CA3010622C - System and method for using acoustic resonant waves to enhance bitumen or heavy oil recovery processes that make use of solvent - Google Patents

Abstract

A system and method are provided for recovering bitumen from a bitumen reservoir using a recovery process that involves solvent, such as a heated solvent vapour process, a solvent injection process in the presence of electromagnetic heating, e.g., radio frequency (RF) heating or other electrical heating, a steam-solvent co-injection process, etc.; in which acoustic resonant waves are used to enhance mixing at the solvent-bitumen interface in the production chamber. The bitumen containing fluid can be recovered after injecting solvent and, if applicable, a heat source such as steam or RF/electrical heating using an injector well, while targeting the interface between the solvent and the bitumen in the reservoir with acoustic energy, using acoustic resonators positioned in the pay region.

Description

SYSTEM AND METHOD FOR USING ACOUSTIC RESONANT WAVES TO ENHANCE
BITUMEN OR HEAVY OIL RECOVERY PROCESSES THAT MAKE USE OF SOLVENT
TECHNICAL FIELD
[0001] The following relates to systems and methods for using acoustic resonant waves to enhance bitumen or heavy oil recovery processes that make use of a solvent.
DESCRIPTION OF THE RELATED ART

[0002] Bitumen is known to be considerably viscous and does not flow like conventional crude oil, and can be present in an oil sand reservoir. As such, bitumen is recovered using what are considered non-conventional methods.

[0003] For example, bitumen reservoirs are typically extracted from a geographical area using either surface mining techniques, wherein overburden is removed to access the underlying pay (e.g., oil sand ore-containing bitumen) and transported to an extraction facility; or using in situ techniques, wherein subsurface formations (containing the pay), e.g., oil sands, are heated such that the bitumen is caused to flow into one or more wells drilled into the pay while leaving formation rock in the reservoir in place. Both surface mining and in situ processes produce a bitumen product that can be subsequently sent to an upgrading and refining facility, to be refined into one or more petroleum products, such as gasoline and jet fuel.

[0004] Bitumen reservoirs that are too deep to feasibly permit bitumen recovery by mining techniques are typically accessed by drilling wellbores into the hydrocarbon bearing formation (i.e., the pay) and implementing an in situ technology.

[0005] There are various in situ technologies available, such as steam driven based techniques, e.g., Steam Assisted Gravity Drainage (SAGD) or Cyclic Steam Stimulation (CSS);
solvent-using techniques, etc.
SUMMARY

[0006] In one aspect, there is provided a method for recovering hydrocarbons from a pay region of a hydrocarbon-containing reservoir, the method comprising: co-injecting steam and solvent into the reservoir via a first well; and generating acoustic waves at a resonant frequency of a mixture of the injected solvent and hydrocarbons in the pay region of the reservoir and directing the acoustic waves toward the pay region, wherein diffusion of the injected solvent into the hydrocarbons to form the mixture is enhanced.

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[0007] In another aspect, there is provided a method for recovering hydrocarbons from a pay region of a hydrocarbon-containing reservoir, the method comprising:
providing radio frequency heating to the reservoir to heat the pay region; injecting solvent into the reservoir via a first well; and generating acoustic waves at a resonant frequency of a mixture of the injected solvent and hydrocarbons in the pay region of the reservoir and directing the acoustic waves toward the pay region, wherein diffusion of the injected solvent into the hydrocarbons to form the mixture is enhanced.

[0008] In yet another aspect, there is provided a method for recovering bitumen from a pay region of a bitumen reservoir, the method comprising: injecting a bitumen-mobilizing substance comprising solvent at least in part, into the bitumen reservoir via a first well; and generating acoustic waves at a resonant frequency of a mixture of the injected solvent and hydrocarbons in the pay region of the reservoir and directing the acoustic waves toward the pay region, wherein diffusion of the injected solvent into the hydrocarbons to form the mixture is enhanced.

[0009] In yet another aspect, there is provided a system for recovering hydrocarbons from a pay region of a hydrocarbon-containing reservoir, the system comprising:
injection apparatus for injecting a hydrocarbon-mobilizing substance comprising solvent at least in part, into the reservoir via a first well; a heat source for providing heating to the reservoir to heat the pay region; and at least one acoustic resonator positioned to direct acoustic energy towards the pay region for generating acoustic waves at a resonant frequency of a mixture of the injected solvent and hydrocarbons in the pay region of the reservoir, wherein diffusion of the injected solvent into the hydrocarbons to form the mixture is enhanced.

[0010] In yet another aspect, there is provided a system for recovering hydrocarbons from a pay region of a hydrocarbon-containing reservoir, the system comprising:
injection apparatus for co-injecting steam and solvent into the reservoir via a first well; and at least one acoustic resonator positioned to direct acoustic energy towards the pay region for generating acoustic waves at a resonant frequency of a mixture of the injected solvent and hydrocarbons in the pay region of the reservoir, wherein diffusion of the injected solvent into the hydrocarbons to form the mixture is enhanced.

[0011] In an implementation, the method can include recovering a hydrocarbon-containing fluid from the reservoir via gravity drainage. The method can also include producing the recovered hydrocarbon-containing fluid to surface, separating the produced hydrocarbon to recover solvent, and reusing the recovered solvent for subsequent solvent injection. The first 23407371.1 well can be a horizontally oriented injector well, the method further comprising producing the hydrocarbon-containing fluid to surface using a horizontally oriented production well positioned below the first well.

[0012] In an implementation, the at least one acoustic resonator is positioned in the pay region via a corresponding vertically oriented wellbore located above the first well. The at least one acoustic resonator can also be positioned in the pay region via a horizontally oriented wellbore located above the first well. The at least one acoustic resonator can also be positioned at surface above the pay region. The method can also include determining at least one additional resonant frequency; and operating the at least one acoustic resonator at the at least one additional resonant frequency. The method can also include determining if the resonant frequency has changed in the mixture and subsequently energizing the mixture using another resonant frequency.

[0013] In an implementation, the at least one acoustic generator can be positioned above a production chamber surrounding the first well. The steam and solvent, in another implementation, can be co-injected to achieve fluid communication between the first well and a second well in a start-up process. The first and second wells can be used for both the start-up process and a production process, both processes using the at least one acoustic generator.
The first and second wells can be used in a subsequent production process. The subsequent production process can be a steam assisted gravity drainage (SAGD) technique.

[0014] Advantages of these systems and methods can include enhancing solvent-bitumen mixing by applying acoustic waves at the resonant frequency of the solvent-bitumen mixture to create vibrational energy that enhances mixing. That is, an acoustic system can be used to amplify a sound whose frequency (or frequencies) matches one of the solvent-bitumen mixture's own natural frequencies of vibration, in order to enhance mixing of the solvent and the bitumen through vibration, and thus facilitate faster mobilization of the bitumen.
BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Embodiments will now be described by way of example with reference to the appended drawings wherein:

[0016] FIG. 1 is a cross-sectional elevation view of a system for recovering bitumen from a bitumen reservoir using acoustic resonant waves generated using acoustic generators positioned in vertically oriented wells;

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[0017] FIGS. 2A and 2B illustrate enlargement of a mixing zone where acoustic resonant waves contact the solvent-bitumen interface

[0018] FIG. 3 is a cross-sectional elevation view illustrating a mixing zone where acoustic resonant waves are contacting a solvent-bitumen interface in a solvent vapour chamber;

[0019] FIG. 4 is a cross-sectional elevation view of a system for recovering bitumen from a bitumen reservoir using acoustic resonant waves generated using acoustic generators positioned in a horizontally oriented well;

[0020] FIG. 5 is a cross-sectional elevation view of a system for recovering bitumen from a bitumen reservoir using acoustic resonant waves generated using acoustic generators positioned in vertically oriented wells positioned to additionally target infill and/or step-out well pairs;

[0021] FIG. 6A is a cross-sectional elevation view of a system for enhancing a solvent-using start-up phase for a solvent-using bitumen recovery process with an acoustic resonator placed above the pay region;

[0022] FIG. 6B is a cross-sectional elevation view of a system for enhancing a solvent-using start-up phase for a solvent-using bitumen recovery process with an acoustic resonator placed in a well;

[0023] FIG. 7 is a flow chart illustrating operations performed in determining resonant frequencies in a solvent-bitumen mixture for use in enhancing a solvent-using bitumen recovery process; and

[0024] FIG. 8 is a flow chart illustrating operations performed in producing bitumen using acoustic resonant waves in a solvent-using bitumen recovery process.
DETAILED DESCRIPTION

[0025] While the following provides examples in the context of bitumen production, it can be appreciated that the principles described herein can be equally applied in extracting other hydrocarbons such as heavy oil from hydrocarbon-containing reservoirs using a bitumen-mobilizing substance that includes solvent at least in part, and acoustic resonant waves.

[0026] Bitumen production that involves solvent injection relies, at least in part, on the solvent mixing with bitumen. The time it takes for this mixing to occur typically contributes to bitumen recovery processes that use solvent being relatively slow. It is recognized that this is 23407371.1 due to an inherent limitation in the length of time it takes for solvent to diffuse into the bitumen to achieve the mixing. Solvent-bitumen mixing can be enhanced by applying acoustic waves at the resonant frequency of the solvent-bitumen mixture to create vibrational energy that enhances mixing. That is, an acoustic system can be used to amplify a sound whose frequency (or frequencies) matches one of the solvent-bitumen mixture's own natural frequencies of vibration, in order to enhance mixing of the solvent and the bitumen through vibration, and thus facilitate faster mobilization of the bitumen. The acoustic resonant waves may also interact with asphaltenes in the bitumen once solvent destabilizes the asphaltenes, and may inhibit potential asphaltene blockages of pores in a formation.

[0027] In the following, there is provided a method for recovering bitumen from a bitumen reservoir using a recovery process that involves solvent, such as a heated solvent vapour process, a solvent injection process in the presence of electromagnetic heating, e.g., radio frequency (RF) heating or other electrical heating, a steam-solvent co-injection process, etc.; in which acoustic resonant waves are used to enhance mixing at the solvent-bitumen interface in the production chamber. The method can include recovering a bitumen containing fluid from a pay region in the bitumen reservoir via gravity drainage. The bitumen containing fluid can be recovered after injecting solvent and, if applicable, a heat source such as steam or RF/electrical heating using an injector well, while targeting the interface between the solvent and the bitumen in the reservoir with acoustic energy, using acoustic resonators positioned in the pay region.
The acoustic resonators generate acoustic waves that are generated at a resonant frequency of the solvent-bitumen mixture.

[0028] There is also provided a system for recovering bitumen from a bitumen reservoir.
The system includes bitumen-mobilizing substance injection apparatus, and at least one acoustic resonator positioned to target a pay region in the bitumen reservoir.
The acoustic resonator is configured to enhance mixing of solvent injected by the solvent injection apparatus and bitumen in the pay region by generating acoustic waves at a resonant frequency of the mixture. The resonant acoustic waves impart vibrations at the solvent-bitumen interface. The system also includes at least one acoustic generator coupled to the plurality of acoustic resonators.

[0029] The method and system can also be used for achieving fluid communication between a well pair, i.e., for implementing a start-up process that involves the use of a solvent.
Such a start-up process can be applied before a solvent-based or other solvent-using 23407371.1 production phase (e.g., solvent/steam co-injection, solvent with RE or other electrical heating, etc.), or before another enhanced oil recovery production phase that doesn't use solvent, e.g., a typical SAGD operation. The method and system can also be used for recovering bitumen in any other well configuration in which solvent can be injected (with or without the presence of a heat source such as steam, RE or electrical heating) and bitumen can be recovered, for example, infill and/or step-out wells.

[0030] In an implementation of the system and method, the acoustic resonators are positioned in the pay region via substantially vertically oriented wells. In other implementations of the system and method, the plurality of acoustic resonators can be positioned in a substantially horizontally oriented well positioned at or near the top of the bitumen reservoir. In other implementations, acoustic resonators can be operated at surface in alignment with the solvent injection well(s).

[0031] Turning now to the figures, FIG. 1 illustrates a bitumen reservoir, hereinafter referred to as the "pay 10"; which is accessed for in situ bitumen recovery using a substantially horizontally oriented well pair 12, that includes an injector well 14 positioned above a producer well 18. The injector well 14 is used to inject a bitumen-mobilizing substance 16 that includes solvent, at least in part e.g., heated solvent or solvent/steam co-injection, etc., which mixes with the bitumen to generate a mobilized fluid 20 that drains downwardly by gravity drainage to the producer well 18. In some implementations, the injector well 14 may include a heat source, e.g., RE heating, an electrical heater, or a closed loop hot oil circulation heater. The producer well 18 gathers the mobilized fluid 20 and is used to transport a produced fluid 21 to surface 22, a process typically referred to as production. As indicated above, the injector well 14 can be used to inject solvent, as well as solvent and other heated sources such as steam. The injector well 14 can also be used for injecting steam in a subsequent production phase, e.g., for implementing a subsequent SAGD production phase.

[0032] Example of solvents that can be used in the present method includes alkanes ranging from a relatively lighter alkane such as methane to a relatively heavier alkane such as heptane, e.g., from a set of solvents including methane (CH4), ethane (C2H6), propane (03H8), butane (C4H10), pentane (C5H12), hexane (C61-114), and heptane (C7H16), etc.
Other examples of solvents include n (normal) and iso-alkanes. Similarly, other solvents (or solvent mixtures) can be used, for example naphtha, toluene, xylene, benzene, diesel, natural gas, etc.

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[0033] The pay 10 typically includes a number of geological materials such as a rock matrix, sand, and fluid such as the bitumen that is being targeted. A formation at least partially underlies the pay 10, and is hereinafter referred to as the "underlying formation 26". In the example shown in FIG. 1, the pay 10 itself underlies a layer of overburden 24 between the pay and the surface 22.

[0034] The production apparatus illustrated in FIG. 1 includes solvent injection equipment and/or heat-source equipment (collectively referred to as "heat injection apparatus") (I) 28 and a solvent treatment and heat injection apparatus 32. The solvent treatment and heat injection apparatus 32 can include only solvent treatment equipment, or solvent treatment equipment along with equipment used to provide a source of heat, such as steam generation equipment, RF or electrical heating sources, etc. Any such solvent treatment equipment can include a solvent supply, a solvent purifier, a heater, a separator, etc. as is known in the art. The bitumen-mobilizing substance 16 containing solvent can be injected into the injector well 14 using the injection equipment (1)28 down the injector well 14 and into the pay 10. The bitumen-mobilizing substance 16 enters (and/or contributes to creating) a production chamber 46 through perforations or slots in a liner of the injector well 14.

[0035] The bitumen-mobilizing substance 16 containing solvent flows out from the injector well 14 to the edges of the chamber 46 and the solvent condenses as it contacts and mixes with the bitumen in the pay 20. This occurs at an interface between the edge of the solvent in the chamber 46 and the bitumen, what is often referred to as the mixing zone 52, shown in FIGS.
2A and 2B. The mixing zone 52 represents substantially the outermost boundary of the region of solvent, within which diffusion/dispersion of the solvent occurs. Because diffusion/dispersion is typically a slow process, the mixing zone is usually a narrow region as shown in FIG. 2A.
Therefore, enhancing the diffusion/dispersion can enhance solvent-bitumen mixing and enlarge the size of the mixing zone 52 as shown in FIG. 2B, to consequently increase the production rate.

[0036] The solvent in the bitumen-mobilizing substance 16 as it mixes with the bitumen, reduces the bitumen's viscosity and creates a solvent-bitumen mixture 20 (along with any other bitumen-containing fluids) that moves towards the producer well 18 by way of gravity drainage.
The mixture 20 can be produced to surface 22 using the producer well 18 and production equipment (P) 30 as is known in the art. The produced fluid 21, which includes partially upgraded oil mixed with solvent can be separated into three components, the oil that can be 23407371.1 sent to downstream facilities for further processing, any recovered solvent, and naturally occurring water. The recovered solvent can be fed back into the system.

[0037] It is known that, for constant boundary conditions, the diffusion boundary ( 6Diff ) can be defined as 6Diff = V4Dt ,where 601ff is the diffusion length, boundary or front (referred to herein as "diffusion boundary"), and D is a diffusion coefficient or diffusivity in dimensions of [length2 time-1], for example m2/sec . The diffusion boundary provides a measure of how far the concentration of solvent has propagated in the x-direction by diffusion in time t (Bird, R.B., Stewart, W.E., Lightfoot, E.N., "Transport Phenomena", John Wiley & Sons, 1976). Typical solvent-bitumen diffusion is on the order of 1.0e-10 (m2/s) which result a small diffusion boundary.

[0038] Further increasing the temperature of the solvent (or solvent injected with the bitumen-mobilizing substance 16) requires additional energy, or further apparatus to add a source of convection heating to the system, which is typically not feasible in a bitumen context.
In the presently described system, it is recognized that solvent-bitumen mixing can be enhanced by interrogating the mixture with acoustic resonant waves 44 in order to introduce vibration of the mixture to facilitate mixing.

[0039] The acoustic generating system in the example shown in FIG. 1 includes a number of spaced apart resonator wells 40 (a first resonator well 40a, a second resonator well 40b, a third resonator well 40c, and a fourth resonator well 40d shown by way of example). The resonator wells 40 facilitate the placement and positioning of acoustic resonators 42 (a first acoustic resonator 42a, a second acoustic resonator 42b, a third acoustic resonator 42c, and a fourth acoustic resonator 42d shown by way of example) within the pay 10 to emit acoustic energy into the pay 10. The number of and spacing between the resonator wells

40 can be determined according to the spread of the acoustic resonant waves 44, and thus the coverage provided per resonator 42. Various acoustic devices can be used for the acoustic resonators 42, for example, oscillators, air guns, explosive guns, mechanical vibrators, sonic or ultrasonic sirens or whistles, or other sound- and vibration-producing mechanical or electrical devices.
[0040] The acoustic resonators 42 are powered by acoustic generators 48 (a first acoustic generator 48a, a second acoustic generator 48b, a third acoustic generator 48c, and a fourth acoustic generator 48d, shown by way of example) via power and/or communication connections between the acoustic generators 48 and the acoustic resonators 42.
The acoustic 23407371.1 generators 48 in this example are controlled by a common controller 50, although it can be appreciated that more than one controller 50 can be used, e.g., dedicated controllers 50 for each acoustic generator 48.

[0041] The acoustic resonators 42a, 42b, 42c, and 42d operate to create acoustic waves in the pay 10 at the resonant frequency, i.e. acoustic resonant waves 44 whose frequency matches one of the natural frequencies of vibration of the solvent-bitumen mixture. The resonant frequency is previously determined for the solvent-bitumen mixture, i.e. in order to determine a frequency that achieves resonance within the mixture wherein the mixture will more easily vibrate and accelerate diffusion. The vibrational energy promotes mixing and potential liquid phase (bitumen-solvent mixture) expulsion into a condensed liquid/vapour solvent phase providing fresh contact between the solvent in the bitumen-mobilizing substance 16 and bitumen at a higher rate. This fresh contact can maintain a higher concentration difference between the solvent in the bitumen-mobilizing substance 16 and the bitumen in the pay 10 over the course of the injection process when compared to heated solvent alone, which can significantly enhance the aforementioned mixing.

[0042] In the example shown in FIG. 1, the acoustic wave source from the resonator(s) 42 is provided above the vapour chamber 46 near the top of the pay 10 to minimize wave dampening while travelling through the solid/semi-solid medium. However, it can be appreciated that the wave source can also be placed at or near the top of the overburden 24 to minimize the need for, and/or depth of the resonator wells 40. For example, a seismic truck or seismic equipment installation could be positioned at the surface 22 above the targeted pay region 10 and well pair(s) 14, 18.

[0043] The solvent treatment and heat injection apparatus 32 and the acoustic generating system can be coordinated to cause heated solvent in the bitumen-mobilizing substance 16 to be injected into the injector well 14, while operating the acoustic generator(s) 48 to enhance the solvent soaking and diffusion process. The produced fluids 21 are then pumped to surface 22.
The mobilized bitumen including any bitumen-solvent mixture 20 is produced using a horizontally oriented producer well 18, which is operated using production equipment 30 to produce the bitumen containing fluids 21 to surface 22. The producer well 18 and production equipment 30 can be similar in structure and function to producer wells used in other advanced oil recovery methods such as SAGD or CSS. The described production process can be 23407371.1 continuous with at least some of the recovered solvent separated from the produced oil and reused as discussed above.

[0044] FIG. 3 illustrates a schematic end view of a production chamber 46 with an interface region 50 shown in the enlarged inset view. The interface region 50 includes a mixing zone 52 where the acoustic resonant waves 44, through the maximized vibrations caused at the resonant frequency, enhance the liquid phase (bitumen-solvent mixture) expulsion into a condensed liquid/vapour solvent phase. This increases the size of the mixing zone 52 (as illustrated in FIG. 2B) and causes more fluid to be mobilized and drain by gravity towards the producer well 18. It can be appreciated that only a portion of the mixing zone 52 is shown in the enlarged view in FIG. 3 and that the interface region 50 extends along as much of the upper surface of the chamber 46 that is within the coverage of the resonant acoustic waves 44. The resonators 42 can also be moved during the production process to change the location of the resonant acoustic source as the chamber grows, to achieve better conformance along the length of the well pair(s) 12, etc.

[0045] Turning now to FIG. 4, an alternative implementation is shown in which an upper horizontally oriented resonator well 54 is used to contain a series of acoustic resonators 42 (a first acoustic resonator 42a, a second acoustic resonator 42b, a third acoustic resonator 42c, and a fourth acoustic resonator 42d shown by way of example). By using a horizontal configuration as shown in FIG. 4, a smaller footprint at surface 22 can be achieved. Moreover, the horizontal configuration requires fewer wells to be drilled, which is balanced against any additional losses resulting from the need to space the resonators 42 progressively further from the acoustic generator 48.

[0046] The resonant acoustic generating system described herein can also be applied to other well configurations, e.g., to infill and/or step-out wells as shown in FIG. 5. FIG. 5 provides a schematic end view of a first well pair 12a and production chamber 46a, a second well pair 12b and production chamber 46b, and a third well pair 12c and production chamber 46c. The spacing of the well pairs 12a, 12b, and 12c creates inter-well-pair regions located therebetween.
To produce bitumen in these areas between adjacent well pairs 12, infill wells 60 can be used (a first infill well 60a and a second infill well 60b), which are drilled into the inter-well-pair regions between the adjacent well pairs 12. These wells 60a, 60b when operated, begin to form respective infill well chambers 62a, 62b. Typically the infill wells 60 are positioned approximately halfway between adjacent well pairs 12 although other locations are possible 23407371.1 depending, e.g., on the physical characteristics of the inter-well-pair regions. Additional resonator wells 40b, 40d and resonators 42b, 42d can be positioned to target solvent-bitumen interfaces 52 corresponding to the infill wells 60a, 60b respectively. While infill wells 60a, 60b are shown in FIG. 5, it can be appreciated that infill well pairs (not shown) can also be used.
For the individual infill wells 60 shown in FIG. 5, the solvent can be injected, followed by a soaking period at which time the resonant acoustic waves 44 can be applied to enhance mixing.
The soaking stage can then followed by production from the same well.

[0047] It can be appreciated that the principles described herein can also equally be applied to solvent-using processes via step-out wells 64 having corresponding chambers 66, also illustrated in FIG. 5. The step-out well 44 is similar in configuration in this example to the infill wells 60a, 60b but is located adjacent a single primary production well pair 12 as opposed to being located between two well pairs 12 as with an infill well 60. For example, a step out well 64 can be positioned at the outer edges of the geographical region of the pay 10 being produced that is beyond either of the outermost well pairs 12. Similar to the infill wells, it can be appreciated that the principles discussed herein equally apply to step-out well pairs (not shown).
Moreover, other implementations are possible, such as the use of solvent-using processes at infill wells 60 (or well pairs) in combination with SAGD well pairs wherein the resonators 42a, 42c, and 42e in FIG. 5 would not be required. Similarly, the application of solvent-using processes at well pairs 12a, 12b, and 12c can be used in combination with steam-based infill wells 60a, 60b and/or steam-based step-out well 44, wherein the resonators 42b, 42d and 42f would not be required.

[0048] The process described herein in which a solvent-using production process is enhanced through the application of resonant acoustic waves 44 can also be used to implement a solvent-using or solvent-based start-up process.

[0049] In steam based advanced oil recovery processes such as SAGD, the SAGD
operation typically begins with a "start-up" phase in which steam is used to achieve fluid communication between the injection well and the production well, referred to as an interwell region. This fluid communication allows warmed and less viscous bitumen and connate reservoir water to flow as an emulsion, by gravity, down toward the lower production well, where it can be produced to surface. Completion of a SAGD production well for the start-up phase often includes configurations for steam circulation and/or bullheading.

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[0050] After the start-up phase is completed, which can typically take about three months for a SAGD well pair, the production well can be recompleted for mechanical lift, e.g., by installing a pump to provide hydraulic force for lifting produced fluids to the surface. The injection well can also be recompleted to enable steam to be injected using, for example, both a long tubing and a short tubing.

[0051] Instead of, or in addition to, using steam or other heating methods (e.g., electrical heating) to achieve the aforementioned fluid communication in the interwell region, solvent can be injected at the injector well 14 and/or producer well 18 as shown in FIG.
6A, and the resonant acoustic waves 44 used to enhance mixing of the solvent and bitumen as herein described. The solvent can be introduced alone or co-injected with steam, or another fluid. It can be appreciated that this solvent introduction stage can include filling the well(s) 14/18 with solvent over a period of a few hours, or solvent injection as described above.
The solvent introduction stage can then followed by a soaking stage, which can last a few days or up to a number of weeks. The soaking stage can also include applying a pressure drop between the wells 14, 18 to promote some solvent communication between the wells 14, 18.
During the soaking stage, the resonant acoustic waves 44 can be applied to enhance mixing as herein described. Once the communication between the wells 14, 18 is achieved, the primary bitumen-mobilizing injection process as shown in FIGS. 1 or 4 can commence. It can be appreciated that the solvent-using or solvent-based start-up process illustrated in FIG.
6A can also be implemented prior to a typical SAGD process and should not be limited to being used with only solvent-using or solvent-based production processes.

[0052] In FIG. 6A, the resonator 42 is placed above the well pair 12, similar to the configuration shown in FIG. 1. As shown in FIG. 6B, the resonator 42 can also be placed in one or both of the injector well 14 and the producer well 18. For example, the resonator 42 can be placed in one of the wells 14, 18 and the other of the wells 14, 18 used to inject the bitumen-mobilizing substance 16 that contain solvent, at least in part. This can be alternated with the resonator 42 placed in the other of the wells 14, 18 such that solvent is injected in the well 14, 18 from where the resonator 42 was previously operated. As shown using dashed lines in FIG.
6B, a resonator 42 can also be placed above the well pair 12 and operated at any time during the start-up process, including during or subsequent to alternating the placement of the resonator 42 in the wells 14, 18 as described above.

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[0053] In order to target the acoustic resonant waves 44 at the mixing zone 52, the resonant frequency of the particular bitumen-solvent mixture is determined.
For example, as shown in FIG. 7, a bitumen-solvent mixture can be prepared or otherwise obtained at step 80 and one or more experimental techniques applied to the mixture to determine the resonant frequency at step 82. For example, one or more bitumen solvent mixtures can be prepared, which contain particular amounts of solvent. The mixture(s) can be tested in a core sample where an intact reservoir core is placed in contact with solvent and, after a period of soaking, resonant waves are applied to determine the effect on the propagation of the mixing zone 52.

[0054] Various techniques are known in the art, which can be used at step 82 to conduct resonance measurements of a substance. For example, it is known to measure the resonant frequency of a geological material using a bar resonance technique. In the bar resonance technique, a drill core containing bitumen and the solvent to be used can be set into mechanical (e.g., sonic and/or ultrasonic) vibration in one or more vibrational modes at one or more frequencies at which the vibrational displacements are at a maximum (i.e. at resonance). The drill core sample can be excited to vibration using drivers with continuously variable frequencies being output, or by impact, etc. Vibrations of the sample are monitored using transducers and analyzed to determine the resonant frequencies.

[0055] Another technique that could be used to conduct resonance measurements includes extracting a core measuring frequencies within the core, above ground.

[0056] The aforementioned resonance measurements can be used to determine a set of one or more resonant frequencies, e.g., a set of harmonics, that are tested in situ at step 84 to determine one or more suitable frequencies for production at step 86. For example, the testing conducted at step 84 could determine that more than one resonant frequency can be effective at enhancing diffusion of the solvent to mobilize bitumen in the pay 10, allowing the production phase to cycle through more than one frequency over time to maximize mobilization and/or to target different materials within the bitumen-containing formation. The process shown in FIG. 7 can be conducted independently of the start-up and/or production phases described herein.
Moreover, the process shown in FIG. 7 can be conducted periodically during production (e.g., on a yearly basis) in order to determine if the resonant frequency of the mixture has changed as a result of the use of different solvents, the nature of the materials in the pay 10, etc. It can also be appreciated that if the resonant frequency or frequencies of a particular solvent-bitumen mixture are already known, the process shown in FIG. 7 may not be required in order to 23407371.1 determine the resonant frequency to be used for the start-up and/or production processes described herein.

[0057] FIG. 8 illustrates an example of a process for using acoustic resonant waves 44 to enhance a solvent-using bitumen production and/or start-up process. As shown in dashed lines in FIG. 8, the acoustic resonant waves 44 can also be used prior to production in implementing a solvent-using start-up process at step 100. A resonant frequency for the solvent-bitumen mixture is determined at step 102, e.g., according to previously obtained experimental data as illustrated by way of example in FIG. 7. The acoustic generators 48 are operated at the determined resonant frequency at step 104 to induce the acoustic resonant waves 44 in the pay 10, which interact with the solvent being injected at 106 to cause vibrations and enhance mixing between the solvent in the bitumen-mobilizing substance 16 and the bitumen in the pay 10. The mobilized bitumen 20 can then be produced to surface 22 at step 108. The controller 50 determines at step 110 if another frequency is to be used (e.g., if more than one resonant frequency is applicable and the production phase cycles through these frequencies). If so, the process can repeat at step 102 with another selected frequency. If no further frequencies are to be used at that time, the controller 50 determines at step 112 whether or not the production phase is done, or otherwise requires the acoustic generators 48 to cease operation. If production at that frequency is to continue, the process continues to repeat at step 104. When production is done at step 112, the process ends at step 114.

[0058] It will be appreciated that any module or component exemplified herein that executes instructions can include or otherwise have access to computer readable media such as storage media, computer storage media, or data storage devices (removable and/or non-removable) such as, for example, magnetic disks, optical disks, or tape.
Computer storage media can include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data. Examples of computer storage media include RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by an application, module, or both. Any such computer storage media can be part of the controller 50, acoustic generators 48, acoustic resonators 42, solvent treatment and heat injection apparatus 32, or any component of or related thereto, or 23407371.1 accessible or connectable thereto. Any application or module herein described can be implemented using computer readable/executable instructions that can be stored or otherwise held by such computer readable media.

[0059] For simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.
In addition, numerous specific details are set forth in order to provide a thorough understanding of the examples described herein. However, it will be understood by those of ordinary skill in the art that the examples described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the examples described herein. Also, the description is not to be considered as limiting the scope of the examples described herein.

[0060] The examples and corresponding diagrams used herein are for illustrative purposes only. Different configurations and terminology can be used without departing from the principles expressed herein. For instance, components and modules can be added, deleted, modified, or arranged with differing connections without departing from these principles.

[0061] The steps or operations in the flow charts and diagrams described herein are just for example. There may be many variations to these steps or operations without departing from the principles discussed above. For instance, the steps may be performed in a differing order, or steps may be added, deleted, or modified.

[0062] Although the above principles have been described with reference to certain specific examples, various modifications thereof will be apparent to those skilled in the art as outlined in the appended claims.
23407371.1

Claims (89)

Claims:

1. A method for recovering hydrocarbons from a pay region of a hydrocarbon-containing reservoir, the method comprising:
co-injecting steam and solvent into the reservoir via a first well;
determining a resonant frequency of a mixture, the mixture comprising the injected solvent and hydrocarbons in the pay region of the reservoir;
generating acoustic waves at the determined resonant frequency of the mixture;
and targeting the pay region where the mixture forms with the acoustic waves generated at the determined resonant frequency of the mixture, wherein at least one of diffusion and dispersion of the injected solvent into the hydrocarbons to form the mixture is enhanced.

2. The method of claim 1, further comprising recovering a hydrocarbon-containing fluid from the reservoir via gravity drainage.

3. The method of claim 2, wherein the first well is a horizontally oriented injector well, the method further comprising producing the hydrocarbon-containing fluid to surface using a horizontally oriented production well positioned below the first well.

4. The method of any one of claims 1 to 3, wherein the at least one acoustic resonator is positioned in the pay region via a corresponding vertically oriented wellbore located above the first well.

5. The method of any one of claims 1 to 3, wherein the at least one acoustic resonator is positioned in the pay region via a horizontally oriented wellbore located above the first well.

6. The method of any one of claims 1 to 3, wherein the at least one acoustic resonator is positioned at surface above the pay region.

7. The method of any one of claims 2 to 6, further comprising producing the recovered hydrocarbon-containing fluid to surface, separating the produced hydrocarbon to recover solvent, and reusing the recovered solvent for subsequent solvent injection.

8. The method of any one of claims 1 to 7, further comprising:
determining at least one additional resonant frequency; and operating the at least one acoustic resonator at the at least one additional resonant frequency.

9. The method of any one of claims 1 to 8, wherein the at least one acoustic resonator is powered by an acoustic generator from surface.

10. The method of claim 9, wherein the at least one acoustic generator is coupled to a controller.

11. The method of any one of claims 1 to 10, wherein the at least one acoustic generator is positioned above a production chamber surrounding the first well.

12. The method of claim 1, wherein the steam and solvent are co-injected to achieve fluid communication between the first well and a second well in a start-up process.

13. The method of claim 12, wherein the first and second wells are used for both the start-up process and a production process, both processes using the at least one acoustic generator.

14. The method of claim 12, wherein the first and second wells are used in a subsequent production process.

15. The method of claim 14, wherein the subsequent production process is a steam assisted gravity drainage (SAGD) technique.

16. The method of any one of claims 1 to 15, further comprising determining if the resonant frequency has changed in the mixture and subsequently energizing the mixture using another resonant frequency.

17. The method of any one of claims 1 to 16, wherein determining the resonant frequency of the mixture comprises obtaining a previously determined resonant frequency.

18. The method of any one of claims 1 to 16, wherein determining the resonant frequency of the mixture comprises obtaining one or more mixtures and applying one or more experimental techniques to the one or more mixtures.

19. The method of any one of claims 2, 4 to 11, and 16 to 18, wherein the first well comprises an infill well.

20. The method of any one of claims 2, 4 to 11, and 16 to 18, wherein the first well comprises a step-out well.

21. A method for recovering hydrocarbons from a pay region of a hydrocarbon-containing reservoir, the method comprising:
providing radio frequency heating to the reservoir to heat the pay region;
determining a resonant frequency of a mixture, the mixture comprising a solvent and hydrocarbons in the pay region of the reservoir;
injecting the solvent into the reservoir via a first well;
generating acoustic waves at the determined resonant frequency of the mixture;
and targeting the pay region where the mixture forms with acoustic waves generated at the determined frequency of the mixture, wherein at least one of diffusion and dispersion of the injected solvent into the hydrocarbons to form the mixture is enhanced.

22. The method of claim 21, further comprising recovering a hydrocarbon-containing fluid from the reservoir via gravity drainage.

23. The method of claim 22, wherein the first well is a horizontally oriented injector well, the method further comprising producing the hydrocarbon-containing fluid to surface using a horizontally oriented production well positioned below the first well.

24. The method of any one of claims 21 to 23, wherein the at least one acoustic resonator is positioned in the pay region via a corresponding vertically oriented wellbore located above the first well.

25. The method of any one of claims 21 to 23, wherein the at least one acoustic resonator is positioned in the pay region via a horizontally oriented wellbore located above the first well.

26. The method of any one of claims 21 to 23, wherein the at least one acoustic resonator is positioned at surface above the pay region.

27. The method of any one of claims 22 to 26, further comprising producing the recovered hydrocarbon-containing fluid to surface, separating the produced hydrocarbon to recover solvent, and reusing the recovered solvent for subsequent solvent injection.

28. The method of any one of claims 21 to 27, further comprising:
determining at least one additional resonant frequency; and operating the at least one acoustic resonator at the at least one additional resonant frequency.

29. The method of any one of claims 21 to 28, wherein the at least one acoustic resonator is powered by an acoustic generator from surface.

30. The method of claim 29, wherein the at least one acoustic generator is coupled to a controller.

31. The method of any one of claims 21 to 30, wherein the at least one acoustic generator is positioned above a production chamber surrounding the first well.

32. The method of claim 21, wherein the radio frequency heating and solvent are applied to achieve fluid communication between the first well and a second well in a start-up process.

33. The method of claim 32, wherein the first and second wells are used for both the start-up process and a production process, both processes using the at least one acoustic generator.

34. The method of claim 32, wherein the first and second wells are used in a subsequent production process.

35. The method of any one of claims 21 to 34, further comprising determining if the resonant frequency has changed in the mixture and subsequently energizing the mixture using another resonant frequency.

36. The method of any one of claims 21 to 35, wherein determining the resonant frequency of the mixture comprises obtaining a previously determined resonant frequency.

37. The method of any one of claims 21 to 35, wherein determining the resonant frequency of the mixture comprises obtaining one or more mixtures and applying one or more experimental techniques to the one or more mixtures.

38. The method of any one of claims 22, 24 to 31, and 35 to 37, wherein the first well comprises an infill well.

39. The method of any one of claims 22, 24 to 31, and 35 to 37, wherein the first well comprises a step-out well.

40. A method for recovering bitumen from a pay region of a bitumen reservoir, the method comprising:
injecting a bitumen-mobilizing substance comprising solvent at least in part, into the bitumen reservoir via a first well;
determining a resonant frequency of a mixture, the mixture comprising the injected solvent and hydrocarbons in the pay region of the reservoir;
generating acoustic waves at the determined resonant frequency of the mixture;
and targeting the pay region where the mixture forms with the acoustic waves generated at the determined resonant frequency of the mixture, wherein at least one of diffusion and dispersion of the injected solvent into the hydrocarbons to form the mixture is enhanced.

41. The method of claim 40, further comprising recovering a bitumen containing fluid from the bitumen reservoir via gravity drainage.

42. The method of claim 41, wherein the first well is a horizontally oriented injector well, the method further comprising producing the bitumen containing fluid to surface using a horizontally oriented production well positioned below the first well.

43. The method of any one of claims 40 to 42, wherein the at least one acoustic resonator is positioned in the pay region via a corresponding vertically oriented wellbore located above the first well.

44. The method of any one of claims 40 to 42, wherein the at least one acoustic resonator is positioned in the pay region via a horizontally oriented wellbore located above the first well.

45. The method of any one of claims 40 to 42, wherein the at least one acoustic resonator is positioned at surface above the pay region.

46. The method of any one of claims 41 to 45, further comprising producing the recovered bitumen to surface, separating the produced bitumen to recover solvent, and reusing the recovered solvent for subsequent solvent injection.

47. The method of any one of claims 40 to 46, further comprising:
determining at least one additional resonant frequency; and operating the at least one acoustic resonator at the at least one additional resonant frequency.

48. The method of any one of claims 40 to 47, wherein the at least one acoustic resonator is powered by an acoustic generator from surface.

49. The method of claim 48, wherein the at least one acoustic generator is coupled to a controller.

50. The method of any one of claims 40 to 49, wherein the at least one acoustic generator is positioned above a production chamber surrounding the first well.

51. The method of claim 40, wherein solvent is injected to achieve fluid communication between the first well and a second well in a start-up process.

52. The method of claim 51, wherein the first and second wells are used for both the start-up process and a production process that uses solvent, both processes using the at least one acoustic generator.

53. The method of claim 51, wherein the first and second wells are used in a subsequent production process.

54. The method of claim 53, wherein the subsequent production process is a steam assisted gravity drainage (SAGD) technique.

55. The method of any one of claims 40 to 54, further comprising determining if the resonant frequency has changed in the mixture and subsequently energizing the mixture using another resonant frequency.

56. The method of any one of claims 40 to 55, wherein determining the resonant frequency of the mixture comprises obtaining a previously determined resonant frequency.

57. The method of any one of claims 40 to 55, wherein determining the resonant frequency of the mixture comprises obtaining one or more mixtures and applying one or more experimental techniques to the one or more mixtures.

58. The method of any one of claims 41, 43 to 50, and 55 to 57, wherein the first well comprises an infill well.

59. The method of any one of claims 41, 43 to 50, and 55 to 57, wherein the first well comprises a step-out well.

60. A system for recovering hydrocarbons from a pay region of a hydrocarbon-containing reservoir, the system comprising:

injection apparatus for injecting a hydrocarbon-mobilizing substance comprising solvent at least in part, into the reservoir via a first well;
a heat source for providing heating to the reservoir to heat the pay region;
a determined resonant frequency of a mixture, the mixture comprising the injected solvent and hydrocarbons in the pay region of the reservoir; and at least one acoustic resonator positioned to target the pay region where the mixture forms with acoustic waves generated at the determined resonant frequency of the mixture, wherein at least one of diffusion and dispersion of the injected solvent into the hydrocarbons to form the mixture is enhanced.

61. The system of claim 60, wherein the heat source comprises at least one radio frequency antenna to providing radio frequency heating to the reservoir to heat the pay region.

62. The system of claim 60, wherein the heat source is an electrical heater.

63. The system of claim 60, wherein the first well is a horizontally oriented injector well, and further comprising a horizontally oriented production well positioned below the first well for producing a hydrocarbon-containing fluid to surface.

64. The system of any one of claims 60 to 63, wherein the at least one acoustic resonator is positioned in the pay region via a corresponding vertically oriented wellbore located above the first well.

65. The system of any one of claims 60 to 63, wherein the at least one acoustic resonator is positioned in the pay region via a horizontally oriented wellbore located above the first well.

66. The system of any one of claims 60 to 63, wherein the at least one acoustic resonator is positioned at surface above the pay region.

67. The system of any one of claims 60 to 66, wherein the at least one acoustic generator is positioned above a production chamber surrounding the first well.

68. The system of any one of claims 60 to 67, further comprising an acoustic generator for powering the at least one acoustic resonator from surface.
CPST Doc: 293725.1

69. The system of claim 68, further comprising a controller coupled to the at least one acoustic generator.

70. The system of claim 68 or claim 69, wherein the system is configured to be operate the at least one acoustic resonator for at least one additional resonant frequency.

71. The system of any one of claims 68 to 70, wherein the system is configured to determine if the resonant frequency has changed in the mixture and subsequently energize the mixture using another resonant frequency.

72. The system of any one of claims 60 to 71, wherein the determined resonant frequency of the mixture is previously determined.

73. The system of any one of claims 60 to 71, wherein the determined resonant frequency of the mixture is determined by obtaining one or more mixtures and applying one or more experimental techniques to the one or more mixtures.

74. The system of any one of claims 61, 62, and 64 to 73, wherein the first well comprises an infill well.

75. The system of any one of claims 61, 62, and 64 to 73, wherein the first well comprises a step-out well.

76. A system for recovering hydrocarbons from a pay region of a hydrocarbon-containing reservoir, the system comprising:
injection apparatus for co-injecting steam and solvent into the reservoir via a first well;
a determined resonant frequency of a mixture, the mixture comprising the injected solvent and hydrocarbons in the pay region of the reservoir; and at least one acoustic resonator positioned to target the pay region where the mixture forms with acoustic waves generated at the determined resonant frequency of the mixture, wherein at least one of diffusion and dispersion of the injected solvent into the hydrocarbons to form the mixture is enhanced.

77. The system of claim 76, wherein the first well is a horizontally oriented injector well, and further comprising a horizontally oriented production well positioned below the first well for producing a hydrocarbon-containing fluid to surface.

78. The system of claim 76 or claim 77, wherein the at least one acoustic resonator is positioned in the pay region via a corresponding vertically oriented wellbore located above the first well.

79. The system of any one of claims 76 to 78, wherein the at least one acoustic resonator is positioned in the pay region via a horizontally oriented wellbore located above the first well.

80. The system of any one of claims 76 to 79, wherein the at least one acoustic resonator is positioned at surface above the pay region.

81. The system of any one of claims 76 to 80, wherein the at least one acoustic generator is positioned above a production chamber surrounding the first well.

82. The system of any one of claims 76 to 81, further comprising an acoustic generator for powering the at least one acoustic resonator from surface.

83. The system of claim 82, further comprising a controller coupled to the at least one acoustic generator.

84. The system of claim 82 or claim 83, wherein the system is configured to be operate the at least one acoustic resonator for at least one additional resonant frequency.

85. The system of any one of claims 83 to 84, wherein the system is configured to determine if the resonant frequency has changed in the mixture and subsequently energize the mixture using another resonant frequency.

86. The system of any one of claims 76 to 85, wherein the determined resonant frequency of the mixture is previously determined.

87. The system of any one of claims 76 to 85, wherein the determined resonant frequency of the mixture is determined by obtaining one or more mixtures and applying one or more experimental techniques to the one or more mixtures.

88. The system of any one of claims 78 to 87, wherein the first well comprises an infill well.

89. The system of any one of claims 78 to 87, wherein the first well comprises a step-out well.