CA3088468C - Methods for establishing fluid communication between a sagd well pair - Google Patents
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Abstract
CA 0IV3 Application CPST Ref: 83862/00690 1 ABSTRACT 2 There is provided a method of establishing fluid communication in an interwell region 3 between an injection well and a production well forming the well pair includes electrically 4 heating the interwell region between injection well and production well. CPST Doc: 281585.1 Date Recue/Date Received 2020-07-30
Description
CA DIV3 Application CPST Ref: 83862/00690
2 BETWEEN A SAGD WELL PAIR
3 FIELD
4 [0001] The present disclosure relates to methods for effecting fluid communication between two wells in a hydrocarbon containing reservoir.
7 [0002] Steam Assisted Gravity Drainage (SAGD) uses a pair of wells to produce a 8 hydrocarbon from a hydrocarbon containing reservoir. Typically, the well pair includes two 9 horizontal wells vertically spaced from one another, with the upper well used to inject steam into the reservoir and the lower well to produce the hydrocarbon. The steam operates to 11 generate a steam chamber in the reservoir, and thermal heat from the steam operates to 12 lower the viscosity of the hydrocarbon, allowing for gravity drainage, and thereby production 13 from the production well. Typically, before production commences from the production well, 14 a "start-up" period is required to warm the interwell region of the reservoir between the two wells. Heating to a mobility threshold enables displacement of the viscous hydrocarbon from 16 the interwell region to result in effective fluid communication between the injection well and 17 the production well.
18 [0003] Steam circulation during the start-up period to pre-heat SAGD well pairs is a 19 routine yet challenging process. Steam circulation may be hydraulically difficult to start or sustain and the circulation effort may be adversely affected by reservoir heterogeneity near 21 the wellbore or between the injector and producer. Non-uniform heating of the wellbore, and 22 interwell region of the hydrocarbon containing reservoir during steam circulation results in 23 less than optimal SAGD production from the reservoir and higher SOR
(steam to oil ratio).
24 Also, steam circulation may not always be suitable for SAGD start-up where the reservoir is relatively shallow, confined by weak or non-existent cap-rock.
26 [0004] Another challenge with steam circulation as a start-up technique results from the 27 delay between drilling the well pairs and the availability of surface facilities to provide steam 28 to the wells. Generally, after SAGD well pairs have been drilled and completed, surface 29 facilities are constructed to enable utilization of steam from a steam generation facility within CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 the SAGD well pair. There can be a significant time elapse after the well pair is drilled until 2 these facilities to provide steam are constructed. Elapsed time varies but delays can be up to 3 two years.
7 [0002] Steam Assisted Gravity Drainage (SAGD) uses a pair of wells to produce a 8 hydrocarbon from a hydrocarbon containing reservoir. Typically, the well pair includes two 9 horizontal wells vertically spaced from one another, with the upper well used to inject steam into the reservoir and the lower well to produce the hydrocarbon. The steam operates to 11 generate a steam chamber in the reservoir, and thermal heat from the steam operates to 12 lower the viscosity of the hydrocarbon, allowing for gravity drainage, and thereby production 13 from the production well. Typically, before production commences from the production well, 14 a "start-up" period is required to warm the interwell region of the reservoir between the two wells. Heating to a mobility threshold enables displacement of the viscous hydrocarbon from 16 the interwell region to result in effective fluid communication between the injection well and 17 the production well.
18 [0003] Steam circulation during the start-up period to pre-heat SAGD well pairs is a 19 routine yet challenging process. Steam circulation may be hydraulically difficult to start or sustain and the circulation effort may be adversely affected by reservoir heterogeneity near 21 the wellbore or between the injector and producer. Non-uniform heating of the wellbore, and 22 interwell region of the hydrocarbon containing reservoir during steam circulation results in 23 less than optimal SAGD production from the reservoir and higher SOR
(steam to oil ratio).
24 Also, steam circulation may not always be suitable for SAGD start-up where the reservoir is relatively shallow, confined by weak or non-existent cap-rock.
26 [0004] Another challenge with steam circulation as a start-up technique results from the 27 delay between drilling the well pairs and the availability of surface facilities to provide steam 28 to the wells. Generally, after SAGD well pairs have been drilled and completed, surface 29 facilities are constructed to enable utilization of steam from a steam generation facility within CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 the SAGD well pair. There can be a significant time elapse after the well pair is drilled until 2 these facilities to provide steam are constructed. Elapsed time varies but delays can be up to 3 two years.
[0005] In one aspect, a method of establishing fluid communication in an interwell region
6 between an injection well and a production well forming the well pair includes electrically
7 heating the interwell region between injection well and production well.
8 [0006] In some implementations, the electrical heating of the interwell region is effected
9 by an electrical heating system disposed within the injection well and/or the production well.
[0007] In another aspect, a method of producing bitumen from an oil sands reservoir 11 includes, during a start-up phase, electrically heating an interwell region of the oil sands 12 reservoir isposed between an injection well and a production well, for establishing a fluid 13 communication between the injection well and the production well. After establishing the fluid 14 communication, a production phase is commenced that includes injecting steam from the injection well into the oil sands reservoir for effecting mobilization of bitumen within the oil 16 sands reservoir. The mobilized bitumen is conducted through the interwell region to the 17 production well and recovered to surface through the production well.
18 [0008] In some implementations, the method further includes, after establishing fluid 19 communication in the interwell region, supplying steam from a steam generator, where the steam being injected is the steam supplied from the steam generator.
Electrically heating the 21 interwell region can be completed prior to, or substantially completed prior to, commissioning 22 of steam facilities for effecting the supplying of steam from the steam generator to the injection 23 well.
24 [0009] The electrical heating of the interwell region can be effected while steam facilities, for effecting the supplying of steam from the steam generator to the injection well, are being 26 constructed.
27 [0010] The electrical heating of the interwell region can be effected by an electrical 28 heating system disposed within the injection well and/or the production well.
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 [0011] The interwell region can be defined within a shallow hydrocarbon reservoir.
2 [0012] The interwell region is the region of the reservoir that is between the injection well 3 and the production well, which in a typical SAGD operation is approximately 5 metres in 4 depth. In some reservoirs, the bitumen saturation is greater than 85% and the porosity is greater than 35%, although reservoirs vary in these characteristics and the bitumen saturation 6 and/or porosity could be lower in some instances.
7 [0013] In another aspect, a method of establishing fluid communication between a well 8 pair within an oil sands reservoir includes electrically heating an interwell region of the oil 9 sands reservoir disposed between an injection well and a production well, to at least contribute to establishing fluid communication in the interwell region. The electrical heating 11 includes: electrically heating a first portion of the interwell region at a first predetermined 12 heating rate; and electrically heating a second portion of the interwell region at a different 13 second redetermined heating rate while the first portion is being heated at the first 14 predetermined rate.
[0014] In some implementations, the first predetermined heating rate and the second 16 predetermined heating rate are selected to effect a substantially uniform heating of the 17 interwell region.
18 [0015] In some implementations, the electrical heating of an interwell region is effected 19 by an electrical heating system disposed within at least one of the injection well and the production well.
21 [0016] In another aspect, a method of establishing fluid communication between a well 22 pair comprising an injection well and a production well within an oil sands reservoir includes 23 heating an interwell region disposed between the injection well and the production well, 24 establishing fluid communication between the two wells. The heating includes heating the interwell region with heat generated by steam injected into at least one well in the well pair 26 and simultaneously with heat generated by an electric heating system.
Heat generated by the 27 electric heating system effects both heating of the interwell region and heating of the injected 28 steam.
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 [0017] In some implementations, the steam injected into the at least one well is injected 2 into the well and circulated to surface.
3 [0018] In some implementations, the steam injected into the at least one well is injected 4 into the reservoir, i.e., bull heading.
[0019] In some implementations, the steam carries a gaseous chemical additive material 6 and condensation of the chemical additive material is mitigated by the electric heating of the 7 steam.
8 [0020] In some implementations, the electric heating system is disposed within at least 9 one of the wells in the well pair.
[0021] In another aspect, a method of producing bitumen from an oil sands reservoir 11 includes, after a fluid communicating interwell region has been established between and 12 injection well and a production well forming a well pair, injecting steam into the oil sands 13 reservoir via the injection well for effecting mobilization of bitumen within the oil sands 14 reservoir. The mobilized bitumen is conducted through the established fluid communicating interwell region to the production well. While the steam is being injected, the injected steam 16 is heated with an electrical heating system situated in the injection well. The mobilized 17 bitumen is recovered to surface through the production well.
18 [0022] In some implementations, the injected steam carries a gaseous chemical additive 19 material, and the electrical heating of the injected steam is such that condensation of the chemical additive material is mitigated.
21 [0023] In some implementations, prior to the injecting steam for effecting mobilization, 22 the interwell region is electrically heated with the electrical heating system, which at least 23 contributes to establishing a fluid communicating interwell region for effecting fluid 24 communication between the injection well and the production well.
[0024] In another aspect, a method of producing bitumen from an oil sands reservoir 26 includes electrically heating an interwell region, of the oil sands reservoir, disposed between 27 an injection well and a production well established within the oil sands reservoir, with an 28 electrical heating system. After the fluid communicating interwell region has been effected, CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 steam assisted gravity drainage (SAGD) is conducted to produce the bitumen, wherein the 2 SAGD includes: injecting steam into the oil sands reservoir via the injection well for effecting 3 mobilization of bitumen disposed within the oil sands reservoir such that the mobilized 4 bitumen is conducted through the established fluid communicating interwell region to the production well; and recovering the mobilized bitumen through the production well. While 6 SAGD is being conducted, a problem is detected requiring well intervention. In response to 7 the detecting of the problem requiring well intervention, SAGD is suspended and the wellbore 8 fluids disposed within one or both of the wells are electrically heated with the electrical heating 9 system. The wellbore fluids are vaporized and are conducted through the respective well to the wellhead.
11 [0025] In some implementations, the electrical heating system is disposed in the injection 12 well and/or the production well.
13 [0026] In another aspect, a method of producing bitumen from an oil sands reservoir 14 includes establishing fluid communication between an injection well and a production well for use as a steam assisted gravity drainage (SAGD) well pair by exclusively using electrical heat 16 applied in situ. The method can further include, only after establishing the fluid 17 communication, commencing injection of steam into the oil sands reservoir via the injection 18 well and producing production fluid from the oil sands reservoir via the production well, 19 wherein the production fluid includes bitumen.
BRIEF DESCRIPTION OF DRAWINGS
21 [0027] The preferred embodiments will now be described with the following 22 accompanying drawings, in which;
23 [0028] Figure 1 is a schematic illustration of a well pair in an oil sands reservoir, where 24 fluid communication between the pair is to be established by embodiments of methods described herein;
26 [0029] Figure 2 is a schematic illustration of a Mineral Insulated ("MI") heater cable;
27 [0030] Figure 3 is a schematic illustration of a system for deploying an electrical heating 28 system within a wellbore for enabling practising of methods described herein;
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 [0031] Figure 4 is a cross-sectional view of a coiled tube, from one end, including three 2 MI heater cables illustrated in Figure 2; and 3 [0032] Figure 5 is a cross-sectional side view of a coiled tube, including three MI heater 4 cables illustrated in Figure 2.
DETAILED DESCRIPTION
6 [0033] There is provided a method for effecting fluid communication between a pair of 7 wells within a hydrocarbon containing reservoir during the start-up phase of a SAGD
8 operation. The wells are separated by an interwell region of the reservoir. For illustrative 9 purposes below, an oil sands reservoir from which bitumen is being produced is described.
However, it should be understood, that the techniques described could be used in other types 11 of hydrocarbon containing reservoirs where SAGD is employed.
12 [0034] Referring to Figure 1, in a typical SAGD well pair, the wells are spaced vertically 13 from one another, such as wells 10 and 20, and the vertically higher well, i.e., well 10, is used 14 for steam injection during a production phase of the SAGD operation, and the lower well, i.e., well 20, is used for production during the production phase. In a conventional start-up phase, 16 steam is circulated through both wells 10 and 20, for the purpose of warming the interwell 17 region 15 primarily by conduction. As the interwell region 15 warms, the viscosity of the 18 bitumen contained in that region is reduced, mobilizing the bitumen which can then be 19 produced from the production well 20.
[0035] In the implementation shown, a cased-hole completion includes casing 40 run 21 down the wellbore 10 and 20 through the production zone. The casing may be cemented to 22 the subterranean oil sands reservoir for effecting zonal isolation. A
liner may be hung from 23 the last section of casing. The liner can be made from the same material as the casing string, 24 but, unlike the casing string, the liner does not extend back to the wellhead. The liner is slotted or perforated to effect communication with the reservoir.
26 [0036] Fluid conducting tubing 50 or multiple tubing strings can be installed inside the 27 last casing string of the injection well, well 10. The tubing(s) 50 is provided to conduct steam 28 and steam condensate from the wellhead 60 to the liner and sequentially to the reservoir.
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 [0037] Fluid conducting tubing 50 or multiple tubing strings can be installed inside the 2 last casing string of the production well, well 20.
3 [0038] In the illustrated embodiment, a perforated liner is provided in each of the wells 4 10, 20, for enabling fluid communication between the tubing 50 and the reservoir 30. During the production phase of the SAGD operation, steam injected through the well 10 (typically 6 referred to as the "injection well") is conducted within the tubing or casing annulus or both, 7 through the liner, and into the reservoir 30. The injected steam mobilizes the bitumen within 8 the oil sands reservoir 30. The mobilized bitumen and steam condensate drains through the 9 interwell region 15 by gravity to the well 20 (typically referred to as the "production well"), collects in the liner and is surfaced through tubing 50 or by artificial lift to the surface 5.
11 [0039] Prior to the production phase, the fluid communication between the wells 10, 20 12 is established through the interwell region 15 during a start-up phase.
Unlike the conventional 13 start-up technique, which relies solely on steam to achieve fluid communication, techniques 14 and systems are described where fluid communication between the injection well 10 and the production well 20 is enabled by electrical heating of the interwell region 15. An in situ 16 electrical heat source raises temperature uniformly, or substantially uniformly, along the 17 wellbore installation and heats the surrounding reservoir by conduction.
Electrical heating of 18 the interwell region 15 is more uniform, relative to steam circulation.
As well, in comparison 19 to using steam circulation for start-up, the heat generated within the interwell region by electrical sources can be easier to control. This is because heating of the interwell region 21 responds faster to odulation of electrical sources than it does for modulation of steam 22 sources.
23 [0040] A typical wellbore includes cement between the casing and the reservoir material.
24 Cement integrity can be compromised by pronounced thermal cycling and/or abrupt transitions of heating rates in situ. Electrical heat provides a controllable heat source that can 26 avoid or reduce these events, and cement integrity is more likely to be maintained for a longer 27 period of time, than in a well pair relying solely on steam circulation for start-up.
28 [0041] In a typical SAGD operation, there are multiple well pairs drilled into the reservoir.
29 After the well pairs are drilled and completed, surface facilities must be built before the SAGD
operation can commence. The surface facilities may include steam generating units or steam CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 distribution pipelines and manifolds. Until the steam generating units are complete, there is 2 no source of steam and the start-up phase cannot commence.
Advantageously, when using 3 electrical heat as the heat source for the start-up phase, the start-up phase can commence 4 at any time after the well pairs are completed and prior to completion of the surface facilities.
Considering the time that can elapse between the well pairs being drilled and the surface 6 facilities being completed can be two or more years, a significant time advantage can be 7 realized by employed electrical heat.
8 [0042] In some implementations, electrical heat is the sole source of heat during the start-9 up phase, and fluid communication in the interwell region 15 can be enabled without any circulation of steam in the injection well 10 or the production well 20. In other implementations, 11 electrical heat is employed as the initial source of heat during the start-up phase, and 12 particularly while a steam source is unavailable. Once surface facilities including a steam 13 source are complete, a final stage of the start-up phase can include both electrical heat 14 and steam injection to displace highly viscous hydrocarbons from interwell region 15. In other implementations electrical heat in the production well 20 and steam circulation in the injection 16 well 10 could be applied for heating interwell region 15. In other implementations, electrical 17 heat is employed as the initial source of heat, and once surface facilities including a steam 18 source unit are complete, the final stage of the start-up phase is by steam circulation only, 19 e.g., in one or both of the wells 10, 20, In any of these implementations, by employing electrical heat as a start-up phase heat source during the time period when steam was 21 unavailable, start-up is achieved sooner than would have been the case if relying on steam 22 only. Accordingly, the SAGD operation can move into the production phase sooner. By 23 accelerating start-up of SAGD, pad economics are improved by virtue of the earlier production 24 of bitumen. Additionally, start-up can be achieved using significantly less steam, resulting in an improved SOR.
26 [0043] In some embodiments, the electrical heating is by an electrical heating system 27 that is disposed in the injection well and/or the production well. In addition to an electrical 28 heater or an electrical heating system, heating can be by one or more other artificial sources 29 of heat. That is, in addition to electrical heating of the interwell region 15, one or more other artificial sources of heat can supply heat to the interwell region 15, such that the heating in 31 the interwell region15 is caused by heat supplied by the electrical heating as well as heating CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 by the other artificial sources of heat. Where, in addition to an electrical heater or an electrical 2 heating system, there is at least one or more other artificial sources of heat that is supplying 3 the heat to the interwell region 15, each one of the multiple artificial sources of heat may be 4 supplying the heat to the interwell region 15 independently of one another or in co-ordination or controlled co-operation with one or more of the other heat sources. Also, each one of the 6 multiple sources of heat may be supplying the heat to the interwell region 15 simultaneously 7 with one or more of the other heat sources, asynchronously relative to one or more of the 8 other heat sources, or any combination thereof. An example of another artificial source of 9 heat is steam. In this respect, heating of the interwell region 15 can also be caused by steam injection through one or both of the wells 10, 20. In some implementations, the steam injection 11 is effected by steam circulation within the well. In such case, the steam is injected through a 12 fluid passage provided within the well (such as, for example, the fluid conducting tubing 50) 13 to the toe of the well, becomes disposed in thermal communication with the reservoir 30 and 14 effects heating of the interwell region 15, and is then returned to the surface 5 through another fluid passage defined within the well (such as, for example, the annulus between the tubing 16 50 and the casing 40). In other implementations, the steam injection is effected by 17 bullheading. In such case, the steam is injected through a fluid passage provided within the 18 well (such as, for example, the fluid conducting tubing and/or the annulus between the tubing 19 50 and the casing 40) and supplied to the reservoir 30.
[0044] In some implementations, the interwell region is defined within a shallow 21 hydrocarbon reservoir that includes bitumen. A shallow hydrocarbon reservoir is a 22 hydrocarbon reservoir that is disposed less than 140 metres from the surface. For shallow 23 hydrocarbon reservoirs, using conventional steam circulation to establish fluid communication 24 between the wells 10, 20 can create environmental risks, as the steam pressure may effect fractures within the oil sands reservoir 30, and thereby effect conduction of the bitumen and/or 26 steam to undesirable locations within the oil sands reservoir 30, or to surface. In this respect, 27 by using electrical system to heat the interwell region 15 and enable displacement of immobile 28 bitumen between the wells 10, 20, the risk of damaging the oil sands reservoir 30, or causing 29 undesirable surface releases of bitumen or steam, is avoided.
[0045] In another aspect, the interwell region 15 is defined within a poor geology 31 reservoir. A poor geology reservoir is a reservoir with a bitumen saturation of less than 85%
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 and a porosity of less than 30%. Bitumen saturation of a reservoir is the mass concentration 2 of bitumen within the reservoir. Porosity of a reservoir is the volumetric fraction of empty 3 space within the reservoir, expressed as a percentage. It can be desirable to use electrical 4 heating to at least partially contribute to the establishment of fluid communication through such an interwell region 15 during the start-up phase, rather than solely relying on steam to 6 establish the fluid communication. This is because it is relatively difficult for steam to be 7 conducted through a poor geology reservoir. Comparatively, the establishment of fluid 8 communication through the interwell region 15 in a poor geology reservoir is faster when 9 electrical heating is used to heat such interwell region 15.
[0046] In some implementations, different portions of the interwell region 15 are 11 independently electrically heated so as to differentially mobilize the fluid within interwell region 12 15. Electrically heating the interwell region 15 can include electrically heating a first portion of 13 the interwell region 15 at a first predetermined heating rate and, while the first portion is being 14 electrically heated at the first predetermined heating rate, electrically heating a second portion of the interwell region at a different second predetermined heating rate. It can be desirable to 16 independently control the rate of heating of one or more portions of the interwell region 15 17 from the rate of heating of one or more other portions of the interwell region 15 if some 18 portions have different thermal characteristics (e.g. thermal conductivity and heat capacity) 19 than other portions and therefore, require different rates of heating to achieve uniform (or substantially uniform) temperature conditions.
21 [0047] In some implementations, heating of the interwell region 15 is by at least both:
22 (i)electrical heating and (ii) steam injection through one or both of the injector and production 23 wells. In such implementations, steam is injected through at least one of the wells 10, 20 while 24 electrically heating the interwell region 15 with an electrical heating system, disposed within a respective one or more of the wells 10, 20 through which the steam is being injected. In this 26 respect, the injected steam is also heated by the electrical heating system. The heating of the 27 steam can improve or maintain steam quality. In some implementations, the steam injection 28 is effected during steam circulation. In other implementations, the steam injection is effected 29 while bullheading.
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 [0048] In some embodiments, for example, during start-up, the injected steam carries a 2 gaseous chemical additive material for supply to the interwell region 15.
The gaseous 3 chemical additive material is configured for promoting establishment of the fluid 4 communicating interwell region 15. Suitable chemical additives include a surface tension adjusting agent, such as a detergent. A surface tension adjusting agent would be configured 6 for affecting the surface tension between the bitumen and the rock such that separation of 7 the bitumen from the rock is facilitated. Suitable chemical additives include cationic 8 surfactants, such as alkyltrimethylammonium bromide and alkyldimethylammonium bromide.
9 Other suitable chemical additives include alcohol propoxylate sulfate and alkyl sulfonate surfactants. Further suitable chemical additives include hydrocarbon materials, such as 11 butane, propane or diesel. Such hydrocarbon materials arc provided for enhancing the 12 mobility of the bitumen within the reservoir. In this respect, in addition to the injected steam 13 being heated by the electrical heating system, where the injected steam is carrying the 14 gaseous chemical additive material, the gaseous chemical additive material is also heated by the electrical heating system, such that condensation of the gaseous chemical additive 16 material is prevented or at least mitigated, and that the chemical additive material remains in 17 the gaseous phase so its supply to the reservoir is enabled.
18 [0049] In another aspect, an electrical heating system disposed within at least one of 19 the injector and production wells 10, 20, at least partially contributes to heating of the interwell region 15. After the interwell region 15 has been heated to effect, SAGD is conducted, and 21 SAGD includes injecting steam from the injection well 10 into the oil sands reservoir 30 for 22 mobilizing bitumen within the oil sands reservoir 30 such that the mobilized bitumen is 23 conducted through the interwell region 15 to the production well 20, and recovering the 24 mobilized bitumen through the production well 20. While SAGD is being conducted, a problem may be detected requiring well intervention. Well intervention may be required, for example, 26 to replace downhole equipment or instrumentation, such as submersible pumps, long tubing, 27 plugged components, or optical fibre. In response to the detecting of the problem, SAGD is 28 suspended so as to permit well intervention. After the suspending of SAGD, wellbore fluids 29 within one or both of the wells 10, 20 may be conducted to the surface by electrically heating the wellbore fluids with the electrical heating system, such that the wellbore fluids are 31 vaporized and are conducted through the respective well 10 or 20 to the surface 5. In some CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 embodiments, for example, the electrical heating system may have also been used to heat 2 the steam being supplied to the injection well 10 during SAGD. By enabling conduction of the 3 wellbore fluids in this manner, use of pumping units or other lifting mechanism can be 4 avoided. As well, removal of the wellbore fluids using electrical heaters is more effective than by using pumping units or other lift mechanisms, and thereby mitigates the risk of possible 6 undesirable chemical reactions between residual wellbore fluids and fluids being introduced 7 to the wellbore during well intervention.
8 [0050] In some embodiments, for example, the electrical heating is by an electrical 9 heating system. In some of these embodiments, for example, an electrical heating system is disposed in one or both of the wells 10. In some of these embodiments, for example, the 11 electrical heating system includes a heater cable. The heater cable includes a wire 12 surrounded by insulation (e.g. mineral insulation) and disposed within a metallic sheath. The 13 wire is electrically coupled to a power source and a controller and, in this respect, is 14 configured to effect heating of the interwell region 15 by conduction.
An example of a suitable heater cable is a mineral-insulated ("MI") heater cable 70. Referring to Figure 2, a MI heater 16 cable 70 includes an electrically conducting core 72, surrounded by a metallic sheath 74 (for 17 example, a 304L sheath) with a mineral insulation layer 76 (for example, magnesium oxide) 18 disposed between the metallic sheath 74 and the core 72. In some embodiments, for 19 example, the heater cable 70 can include relatively hotter and relatively colder sections. This is enabled by using different materials in different sections of the cable. In this respect, by 21 having relatively hotter and relatively colder section, different heating rates can be provided 22 for different portions of the interwell region 15 in some embodiments.
23 [0051] Referring to Figure 3, in some of these embodiments, for example, the heater 24 cable is deployed within a coiled tube 60. Referring to Figures 4 and 5, in some embodiments, for example, multiple cables 70 are deployed within the coiled tube 60. In some embodiments, 26 for example, the cables 70 are mounted to a support rod 80 for maintaining positioning the 27 cables 70. In the illustrated embodiment, for example, the heater cable is a three (3) phase 28 heater consisting of three (3) single conductor MI heater cables 70 disposed in a coiled tube 29 60 that is deployed from a reel 90 disposed on the surface 5. The MI
heater cables 70 are assembled into complete heater units by installing a wye splice 100 at the bottom of the 31 cables 70 for forming a dielectrically insulated connection.
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 [0052] Other forms of electrical heating devices can be used, and are not limited to those 2 discussed herein.
[0053] Reference throughout the specification to "one embodiment," "an embodiment,"
4 "some embodiments," "one aspect," "an aspect," or "some aspects" means that a particular feature, structure, method, or characteristic described in connection with the embodiment or 6 aspect is included in at least one embodiment of the present invention.
In this respect, the 7 appearance of the phrases "in one embodiment" or "in an embodiment" or "in some 8 embodiments" in various places throughout the specification are not necessarily all referring 9 to the same embodiment. Furthermore, the particular features, structures, methods, or characteristics may be combined in any suitable manner in one or more embodiments.
[0054] Each numerical value should be read once as modified by the term "about" (unless 12 already expressly so modified), and then read again as not so modified unless otherwise 13 indicated in context. Also, in the summary arid this detailed description, it should be 14 understood that a concentration range listed or described as being useful, suitable, or the like, is intended that any and every concentration within the range, including the end points, 16 is to be considered as having been stated. For example, "a range of from 1 to 10" is to be 17 read as indicating each and every possible number along the continuum between about 1 18 and about 10. Thus, even if specific data points within the range, or even no data points within 19 the range, are explicitly identified or refer to only a few specific data points, it is to be understood that inventors appreciate and understand that any and all data points within the 21 range are to be considered to have been specified, and that inventors have disclosed and 22 enabled the entire range and all points within the range.
[0055] In the above description, for purposes of explanation, numerous details are set 24 forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that these specific details are not required in order to 26 practice the present disclosure. Although certain dimensions and materials are described for 27 implementing the disclosed example embodiments, other suitable dimensions and/or 28 materials may be used within the scope of this disclosure. All such modifications and 29 variations, including - all suitable current and future changes in technology, are believed to be within the sphere and scope of the present disclosure.
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30
[0007] In another aspect, a method of producing bitumen from an oil sands reservoir 11 includes, during a start-up phase, electrically heating an interwell region of the oil sands 12 reservoir isposed between an injection well and a production well, for establishing a fluid 13 communication between the injection well and the production well. After establishing the fluid 14 communication, a production phase is commenced that includes injecting steam from the injection well into the oil sands reservoir for effecting mobilization of bitumen within the oil 16 sands reservoir. The mobilized bitumen is conducted through the interwell region to the 17 production well and recovered to surface through the production well.
18 [0008] In some implementations, the method further includes, after establishing fluid 19 communication in the interwell region, supplying steam from a steam generator, where the steam being injected is the steam supplied from the steam generator.
Electrically heating the 21 interwell region can be completed prior to, or substantially completed prior to, commissioning 22 of steam facilities for effecting the supplying of steam from the steam generator to the injection 23 well.
24 [0009] The electrical heating of the interwell region can be effected while steam facilities, for effecting the supplying of steam from the steam generator to the injection well, are being 26 constructed.
27 [0010] The electrical heating of the interwell region can be effected by an electrical 28 heating system disposed within the injection well and/or the production well.
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 [0011] The interwell region can be defined within a shallow hydrocarbon reservoir.
2 [0012] The interwell region is the region of the reservoir that is between the injection well 3 and the production well, which in a typical SAGD operation is approximately 5 metres in 4 depth. In some reservoirs, the bitumen saturation is greater than 85% and the porosity is greater than 35%, although reservoirs vary in these characteristics and the bitumen saturation 6 and/or porosity could be lower in some instances.
7 [0013] In another aspect, a method of establishing fluid communication between a well 8 pair within an oil sands reservoir includes electrically heating an interwell region of the oil 9 sands reservoir disposed between an injection well and a production well, to at least contribute to establishing fluid communication in the interwell region. The electrical heating 11 includes: electrically heating a first portion of the interwell region at a first predetermined 12 heating rate; and electrically heating a second portion of the interwell region at a different 13 second redetermined heating rate while the first portion is being heated at the first 14 predetermined rate.
[0014] In some implementations, the first predetermined heating rate and the second 16 predetermined heating rate are selected to effect a substantially uniform heating of the 17 interwell region.
18 [0015] In some implementations, the electrical heating of an interwell region is effected 19 by an electrical heating system disposed within at least one of the injection well and the production well.
21 [0016] In another aspect, a method of establishing fluid communication between a well 22 pair comprising an injection well and a production well within an oil sands reservoir includes 23 heating an interwell region disposed between the injection well and the production well, 24 establishing fluid communication between the two wells. The heating includes heating the interwell region with heat generated by steam injected into at least one well in the well pair 26 and simultaneously with heat generated by an electric heating system.
Heat generated by the 27 electric heating system effects both heating of the interwell region and heating of the injected 28 steam.
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 [0017] In some implementations, the steam injected into the at least one well is injected 2 into the well and circulated to surface.
3 [0018] In some implementations, the steam injected into the at least one well is injected 4 into the reservoir, i.e., bull heading.
[0019] In some implementations, the steam carries a gaseous chemical additive material 6 and condensation of the chemical additive material is mitigated by the electric heating of the 7 steam.
8 [0020] In some implementations, the electric heating system is disposed within at least 9 one of the wells in the well pair.
[0021] In another aspect, a method of producing bitumen from an oil sands reservoir 11 includes, after a fluid communicating interwell region has been established between and 12 injection well and a production well forming a well pair, injecting steam into the oil sands 13 reservoir via the injection well for effecting mobilization of bitumen within the oil sands 14 reservoir. The mobilized bitumen is conducted through the established fluid communicating interwell region to the production well. While the steam is being injected, the injected steam 16 is heated with an electrical heating system situated in the injection well. The mobilized 17 bitumen is recovered to surface through the production well.
18 [0022] In some implementations, the injected steam carries a gaseous chemical additive 19 material, and the electrical heating of the injected steam is such that condensation of the chemical additive material is mitigated.
21 [0023] In some implementations, prior to the injecting steam for effecting mobilization, 22 the interwell region is electrically heated with the electrical heating system, which at least 23 contributes to establishing a fluid communicating interwell region for effecting fluid 24 communication between the injection well and the production well.
[0024] In another aspect, a method of producing bitumen from an oil sands reservoir 26 includes electrically heating an interwell region, of the oil sands reservoir, disposed between 27 an injection well and a production well established within the oil sands reservoir, with an 28 electrical heating system. After the fluid communicating interwell region has been effected, CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 steam assisted gravity drainage (SAGD) is conducted to produce the bitumen, wherein the 2 SAGD includes: injecting steam into the oil sands reservoir via the injection well for effecting 3 mobilization of bitumen disposed within the oil sands reservoir such that the mobilized 4 bitumen is conducted through the established fluid communicating interwell region to the production well; and recovering the mobilized bitumen through the production well. While 6 SAGD is being conducted, a problem is detected requiring well intervention. In response to 7 the detecting of the problem requiring well intervention, SAGD is suspended and the wellbore 8 fluids disposed within one or both of the wells are electrically heated with the electrical heating 9 system. The wellbore fluids are vaporized and are conducted through the respective well to the wellhead.
11 [0025] In some implementations, the electrical heating system is disposed in the injection 12 well and/or the production well.
13 [0026] In another aspect, a method of producing bitumen from an oil sands reservoir 14 includes establishing fluid communication between an injection well and a production well for use as a steam assisted gravity drainage (SAGD) well pair by exclusively using electrical heat 16 applied in situ. The method can further include, only after establishing the fluid 17 communication, commencing injection of steam into the oil sands reservoir via the injection 18 well and producing production fluid from the oil sands reservoir via the production well, 19 wherein the production fluid includes bitumen.
BRIEF DESCRIPTION OF DRAWINGS
21 [0027] The preferred embodiments will now be described with the following 22 accompanying drawings, in which;
23 [0028] Figure 1 is a schematic illustration of a well pair in an oil sands reservoir, where 24 fluid communication between the pair is to be established by embodiments of methods described herein;
26 [0029] Figure 2 is a schematic illustration of a Mineral Insulated ("MI") heater cable;
27 [0030] Figure 3 is a schematic illustration of a system for deploying an electrical heating 28 system within a wellbore for enabling practising of methods described herein;
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 [0031] Figure 4 is a cross-sectional view of a coiled tube, from one end, including three 2 MI heater cables illustrated in Figure 2; and 3 [0032] Figure 5 is a cross-sectional side view of a coiled tube, including three MI heater 4 cables illustrated in Figure 2.
DETAILED DESCRIPTION
6 [0033] There is provided a method for effecting fluid communication between a pair of 7 wells within a hydrocarbon containing reservoir during the start-up phase of a SAGD
8 operation. The wells are separated by an interwell region of the reservoir. For illustrative 9 purposes below, an oil sands reservoir from which bitumen is being produced is described.
However, it should be understood, that the techniques described could be used in other types 11 of hydrocarbon containing reservoirs where SAGD is employed.
12 [0034] Referring to Figure 1, in a typical SAGD well pair, the wells are spaced vertically 13 from one another, such as wells 10 and 20, and the vertically higher well, i.e., well 10, is used 14 for steam injection during a production phase of the SAGD operation, and the lower well, i.e., well 20, is used for production during the production phase. In a conventional start-up phase, 16 steam is circulated through both wells 10 and 20, for the purpose of warming the interwell 17 region 15 primarily by conduction. As the interwell region 15 warms, the viscosity of the 18 bitumen contained in that region is reduced, mobilizing the bitumen which can then be 19 produced from the production well 20.
[0035] In the implementation shown, a cased-hole completion includes casing 40 run 21 down the wellbore 10 and 20 through the production zone. The casing may be cemented to 22 the subterranean oil sands reservoir for effecting zonal isolation. A
liner may be hung from 23 the last section of casing. The liner can be made from the same material as the casing string, 24 but, unlike the casing string, the liner does not extend back to the wellhead. The liner is slotted or perforated to effect communication with the reservoir.
26 [0036] Fluid conducting tubing 50 or multiple tubing strings can be installed inside the 27 last casing string of the injection well, well 10. The tubing(s) 50 is provided to conduct steam 28 and steam condensate from the wellhead 60 to the liner and sequentially to the reservoir.
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 [0037] Fluid conducting tubing 50 or multiple tubing strings can be installed inside the 2 last casing string of the production well, well 20.
3 [0038] In the illustrated embodiment, a perforated liner is provided in each of the wells 4 10, 20, for enabling fluid communication between the tubing 50 and the reservoir 30. During the production phase of the SAGD operation, steam injected through the well 10 (typically 6 referred to as the "injection well") is conducted within the tubing or casing annulus or both, 7 through the liner, and into the reservoir 30. The injected steam mobilizes the bitumen within 8 the oil sands reservoir 30. The mobilized bitumen and steam condensate drains through the 9 interwell region 15 by gravity to the well 20 (typically referred to as the "production well"), collects in the liner and is surfaced through tubing 50 or by artificial lift to the surface 5.
11 [0039] Prior to the production phase, the fluid communication between the wells 10, 20 12 is established through the interwell region 15 during a start-up phase.
Unlike the conventional 13 start-up technique, which relies solely on steam to achieve fluid communication, techniques 14 and systems are described where fluid communication between the injection well 10 and the production well 20 is enabled by electrical heating of the interwell region 15. An in situ 16 electrical heat source raises temperature uniformly, or substantially uniformly, along the 17 wellbore installation and heats the surrounding reservoir by conduction.
Electrical heating of 18 the interwell region 15 is more uniform, relative to steam circulation.
As well, in comparison 19 to using steam circulation for start-up, the heat generated within the interwell region by electrical sources can be easier to control. This is because heating of the interwell region 21 responds faster to odulation of electrical sources than it does for modulation of steam 22 sources.
23 [0040] A typical wellbore includes cement between the casing and the reservoir material.
24 Cement integrity can be compromised by pronounced thermal cycling and/or abrupt transitions of heating rates in situ. Electrical heat provides a controllable heat source that can 26 avoid or reduce these events, and cement integrity is more likely to be maintained for a longer 27 period of time, than in a well pair relying solely on steam circulation for start-up.
28 [0041] In a typical SAGD operation, there are multiple well pairs drilled into the reservoir.
29 After the well pairs are drilled and completed, surface facilities must be built before the SAGD
operation can commence. The surface facilities may include steam generating units or steam CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 distribution pipelines and manifolds. Until the steam generating units are complete, there is 2 no source of steam and the start-up phase cannot commence.
Advantageously, when using 3 electrical heat as the heat source for the start-up phase, the start-up phase can commence 4 at any time after the well pairs are completed and prior to completion of the surface facilities.
Considering the time that can elapse between the well pairs being drilled and the surface 6 facilities being completed can be two or more years, a significant time advantage can be 7 realized by employed electrical heat.
8 [0042] In some implementations, electrical heat is the sole source of heat during the start-9 up phase, and fluid communication in the interwell region 15 can be enabled without any circulation of steam in the injection well 10 or the production well 20. In other implementations, 11 electrical heat is employed as the initial source of heat during the start-up phase, and 12 particularly while a steam source is unavailable. Once surface facilities including a steam 13 source are complete, a final stage of the start-up phase can include both electrical heat 14 and steam injection to displace highly viscous hydrocarbons from interwell region 15. In other implementations electrical heat in the production well 20 and steam circulation in the injection 16 well 10 could be applied for heating interwell region 15. In other implementations, electrical 17 heat is employed as the initial source of heat, and once surface facilities including a steam 18 source unit are complete, the final stage of the start-up phase is by steam circulation only, 19 e.g., in one or both of the wells 10, 20, In any of these implementations, by employing electrical heat as a start-up phase heat source during the time period when steam was 21 unavailable, start-up is achieved sooner than would have been the case if relying on steam 22 only. Accordingly, the SAGD operation can move into the production phase sooner. By 23 accelerating start-up of SAGD, pad economics are improved by virtue of the earlier production 24 of bitumen. Additionally, start-up can be achieved using significantly less steam, resulting in an improved SOR.
26 [0043] In some embodiments, the electrical heating is by an electrical heating system 27 that is disposed in the injection well and/or the production well. In addition to an electrical 28 heater or an electrical heating system, heating can be by one or more other artificial sources 29 of heat. That is, in addition to electrical heating of the interwell region 15, one or more other artificial sources of heat can supply heat to the interwell region 15, such that the heating in 31 the interwell region15 is caused by heat supplied by the electrical heating as well as heating CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 by the other artificial sources of heat. Where, in addition to an electrical heater or an electrical 2 heating system, there is at least one or more other artificial sources of heat that is supplying 3 the heat to the interwell region 15, each one of the multiple artificial sources of heat may be 4 supplying the heat to the interwell region 15 independently of one another or in co-ordination or controlled co-operation with one or more of the other heat sources. Also, each one of the 6 multiple sources of heat may be supplying the heat to the interwell region 15 simultaneously 7 with one or more of the other heat sources, asynchronously relative to one or more of the 8 other heat sources, or any combination thereof. An example of another artificial source of 9 heat is steam. In this respect, heating of the interwell region 15 can also be caused by steam injection through one or both of the wells 10, 20. In some implementations, the steam injection 11 is effected by steam circulation within the well. In such case, the steam is injected through a 12 fluid passage provided within the well (such as, for example, the fluid conducting tubing 50) 13 to the toe of the well, becomes disposed in thermal communication with the reservoir 30 and 14 effects heating of the interwell region 15, and is then returned to the surface 5 through another fluid passage defined within the well (such as, for example, the annulus between the tubing 16 50 and the casing 40). In other implementations, the steam injection is effected by 17 bullheading. In such case, the steam is injected through a fluid passage provided within the 18 well (such as, for example, the fluid conducting tubing and/or the annulus between the tubing 19 50 and the casing 40) and supplied to the reservoir 30.
[0044] In some implementations, the interwell region is defined within a shallow 21 hydrocarbon reservoir that includes bitumen. A shallow hydrocarbon reservoir is a 22 hydrocarbon reservoir that is disposed less than 140 metres from the surface. For shallow 23 hydrocarbon reservoirs, using conventional steam circulation to establish fluid communication 24 between the wells 10, 20 can create environmental risks, as the steam pressure may effect fractures within the oil sands reservoir 30, and thereby effect conduction of the bitumen and/or 26 steam to undesirable locations within the oil sands reservoir 30, or to surface. In this respect, 27 by using electrical system to heat the interwell region 15 and enable displacement of immobile 28 bitumen between the wells 10, 20, the risk of damaging the oil sands reservoir 30, or causing 29 undesirable surface releases of bitumen or steam, is avoided.
[0045] In another aspect, the interwell region 15 is defined within a poor geology 31 reservoir. A poor geology reservoir is a reservoir with a bitumen saturation of less than 85%
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 and a porosity of less than 30%. Bitumen saturation of a reservoir is the mass concentration 2 of bitumen within the reservoir. Porosity of a reservoir is the volumetric fraction of empty 3 space within the reservoir, expressed as a percentage. It can be desirable to use electrical 4 heating to at least partially contribute to the establishment of fluid communication through such an interwell region 15 during the start-up phase, rather than solely relying on steam to 6 establish the fluid communication. This is because it is relatively difficult for steam to be 7 conducted through a poor geology reservoir. Comparatively, the establishment of fluid 8 communication through the interwell region 15 in a poor geology reservoir is faster when 9 electrical heating is used to heat such interwell region 15.
[0046] In some implementations, different portions of the interwell region 15 are 11 independently electrically heated so as to differentially mobilize the fluid within interwell region 12 15. Electrically heating the interwell region 15 can include electrically heating a first portion of 13 the interwell region 15 at a first predetermined heating rate and, while the first portion is being 14 electrically heated at the first predetermined heating rate, electrically heating a second portion of the interwell region at a different second predetermined heating rate. It can be desirable to 16 independently control the rate of heating of one or more portions of the interwell region 15 17 from the rate of heating of one or more other portions of the interwell region 15 if some 18 portions have different thermal characteristics (e.g. thermal conductivity and heat capacity) 19 than other portions and therefore, require different rates of heating to achieve uniform (or substantially uniform) temperature conditions.
21 [0047] In some implementations, heating of the interwell region 15 is by at least both:
22 (i)electrical heating and (ii) steam injection through one or both of the injector and production 23 wells. In such implementations, steam is injected through at least one of the wells 10, 20 while 24 electrically heating the interwell region 15 with an electrical heating system, disposed within a respective one or more of the wells 10, 20 through which the steam is being injected. In this 26 respect, the injected steam is also heated by the electrical heating system. The heating of the 27 steam can improve or maintain steam quality. In some implementations, the steam injection 28 is effected during steam circulation. In other implementations, the steam injection is effected 29 while bullheading.
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 [0048] In some embodiments, for example, during start-up, the injected steam carries a 2 gaseous chemical additive material for supply to the interwell region 15.
The gaseous 3 chemical additive material is configured for promoting establishment of the fluid 4 communicating interwell region 15. Suitable chemical additives include a surface tension adjusting agent, such as a detergent. A surface tension adjusting agent would be configured 6 for affecting the surface tension between the bitumen and the rock such that separation of 7 the bitumen from the rock is facilitated. Suitable chemical additives include cationic 8 surfactants, such as alkyltrimethylammonium bromide and alkyldimethylammonium bromide.
9 Other suitable chemical additives include alcohol propoxylate sulfate and alkyl sulfonate surfactants. Further suitable chemical additives include hydrocarbon materials, such as 11 butane, propane or diesel. Such hydrocarbon materials arc provided for enhancing the 12 mobility of the bitumen within the reservoir. In this respect, in addition to the injected steam 13 being heated by the electrical heating system, where the injected steam is carrying the 14 gaseous chemical additive material, the gaseous chemical additive material is also heated by the electrical heating system, such that condensation of the gaseous chemical additive 16 material is prevented or at least mitigated, and that the chemical additive material remains in 17 the gaseous phase so its supply to the reservoir is enabled.
18 [0049] In another aspect, an electrical heating system disposed within at least one of 19 the injector and production wells 10, 20, at least partially contributes to heating of the interwell region 15. After the interwell region 15 has been heated to effect, SAGD is conducted, and 21 SAGD includes injecting steam from the injection well 10 into the oil sands reservoir 30 for 22 mobilizing bitumen within the oil sands reservoir 30 such that the mobilized bitumen is 23 conducted through the interwell region 15 to the production well 20, and recovering the 24 mobilized bitumen through the production well 20. While SAGD is being conducted, a problem may be detected requiring well intervention. Well intervention may be required, for example, 26 to replace downhole equipment or instrumentation, such as submersible pumps, long tubing, 27 plugged components, or optical fibre. In response to the detecting of the problem, SAGD is 28 suspended so as to permit well intervention. After the suspending of SAGD, wellbore fluids 29 within one or both of the wells 10, 20 may be conducted to the surface by electrically heating the wellbore fluids with the electrical heating system, such that the wellbore fluids are 31 vaporized and are conducted through the respective well 10 or 20 to the surface 5. In some CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 1 embodiments, for example, the electrical heating system may have also been used to heat 2 the steam being supplied to the injection well 10 during SAGD. By enabling conduction of the 3 wellbore fluids in this manner, use of pumping units or other lifting mechanism can be 4 avoided. As well, removal of the wellbore fluids using electrical heaters is more effective than by using pumping units or other lift mechanisms, and thereby mitigates the risk of possible 6 undesirable chemical reactions between residual wellbore fluids and fluids being introduced 7 to the wellbore during well intervention.
8 [0050] In some embodiments, for example, the electrical heating is by an electrical 9 heating system. In some of these embodiments, for example, an electrical heating system is disposed in one or both of the wells 10. In some of these embodiments, for example, the 11 electrical heating system includes a heater cable. The heater cable includes a wire 12 surrounded by insulation (e.g. mineral insulation) and disposed within a metallic sheath. The 13 wire is electrically coupled to a power source and a controller and, in this respect, is 14 configured to effect heating of the interwell region 15 by conduction.
An example of a suitable heater cable is a mineral-insulated ("MI") heater cable 70. Referring to Figure 2, a MI heater 16 cable 70 includes an electrically conducting core 72, surrounded by a metallic sheath 74 (for 17 example, a 304L sheath) with a mineral insulation layer 76 (for example, magnesium oxide) 18 disposed between the metallic sheath 74 and the core 72. In some embodiments, for 19 example, the heater cable 70 can include relatively hotter and relatively colder sections. This is enabled by using different materials in different sections of the cable. In this respect, by 21 having relatively hotter and relatively colder section, different heating rates can be provided 22 for different portions of the interwell region 15 in some embodiments.
23 [0051] Referring to Figure 3, in some of these embodiments, for example, the heater 24 cable is deployed within a coiled tube 60. Referring to Figures 4 and 5, in some embodiments, for example, multiple cables 70 are deployed within the coiled tube 60. In some embodiments, 26 for example, the cables 70 are mounted to a support rod 80 for maintaining positioning the 27 cables 70. In the illustrated embodiment, for example, the heater cable is a three (3) phase 28 heater consisting of three (3) single conductor MI heater cables 70 disposed in a coiled tube 29 60 that is deployed from a reel 90 disposed on the surface 5. The MI
heater cables 70 are assembled into complete heater units by installing a wye splice 100 at the bottom of the 31 cables 70 for forming a dielectrically insulated connection.
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30 CA DIV3 Application CPST Ref: 83862/00690 [0052] Other forms of electrical heating devices can be used, and are not limited to those 2 discussed herein.
[0053] Reference throughout the specification to "one embodiment," "an embodiment,"
4 "some embodiments," "one aspect," "an aspect," or "some aspects" means that a particular feature, structure, method, or characteristic described in connection with the embodiment or 6 aspect is included in at least one embodiment of the present invention.
In this respect, the 7 appearance of the phrases "in one embodiment" or "in an embodiment" or "in some 8 embodiments" in various places throughout the specification are not necessarily all referring 9 to the same embodiment. Furthermore, the particular features, structures, methods, or characteristics may be combined in any suitable manner in one or more embodiments.
[0054] Each numerical value should be read once as modified by the term "about" (unless 12 already expressly so modified), and then read again as not so modified unless otherwise 13 indicated in context. Also, in the summary arid this detailed description, it should be 14 understood that a concentration range listed or described as being useful, suitable, or the like, is intended that any and every concentration within the range, including the end points, 16 is to be considered as having been stated. For example, "a range of from 1 to 10" is to be 17 read as indicating each and every possible number along the continuum between about 1 18 and about 10. Thus, even if specific data points within the range, or even no data points within 19 the range, are explicitly identified or refer to only a few specific data points, it is to be understood that inventors appreciate and understand that any and all data points within the 21 range are to be considered to have been specified, and that inventors have disclosed and 22 enabled the entire range and all points within the range.
[0055] In the above description, for purposes of explanation, numerous details are set 24 forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that these specific details are not required in order to 26 practice the present disclosure. Although certain dimensions and materials are described for 27 implementing the disclosed example embodiments, other suitable dimensions and/or 28 materials may be used within the scope of this disclosure. All such modifications and 29 variations, including - all suitable current and future changes in technology, are believed to be within the sphere and scope of the present disclosure.
CPST-#281580-v1-Description283862-690).docx Date Recue/Date Received 2020-07-30
Claims (25)
1. A method of producing bitumen from an oil sands reservoir, comprising:
after a fluid communicating interwell region has been established between an injection well and a production well forming a well pair, injecting steam into the oil sands reservoir via the injection well for effecting mobilization of bitumen within the oil sands reservoir such that the mobilized bitumen is conducted through the established fluid communicating interwell region to the production well, wherein fluid communication is established between the injection well and the production well in the absence of steam injection into the injection well and the production well;
while the steam is being injected, heating the injected steam with an electrical heating system situated in the injection well; and recovering the mobilized bitumen through the production well.
after a fluid communicating interwell region has been established between an injection well and a production well forming a well pair, injecting steam into the oil sands reservoir via the injection well for effecting mobilization of bitumen within the oil sands reservoir such that the mobilized bitumen is conducted through the established fluid communicating interwell region to the production well, wherein fluid communication is established between the injection well and the production well in the absence of steam injection into the injection well and the production well;
while the steam is being injected, heating the injected steam with an electrical heating system situated in the injection well; and recovering the mobilized bitumen through the production well.
2. The method of claim 1, wherein the injected steam carries a gaseous chemical additive material, and the electrical heating of the injected steam is such that condensation of the chemical additive material is mitigated.
3. The method of claim 1 or claim 2, further comprising: prior to the injecting steam for effecting mobilization, electrically heating the interwell region with the electrical heating system, for at least contributing to establishing the fluid communicating interwell region for effecting fluid communication between the injection well and the production well.
4. The method of any one of claims 1 to 3, wherein the injected steam is circulated to the surface.
5. The method of any one of claims 1 to 4, wherein the interwell region is defined within the oil sands reservoir that is disposed less than 140 metres from the surface.
6. The method of any one of claims 1 to 5, wherein the oil sands reservoir has a bitumen CPST Doc: 384306.2 Date recue/date received 2021-10-26 CA 0IV3 Application CPST Ref: 83862/00690 saturation of less than 85% and a porosity of less than 30%.
7. The method of any one of claims 2 to 6, wherein the additive comprises butane, propane, diesel, or a combination thereof.
8. The method of claim 7, wherein the additive comprises butane.
9. The method of claim 7, wherein the additive comprises propane.
10. The method of claim 7, wherein the additive comprises diesel.
11. The method of any one of claims 2 to 10, wherein the injected steam and the additive are circulated to the surface.
12. The method of any one of claims 1 to 11, further comprising operating an electrical heating system disposed within the production well.
13. The method of any one of claims 1 to 12, further comprising detecting an event requiring well intervention and, in response to such event, suspending injection of steam.
14. The method of claim 13, further comprising conducting wellbore fluids to the surface by electrically heating the wellbore fluids with the electrical heating system disposed within the injection well while injection of steam is suspended.
15. The method of any one of claims 13 and 14, further comprising conducting wellbore fluids to the surface by electrically heating the wellbore fluids with the electrical heating system disposed within the production well while injection of steam is suspended.
16. The method of any one of claims 14 and 15, wherein wellbore fluids within the injection well are conducted to the surface.
CPST Doc: 281591.v1 Date recue/date received 2021-10-26 CA 0IV3 Application CPST Ref: 83862/00690
CPST Doc: 281591.v1 Date recue/date received 2021-10-26 CA 0IV3 Application CPST Ref: 83862/00690
17. The method of any one of claims 14 and 15, wherein wellbore fluids within the production well are conducted to the surface.
18. The method of any one of claims 14 and 15, wherein wellbore fluids within both the injection well and production well are conducted to the surface.
19. The method of any one of claims 14 to 18, wherein the step of electrically heating the wellbore fluids while injection of steam is suspended comprises vaporizing the wellbore fluids with the electrical heating system disposed within the injection well.
20. The method of any one of claims 15 to 19, wherein the step of electrically heating the wellbore fluids while injection of steam is suspended comprises vaporizing the wellbore fluids with the electrical heating system disposed within the production well.
21. The method of any one of claims 15 to 20, wherein the step of electrically heating the wellbore fluids while injection of steam is suspended comprises electrically heating the wellbore fluids with both of the electrical heating systems disposed in the production well and the injection well.
22. The method of any one of claims 14 to 21, wherein the step of conducting wellbore fluids to the surface by electrically heating the wellbore fluids with the electrical heating system disposed within the injection well while injection of steam is suspended is performed in the absence of the operation of pumping units or other lifting mechanism in the injection well.
23. The method of any one of claims 14 to 22, wherein the step of conducting wellbore fluids to the surface by electrically heating the wellbore fluids with the electrical heating system disposed within the injection well while injection of steam is suspended is performed in the absence of the operation of pumping units or other lifting mechanism in the production well.
CPST Doc: 281591.v1 Date recue/date received 2021-10-26 CA 0IV3 Application CPST Ref: 83862/00690
CPST Doc: 281591.v1 Date recue/date received 2021-10-26 CA 0IV3 Application CPST Ref: 83862/00690
24. The method of any one of claims 15 to 23, wherein the step of conducting wellbore fluids to the surface by electrically heating the wellbore fluids with the electrical heating system disposed within the production well while injection of steam is suspended is performed in the absence of the operation of pumping units or other lifting mechanism in the production well.
25. The method of any one of claims 15 to 24, wherein the step of conducting wellbore fluids to the surface by electrically heating the wellbore fluids with the electrical heating system disposed within the production well while injection of steam is suspended is performed in the absence of the operation of pumping units or other lifting mechanism in the injection well.
CPST Doc: 281591.v1 Date recue/date received 2021-10-26
CPST Doc: 281591.v1 Date recue/date received 2021-10-26
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA3157754A CA3157754A1 (en) | 2014-03-10 | 2014-03-21 | Methods for establishing fluid communication between a sagd well pair |
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| US201461950457P | 2014-03-10 | 2014-03-10 | |
| US61/950,457 | 2014-03-10 | ||
| US201461968247P | 2014-03-20 | 2014-03-20 | |
| CA2846924A CA2846924A1 (en) | 2014-03-10 | 2014-03-20 | Methods for establishing fluid communication between a sagd well pair |
| US61/968,247 | 2014-03-20 | ||
| CA2,846,924 | 2014-03-20 | ||
| CA2988164A CA2988164C (en) | 2014-03-10 | 2014-03-21 | Methods for establishing fluid communication between a sagd well pair |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2988164A Division CA2988164C (en) | 2014-03-10 | 2014-03-21 | Methods for establishing fluid communication between a sagd well pair |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA3157754A Division CA3157754A1 (en) | 2014-03-10 | 2014-03-21 | Methods for establishing fluid communication between a sagd well pair |
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| CA3088468A1 CA3088468A1 (en) | 2015-09-10 |
| CA3088468C true CA3088468C (en) | 2022-07-19 |
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| CA2846924A Abandoned CA2846924A1 (en) | 2014-03-10 | 2014-03-20 | Methods for establishing fluid communication between a sagd well pair |
| CA3088468A Active CA3088468C (en) | 2014-03-10 | 2014-03-21 | Methods for establishing fluid communication between a sagd well pair |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2846924A Abandoned CA2846924A1 (en) | 2014-03-10 | 2014-03-20 | Methods for establishing fluid communication between a sagd well pair |
Country Status (1)
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| CA (2) | CA2846924A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015066796A1 (en) | 2013-11-06 | 2015-05-14 | Nexen Energy Ulc | Processes for producing hydrocarbons from a reservoir |
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- 2014-03-20 CA CA2846924A patent/CA2846924A1/en not_active Abandoned
- 2014-03-21 CA CA3088468A patent/CA3088468C/en active Active
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| Publication number | Publication date |
|---|---|
| CA3088468A1 (en) | 2015-09-10 |
| CA2846924A1 (en) | 2015-09-10 |
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