U.S. patent application number 13/820056 was filed with the patent office on 2013-08-15 for synchronised system for the production of crude oil by means of in-situ combustion.
This patent application is currently assigned to PACIFIC RUBIALES ENERGY CORP.. The applicant listed for this patent is Mkac Fuenmayor, Ronald Pantin, Luis Andres Rojas. Invention is credited to Mkac Fuenmayor, Ronald Pantin, Luis Andres Rojas.
Application Number | 20130206384 13/820056 |
Document ID | / |
Family ID | 44718315 |
Filed Date | 2013-08-15 |
United States Patent
Application |
20130206384 |
Kind Code |
A1 |
Pantin; Ronald ; et
al. |
August 15, 2013 |
SYNCHRONISED SYSTEM FOR THE PRODUCTION OF CRUDE OIL BY MEANS OF
IN-SITU COMBUSTION
Abstract
A synchronized crude oil production system using in-situ
combustion that measures, monitors, and controls the operating
conditions in real time. The system includes at least one injection
well, at least one production well, and at least one inclined
synchronization well. The end of the production well(s) and the end
of the inclined synchronization well(s) within the reservoir are
oriented outward the injection well and the wells include
measurement, monitoring, and control elements. The measurement and
monitoring elements transmit signals and data collected to one or
more processing units which, together or independently, use an
analytical model to assess the combustion conditions in the
well-subsurface system and the forward move of the combustion front
and, depending on the results, synchronize the production
operations. Each well being operated and handled remotely at the
control valves thereof in order to influence the displacement
direction of the combustion front.
Inventors: |
Pantin; Ronald; (Bogota,
CO) ; Rojas; Luis Andres; (Bogota, CO) ;
Fuenmayor; Mkac; (Calgary, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Pantin; Ronald
Rojas; Luis Andres
Fuenmayor; Mkac |
Bogota
Bogota
Calgary |
|
CO
CO
CA |
|
|
Assignee: |
PACIFIC RUBIALES ENERGY
CORP.
Toronto, Ontario
ON
|
Family ID: |
44718315 |
Appl. No.: |
13/820056 |
Filed: |
May 7, 2011 |
PCT Filed: |
May 7, 2011 |
PCT NO: |
PCT/IB2011/000975 |
371 Date: |
May 2, 2013 |
Current U.S.
Class: |
166/50 ;
166/52 |
Current CPC
Class: |
E21B 43/243 20130101;
E21B 43/305 20130101 |
Class at
Publication: |
166/50 ;
166/52 |
International
Class: |
E21B 43/30 20060101
E21B043/30 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 31, 2010 |
CO |
10-107350 |
Claims
1. A synchronized crude oil production system using in-situ
combustion that measures, monitors, and controls operating
conditions in real time, the system comprising: an injection well;
a production well; and an inclined synchronization well, wherein an
end of the production well and an end of the inclined
synchronization well within a reservoir are oriented outward with
respect to the injection well, wherein the injection, production,
and inclined synchronization wells include a plurality of
measurement, monitoring, and control elements, wherein the
plurality of measurement and monitoring elements transmit signals
and data collected thereby to one or more processing units, wherein
the one or more processing units, together or independently, use an
analytical model to assess combustion conditions in a
well-subsurface system and a forward move of a combustion front and
synchronize production operations, wherein each well is configured
to be operated and handled remotely at control valves thereof in
order to influence a displacement direction of the combustion
front.
2. The system according to claim 1, wherein the production well is
inclined.
3. The system according to claim 1, wherein the production wells is
multilateral.
4. The system according to claim 1, wherein the injection well, the
production well, and the inclined synchronization well are in a
particular geometrical arrangement according to requirements of the
well-subsurface system to be produced.
5. The system according to claim 1, wherein the inclined
synchronization wells is in a relative position within the
arrangement that is relatively closer to the production well than
to the injection well.
6. The system according to claim 1, wherein the inclined
synchronization well is located within the zone Z between the
production well and the injection well.
7. The system according to claim 2, wherein the injection well, the
production well, and the inclined synchronization well are in a
particular geometrical arrangement according to requirements of the
well-subsurface system to be produced.
8. The system according to claim 3, wherein the injection well, the
production well, and the inclined synchronization well are in a
particular geometrical arrangement according to requirements of the
well-subsurface system to be produced.
9. The system according to claim 2, wherein the inclined
synchronization well is in a relative position within the
arrangement that is relatively closer to the production well than
to the injection well.
10. The system according to claim 3, wherein the inclined
synchronization well is in a relative position within the
arrangement that is relatively closer to the production well than
to the injection well.
11. The system according to claim 4, wherein the inclined
synchronization well is in a relative position within the
arrangement that is relatively closer to the production well than
to the injection well.
12. The system according to claim 2, wherein the inclined
synchronization well is located within the zone Z between the
production well and the injection well.
13. The system according to claim 3, wherein the inclined
synchronization well is located within the zone Z between the
production well and the injection well.
14. The system according to claim 4, wherein the inclined
synchronization well is located within the zone Z between the
production well and the injection well.
15. The system according to claim 5, wherein the inclined
synchronization well is located within the zone Z between the
production well and the injection well.
Description
[0001] The invention relates to a synchronized crude oil production
system using in-situ combustion. The system measures, monitors and
controls the operating conditions in real time and comprises at
least one injection well (1), at least one production well (2) and
at least one inclined synchronization well (3). According to the
invention, the end of at least one production well (2) and the end
of at least one inclined synchronization well (3) are oriented
outward the injection well (1). In addition, the system comprises
measurement, monitoring and control elements that transmit signals
and information detected thereby to one or more processing units
which, together or independently, use an analytical model to assess
the combustion conditions and the advance of the combustion front
and, depending on the results, synchronize the production
operations, each well being operated and handled remotely at the
control valves thereof in order to influence the displacement of
the combustion front.
BACKGROUND
[0002] Heavy crude oil or extra heavy crude oil is any type of
high-density crude oil which does not flow easily. It is referred
to as "heavy" because its density or API gravity is less than
21.9.degree. API.
[0003] The largest reserves of heavy crude oil in the world are
located north of the Orinoco River in Venezuela, but 30 or more
countries are known to have reserves. Canada has large heavy crude
oil reserves, mainly in the provinces of Alberta and Saskatchewan.
In this sense, in the last decades, specialized techniques have
been developed for the efficient and economical production of such
deposits.
[0004] Production, of heavy and extra heavy crude oil present
special challenges compared to light crude oil due to their high
viscosity, and consequently low mobility and low API gravity.
[0005] To overcome such challenges, several Thermal Recovery
methods have been developed. Among such methods, there are
different types of steam injection techniques such as Steam
Assisted Gravity Drainage (SAGD). This technique involves the use
of two horizontal wells instead of vertical wells, wherein the
operators inject high temperature steam into the upper wellbore,
the steam flows through the well, heats the oil by heat transfer
and reduces its viscosity, causing the heated oil to drain into the
lower horizontal wellbore. According to literature available, SAGD
has an estimated recovery rate of 20%-50% of in situ oil, however,
the implementation rate is limited to a type of oil reservoirs,
mostly those not affected by strong aquifers and with an excellent
vertical communication.
[0006] Another broadly used method, with a greater implementation
range, is in situ combustion. Such method involves heating and
oxidizing a small amount of oil existing within the reservoir in
order to generate thermal energy. Such energy allows displacement
of a considerable oil bank from the injection wells to production
wells mostly due to the viscosity reduced, vaporization and carry
forward of the gases formed in the combustion process. Although
this type of process has existed for a long time, there have been
technical-operating difficulties discouraging its application, such
as the control and monitoring of the combustion front, which
directly affects the volumetric sweep efficiency and, therefore,
the recovery of the oil existing gin the reservoir. However, there
have been efforts to overcome such difficulties which have reached
reservoir recovery over 60%, as reported in several bibliographic
sources and pilot and commercial projects carried out around the
world. Heavy crude oil reservoirs subjected to hydraulic pressure
respond favorably to this type of method.
[0007] Generally, three chemical processes take place in an in situ
combustion: Oxidation: The combustion zone acts like a piston
displacing the fluids in the combustion front to the production
wells. Coking: Oxygen combines with oil resulting in carbon dioxide
and heat. The combustion reaction is maintained by injecting air,
and the CO.sub.2 released in the reservoir produces a decrease of
the relative permeability to water, which minimizes the water
mobility respecting oil.
[0008] Cracking: The thermal cracking creates a coke deposit in the
fire front generating, in some cases, an improvement of the crude
oil, combustion gases vaporize the water, improve the displacement
of fluids and increase the sweep efficiency of the process. In
summary, the in situ combustion process has a number of advantages,
mainly in reservoirs with high water saturation or direct influence
of aquifers with strong hydraulic drive: improvement of the crude
oil vs. water mobility ratio by reducing the relative permeability
to water, positive influence on the gravitational segregation by
creating a secondary high pressure gas layer and reduction of crude
oil viscosity by heating and miscibility of CO.sub.2 produced. In
addition, the saturation of residual oil is reduced and saturation
of irreducible water increases due to the temperature increase as
reported in the oil industry literature, which increases the oil
flow and decreases the water flow.
[0009] Given the significant increase of heavy and extra-heavy
crude oil reserves worldwide, the search of technologies optimizing
the above-mentioned technologies has been a concern in the world
oil industry. In particular, there is a need for a production
method monitoring and controlling the specific operations existing
in an in situ combustion, thereby increasing the hydrocarbon
production and reserves, meaning the amount of oil recoverable from
the reservoir in cost-effective conditions.
[0010] In this sense, the main purpose of the present invention is
to provide a synchronized crude oil production system using in-situ
combustion, comprising real time measurement, monitoring and
control elements for the combustion front and further comprising a
geometry and type of well that make easier and more efficient the
management of monitoring and control operations of such combustion
front.
[0011] Another purpose of the present invention is to provide a
synchronized crude oil production system using in-situ combustion
comprising a type of well referred to as inclined "synchronization"
well, also equipped with measurement and monitoring elements, that
may fulfill different functions within the system making more
efficient the control operations in the combustion front. The main
purpose of the inclined synchronization wells (3) is not only to
produce a higher volume of hydrocarbons, but to complement the
measurement, monitoring and control of the combustion front in
order to make the process for efficient and achieve a greater
hydrocarbon recovery. There is a significant economic justification
regarding inclined wells. An inclined well is much more economical
and easier to drill than a horizontal well, although it has its
advantages due to its larger flow area. Its geometry or
architecture does not require the use of sophisticated drilling
equipment like horizontal wells, where it is necessary to "sail"
through sometime very low-density sands that make difficult its
trajectory. Such "Measurement While Drilling" ("MWD") tools are
very expensive and put up the cost of the well. In field with large
volumes of reserves and where it is convenient to implement in situ
combustion processes requiring to drill economical wells the cost
of wells is extremely important, representing over 60% of the
overall cost of the investments in to project. This is why it is
important to count on inclined, synchronized wells located at the
reservoir, allowing to monitor and control the combustion front and
to maintain and improve the volumetric sweep efficiency, maximizing
the oil reserve recovery.
DESCRIPTION OF THE INVENTION
Description of the Figures
[0012] FIG. 1 is a drawing of a prior art arrangement for crude oil
recovery from a reservoir by in situ combustion showing the two
main zones of the well-subsurface system and the combustion front
displacing from the injection well 1 to the horizontal production
well 2, combustion zone C and a zone adjacent to the combustion
front, the non-combustion zone D.
[0013] FIG. 2 is an upper view of a prior art arrangement for crude
oil recovery showing an ideal theoretical displacement of the
combustion front of the well-subsurface system from an injection
well 1 to vertical production wells 2. The arrows in this figure
show the direction of the combustion front.
[0014] FIG. 3 is an upper view of an arrangement for crude oil
recovery from a reservoir showing one of many theoretical forms
that a combustion front in the well-subsurface system might have
due to the irregular displacement of the crude oil. This figure
intends to show that in real life, the combustion front is not
homogeneous, which certainly affects the productivity of the
process, the volumetric sweep efficiency and accordingly the
hydrocarbon reserve recovery. In this figure, the arrows show the
direction of the combustion front.
[0015] FIG. 4a is an upper view of an arrangement for crude oil
recovery from a well-subsurface system according to a first
embodiment of the invention with inclined production wells at
instant t.sub.1 (referential), showing an irregular combustion
front under undesired conditions without applying Synchronized
Operations Management "SOM" to monitor and control the combustion
front and improve the sweep or displacement efficiency and the
hydrocarbon reserve recovery. In this figure, the arrows show the
direction of the combustion front.
[0016] FIG. 4b is an upper view of an arrangement for crude oil
recovery from a well-subsurface system according to the embodiment
of FIG. 4a at instant t.sub.2 (referential and subsequent to
t.sub.1) showing a uniform, optimal combustion front under desired
operating conditions, after the synchronization operations by
monitoring and control of the invention. In this case, synchronized
operations management concepts have been applied for measuring,
monitoring and controlling the combustion front. In this figure,
the arrows show the direction of the combustion front.
[0017] FIG. 5 is an interior side view of zone X of FIG. 4b,
showing the relative position among injection wells, inclined
production wells and synchronization wells, highlighting a first
embodiment of the invention with inclined synchronization wells and
production wells.
[0018] FIG. 6 is an upper view of an arrangement for crude oil
recovery from a well-subsurface system according to a second
embodiment of the invention using multilateral production wells and
inclined synchronization wells strategically located. Such
configuration of multilateral production wells and inclined
synchronization wells represents an optional embodiment of the
invention. Note that the direction of the multilateral section of
production wells and inclined synchronization wells is outward. In
this figure, the arrows show the direction of the combustion
front.
[0019] FIG. 7 is an interior side view of zone X of FIG. 6 showing
the relative position among the injection well, the multilateral
wells and the inclined synchronization wells highlighting an
optional embodiment of the invention.
[0020] FIG. 8 is an upper view of an arrangement for crude oil
recovery from a well-subsurface system according to an optional
embodiment of the invention showing a uniform, optimal combustion
front under desired operating conditions after the synchronization
operations by monitoring and control of the invention. In this
figure, the arrows show the direction of the combustion front.
[0021] FIG. 9 is a map representing a referential reservoir used
for a simulation of an arrangement according to FIG. 6 of the
invention showing several layers, oil sands from which oil is
recovered and the last layer represents an aquifer or water zone
which is the main source of water.
[0022] FIG. 10 is a chart representing the production data from
synchronization wells (3a), (3b), (3c) and (3d) according to FIG. 9
in barrels per day as a function of time obtained by simulation.
Such wells are normally useful to support production wells in crude
oil recovery.
[0023] FIG. 11 is a chart representing the estimate production of
barrels per day as a function of time for multilateral wells 2a,
2b, 2c and 3d resulting from a referential simulation.
DESCRIPTION
[0024] The present invention provides a synchronized arrangement of
wells in an oil reservoir for measuring, monitoring and controlling
in situ combustion front parameters to achieve a more efficient
hydrocarbon recovery from the well-subsurface system. In order for
the in situ combustion recovery process to be efficient, mainly in
reservoirs with high hydraulic pressure, it is necessary to improve
the water/oil mobility ratio due to the decrease of the relative
water permeability respecting oil and due to the heat created in
the reservoir, taking advantage of the positive effects of the
miscibility of CO.sub.2 in crude oil. The result is an enhanced
efficiency of displacement or volumetric sweep and, therefore, a
greater hydrocarbon reserves recovery.
[0025] Thermal processes and kinetic reactions taking place in an
in situ combustion process are the typical ones. On the one hand,
there will be a heat oil front in the combustion zone C (see FIG.
1) that will result in an oil viscosity decrease and, therefore,
will increase mobility respecting water, making easier the entrance
of oil into the closest production well (2). Regarding the crude
oil located in the non-combustion zone D or zone not affected
directly by the combustion front (see FIG. 1), the heat transferred
will also have a positive effect in reducing the crude oil
viscosity, resulting in an improved oil mobility thus increasing
the probability of more hydrocarbon reserves recovery.
[0026] Another beneficial aspect is the flowing of combustion
byproduct gases to higher zones of the sand structure or the upper
zone of the reservoir. The combined effect of the heat transfer,
the oil viscosity reduction and gravitational segregation resulting
from the formation of a secondary gas layer at a higher pressure
makes the oil flow downwards thereby enhancing the sweep
efficiency, increasing the oil displacement and thus increasing the
hydrocarbon reserves recovery.
[0027] FIG. 2 shows a prior art combustion crude oil recovery
system showing comprising an arrangement of 5 inverted wells, which
for referential purposes include a vertical injection well (1) and
four vertical production wells (2). In this figure, the injection
well (1) is located within the arrangement within the area defined
by the production wells (2). The function of the injection well (1)
is to provide air, oxygen or a mixture of oxidizing gases to
displace the crude oil within its influence area and maintain the
combustion reaction in the reservoir. Zone (A) represents the
limits of the combustion front within the reservoir and the arrows
thereon represent the same theoretical direction of the front as it
goes forward to reach the production wells (2) and thus recover the
oil from the reservoir. In real life, the combustion front does not
travel homogeneously, and therefore, as time goes by, the form of
zone A departs from symmetry. FIG. 3 shows a referential example of
a combustion crude oil recovery system wherein zone B represents a
combustion zone near reality, when no measures to control it are
taken. As shown, the combustion front in amorphous and thus the oil
in the vicinity of the production well (2c) cannot be recovered
from the reservoir, affecting significantly the productivity of
production wells, the volumetric sweep efficiency and the
hydrocarbons reserves recovery. This reality may be corrected by
including a greater number of production wells (2) within the
arrangement each including, in turn, monitoring and controlling
tools for the combustion reactions and the forward move of the
combustion front so as to control the direction desired. However,
such addition of production wells (2) involves additional costs in
well drilling and completion operations which are useless once the
combustion front (zone B) has passed through the area underneath
such wells.
DETAILED DESCRIPTION OF THE INVENTION
[0028] The synchronized crude oil production system using the in
situ combustion process of the present invention provides:
including measurement, monitoring and control elements in the
vertical injection wells (1), production wells (2) present in a
well arrangement, and further introducing a new type of well
referred to as inclined "synchronization well" (3), including, in
turn, measurement elements for pressure and temperature, among
other variables, at different levels of the well, and monitoring
and control elements for the gases created from the combustion
front. A system according to the invention comprises at least one
injection well (1), at least one production well (2) and at least
one synchronization well (3). FIGS. 4a and 4b include for
referential purposes at least four inclined synchronization wells
(3) in an arrangement comprising one injection well (1) and four
inclined production wells (2).
[0029] The term "inclined" used in reference to certain wells
should be understood so that the inclination of the well may go
from the surface to one end thereof or comprise a vertical section
and an inclined section, where the inclined section is in contrast
with a substantially horizontal or substantially vertical section.
In this sense, an inclined production well (2) and an inclined
synchronization well (3) of the present invention does not include
a horizontal well configuration such as that of the prior art,
which include a substantially vertical section and a substantially
horizontal section attached thereto.
[0030] As mentioned above, each injection (1), productions (2) and
synchronization (3) well has measurement, monitoring and control
elements for the combustion front (zone B), being such elements
related to the functions of each well within the arrangement.
Generally air, oxidizing gas, a mixture of oxidizing gases and
other fluids are injected through the injection well (1) in order
to displace the crude oil and maintain the combustion reaction to
the production (2) and synchronization (3) wells more efficiently.
Regarding new production wells that may exist in the field (2),
they will fulfill a double function: first, such wells will serve
to produce the crude oil displaced by the combustion front
(combustion zone) and adjacent zones (zones influenced indirectly
by heat transfer), including the crude oil displaced by
gravitational segregation. Second, production wells (2) will serve
as monitoring wells for the combustion conditions in the
well-subsurface system. Inclined synchronization wells (3), duly
equipped with remote pressure and temperature sensors, will have,
among others, several functions. First, they serve as a support for
production wells (2) for measuring, monitoring and controlling the
combustion front by synchronized operations management; second,
they will serve as additional production wells, and third, they may
serve as wells for the release of undesired gases from the
well-subsurface system, when required. Finally, such inclined
synchronization wells (3) may be converted into oxidizing gas
injection wells, if it is so required and permitted by the
conditions of the process. Their construction is carried out so
that such function is feasible technically (see FIGS. 5 and 7).
[0031] Among the measurement and monitoring equipment to be
installed there are remote pressure and temperature sensors
operating in real time, however, there may be other combustion
front control elements, such as 4D seismic data recovery, flow logs
and imaging equipment installed in some or all of the wells. Such
measurement and monitoring elements send the signals and data
collected by them to a processing unit in charge of evaluating the
combustion conditions of the well-subsurface system and the forward
move of the combustion front. If the data collected in each type of
well is within the desired operating conditions, the injection (1),
production (2) and inclined synchronized (3) wells will continue
with their basic functions within the arrangement. On the contrary,
if the data collected show that a zone is being affected adversely
or preferentially by the combustion process to an undesired
direction, "Synchronized Operations Management", "SOM", consisting
in synchronizing the production operations so that each well or
group of wells is handled remotely in its control valves to
influence the displacement direction of the combustion front and
make it uniform. For example, if at certain moment the combustion
front goes preferentially or prematurely towards certain direction,
a temperature or pressure profile change will be detected at any
inclined synchronization well (3) or production well (2), these
changes being immediately registered in the data processing unit,
where the operators may issue instructions in real time to any or
all inclined synchronization wells (3) or production wells (2).
Such instructions consist in the synchronized and remote management
of the production control valves of the wells, causing the
modification of the production pattern and accordingly the forward
move of the combustion front, redirecting it towards the direction
desired. The operator may even send instructions to the injection
well in order to decrease, increase or regulate the amount of
oxidizing gas being injected into the well-subsurface system.
[0032] Instruction may be also given for the complete shutdown of
wells, including the activation of water injection systems to
control any abnormal situation taking place in any well or the
reservoir itself.
[0033] Another alternative is that inclined synchronization wells
(3) may act as release wells or valves in case that gas
concentration within the reservoir exceeds permitted values; in
such case, the control unit can send an instruction to activate the
release or gas extraction function.
[0034] The number and geometry of the injection well (1),
production well (2) and inclined synchronization well (3) in the
arrangement of the system of the present invention will depend on
the type of reservoir, the type of arrangement and the exploitation
conditions of the reservoir. Injection (1), production (2) and
inclined synchronization (3) wells are in a particular geometric
arrangement according to the requirements of the well-subsurface
system to be produced.
[0035] Each well of the arrangement of FIGS. 4a and 4b, whether
injection wells (1), inclined production wells (2) or inclined
synchronization wells (3), will be connected to one or several
processing units jointly or independently. In any connection
configuration, the processing unit is capable of interpreting the
measurements from every well and sending the signals in order for
the operator take the necessary correctives. Therefore, the
invention provides an intelligent measurement, monitoring and
control system which steps comprise evaluating in real time and
constantly the conditions of in situ combustion reaction in the
well-subsurface system (at different interest points duly
identified), sending of signals to the processing unit, analyzing
independent evaluations from each of the wells and, based on the
results, determining automatically by software or computing model
the correctives necessary to uniform the combustion front.
PREFERRED EMBODIMENTS OF THE INVENTION
[0036] In a first preferred embodiment of the invention, the
injection wells (1) are vertical, the production wells (2) are
inclined and synchronization wells (3) are inclined as shown in
FIG. 5. Such configuration allows a better coverage of the area of
the well-subsurface system to be produced, making more efficient
the monitoring process and accordingly the production process. The
use of vertical production wells generally has the restriction that
its function is limited to a single point of the well and/or
subjacent area thereof. On the contrary, this preferred embodiment
of the invention involves the use of vertical injection wells (1)
and inclined production wells (2), so as to access to a specific
region considered as relevant in the well-subsurface system.
Regarding synchronization wells (3), strategically located within
the arrangement of the invention, their configuration is inclined,
permitting a better position with a greater flow area and
orientation towards the points into the well-subsurface system
considered as relevant for monitoring purposes.
[0037] In a second preferred embodiment of the invention, injection
wells (1) are vertical, production wells (2) are multilateral, and
synchronization wells (3) are inclined as shown in FIGS. 6 and 7.
This configuration allows a greater coverture of the
well-subsurface area to be produced, making more efficient the
monitoring process and accordingly, the production process. Such
preferred embodiment involves the use of vertical injection wells
(1) and multilateral production wells (2) so as to cover a greater
area of the well-subsurface system. Regarding the inclined
synchronization wells (3), they are strategically located within
the arrangement of the invention, their configuration is always
inclined, which allows a better position with a greater flow area
and orientation towards the points into the well-subsurface system
considered as relevant for monitoring purposes.
[0038] For the two preferred embodiments described above, the
relative position of the inclined synchronization wells (3) in the
arrangement is relatively close to the production well (2) and, if
more than one production wells (2), preferably the zone adjacent to
the two closest production wells (2). Preferably, however, the
synchronization wells (3) shall be close to an intermediate and
strategic position from the geological point of view to the
injection well and the production wells (2), and placed within the
zone Z (shown in FIGS. 4a, 4b, 5, 6, 7 and 8).
[0039] Regarding the production wells (2) and inclined
synchronization wells (3) they are oriented so that the end of the
production wells (2) and the end of the inclined synchronization
wells (3) within the reservoir is outward respecting the injection
well (1). Generally, production wells (2) have a single inclined or
multilateral portion. However, they may have a substantially
vertical section and/or one or more inclined sections, which make
them multilateral. The number of production wells (2) and inclined
synchronization wells (3) may vary depending on the features of the
reservoir and the location of existing wells in the field at the
beginning of the in situ combustion process. Such preferred
embodiments and relative arrangements of the injection wells (1),
production wells (2) and inclined synchronization wells (3) to
carry out the invention are shown in FIGS. 4a, 4b, 5, 6, 7, and
8.
EXAMPLE (NUMERICAL SIMULATION)
[0040] With the purpose of evidencing the advantages of the
invention, a numerical simulation was carried out by using the
STARS numerical simulator by CMG in one of the fields of Pacific
Rubiales Energy. STARS include the multiphasic flow of oil, water
and gas, the heat transfer, compositional changes and chemical,
physical and kinetic reactions taking place in the reservoir during
in situ combustion. In order to evaluate the behavior of the
reservoir subjected to in situ combustion using different well
arrangements and in this case combination of injection wells (1),
multilateral production wells (2) and inclined synchronization
wells (3), an historical comparison of the production of production
wells existing in the field was carried out and the typical kinetic
reactions of the process were applied, among other reservoir and
design variables, such as: Four inclined synchronization wells (3)
four multilateral production wells (2), one vertical injection well
(1) injecting constantly 2.5 million cubic feet of air per day
during 5 years in an area of 25 acres in a crude oil reservoir of
more than 2,800 feet in depth.
[0041] The spacing and location of wells may be seen in FIG. 9,
showing an schematic view of the reservoir, where simulations where
carried out in order to determine the behavior of the production
for each of the wells involved and the hydrocarbon reserves that
may be recovered by using the process and well arrangement
described. Such spacing and location of the wells is related to the
arrangement shown in FIG. 6. The reservoir section selected in
shown in FIG. 9.
Results of Numerical Simulations
[0042] The results of numerical simulations are summarized as
follows:
[0043] The estimated production of the inclined synchronization
wells (3) used in the simulation is shown in FIG. 10. The
production of vertical wells was higher than 1,000 BPD at the
beginning and it was maintained for a reasonable time period as a
consequence of the in situ combustion process using the
synchronization technique explained in previous chapters.
[0044] Likewise, FIG. 11, shows the oil production of "outward"
multilateral production wells 2a, 2b, 2c and 2d in the selected
sector. Such wells began with production rates higher than 3,000
BPD and were maintained over 1,000 BPD.
[0045] The foregoing behavior and the one of synchronization wells
allow concluding that the proposed well arrangement is successful
in increasing the volumetric sweep efficiency and accordingly the
recovery of hydrocarbon reserves in over 40% of the oil originally
on site.
[0046] The description of the present invention is referential, so
it must be understood broadly. Also, figures and examples are for
reference purposes to assist in understanding the principles and
contributions of the invention to the prior art and shall not be
understood as exhaustive and/or exclusive.
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