CA2913609C - Recovery of hydrocarbons from underground reservoirs - Google Patents

Abstract

In accordance with the present methods and systems, at least a portion of a production well is positioned in a formation that is distinct from, but adjacent to, a target reservoir. Fluid communication is provided between the production well and the reservoir through perforating, fracturing, acidizing, drilling, jetting, or other appropriate techniques, thereby permitting recovery of hydrocarbons from the target reservoir. The methods and systems can provide access to oil or hydrocarbons that are stranded in, or not economically recoverable from, underground reservoirs; they can also facilitate drilling of production wells where target reservoirs are or have become unconsolidated.

Description

RECOVERY OF HYDROCARBONS FROM UNDERGROUND RESERVOIRS
TECHNICAL FIELD
[001] The technical field relates to methods and systems for recovering hydrocarbons from an underground reservoir.
BACKGROUND

[002] Current methods for recovering hydrocarbons from underground reservoirs are not always efficient. For light oil, only about 50% of the original oil in place in a reservoir is recovered by existing technologies. For heavy oil, the recovery in some cases is less than 10%.
In certain situations, bitumen is so heavy that it does not flow at all and no oil can be recovered by conventional drilling and pumping; instead, enhanced oil recovery (EOR) processes are required. Exemplary EOR technologies include polymer enhanced waterfloods, solvent enhanced gas floods, and the addition of thermal energy (e.g., steam, in-situ combustion, or electricity). For heavy oil and bitumen recovery, steam assisted gravity drainage (SAGD) has become increasingly popular due to a high recovery factor. Despite enhanced recovery processes, though, significant quantities of hydrocarbons are left behind in the reservoirs after initial recovery (e.g., cellar oil).

[003] Given today's high demand for oil, there remains a need for further recovery of residual hydrocarbons, especially bitumen and other residual heavy oil. Currently, known heavy oil reservoirs in North America and vast reservoirs elsewhere in the world contain significant amounts of hydrocarbons. A technology for recovering a greater percentage of the residual or stranded oil from existing reservoirs could present immense opportunities for the oil industry.

[004] While various attempts have been made to enhance hydrocarbon recovery or to recover stranded hydrocarbons, there still exists a need for improved methods and solutions (e.g., methods and solutions which can be simpler, more efficient in terms of yield, or more cost effective).

SUMMARY

[005] In general, the present specification describes methods and related systems for recovering hydrocarbons from a hydrocarbon-bearing formation.

[006] In one implementation, there is provided a method for recovering hydrocarbons. The method includes producing the hydrocarbons from a portion of a production well located in an adjacent location outside of the hydrocarbon-bearing formation via a plurality of channels between the hydrocarbon-bearing formation and the adjacent location, the plurality of channels fluidly connecting the hydrocarbon-bearing formation and the portion of the production well.

[007] In some aspects of the method, at least a portion of a first production well is positioned in a formation adjacent to the hydrocarbon-bearing formation, and a plurality of channels communicating with the production well are formed. The channels extend from the portion of the production well to the hydrocarbon-bearing formation, so as to provide continuity between the production well and the hydrocarbon-bearing formation. The hydrocarbons can be collected from the hydrocarbon-bearing formation through the production well and can be produced to surface.

[008] In another implementation, there is provided a method for recovering hydrocarbons from a hydrocarbon-bearing formation. The method includes the steps of providing at least a portion of a production well at an adjacent location outside of the hydrocarbon-bearing formation, providing an injection well adapted for injecting a heated fluid or viscosity-reducing agent into the hydrocarbon-bearing formation, providing a plurality of channels that provide fluid communication between the portion of the production well and the hydrocarbon-bearing formation, and producing hydrocarbons from the hydrocarbon-bearing formation through the portion of the production well. The hydrocarbons are produced via at least some of the plurality of channels that provide fluid communication from the hydrocarbon-bearing formation to the portion of the production well located outside of the hydrocarbon-bearing formation.

[009] In some aspects of the methods, the hydrocarbon-bearing formation contains bitumen. In some aspects of the method, the adjacent location is in an underlying formation that is beneath the hydrocarbon-bearing formation. In some aspects of the methods, the underlying formation contains hydrocarbons. In some aspects of the methods, the underlying formation has a higher degree of consolidation than the hydrocarbon-bearing formation.

[010] In some aspects of the methods, the channels further provide fluid communication between the portion of the production well and the underlying formation, and the underlying formation contains additional hydrocarbons. In some aspects, the methods for recovering hydrocarbons include the step of recovering the additional hydrocarbons from the underlying formation through the production well. In some aspects of the methods, the injection well is arranged substantially parallel to the portion of the production well.

[011] In some aspects of the methods, the portion of the production well is oriented at an angle from vertical to horizontal or beyond horizontal, so as to collect the hydrocarbons from the hydrocarbon-bearing formation. In some aspects of the methods, the portion of the production well is positioned substantially horizontal. In some aspects of the methods, the heated fluid is steam.

[012] In some aspects of the methods, the hydrocarbon-bearing formation includes a formation production well. In some aspects of the methods, the adjacent location includes an additional production well. In some aspects of the methods, the hydrocarbon-bearing formation includes at least two formation production wells and an infill region between the at least two formation production wells; the portion of the production well is positioned in the underlying formation under the infill region.

[013] In some aspects of the methods, the channels are formed by perforating, hydraulic fracturing, acid fracturing, acidizing, drilling, or jetting. In some aspects of the methods, the channels are formed by acidizing or acid fracturing, and acid is directed by orifices or jets from the portion of the production well towards the hydrocarbon-bearing formation.
In some aspects of the methods, the channels are formed by hydraulic fracturing using a fracturing fluid, and the fracturing fluid contains a proppant. In some aspects of the methods, the channels are formed by perforation using a stream of hot gas and fine metal particles. In some aspects of the methods, the channels are formed by drilling using a rotating drill bit. In some aspects of the methods, the channels are formed by jetting using a high-pressure fluid. In some aspects of the methods, the high-pressure fluid contains at least one of (a) fine particles to augment the jetting process, (b) acid, and (c) an abrasive grit.

[014] In some aspects of the methods, the hydrocarbon-bearing formation is partially depleted by a previous recovery operation. In some aspects, the methods include the step of recovering the hydrocarbons from the hydrocarbon-bearing formation through the production well. In some aspects, the methods include the step of draining the hydrocarbons by gravity into the production well. In some aspects of the methods, the production well is drilled from a mine face at the adjacent location.

[015] In some aspects of the methods, producing the hydrocarbons includes operating a steam assisted in-situ hydrocarbon recovery process. In some aspects of the methods, the steam assisted in-situ hydrocarbon recovery process includes a steam assisted gravity drainage system.
In some aspects of the methods, the steam assisted in-situ hydrocarbon recovery process includes a cyclic steam stimulation system. In some aspects of the methods, producing the hydrocarbons includes operating a combustion process by injecting a combustible fuel into the hydrocarbon-bearing formation using the injection well. In some aspects of the methods, producing the hydrocarbons includes using at least one of electrical heating, electromagnetic heating, radio frequency heating, solvent injection, carbon dioxide flooding, non-condensable gas injection, flue gas flooding, surfactants injection, alkaline chemicals injection, and microbial enhanced recovery.

[016] In another implementation, there is provided a method for recovering bitumen from a bitumen-bearing formation. The method includes mobilizing the bitumen in the bitumen-bearing formation by injecting steam into the bitumen-bearing formation by way of an injection well included in the bitumen-bearing formation, draining the mobilized bitumen by gravity through a plurality of channels, and producing the bitumen from a portion of a production well located in an underlying formation beneath the bitumen-bearing formation, the plurality of channels fluidly connecting the bitumen-bearing formation and the portion of the production well.

[017] In another implementation, there is provided a system for recovering hydrocarbons from a hydrocarbon-bearing formation. The recovery system includes a production well, at least a portion of which is positioned in a location adjacent to the hydrocarbon-bearing formation. The recovery system also includes an injection well adapted for injecting a heated fluid or viscosity-reducing agent, at least a portion of which is positioned in the hydrocarbon-bearing formation, and a plurality of channels that communicate with the production well. The channels extend from the portion of the production well to the hydrocarbon-bearing formation to provide continuity between the production well and the hydrocarbon-bearing formation.

[018] In some aspects of the system, the hydrocarbon-bearing formation contains bitumen and the adjacent location is an underlying formation that is beneath the hydrocarbon-bearing formation.

[019] In some aspects, the system includes production equipment for producing the hydrocarbons from the hydrocarbon-bearing formation through the production well. In some aspects of the system, the heated fluid includes steam.

[020] In some aspects of the system, the production equipment includes a steam assisted gravity drainage system. In some aspects of the system, the production equipment includes a cyclic steam stimulation system. In some aspects of the system, the production equipment is configured to operate a combustion process by injecting a combustible fuel into the hydrocarbon-bearing formation using the injection well. In some aspects of the system, the production equipment is configured to mobilize the hydrocarbons using at least one of electrical heating, electromagnetic heating, radio frequency heating, solvent injection, carbon dioxide flooding, non-condensable gas injection, flue gas flooding, surfactants injection, alkaline chemicals injection, and microbial enhanced recovery.

[021] In some aspects of the system, the production well is drilled from a drainage pit at the adjacent location.

[022] In a further implementation, there is provided a system for recovering bitumen from a bitumen-bearing formation. The system includes a production well that has a substantially horizontal portion positioned in an underlying formation beneath the bitumen-bearing formation and adapted to receive mobilized bitumen, an injection well that is adapted to inject steam into the bitumen-bearing formation and has at least a portion positioned in a bitumen-bearing formation, and a plurality of channels that communicate fluidly with the production well, the channels extending from the horizontal portion of the production well to the bitumen-bearing formation to provide continuity between the production well and the bitumen-bearing formation to allow mobilized bitumen to drain from the bitumen-bearing formation into the production well.

[023] Methods and systems described herein can enhance recovery of hydrocarbons from reservoirs in several respects. In some implementations, for example, the methods and systems can provide access to hydrocarbons that are generally considered to be stranded (e.g., cellar hydrocarbons, bypassed hydrocarbons, etc.). Furthermore, methods and systems described herein can provide dual access to hydrocarbons from a target reservoir and to hydrocarbons from a formation adjacent to (e.g., beneath, next to, etc.) the target reservoir.
In some implementations, the methods and systems can facilitate drilling of production wells where target reservoirs are relatively unconsolidated. Methods and systems described herein can also be implemented where given reservoir conditions (e.g., thickness of a reservoir) do not favourably accommodate a production well within the reservoir.

[024] The details of one or more implementations are set forth in the description below. Other features and advantages will be apparent from the specification and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS

[025] Features and advantages of embodiments of the present application will become apparent from the following detailed description and the appended drawings, in which:

[026] FIG. la is a schematic view showing a typical configuration of injection/production wells in a hydrocarbon reservoir for SAGD;

[027] FIG. lb is a cross-sectional view taken from A-A in FIG. I a, additionally showing a steam chamber created in the reservoir;

[028] FIGs. 2a-2d are schematic views showing cellar oil trapped under SAGD
production wells at the bases of reservoirs which are in various geological shapes, in which FIG. 2a shows an undulating base of a pay zone, FIG. 2b shows a dipping base of a pay zone, FIG. 2c shows a faulted base of a pay zone, and FIG. 2d shows a partially collapsed base of a pay zone;

[029] FIG. 3a shows an exemplary arrangement of a pair of horizontal injection/production wells for a SAGD operation in accordance with methods and system described herein, in which the steam injector is in the reservoir (pay) and the production well is in an adjacent, underlying formation;

[030] FIG. 3b is a cross-sectional view taken from B-B in FIG. 3a, additionally showing a steam chamber created in the reservoir;

[031] FIG. 4a is a schematic view showing perforations that connect a SAGD
production well to a reservoir formation;

[032] FIG. 4b is a cross-sectional view of FIG. 4a, additionally showing a steam chamber created in the reservoir, with perforations connecting the production well to the steam chamber;

[033] FIG. 4c shows a jet perforator firing streams of hot gas and fine metal particles at high speed through the wall of the production casing or liner and into a formation adjacent to a production well;

[034] FIG. 5a is a schematic view showing fractures that connect a SAGD
production well to a reservoir formation;

[035] FIG. 5b is a cross-sectional view of FIG. 5a, additionally showing a steam chamber created in the reservoir, with fractures connecting the production well to the steam chamber;

[036] FIG. 5c is a schematic view showing a formation rock being fractured by fracturing fluid at high pressure;

[037] FIG. 5d is a schematic view showing a proppant holding open a fractured portion of a formation rock;

[038] FIG. 6a is a schematic view showing acidized fractures that connect a SAGD production well to a reservoir formation;

[039] FIG. 6b is a cross-sectional view of FIG. 6a, additionally showing a steam chamber created in the reservoir, with acidized channels or fractures connecting the production well to the steam chamber;

[040] FIG. 6c shows a sample fracture face before and after acidization;

[041] FIG. 7a is a schematic view showing drilled boreholes that connect a SAGD production well to a reservoir formation;

[042] FIG. 7b is a cross-sectional view of FIG. 7a, additionally showing a steam chamber created in the reservoir, with drilled boreholes connecting the production well to the steam chamber;

[043] FIG. 8a is a schematic view showing hydraulically jetted perforations that connect a SAGD production well to a reservoir formation;

[044] FIG. 8b is a cross-sectional view of FIG. 8a, additionally showing a steam chamber created in the reservoir, with hydraulically jetted perforations connecting the production well to the steam chamber;

[045] FIG. 8c is a schematic view showing a hydraulic jetting tool boring a perforation through a production casing or uncased borehole into a formation;

[046] FIG. 9a is a schematic view showing drilled or jetted boreholes that connect an offset production well to a reservoir formation;

[047] FIG. 9b is a cross-sectional view of FIG. 9a, additionally showing a steam chamber created in the reservoir, with drilled or jetted boreholes connecting the production well to the steam chamber;

[048] FIG. 10 is a schematic view showing both an injection well and a production well being initiated from a mine face, in which the production well is located in an adjacent formation beneath a hydrocarbon-bearing reservoir; and

[049] FIG. 11 is a schematic view showing a production well located in a formation beneath a hydrocarbon-bearing reservoir and, at the same time, positioned under an infill region formed between two SAGD steam chambers within the reservoir, where the production well is connected to the reservoir through perforations, fractures, acidized channels, drilled boreholes, or hydraulically jetted boreholes.

DETAILED DESCRIPTION

[050] The present description relates to methods and systems for recovering hydrocarbons from underground reservoirs. Generally, in these methods and systems, at least a portion of a first production well is positioned in a geological formation that is adjacent to and distinct from a target hydrocarbon-bearing reservoir, and channels are formed between the production well and the reservoir to establish fluid communication therebetween. The channels can be provided by various techniques, including, without limitation, perforating, fracturing, acidizing, drilling, jetting, and the like. Hydrocarbons can then be collected from the reservoir through the production well and recovered to surface.

[051] Conventionally, a production wellbore is provided within, and collects production fluid from, a hydrocarbon-bearing or oil-bearing reservoir. Much effort has been invested in attempting to access cellar or stranded oil; however, such attempts have almost always been made through a production well drilled into the target reservoir formation.
The present methods and systems take a different approach by intentionally locating a production well in a formation adjacent to (e.g., beneath, next to, etc.) the target reservoir formation, with the aim of improving overall recovery of hydrocarbons from the reservoir.

[052] Throughout this specification, numerous terms and expressions are used in accordance with their ordinary meanings. Provided below is a discussion of some terms and expressions that are used herein.

[053] A "formation" or "geological formation" is a fundamental unit of lithostratigraphic classification. A formation includes rock strata that have comparable lithologies, facies, or other similar properties. Formations can be defined on the basis of the thickness of the rock strata of which they consist, and the thickness of different formations can vary widely.
A given stratigraphic column can include a number of formations. In the oil sands area of Northeastern Alberta, for example, the stratigraphic column consists of the following major formations (from basement to surface): Pre-Cambrian (basement), Devonian carbonates, McMurray oil sands, Wabiskaw sands and mudstones, Clearwater shales, Grand Rapids sandstones, and Quaternary sediments.

[054] The "McMurray formation" or "McMurray sands" is a stratigraphic unit of Early Cretaceous age in the Western Canada Sedimentary Basin of Northeastern Alberta. It lies unconformably on Pre-Cretaceous erosion surfaces that generally comprise Devonian limestone, which is mainly carbonate rock. The McMurray sands are largely unconsolidated and the sand grains that form the formation are mostly held together by very viscous crude oil. The McMurray formation holds most of the vast hydrocarbon resources of the Athabasca bituminous sand deposit.

[055] As used herein, the term "overburden" refers to the sediments or earth materials overlaying a formation containing a hydrocarbon-bearing zone.

[056] The term "reservoir" refers to a subsurface formation containing one or more natural accumulations of hydrocarbons, which are generally confined by relatively impermeable rock or other geological layers of materials. Typically, a reservoir formation containing recoverable hydrocarbons, referred to as the "pay", is formed between a top cap layer and a bottom base.

[057] As used herein, "oil sands reservoir" refers to a subsurface formation that is primarily composed of a matrix of unconsolidated sand, with hydrocarbons, such as bitumen or extremely heavy crude oil, occurring in the porous matrix.

[058] The term "hydrocarbons" refers to a combination of different hydrocarbons or a combination of various types of molecules that contain carbon atoms and attached hydrogen atoms. Hydrocarbons include a large number of different molecules in gaseous, liquid, or solid phase having a wide range of molecular weights, and can include bitumen, heavy oil, lighter grades of oil, and natural gas. Elements (e.g., sulphur, nitrogen, oxygen), metals (e.g., iron, nickel, vanadium), and compounds (e.g., carbon dioxide, hydrogen sulphide) are sometimes present in the form of impurities in a desired hydrocarbon mixture.

[059] The term "perforating" or "perforation" refers to eroding a hole (e.g., in the casing of a well and the formation surrounding the well). By way of example, jet perforators can fire a stream of hot gas and fine metal particles at a speed of ¨10,000 m/s towards the wall of a production casing. The depth of perforation can be augmented by simultaneous application of high pressure gas, or by sleeves of propellant external to the perforating device (also known as a perforating gun).

[060] As used herein, "fracturing" includes a process for structurally degrading a geological formation around a wellbore by applying thermal and/or mechanical stress. Such structural degradation generally enhances the permeability of the formation to fluids.
Examples of hydraulic fracturing for use in the present methods and systems include, without limitation, hydraulic fracturing and acid fracturing.

[061] "Hydraulic fracturing" refers to a method of using pump rate and hydraulic pressure of a hydraulic fracturing fluid, which can be a liquid or gas or a combination thereof, to fracture or crack a subterranean formation, thereby creating relatively large flow channels through which hydrocarbons can move into a well.

[062] "Proppant" or "propping agent" refers to sized particles mixed with fracturing fluid to hold fractures open after a hydraulic fracturing treatment. In addition to naturally occurring sand grains, man-made or specially engineered proppants, such as resin-coated sand and ceramic beads, can also be used. Proppant materials are carefully sorted for size and sphericity to provide an efficient conduit for production of fluid from a reservoir to a wellbore.

[063] "Acid fracturing" refers to a fracturing method in which an acid is used in the fracturing fluid to increase or restore permeability to a formation.

[064] The term "acidizing" refers to injecting an acid into a formation that can be dissolved by acid, such as a formation containing calcium carbonate sediments, thereby creating flow paths in the target formation. Exemplary acids for use herein include, without limitation, hydrochloric acid (HC1).

[065] The term "drilling" refers to the creation of a borehole in a formation by rotating a drill bit and simultaneously applying an axial load to the bit.

[066] As used herein, "directional drilling" refers to steering the drill bit in a desired direction.

[067] The expression "coiled tubing drilling" refers to use of continuous, non-segmented pipe to convey the drilling assembly to the formation. The coiled tubing itself does not rotate. The drilling assembly includes a downhole motor that rotates the drill bit and can also contain a directional measurement device and a steering assembly.

[068] The term "jetting" refers to pumping fluids at high pressure through a nozzle to erode a hole into a formation. The nozzle can be conveyed to the formation via jointed or continuous pipe. The high-pressure fluid can contain fine particles to augment the jetting process, or acid to dissolve rock simultaneously.

[069] "Sand control" includes preventing or otherwise alleviating the buildup of particles in a production well. Sand can present major obstacles to production through reduced production rates, sand bridging, erosion of equipment, and sand disposal and removal.
Sand control can be a substantial problem when the produced fluids flow from an unconsolidated formation.

[070] A "production well" or "producer" includes any well or wellbore from which hydrocarbons can be produced, regardless of its configuration or arrangement.
The production well can be configured vertically, horizontally, or at any angle from vertical to horizontal or beyond horizontal, in any portion thereof.

[071] As used herein, "vertical" direction is the direction of gravity force and "horizontal"
direction is perpendicular to the direction of gravity force.

[072] "Stranded hydrocarbons" include hydrocarbons of any viscosity that are not recoverable at commercially attractive extraction rates at given reservoir conditions and/or recovery operations. Examples of stranded hydrocarbons recovered by the present methods and systems include, without limitation, cellar hydrocarbons and hydrocarbons in an infill or bypassed region.

[073] The expression "cellar hydrocarbons" refers to the stranded hydrocarbons that are accumulated or located at the base of a reservoir.

[074] As used herein, "infill region" or "bypassed region" refers to an area formed between at least two production wells in a reservoir, in which a significant quantity of hydrocarbons, in the form of bitumen, heavy oil, or otherwise, remains unrecovered by normal recovery operations.

[075] A "chamber" within a reservoir or formation includes a region that is in fluid communication with a particular well or wells, such as an injection or production well. For example, in a SAGD process, a steam chamber is the region of the reservoir in fluid communication with a steam injection well; this is also the region that is subject to depletion, primarily by gravity drainage, into a production well. Thus, a chamber can be a depleted region.

[076] Specific examples of the present methods and systems are described below with reference to the drawings. Details are provided for the purpose of illustration, and the methods and systems can be practiced without some or all of the features discussed herein.
For clarity, technical materials that are known in the fields relevant to the present methods and systems are not discussed in detail.

[077] Some of the drawings and implementations described herein refer to a SAGD operation.
However, it should be understood that other configurations can be used that may or may not involve the use of steam. For example, an injection well may be used to inject a solvent or other chemical that can be used to modify the viscosity of the hydrocarbons in the formation, so that the hydrocarbons can be produced by gravity to flow to the production well. In other configurations, a source of thermal energy other than steam, such as in-situ combustion, electric heat, radio frequency energy, and the like, or a combination of any of the foregoing, can be used to heat the formation and again modify the viscosity of the hydrocarbons to cause production of hydrocarbons by gravity drainage. The implementations described below are considered in the exemplary context of SAGD, but are not intended to be limited to SAGD
applications.

[078] FIG. la illustrates the basic principles of a SAGD operation in a hydrocarbon-containing reservoir (10). A horizontal steam injection well (11) is located above a horizontal production well (12) in the same geological formation (10). Steam (13) is injected into the injection well (11) to form a steam chamber above the well pair, and production fluid (14) (e.g., including hydrocarbons and hot water, such as hot water from condensed steam) is collected in the production well (12) and produced to surface. In the illustrated implementation, the steam injection well (11) and the production well (12) are both located within the steam chamber or heat affected zone (20). There is a steam/liquid interface between the steam injection well (11) and the production well (12). In some implementations, the production well (12) is not in direct contact with gaseous steam; in such implementations, the liquid below the steam/liquid interface is a mixture of hydrocarbons and condensed steam (hot water). The gas/liquid interface between the injection well (11) and the production well (12) is also present in other implementations that involve the injection of a gaseous solvent, such as butane and the like, a gaseous chemical, such as carbon dioxide and the like, or air for combustion.

[079] Referring to FIG. lb, a steam-filled chamber (20) is created by steam (13'), which is injected into the reservoir (10) through the injection well (11), moving into the formation around the injection well (11). The steam chamber (20) surrounds the injection well (11) and extends from the horizontal production well (12) towards the top of the reservoir (10). Production fluid (14'), which includes condensed steam and hydrocarbons (e.g., bitumen), flows down the sides of the steam chamber (20) towards the production well (12). In some implementations, the injection well (11) is at a higher pressure than the production well (12). In further implementations, the injection well (11) is at a slightly higher pressure than the production well (12). In some implementations, it is desirable to maintain a small temperature difference or "subcool" between the injection well (11) and the production well (12), to ensure that the production well is immersed in liquid.

[080] Referring to FIGs. 2a-2d, geological formations typically are not perfectly horizontal.
There can be undulations (16) (FIG. 2a) or an inclination (17) at the top or bottom of a formation (FIG. 2b), displacements or faults (18) (FIG. 2c), or large sink holes (19) caused by dissolution of rock minerals (FIG. 2d). Even though SAGD operators generally attempt to drill the SAGD
well pairs (injection well (11) and production well (12)) more or less horizontally, a significant volume of cellar hydrocarbons (30) can be below the SAGD well pair, as illustrated in FIGs. 2a-2d.

[081] Production wells have historically been positioned in the target reservoir formations for collection of hydrocarbons therefrom. Using SAGD as an example, the production well has been located in the same reservoir formation as the injection well, as illustrated in FIGs. la, lb, and 2a-2d.

[082] In the present methods and systems, though, a production well is positioned in an adjacent location that borders the target reservoir. In some implementations, the adjacent location is a formation but not a reservoir. In some implementations, the adjacent location is a formation and also a reservoir.

[083] In one implementation, there is provided a method for recovering hydrocarbons from a hydrocarbon-bearing formation. The method includes producing the hydrocarbons from a portion of a production well located in an adjacent location outside of the hydrocarbon-bearing formation via a plurality of channels between the hydrocarbon-bearing formation and the adjacent location. The plurality of channels fluidly connect the hydrocarbon-bearing formation and the portion of the production well.

[084] In another implementation, there is provided a method for recovering hydrocarbons from a hydrocarbon-bearing formation. The method includes the steps of providing at least a portion of a production well outside of the hydrocarbon-bearing formation, providing a plurality of channels that provide fluid communication between the portion of the production well and the hydrocarbon-bearing formation, and producing hydrocarbons from the hydrocarbon-bearing formation through the portion of the production well. Hydrocarbons are produced via at least some of the plurality of channels that provide fluid communication from the hydrocarbon-bearing formation to the portion of the production well located outside of the hydrocarbon-bearing formation.

[085] FIGs. 3a and 3b exemplify one arrangement of a production well relative to an injection well in the context of a SAGD operation. As shown in FIGs. 3a, an injection well (11) and a production well (12) are drilled either vertically or at an inclination through the overburden (50) that overlays a reservoir (pay) (10). When the injection well (11) reaches a suitable depth within the reservoir (10), the injection well (11) is then horizontally extended between the top (21) and base (22) of the reservoir (10). In comparison, the production well (12) is drilled further down below the base (22) of the reservoir (10) and then horizontally extended within an underlying formation (40) that is beneath the reservoir (10). FIG. 3b shows a steam chamber (20) created by steam (13') injected through the injection well (11) in the reservoir (10).
Once the hydrocarbons within the chamber (20), including any cellar hydrocarbons (30), are sufficiently mobilized, production fluid (14'), which includes mobilized hydrocarbons and condensed steam, are drained into the lower portion of the chamber (20) and into the production well (12).
As the person skilled in the art will appreciate, various well-drilling and completion technologies are currently available to drill the wells and connect the production well in the underlying formation to the hydrocarbon-bearing reservoir. Production wells can be placed at underground locations with desired configurations using technologies known to the skilled person. While the implementation shown in FIGs. 3a and 3b represents one production well (12), more than one production well (12) can be used in other implementations.

[086] Once the production well is positioned in a formation adjacent to the target reservoir, means for fluid communication ¨ such as channels (100) between the hydrocarbon-bearing reservoir and the underlying formation, as shown in FIGs. 3a and 3b ¨ are established between the production well and the target reservoir or a specific pay zone in the reservoir. Numerous techniques are available to accomplish this step, including, without limitation, perforating, hydraulic fracturing, acid fracturing, acidizing, drilling, jetting, etc.
Using one or more of these techniques, multiple pathways or channels can be created between the production well and the reservoir, to allow mobilization of cellar oil and other hydrocarbons and the collection of such hydrocarbons into the production well.

[087] Having regard to the geological and operational factors at play, the skilled person would be able to choose a suitable method for establishing fluid communication in a given set of conditions. For example, where the adjacent formation surrounding a production well is sandstone, hydraulic fracturing can be used. In contrast to sandstone, carbonate rock or limestone is relatively soft and can be dissolved by acid; therefore, acidizing or acid fracturing is considered to be more effective than fracturing in a carbonate formation. The acid can dissolve a portion of the carbonate rock to increase permeability and conductivity within the stimulated formation.

[088] FIGs. 4a-8c illustrate various processes of forming a plurality of channels extending from a production well toward a target reservoir in the context of an exemplary recovery method ¨
namely, a SAGD extraction process. As shown in these drawings, the channels provide fluid communication between the production well and the reservoir, particularly the lower portion of a steam chamber created in the reservoir.

[089] Referring to FIGs. 4a-4c, perforations (23) can be formed upwards from a production well (12) using a jet perforator (41). In the implementation illustrated by FIGs. 4a and 4b, perforations (23) are located at or near the base (22) of the reservoir (10).
Perforations (23) allow production fluid (14') to flow into the production well (12) from the reservoir (10) when the production well (12) is located in an adjacent formation (40). FIG. 4c illustrates the jet perforator (41) firing a stream of hot gas and fine metal particles (42) towards the wall of the production casing or cemented liner (44) inside the production well (12) at different stages.
From left to right, FIG. 4c shows an unfired charge (79), a charge being fired (80) to create perforation (23), and two perforations (23) through which production fluid (14') enters the production well (12). In one implementation, the jet perforator (41) fires the stream (42) at a speed of up to 10,000 m/s. Jet perforations (23) can range from 6 mm to over 30 mm in diameter. Deep penetrating perforations tend to have a smaller entrance hole and are used in harder formations, while big hole charges are used in softer formations. In one implementation, the jet perforator (41) erodes one or more holes in the production casing or cemented liner (44).
Depth of perforations (23) can range from about 200 mm to about 2,000 mm, depending on the strength of the formation, the strength of the casing (including steel casing, cemented liner, and the like), and the size of the charge. In some implementations, the depth of at least one of the perforations (23) is greater than 100 mm into the formation.

[090] Referring to FIGs. 5a-5d, fractures (24) can be formed upwards from a production well (12) by hydraulic fracturing. In the implementation illustrated by FIGs. 5a and 5b, fractures (24) are located at or near the base (22) of the reservoir (10). Fractures (24) allow production fluid (14') to flow into the production well (12) from the steam chamber (20) when the production well (12) is located in an adjacent formation (40). FIG. 5c illustrates the creation of fractures (24) by hydraulic fracturing, where fracturing fluid (51) is injected at high pressure to fracture or force apart the rocks in the adjacent formation (40) and reservoir (10). In the implementation shown in FIG. 5d, a proppant (52), such as sand grains, ceramic beads, and/or the like (including a combination of any of the foregoing), is added to the fracturing fluid and pumped into the fractures (24). The proppant (52) maintains conductivity in the fracture (24) and ensures that fluids can flow through the fracture (24) towards the production well (12). In some circumstances, the fracturing fluid can leak off into the formation and the fractures (24) can close. The proppant (52) can hold the surfaces at fractures (24) apart, leaving a highly conductive conduit from the reservoir (10) into the wellbore of the production well (12). The proppant (52) can also function as a medium for sand control.

[091] Referring to FIGs. 6a-6c, acidized fractures or channels (25) can be formed upwards from a production well (12) by acid fracturing or acidizing. Acidization is usually applied to a carbonate formation, extending some distance from the wellbore. For example, hydrochloric acid (HCl) dissolves some of the calcium carbonate rock in a formation, resulting in improved flow paths through the rock. In some implementations, acids, including hydrochloric acid and the like, can be used to dissolve rock to create acidized fissures or fractures. In some implementations, acid is forced into the formation by fracturing or cracking the rock with hydraulic pressure. Pressure can vary greatly depending on formation depth and composition. In the implementation illustrated in FIGs. 6a and 6b, acidized fractures (25) are located at or near the base (22) of the reservoir (10). Similar to the fractures (24) shown in FIGs. 5a-5d, acidized fractures (25) allow production fluid (14') to flow into the production well (12) from the steam chamber (20) when the production well (12) is located in an adjacent formation (40). FIG. 6c illustrates the effect of acidization on limestone. With acidizing or acidized fracturing, the limestone has improved flow paths or conductivity. In some implementations, to ensure that the acid goes towards the target reservoir (10), the fluid containing the acid can be directed by appropriately oriented orifices or jets.

[092] Referring to FIGs. 7a-7b, small diameter drilled boreholes (26) can be formed to connect the production well (12) to the reservoir (10). A conventional drilling rig, service rig, or coiled tubing drilling unit can be used to drill such boreholes. The diameters of drilled boreholes can vary greatly, depending on the equipment used. In some implementations, the drilled boreholes have a diameter in the range of about 30 mm to over 200 mm. In the implementation illustrated by FIGs. 7a and 7b, drilled boreholes (26) are located at or near the base (22) of the reservoir (10). Boreholes (26) allow production fluid (14') to flow into the production well (12) from the steam chamber (20) when the production well (12) is located in an adjacent formation (40).

[093] In some implementations, a mobile coiled tubing drilling unit can be used to drill boreholes (26). In one implementation, the mobile coiled tubing drilling unit includes a control unit, a power source, and a reel of coiled tubing, and is mounted on a truck.
The coiled tubing is spooled onto the reel for storage and transport. When the drilling unit is in operation, the continuous tubing passes over a guide or goose neck and feeds into an injector (tractor mechanism), which deploys and retrieves the coiled tubing string. The tubing is then inserted into a wellbore through pressure containment devices or blowout preventer (BOP) stacks on top of the wellhead. This process is reversed to retrieve and spool coiled tubing back onto the reel.
For drilling the boreholes (26), a drilling assembly is located at the end of the coiled tubing. The assembly can include data sensors, an orienting device, a bent housing motor, and a drill bit. The data sensors and orienting device steer the drilling assembly for directional drilling, and the drill bit driven by the motor can bore a hole through the wall of the wellbore at a desired angle. Data transmitted by the data sensors are received and processed by the control unit at the surface. In some implementations, the bent housing in the motor can be replaced by a steerable device that is oriented by the driller in the surface control unit. In some implementations, a small diameter and flexible drilling assembly, similar to a speedometer cable with a mill (bit) on the end, is directed towards the side of the well. A motor in the drilling assembly turns the inner shaft, and the inner shaft in turn rotates the mill so that it can drill a borehole into the formation.

[094] Referring to FIGs. 8a-8c, jetted perforations (27) can be formed using a hydraulic jetting tool (81) that runs on jointed tubing or coiled tubing. In the illustrated implementation, pressurized jetting fluid is directed through an orifice or nozzle towards the casing, liner, or inner wall of an uncased borehole, and the jetting fluid erodes a hole into the rock surrounding the wellbore. This is commonly known as "hydro-jetting" or "hydro-slotting". In the implementation illustrated by FIGs. 8a-8b, jetted perforations (27) are located at or near the base (22) of the reservoir (10). Similar to the fractures (24) shown in FIGs. 5a-5d, jetted perforations (27) allow production fluid (14') to flow into the production well (12) from the steam chamber (20) when the production well (12) is located in an adjacent formation (40).
The hydraulic jetting tool (81), which creates deep perforations, can be oriented to avoid boring towards the injection well (11) or to achieve lateral access. In some implementations, the hydraulic jetting tool can also inject fluids, such as acid, to dissolve rock, including limestone and the like. In some implementations, the jetting fluid contains fine particles to augment the jetting process, acid, an abrasive grit, or a combination of any of the foregoing. FIG. 8c shows a hydraulic jetting tool (81) boring a jetted perforation (27) through the production casing or liner in the production well (12) into the formation (40) and reservoir (10). The diameters of jetted perforations can vary greatly. In some implementations, at least one of the jetted perforations (27) has a diameter in the range of 20 mm to 200 mm. In some implementations, a small diameter and flexible pipe (e.g., coiled tubing) with a jetting nozzle at the end is directed towards the side of the borehole. Fluid is pumped through the nozzle, jetting a hole into the formation.

[095] In the present methods and systems, the configuration of production wells can vary based on the characteristics of a given reservoir and a given adjacent location and the recovery process chosen. A production well can be vertical, inclined, curved, horizontal, past horizontal, or at any angle between vertical and horizontal, partially or in its entirety, and can be positioned in various arrangements with respect to other wells, if any. For a given set of geological and operational parameters, the skilled person is able to devise suitable configurations, shapes, and arrangements of production wells in order to maximize recovery.

[096] In some implementations, the production well can be configured with an incline or can be curved. For example, a production well can have vertical, curved, and horizontal sections, as in typical SAGD well pairs, or can be arranged vertically or at an incline, as in a typical cyclic steam stimulation (CSS) process. In some implementations, at least a portion of the production well is oriented at an angle from vertical to horizontal or beyond horizontal, so as to collect the hydrocarbons from the hydrocarbon-bearing formation. In some implementations, at least a portion of the production well is positioned substantially horizontal.

[097] Where SAGD is used as the recovery method, for example, a production well does not necessarily have to be positioned vertically below the injection well. In certain geological or operational conditions, it can be beneficial to have a sidetracked or offset production well. In the implementation shown in FIGs. 9a and 9b, a production well (12) is located in an offset position relative to an injection well (11), with drilled or jetted boreholes (28) formed accordingly to connect the production well (12) in the adjacent formation (40) to the reservoir (10) or the bottom of the steam chamber (20).

[098] In some implementations, the injection well (11) is not initiated from a vertical or inclined orientation, or the production well (12) is not initiated from a vertical or inclined orientation; in other implementations, neither the injection well (11) nor the production well (12) is initiated from a vertical or inclined orientation. In some implementations, one or more of the injection wells (11) is initiated from an access location near a hydrocarbon-bearing formation. In some implementations, one or more of the production wells (12) is initiated from an access location adjacent to a formation. In some implementations, both injection well (11) and production well (12) are initiated from a mine face located in an underlying formation, as further described in Canadian Patent No. 2,863,396, entitled In Situ Gravity Drainage System and Method For Extracting Bitumen From Alternative Pay Regions.

[099] In the implementation illustrated in FIG. 10, an injection well (11) and a production well (12) are initiated from a mine face of an adjacent formation (40) below the reservoir (10), which itself is under overburden (50). A drainage pit (88) is excavated at a site (82) using excavation equipment (84) to create an exposed region (90). The mine face can then be accessed within the exposed region (90). The injection well (11) is drilled into the reservoir (10). The production well (12) is drilled into the underlying adjacent formation (40) and below the injection well (11).
Fluid communication between the reservoir (10) and the production well (12) is established by channels (100), which can be created using the methods described in the present description, such as perforating, jetting, fracturing, acidizing, drilling, and the like or a combination of any of the foregoing.

[0100] In some implementations, an infill well can be drilled between production wells for more efficient recovery of hydrocarbons from a reservoir. The infill well can be added at the time of primary or initial recovery, or at a later time for further recovery. In the present methods and systems, such an infill well can be located in a formation that is adjacent to the oil-bearing reservoir. Referring to FIG. 11, an infill or bypassed region (70) containing unswept hydrocarbons is formed between two mature steam chambers (60a, 60b), each containing a pair of wells (injection well (61a, 61b) and formation production well (62a, 62b)) for primary recovery of hydrocarbons. An additional production well (64) (i.e., an infill well) can then be drilled into a cooler, more consolidated underlying formation (40), instead of being drilled into the reservoir formation that was disturbed and unconsolidated by prior SAGD
operations. In some implementations, for example, the hydrocarbon-bearing formation contains at least two formation production wells with an infill region therebetween, where at least a portion of the production well is positioned in the underlying formation, under the infill region.

[0101] Drilling into an unconsolidated formation is significantly more difficult than drilling through a competent formation. When a reservoir, particularly an oil sands reservoir, is disturbed by heat during a SAGD or other EOR process (e.g., in-situ combustion, electric heating (including electromagnetic heating and electrical resistive heating), radio frequency heating, solvent injection, carbon dioxide flooding, non-condensable gas injection, flue gas flooding, surfactants injection, alkaline chemicals injection, microbial enhanced recovery, and the like, or a combination of any of the foregoing), the formation can become unconsolidated, such that it has little or no residual strength. In such circumstances, drilling new production wells into the unconsolidated formation can be undesirable. The present methods and systems facilitate drilling of a production well by positioning the well in an adjacent formation that is more consolidated and competent than the target reservoir. Where the adjacent formation is sufficiently competent, it is often unnecessary to install a slotted liner or a cemented liner that will have to be perforated at a later time.

[0102] Formations adjacent to target reservoirs can also have certain amounts of hydrocarbons.
In addition to providing access to hydrocarbons in the target reservoir, the methods and systems described herein can also provide access to hydrocarbons in adjacent formations. For example, where a production well positioned in the adjacent formation is fractured to provide continuity to or communication with the target reservoir, the formed fractures or cracks can also connect the production well to the adjacent formation and thereby permit access to hydrocarbons in the adjacent formation. In some implementations, channels provide fluid communication between at least a portion of a first production well and the adjacent formation containing additional hydrocarbons. The additional hydrocarbons from the adjacent formation can then be recovered, along with hydrocarbons from the target reservoir, through the production well.

[0103] In the Athabasca oil sands region, the McMurray formation is the target oil reservoir.
The McMurray sands are underlain by the Devonian carbonates, in which pockets of oil are often contained. The McMurray sands are sometimes separated from the Devonian carbonates by the Continental formation, which can be permeable and porous and can contain bitumen. In other parts of the world, the oil-bearing formations can be underlain by formations that may or may not be hydrocarbon-bearing.

[0104] The present methods and systems can be implemented during initial recovery of hydrocarbons; they can also be used in a partially depleted reservoir following a prior recovery operation. If a target reservoir contains bitumen or heavy oil, it is usually necessary to mobilize hydrocarbons prior to production. Many techniques for mobilization are known to the skilled person, including, without limitation, injection of hot fluids (e.g., steam), injection of air for in-situ combustion, electrical-resistive heating, electromagnetic heating, injection of polymers for mobility control, injection of viscosity-reducing agents or solvents, microbial treatment, and other similar methods. In some implementations, then, the hydrocarbon-bearing formation contains an injection well that is adapted for injecting a heated fluid or viscosity-reducing agent.
While the implementations shown in FIGs. 3a-9b use one production well and one injection well, any number of production wells and injection wells can be used.

[0105] Although the present specification has described particular embodiments and examples of the methods and systems discussed herein, it will be apparent to persons skilled in the art that modifications can be made to the embodiments without departing from the scope of the appended claims.

Claims (41)

1. A method for recovering hydrocarbons from a hydrocarbon-bearing formation, comprising:
providing at least a portion of a production well at an adjacent formation outside of the hydrocarbon-bearing formation;
providing an injection well adapted for injecting a heated fluid or viscosity-reducing agent into the hydrocarbon-bearing formation;
providing a plurality of channels that provide fluid communication between the portion of the production well and the hydrocarbon-bearing formation; and producing hydrocarbons from the hydrocarbon-bearing formation through the portion of the production well, wherein the hydrocarbons are produced via at least some of the plurality of channels that provide fluid communication from the hydrocarbon-bearing formation to the portion of the production well located outside of the hydrocarbon-bearing formation.

2. The method of claim 1, wherein the hydrocarbon-bearing formation contains bitumen.

3. The method of claim 1 or claim 2, wherein the adjacent formation is in an underlying formation that is beneath the hydrocarbon-bearing formation.

4. The method of claim 3, wherein the underlying formation contains hydrocarbons.

5. The method of claim 3 or claim 4, wherein the underlying formation has a higher degree of consolidation than the hydrocarbon-bearing formation.

6. The method of any one of claims 3-5, wherein the channels further provide fluid communication between the portion of the production well and the underlying formation, and the underlying formation contains additional hydrocarbons.

7. The method of claim 6, further comprising recovering the additional hydrocarbons from the underlying formation through the production well.

8. The method of any one of claims 1-7, wherein the portion of the production well is oriented at an angle from vertical to horizontal or beyond horizontal, so as to collect the hydrocarbons from the hydrocarbon-bearing formation.

9. The method of claim 8, wherein the portion of the production well is positioned substantially horizontal.

10. The method of any one of claims 1-9, wherein the heated fluid comprises steam.

11. The method of any one of claims 1-10, wherein the injection well is arranged substantially parallel to the portion of the production well.

12. The method of any one of claims 1-11, wherein the hydrocarbon-bearing formation includes a formation production well.

13. The method of claim 3, wherein:
the hydrocarbon-bearing formation includes at least two formation production wells and comprises an infill region between the at least two formation production wells; and the portion of the production well is positioned in the underlying formation under the infill region.

14. The method of any one of claims 1-13, wherein the channels are formed by perforating, hydraulic fracturing, acid fracturing, acidizing, drilling, or jetting.

15. The method of any one of claims 1-13, wherein:
the channels are formed by acidizing or acid fracturing; and acid is directed by orifices or jets from the portion of the production well towards the hydrocarbon-bearing formation.

16. The method of any one of claims 1-13, wherein:
the channels are formed by hydraulic fracturing using a fracturing fluid; and the fracturing fluid contains a proppant.

17. The method of any one of claims 1-13, wherein the channels are formed by perforating using a stream of hot gas and fine metal particles.

18. The method of any one of claims 1-13, wherein the channels are formed by drilling using a rotating drill bit.

19. The method of any one of claims 1-13, wherein the channels are formed by jetting using a high-pressure fluid.

20. The method of claim 19, wherein the high-pressure fluid contains at least one of:
(a) fine particles to augment the jetting process; (b) acid; and (c) an abrasive grit.

21. The method of any one of claims 1-20, wherein the hydrocarbon-bearing formation is partially depleted by a previous recovery operation.

22. The method of any one of claims 1-21, further comprising recovering the hydrocarbons from the hydrocarbon-bearing formation through the production well.

23. The method of any one of claims 1-22, wherein producing the hydrocarbons comprises draining the hydrocarbons by gravity into the production well.

24. The method of claim 1, wherein producing the hydrocarbons comprises operating a steam assisted in-situ hydrocarbon recovery process.

25. The method of claim 24, wherein the steam assisted in-situ hydrocarbon recovery process comprises a steam assisted gravity drainage system.

26. The method of claim 24, wherein the steam assisted in-situ hydrocarbon recovery process comprises a cyclic steam stimulation system.

27. The method of claim 1, wherein producing the hydrocarbons comprises operating a combustion process by injecting a combustible fuel into the hydrocarbon-bearing formation using the injection well.

28. The method of claim 1, wherein producing the hydrocarbons comprises using at least one of electrical heating, electromagnetic heating, radio frequency heating, solvent injection, carbon dioxide flooding, non-condensable gas injection, flue gas flooding, surfactants injection, alkaline chemicals injection, and microbial enhanced recovery.

29. The method of any one of claims 1-28, wherein the production well is drilled from a mine face at the adjacent formation.

30. The method of any one of claims 1-29, wherein the adjacent formation includes an additional production well.

31. A method for recovering bitumen from a bitumen-bearing formation, comprising:
mobilizing the bitumen in the bitumen-bearing formation by injecting steam into the bitumen-bearing formation by way of an injection well in the bitumen-bearing formation;
draining the mobilized bitumen by gravity through a plurality of channels; and producing the bitumen from a portion of a production well located in an underlying formation beneath the bitumen-bearing formation, the plurality of channels fluidly connecting the bitumen-bearing formation and the portion of the production well.

32. A system for recovering hydrocarbons from a hydrocarbon-bearing formation, comprising:
a production well, at least a portion of which is positioned in an adjacent formation adjacent to the hydrocarbon-bearing formation;
an injection well adapted for injecting a heated fluid or viscosity-reducing agent, at least a portion of which is positioned in the hydrocarbon-bearing formation; and a plurality of channels that communicate with the production well, the channels extending from the portion of the production well to the hydrocarbon-bearing formation, thereby providing fluid continuity between the production well and the hydrocarbon-bearing formation.

33. The system of claim 32, wherein:
the hydrocarbon-bearing formation contains bitumen; and the adjacent formation is in an underlying formation that is beneath the hydrocarbon-bearing formation.

34. The system of claim 32 or claim 33, comprising production equipment for producing the hydrocarbons from the hydrocarbon-bearing formation through the production well.

35. The system of any one of claims 32-34, wherein the heated fluid comprises steam.

36. The system of claim 34, wherein the production equipment comprises a steam assisted gravity drainage system.

37. The system of claim 34, wherein the production equipment comprises a cyclic steam stimulation system.

38. The system of claim 34, wherein the production equipment is configured to operate a combustion process by injecting a combustible fuel into the hydrocarbon-bearing formation using the injection well.

39. The system of claim 34, wherein the production equipment is configured to mobilize the hydrocarbons using at least one of electrical heating, electromagnetic heating, radio frequency heating, solvent injection, carbon dioxide flooding, non-condensable gas injection, flue gas flooding, surfactants injection, alkaline chemicals injection, and microbial enhanced recovery.

40. The system of any one of claims 32-39, wherein the production well is drilled from a drainage pit at the adjacent formation.

41. A system for recovering bitumen from a bitumen-bearing formation, comprising:
an injection well adapted for injecting steam into the bitumen-bearing formation to mobilize bitumen, at least a portion of which is positioned in the bitumen-bearing formation;
a production well, having a substantially horizontal portion positioned in an underlying formation beneath the bitumen-bearing formation, the production well adapted to receive mobilized bitumen; and a plurality of channels that communicate fluidly with the production well, the channels extending from the horizontal portion of the production well to the bitumen-bearing formation, thereby providing continuity between the production well and the bitumen-bearing formation to allow mobilized bitumen to drain from the bitumen-bearing formation into the production well.