a non-condensable gas is
injected into the reservoir to maintain the pressure in the fluid
chamber and allow production to continue without the injection of
further mobilizing fluid. The mobilizing fluid is often steam but
may also include hot water, light hydrocarbons, solvents,
surfactants, non-condensing gases, or mixtures thereof.
[0004] Efficiency of thermal recovery processes, such as SAGD or
CSS, is measured by the cumulative steam-oil ratio (cSOR). This is
the ratio of cumulative volume of steam injected over the
cumulative volume of oil produced. As the hydrocarbon content of
the reservoir is produced and the remaining hydrocarbon content
declines, the cSOR will increase. The higher the cSOR, the higher
the steam usage. As the cSOR increases, the process becomes less
economical. At some point, it may no longer be economical to
continue injection of steam or other mobilizing fluid. At this
time, fluid injection may be reduced or discontinued and the fluid
chamber is now depleted or "mature".
[0005] Hydrocarbon recovery efficiency is also a function of well
spacing. If the spacing between wells is too large, recovery
efficiency will be reduced. However, well spacing and recovery
efficiency is contrasted with the costs of drilling and completing
wells. Traditionally, wells are positioned within a reservoir so
that drilling and completion costs are minimized. This usually
entails placing the wells on wider spacing with the intent that
each such well (or well pair, in the case of traditional SAGD) will
recover hydrocarbons from as broad an area as is feasible. Standard
spacing in a SAGD recovery process using horizontal well pairs
typically spaces the well pairs about 75 to 150 meters apart,
depending on the specific reservoir and its characteristics.
[0006] When the well spacing selected in a given reservoir is
sufficiently large that recovery efficiency is unduly compromised,
one well known remedial approach is to drill infill wells between
the original wells so as to recover hydrocarbons that would
otherwise be bypassed. Infill wells are generally introduced into
the reservoir near the end of the operational phase when the
hydrocarbon production from the existing wells or well pairs is
becoming less economical and bypassed reserves are identified. The
infill wells may be operated at the same time as the existing wells
and/or after the existing wells are no longer economical and have
entered the blowdown phase.
[0007] This approach has the disadvantage of requiring that
existing operating wells may be operated inefficiently before
bypassed reserves are identified and the reservoir will also
require additional wells to be drilled and completed at a later
stage in the recovery process with the associated costs of bringing
appropriate equipment on site to drill and complete the wells. The
overall cost of recovery may therefore be increased.
[0008] There therefore remains a need for a hydrocarbon recovery
process that utilizes a well spacing, or well spacing strategy,
aimed at efficient oil recovery and minimized overall costs.
SUMMARY
[0009] It is an object of the present method to obviate or mitigate
at least one disadvantage of previous systems.
[0010] In one aspect, the present method is a method for producing
viscous hydrocarbons from a subterranean formation using a group of
wells. The method may include providing two or more wells within a
formation, each well having an injection means and a production
means. The method may include independently operating a recovery
process at each of the two or more wells, the recovery process
comprising injecting a first amount of a mobilizing fluid through
the injection means into the formation, to mobilize the viscous
hydrocarbons in the formation, and producing the mobilized
hydrocarbons through the production means. The hydrocarbon recovery
process is a predominantly gravity-dominated process. The method
may include forming fluid chambers adjacent each of the two or more
wells in the reservoir as the mobilized hydrocarbons are produced.
The method may include establishing hydraulic communication between
the fluid chambers for at least two of the two or more wells to
form a cluster of wells. The method may include continuing
injection and production from at least one of the two or more wells
in the cluster and ceasing injection and continuing production from
at least one of the two or more wells in the cluster. The injection
of mobilizing fluid in the at least one well in the cluster is a
second amount of mobilizing fluid, greater than the first amount of
mobilizing fluid. Further, the two or more wells are spaced
sufficiently close to establish fluid communication between the two
or more wells. The gravity dominated recovery process may be steam
assisted gravity drainage operating in horizontal well pairs, or in
single vertical, inclined or horizontal wells.
[0011] In a further aspect, the present method is a method for
producing viscous hydrocarbons from a subterranean formation using
a group of wells. The method includes providing two or more wells
within a formation, each well having an injection means and a
production means, the injection means being positioned in the well
closer to the surface than the production means. The method may
also include independently operating a predominantly
gravity-dominated recovery method in the two or more wells
comprising the steps of injecting a first amount of a mobilizing
fluid through the injection means into the formation, to mobilize
the viscous hydrocarbons; and substantially concurrently producing
the mobilized hydrocarbons through the production means, wherein
producing the mobilized hydrocarbons forms fluid chambers in the
formation adjacent each of the two or more wells. The method may
also include establishing hydraulic communication between the fluid
chambers formed adjacent at least two of the two or more wells to
form a cluster of wells. The method may also include continuing
injection and production from at least one of the two or more wells
in the cluster and ceasing injection and continuing production from
at least one of the two or more wells in the cluster. The injection
of mobilizing fluid in the at least one of the two or more wells in
the cluster is a second amount of mobilizing fluid greater than the
first amount of mobilizing fluid. Further, the two or more wells
may be spaced sufficiently close to establish fluid communication
between the two or more wells. The gravity dominated recovery
process may be steam assisted gravity drainage, operated in
horizontal well pairs, or in single vertical, inclined or
horizontal wells.
[0012] Other aspects and features of the present disclosure will
become apparent to those ordinarily skilled in the art upon review
of the following description of specific embodiments in conjunction
with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Aspects of the present disclosure will be described by way
of example only with reference to the attached figures.
[0014] FIG. 1 is a graph showing the cumulative steam oil ratio
(cSOR) for a simulation of a base case of vertical wells operating
single vertical well SAGD as compared to vertical wells operating
the present method.
[0015] FIG. 2 is a graph showing the cSOR for a simulation of a
base case of horizontal well pairs operating SAGD as compared to
horizontal well pairs operating the present method.
[0016] FIG. 3 is a graph showing the oil recovery for the
simulation shown in FIG. 2.
DETAILED DESCRIPTION
[0017] The present method provides for the efficient recovery of
unmobilized hydrocarbons using a recovery process and a number of
closely spaced wells which begin as separate entities operating
under a gravity dominated process, but which evolve into an
operational group of interconnected wells. The present method thus
includes an inter-well recovery stage involving a hybrid of gravity
and convective processes during the operational phase and
sufficiently close well spacing to allow the inter-well recovery
phase to recover hydrocarbons in an efficient manner. This process
may eliminate the need for infill wells to be drilled and completed
in the reservoir.
[0018] By using a closer well spacing than traditionally selected
for a group of wells, in conjunction with a recovery process which
includes an inter-well operational phase, hydrocarbon recovery may
be improved.
[0019] The present method positions wells at a closer spacing than
is traditionally used in reservoirs. The well spacing used in the
present method is sufficiently close so that there may no longer be
a need for subsequent infill wells during the life of the
inter-well phase of the recovery process. Although this may require
additional wells to be drilled and completed at an earlier stage in
the recovery process than with traditional recovery processes, the
present method provides for an improved overall hydrocarbon
recovery than is achieved using traditional methods with wider well
spacing and no inter-well operational phase.
[0020] In the present method, well groupings or "clusters" are used
for inter-well operation. The group of wells comprises two or more
wells. The wells are spaced sufficiently close within a reservoir
so that although the wells are initially operated independently,
hydraulic communication between the wells is established at a later
point in the wells' operational phase.
[0021] Once hydraulic communication is established between the
wells, an inter-well recovery process phase is initiated so that
the group of wells forms an operational cluster of wells. The
number of wells that form the cluster may vary over time. The
hydraulic communication between wells within a group may be
established simultaneously or sequentially. Further, variations in
operating conditions and/or reservoir properties may mean that all
wells may not communicate discernibly. Thus, an initial group of
wells may evolve into two or more subgroups, each of which
constitutes a cluster of communicating wells, but between or among
which clusters there is no discernable communication. Communication
between these clusters or subgroups of wells may be established
over time.
[0022] Hydraulic communication in this context refers to the merger
or coalescence of mobilized zones between or among wells. The
mobilized zones may include fluid chambers, such as steam chambers,
formed as a result of the thermal recovery processes and injection
of heated fluids. The occurrence of the merger or coalescence is
measurable by means known within the field, such as pressure
monitoring at the wells.
[0023] Once the wells form a cluster with inter-well hydraulic
communication, the wells are operated such that at least one well
in the cluster continues operating both injection and production in
its recovery process, such as a single vertical well SAGD mode or
SAGD recovery process using horizontal well pairs. The operations
at the other wells in the cluster may be modified so that there is
at least one well within the cluster that will cease operating the
recovery method and instead will be placed on production only with
no injection of mobilizing fluid. Within the cluster, only one well
may continue with the recovery process with both injection and
production while all of the remaining wells in the cluster are
placed on production only. In a further aspect, the well continuing
with both injection and production may cease production for a
period of time. In a further aspect, production in one or more of
the wells within the cluster may alternate with periods of shut in
to allow for further time for mobilization of the hydrocarbons in
the reservoir.
[0024] During this inter-well operational phase, the at least one
well that remains operating in the recovery process will inject
mobilizing fluid into the reservoir in an amount in excess of the
amount required for that well. The excess mobilizing fluid will
therefore move laterally and downward in the reservoir towards the
pressure sinks at the other wells in the cluster. The pressure
sinks are the result of the discontinued injection of mobilizing
fluid and the continued production of hydrocarbons. The amount of
excess mobilizing fluid injected to operate the recovery process at
all of the wells in the cluster will be a function of many factors,
including well spacing and reservoir characteristics. Governance of
the amount of excess mobilizing fluid to be injected may be
established by monitoring cSOR and production rates at all of the
wells and making adjustments to injection and production rates so
as to optimize economics or other key performance indices.
[0025] As the inter-well recovery process continues in the cluster,
the fluid chambers mature and the steam-oil ratio increases. At
some point, the process will transition to the blowdown phase. At
this point, the wells may continue to operate as a cluster with
non-condensing gas injected into the well(s) operating the recovery
process while the remaining wells continue production until the
cluster reaches its economic limit.
[0026] The roles of the wells within the cluster are flexible. Once
the wells have established hydraulic communication and are
operating as a cluster with inter-well operations, the recovery
process carried out at each well may vary. For example, if one well
is undergoing both injection and production for SAGD while the
remaining wells are producing with no injection, the well that is
undergoing SAGD may cease injecting steam and only produce
hydrocarbons while another well within the cluster may be
re-activated to operate SAGD with both injection and production.
Wells within the cluster may be re-purposed generally over the
operational and blowdown phases to allow for efficient hydrocarbon
recovery from the reservoir.
[0027] In one example of the present method, a single vertical or
inclined well SAGD process is used as the thermal recovery process
operating in the wells. Single vertical or inclined well SAGD
process is described in more detail in U.S. patent application Ser.
No. 14/195,518 which is incorporated herein by reference. In the
single well SAGD process, the vertical or inclined well includes an
individual wellbore whose openings to the reservoir have been
configured to allow for concurrent injection and production. The
injection and production intervals in the wellbore are isolated
from each other. Steam or other mobilizing fluids are injected
through an upper open interval in the wellbore and mobilized fluids
are produced from a lower open interval in the same wellbore, in a
gravity-dominated process. There is a convergence of flow toward
and into the bottom producing interval. The reservoir may have a
high mobility zone located substantially opposite the producing
interval of the single vertical well. The high mobility zone may be
either pre-existing or artificially established.
[0028] The present example involves two single vertical well SAGD
wells spaced apart to form a group of wells. In this example, the
well spacing uses a 5 spot pattern, which is a general square shape
with a well at each corner and one well in the middle. In the
simulation, only two wells are operating, the center well and a
corner well. The well spacing is 75 meters along the edge of the
square, between wells in each corner. The wells are initially
operated as individual wells using a single well SAGD process in a
start-up and operational phase. A start-up phase is implemented at
each individual well to mobilize hydrocarbons in the immediate
vicinity of the well and thereby provide an initial means for
vertical flow. A typical start up process would involve the
circulation of steam or other mobilizing fluid within the wellbore
for a period of time sufficient to achieve adequate mobilization of
the hydrocarbons within the reservoir in the vicinity of the
wellbore. Other start-up processes include electrical or
electromagnetic heating or the injection of non-thermal fluids such
as solvent.
[0029] Following the start-up phase, the single well SAGD process
is operated at each well, independently of other wells, by
injecting steam or other fluids into the injection means and
producing fluids from the production means. During operation,
vertical flow in the reservoir in the vicinity of each well is
facilitated and/or impediments to steam chamber growth may be
avoided by creating a basal mobile zone opposite the production
means or using an existing mobile zone within the reservoir
opposite the production means. The injected steam may also include
a solvent or surfactant. In some cases, particularly when a mixture
of steam and solvent or surfactant is injected, it is not necessary
to create a basal mobile zone.
[0030] Operation of the wells independently continues until the
steam chambers for one well communicates hydraulically with the
steam chambers for one or more other wells, whether simultaneously
or sequentially. In the simulation, as shown in the graph in FIG.
1, hydraulic communication between wells is established at about
700 days. At this point, the wells form a cluster and are
hydraulically joined.
[0031] The wells within the cluster are operated so that at least
one well in the cluster continues operating a single vertical or
inclined well SAGD process with injection of steam through the
injection means and producing of fluids through the production
means. In the 5 spot pattern, the well in the center of the square
shape continues operating both injection and production. The other
well in the cluster, namely the well positioned at one of the
corners of the square shape of the 5 spot pattern, cease its SAGD
process by ceasing to inject steam through the injection means but
will continue production of fluids through the production interval.
The (center) well which continues to operate a SAGD process may
inject an excess of steam over and above that required for the
single well SAGD process. The excess steam will move laterally and
downwards toward the pressure sinks at the production means of the
other well in the cluster. The pressure sinks are the result of
discontinued injection into the upper intervals and the continued
production from the lower intervals.
[0032] As the cluster based recovery process matures, and the
steam-oil ratio increases, the cluster will transition to the
blowdown phase. In this phase, non-condensing gas may be injected
into the upper interval of the injector or injectors within the
cluster and these and the other wells within the cluster will
continue production of fluids from their production intervals until
they reach their economic limit.
[0033] FIG. 1 is a graph showing the cSOR ratio for the simulated
operational period for the two single vertical well SAGD wells
operating the present method (B) as compared to a base case with
using two single vertical wells operating only single vertical well
SAGD for the entire operational period (A). FIG. 1 shows that the
cSOR is lower in the wells using the present method.
[0034] Once the wells transition into operation as a cluster, the
wells may be re-purposed for efficient hydrocarbon recovery. This
may occur at any phase of the overall recovery process within the
cluster. As set out above, only one well in the cluster needs to
operate in a single well SAGD mode but multiple wells may do so.
The remaining wells, including at least one well, will operate in a
production only mode, without an injection of steam through their
wellbores. Further, during this operational phase, the process
within a particular well in a cluster may change, with the well
undergoing the single well SAGD process changing to production only
and one or more different wells in the cluster changing from
production only to undergoing the single well SAGD process.
[0035] Also, within the overall recovery process as described, and
consistent with sound oilfield operating practice, cyclic
stimulation, such as cyclic steam stimulation, may be practiced
from time to time at individual wells to enhance reservoir
transmissibility in the vicinity of those wells.
[0036] The process is described with the injection of steam as an
example. However, any suitable fluid and/or additive may be
injected into the reservoir including but not limited to steam, hot
water, light hydrocarbons, solvents, surfactants, non-condensing
gases including light hydrocarbons and oxygen comprising gases, or
mixtures thereof.
[0037] The process is described using single vertical or inclined
well SAGD as an example. However, other gravity dominated recovery
processes may also be used in the present method. These include,
but are not limited to, single horizontal well SAGD and SAGD using
horizontal well pairs. All of these gravity dominated recovery
processes, and the hybrid processes employed during the follow-up
inter-well phase, may include additives or alternatives to steam,
such as hot water, solvent, surfactant, and non-condensing gas,
including oxygen comprising gas.
[0038] In SAGD using horizontal well pairs, a simulation was run to
assess hydrocarbon recovery and cSOR when using SAGD operating in
the well pairs and comparing it to operating the method of the
present invention. The base case operated SAGD in two horizontal
SAGD well pairs for 3650 days (10 years). A comparative example
operated SAGD in the two SAGD horizontal well pairs for 1200 days
(over 3 years). At this point, hydraulic communication was
determined to be established between the SAGD well pairs. The two
well pairs could now be operated as an interwell group or cluster
of wells. One injector was shut in so that the injection of steam
ceased in one well pair. The injection of steam continued in the
other well pair. Both well pairs continued production. The well
pairs were operated up to 3650 days. As shown in FIG. 2, the data
showed substantially identical cSOR for both cases of approximately
2.5. The comparative case using the present method had a slightly
higher hydrocarbon recovery as shown in FIG. 3 as compared to the
base case operating SAGD throughout the life of the SAGD well
pairs. The overall result is that the present method is more
efficient since more hydrocarbons were recovered using a
substantially same amount of steam as the SAGD process.
[0039] Reference is made to exemplary aspects and specific language
is used herein. It will nevertheless be understood that no
limitation of the scope of the disclosure is intended. Alterations
and further modifications of the features described herein, and
additional applications of the principles described herein, which
would occur to one skilled in the relevant art and having
possession of this disclosure, are to be considered within the
scope of this disclosure. Further, the terminology used herein is
used for the purpose of describing particular embodiments only and
is not intended to be limiting, as the scope of the disclosure will
be defined by the appended claims and equivalents thereof. All
publications, patents, and patent applications mentioned in this
specification are herein incorporated by reference to the same
extent as if each individual publication, patent or patent
application were each specifically and individually indicated to be
incorporated by reference.
* * * * *