WAFFLE WELL PATTERN WITH NETWORKED WELLS FOR HYDROCARBON RECOVERY AND RELATED METHODS

TECHNICAL FIELD

The technical field generally relates to hydrocarbon recovery operations, and more particularly to well patterns for recovering hydrocarbons from a subterranean reservoir.

BACKGROUND

Recovery of hydrocarbons can include providing wells that are drilled into a reservoir and can have different patterns depending on certain factors. There are various challenges with respect to recovering hydrocarbons via wells and promoting efficient and effective recovery.

SUMMARY

Techniques described herein relate to various well patterns, systems and methods where well sections intersect to provide enhanced operations.

In some implementations, there is provided a method for recovering hydrocarbons from a subterranean reservoir comprising: providing a multileg horizontal well in the reservoir, the multileg horizontal well comprising a vertical well section and multiple horizontal legs extending from the vertical well section; providing a crossover well in the reservoir, the crossover well sharing at least a portion of the vertical well section of the multileg horizontal well and comprising a spine well section and rib well sections extending from the spine well section, wherein a plurality of the rib well sections intersect with a plurality of the multiple horizontal legs to form a waffle well network; and producing hydrocarbons that flow through the waffle well network for recovery at surface.

In some implementations, the hydrocarbons comprise oil. In some implementations, the hydrocarbons comprise heavy oil. In some implementations, the reservoir is unconsolidated. In some implementations, the reservoir is consolidated. In some implementations, the reservoir is semi-consolidated. In some implementations, the method includes a pre-treatment stage where a treatment fluid is injected or circulated into the waffle well network prior to the step of producing. In some implementations, the pre-treatment fluid comprises steam, acid, hot water, surfactant, or a combination thereof. In some implementations, the horizontal legs and the rib well sections are aligned in a same plane within the reservoir within 1 meter of each other at intersections thereof. In some implementations, intersections of the rib well sections and the leg well sections include partial intersections, full intersections, and/or spaced-apart intersections with fluid communication between the corresponding well sections. In some implementations, at least 50% of the crossovers between rib well sections and leg well sections provide respective intersections. In some implementations, the rib well sections extend at a forward angle from the spine well section. In some implementations, the forward angle is between 20 and 70 degrees. In some implementations, the rib well sections each have a substantially same length. In some implementations, the rib well sections are each generally straight. In some implementations, the rib well sections are evenly spaced apart from each other along the spine well section. In some implementations, the rib well sections are open hole. In some implementations, at least some of the rib well sections intersect with respective multiple leg well sections. In some implementations, at least some of the leg well sections are intersected by multiple rib well sections. In some implementations, the spine well section is generally parallel with respect to adjacent leg well sections. In some implementations, the spine well section is provided as a dedicated well section distinct from the leg well sections. In some implementations, the spine well section is provided as a one of the leg well sections. In some implementations, all of the leg well sections are intersected by at least one rib well section. In some implementations, the rib well sections extend from both sides of the spine well section such that the crossover well is a fishbone well. In some implementations, the rib well sections extend from one side of the spine well section such that the crossover well is a feather well, where the spine well section is a shaft well section and the rib well sections are barb well sections. In some implementations, a tertiary well is provided and intersects with rib well sections and leg well sections. In some implementations, the method includes completing at least one of the rib well sections with a liner prior to producing. In some implementations, the liner is a slotted liner. In some implementations, the liner is a blank liner.

In some implementations, there is provided a method for recovering hydrocarbons from a subterranean reservoir comprising: providing a multileg horizontal well in the reservoir, the multileg horizontal well comprising a vertical well section and multiple horizontal legs extending from the vertical well section; providing a crossover well in the reservoir, the crossover well comprising a spine well section and rib well sections extending from the spine well section, wherein a plurality of the rib well sections intersect with a plurality of the multiple horizontal legs to form a waffle well network; and producing hydrocarbons that flow through the waffle well network for recovery at surface.

In some implementations, the crossover well comprises a crossover vertical well section coupled to the spine well section. In some implementations, the crossover vertical well section is distinct from the vertical well section of the multileg horizontal well. The method can include one or more additional features are described herein.

In some implementations, there is provided a waffle well system for recovering hydrocarbons from a subterranean reservoir comprising: a multileg horizontal well in the reservoir, the multileg horizontal well comprising a vertical well section and multiple horizontal legs extending from the vertical well section; a crossover well in the reservoir, the crossover well sharing at least a portion of the vertical well section of the multileg horizontal well and comprising a spine well section and rib well sections extending from the spine well section, wherein a plurality of the rib well sections intersect with a plurality of the horizontal legs; a wellhead provided at surface and coupled to the vertical well section; and a recovery unit provided at surface and coupled to the wellhead, the recovery unity being configured to cause production of hydrocarbons that flow through the multileg horizontal well and the crossover well for recovery at surface.

In some implementations, there is provided a well system for recovering hydrocarbons from a subterranean reservoir comprising: a first well in the reservoir, the first well comprising a vertical well section and at least one horizontal leg extending from the vertical well section; a crossover well in the reservoir, the crossover well comprising a spine well section and rib well sections extending from the spine well section, wherein a plurality of the rib well sections intersect with at least one of the at least one horizontal leg; a wellhead provided at surface and coupled to the vertical well section; and a recovery unit provided at surface and coupled to the wellhead, the recovery unity being configured to cause production of hydrocarbons that flow through the multileg horizontal well and the crossover well for recovery at surface.

In some implementations, there is provided a method for recovering hydrocarbons from a subterranean reservoir comprising: providing a multileg horizontal well in the reservoir, the multileg horizontal well comprising a vertical well section and multiple horizontal legs extending from the vertical well section; providing a crossover well in the reservoir, the crossover well sharing at least a portion of the vertical well section of the multileg horizontal well and having a horizontal well section extending across and in spaced-apart relation to a plurality of the horizontal legs; performing a fracturing operation in the crossover well to form fractures that extend from the crossover well to at least some of the horizontal legs, thereby forming an interconnected well network; and producing hydrocarbons that flow through the interconnected well network for recovery at surface.

In some implementations, the crossover well is located above the legs. In some implementations, the crossover well is located below the legs. In some implementations, the crossover well extends diagonally across the legs. In some implementations, the fracturing operation is performed using multistage fracturing, optionally via sliding sleeves. In some implementations, there is a single crossover well. In some implementations, the crossover well is spaced apart by a vertical offset distance of up to two meters. In some implementations, the crossover well is configured based on a predetermined determination that includes at least one of reservoir quality and distribution and calculated fracture half length; and/or the crossover well is sized based on at least one of reservoir quality, consolidation, gravity of the hydrocarbons, and optionally a size of a casing in a build section of the vertical well section.

In some implementations, there is provided a method for recovering hydrocarbons from a subterranean reservoir comprising: providing a multileg horizontal well in the reservoir, the multileg horizontal well comprising a vertical well section and multiple horizontal legs extending from the vertical well section; providing a crossover well in the reservoir, the crossover well having a horizontal well section extending across and in spaced-apart relation to a plurality of the horizontal legs; performing a fracturing operation in the crossover well to form fractures that extend from the crossover well to at least some of the horizontal legs, thereby forming an interconnected well network; producing hydrocarbons that flow through the interconnected well network for recovery at surface.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1 to 32 are various views of well systems and arrangements as well as related features and example information according to the technology described herein. FIGS. 1 to 15, 24 to 27 and 33 to 36 are top plan schematics of well systems; FIGS. 16 to 20 and 23 are side cross-sectional views of parts of well sections; FIGS. 21 and 22 are side view schematics of well systems; FIGS. 28 and 30 to 32 are view of example well systems; and FIG. 29 is a graph illustrating production from an example waffle well system. FIG. 37 shows an example of a fracture-enhanced well network.

DETAILED DESCRIPTION

The present description relates to systems and methods for recovering hydrocarbons using in situ wells provided in the reservoir to form a well network that includes a multileg horizontal well and a crossover well, such as a fishbone well or a feather well, that include intersecting well sections or fracture-enhanced connections. The well network that is formed can be referred to as a “waffle” well. The multileg horizontal and the crossover wells can have various features, some of which will be described in further detail below. The addition of the intersecting fishbone or feather well can facilitate an increase in hydrocarbon recovery rate and recovery factor comparted to conventional multileg horizontal applications.

Summary of Overall System and Method

Referring to FIG. 1, the waffle well system 10 can include a multileg horizontal well 12 and a crossover well 14, which is shown here as a fishbone well, that are provided in the reservoir 16. The multileg horizontal well 12 includes a vertical section 18 extending from the surface and multiple legs 20 extending horizontally from the vertical section 18. The fishbone well 14 can share the vertical section 18 of the multileg horizontal well 12 and include a spine well section 22 from which several rib well sections 24 extend. The multileg horizontal well 12 and the fishbone well 14 are provided generally at the same elevation such that intersection of rib well sections and leg well sections is provided and forms a well network. The waffle well thus includes intersections or crossovers between the wells and can include various combinations of fishbone wells, feather wells and other well patterns, some examples of which will be described below. For feather wells, the spine well section can be referred to as the shaft well section and the rib well sections can be referred to as barb well sections. In the present description, the term crossover well is generally used to include wells with at least one section that intersects with one or more of the multileg horizontal well and can include fishbone wells, feather wells, and other types of wells having lateral sections extending from a main section and which can facilitate crossovers with the multileg horizontal well.

Well Pattern Implementations

Referring to FIGS. 1 to 24, it should be appreciated that various arrangements and patterns are possible when providing the networked waffle well system with the crossover and multileg horizontal wells. For example, the spine well section of the fishbone or feather well 14 can be provided as a distinct well section in the middle of the leg well sections (e.g., FIG. 1), as a distinct well section in between two outer leg well sections (e.g., FIG. 2), or as a distinct well section stepped out from an outermost leg well section (e.g., FIG. 10). In addition, the spine well section 22 of the fishbone well 14 can be a distinct well section (e.g., FIGS. 1, 2, 3, 5, 6, etc.) or it can share a previously drilled leg well section (e.g., FIGS. 4 and 11). It is also noted that the vertical section of the fishbone well 14 could be shared with the vertical section 18 of the multileg horizontal well (e.g., FIG. 1), could be drilled off an adjacent well as shown in FIG. 22, or could be its own dedicated vertical well section drilled from the surface. The spine well section 22 that is generally parallel with respect to the leg well sections 20 (e.g., FIGS. 1, 2, 3, etc.) or provided at an angle (e.g., FIG. 13) such that the spine well section intersects certain leg well sections or not. FIGS. 2 and 10 illustrate examples where the crossover well 14 is a feather well where barb well sections extend from only one side of the shaft well section. It is also noted that various terms can be used to describe different sections of the wells, such as the “build section” to describe the section in between vertical and horizontal portions of the well. In the present document, it should be noted that the expressions vertical and horizontal well sections together form an overall well that may include other sections, such as a build section or other parts of the well.

Furthermore, the fishbone or feather well 14 can have rib well sections 24 that have various angles, orientations, curvatures, sizes, spacings, distributions and completions. FIGS. 1 to 24 illustrate various examples of different arrangements where the rib well sections are provided with various characteristics. The rib well sections 24 can extend from both sides of the spine well section (e.g., FIGS. 1, 3, 4, etc.) or from a single side (e.g., FIGS. 2, 10). The rib well sections 24 can also extend at substantially the same angle with respect to the sine well section (e.g., FIGS. 1, 3, etc.) or at different angles (e.g., FIG. 9). The rib well sections 24 can also be evenly spaced apart from each other (e.g., FIG. 1) or not (e.g., FIG. 8). The rib well sections 24 can also each have generally the same length (e.g., FIG. 1) or not (e.g., FIG. 2). The rib well sections 24 can also be provided so that their length is in part determined based on the intersection at or near their distal end with a leg well section; for instance, FIGS. 2 and 4 show that the furthest rib well section 24 is shorter than the previous ones to only intersect the adjacent leg well section, as at the well angle the distal rib well sections would not pass through the further leg well sections. In addition, one or more of the rib well sections 24 can intersect multiple leg well sections, although some can still only intersect one leg section. It is also possible for certain rib well sections 24 to not intersect any leg well sections (e.g., distal rib well sections in FIG. 5). Pairs of rib well sections can extend from the spine well section in opposed directions from a same junction (e.g., FIGS. 1, 4, 5, 6, etc.), or the rib well sections 24 can be offset from each other along the spine well section (e.g., FIGS. 3, 12).

Referring to FIGS. 25 to 27, the multileg horizontal well 12 can itself take the form of a feather well (FIGS. 25 and 27) or a fishbone well (FIG. 26) and the crossover well 14 can be provided accordingly as a fishbone or feather well. FIG. 25 shows a pattern where two feather wells are arranged with crossovers to provide the waffle well 10 which can be said to be a 4-by-4 waffle well since each well has four laterals that crossover. FIG. 26 shows a pattern where the initial well is a fishbone well and there are two feather wells 14A and 14B extending on either side of the spine of the main fishbone well. FIG. 27 shows a pattern with two intersecting feather wells where one of the barb well sections is provided to pass through lateral sections of both wells and can be referred to as a primary crossover well section 24′. It is possible to provide a primary crossover well section 24′ in various different patterns and scenarios to have a well section that has a high number of intersections.

In the illustrations, the rib well sections 24 pass through leg well sections 20 that are part of a single multileg horizontal well 12, but it should be noted that the rib well sections could pass through leg well sections that are part of multiple multileg horizontal wells. It is also possible for a single fishbone well 14 to be arranged to access multiple multileg horizontal wells (e.g., FIG. 24). The orientations of the fishbone well 14 could be adapted depending on the arrangement of the multileg horizontal wells to intersect with target leg well sections.

In some implementations, the fishbone or feather well 14 and the multileg horizontal well 12 and their corresponding well sections are generally aligned on a same plane through the reservoir. For example, if the multileg horizontal well deviates to follow a geological feature such as a base of the reservoir that has changing elevation, the fishbone well can also be provided to follow a generally same plane. Alternatively, the fishbone well 14 could be provided on a different plane or trajectory and the rib well sections could be provided with orientations that are angled upward or downward to intersect with corresponding leg well sections. FIG. 23 illustrates how the rib well sections 24 can be oriented horizontally or angled from a spine well section of the fishbone well 14, while FIGS. 21 and 22 show how a fishbone well 14 can be located below the multileg horizontal well 12 and the rib well sections 24 can be angled upward to intersect with the multileg horizontal well 12.

The rib well sections 24 are provided to enable intersection of the fishbone well 14 with the multileg horizontal well 12. The intersection of well sections facilitates fluid communication between the well sections and the overall well network. It is possible that not all of the well sections intersect, and the intersections may include full, partial or proximate intersection. For example, FIGS. 16 to 19 show different types of intersections between the rib well sections 24 and the leg well sections 20. FIGS. 16 and 17 show partial intersection, FIG. 18 shows full intersection, and FIG. 19 shows proximate intersection where there is fluid communication between the adjacent wellbores through an interwell reservoir region which can depend on reservoir features such as permeability and operating conditions such as production pressure. In some implementations, a certain threshold of the crossover points can be considered to have certain intersection features, e.g., at least 50% of crossovers intersect within 1 meter; at least 75% of crossovers intersect within 5 meters, 3 meters, 1 meter or 0.5 meter.

Referring now to FIG. 33, at least one of the multilateral wells 12, 14 can be configured such that it includes at least one lateral that itself has a deviated trajectory. A deviated well section 26 can be provided based on reservoir characteristics or other factors. The deviated well section can be provided on well 12 and/or 14.

Referring to FIG. 34, in addition to wells 12 and 14, it is possible to include a tertiary well that is drilled from the same vertical or not, to provide additional crossovers. This additional well can be referred to as a tertiary well 28 and it can be a single wellbore or a multilateral itself. The inclusion of a tertiary well 28 may depend on various factors such as past collapse events, spacing between legs and ribs/barbs, recovery strategies, and so on. In the example embodiment of FIG. 34, the three wells 12, 14, 28 can extend from the same vertical section or one or all of them can have separate vertical sections. In FIG. 35, an example is shown where the wells 12, 14 extend from dedicated separate vertical sections and intersect along a generally horizontal plane. There could be a tertiary well added to the example of FIG. 35 and having at least one well section that runs at an angle with respect to the laterals of wells 12 and 14, and there could also be a fourth well having at least one well section that runs at another angle with respect to the other wells. The tertiary and fourth wells could extend from one or more of the same verticals as wells 12 and 14, or they could have their own dedicated vertical sections. More than four wells is also possible.

In some implementations, referring to FIG. 36, the crossover well 14 can include a single well section that extends from the vertical section and intersects with multiple legs of the multileg horizontal well 12. The crossover well 14 can be designed to crossover all of the leg well sections, as shown, or a select subset of the leg well sections.

It is also noted that one or more of the waffle well systems 10 can be provided in a pay zone of a reservoir, arranged adjacent to one another or stacked on top of one another. FIG. 24 shows examples of well systems 10 that extend from a single well pad.

Turning to FIG. 28, an example of a waffle well system is shown including a multileg horizontal well and a fishbone well where the rib well sections are provided regularly spaced along part of the spine well section, are offset from each other, and have an increasingly forward angle toward the toe end of the spine well section. Each rib well section is drilled to intersect all of the leg well sections on the corresponding side where it extends.

It is noted that the networked waffle well system can facilitate increased recovery rate and factor, providing the hydrocarbons with multiple flow channel options during production which can notably of interest if there are any formation collapse issues. For instance, if part of the formation collapses and thereby blocks a part of one of the leg well sections, then the fishbone well can still enable access of the blocked off region of the reservoir. The waffle well system can facilitate enhancements notably in formations that are susceptible to partial collapse and/or situations where system robustness or flow channel redundancy is desired. For instance, the waffle well system can be suited for use in unconsolidated formations with optional use of strategically placed slotted and/or blank liners; although also in consolidated formations with no liners. In one implementation, a conventional well design that includes a certain number of laterals can be adapted to a waffle well design with the same or similar number of laterals but in the crossover configuration, thus providing advantages of the waffle design with little or no impact on drilling time and cost especially if all of the waffle well is drilled during s single drilling operation.

The waffle well can include certain spacing considerations between well sections and crossovers of the wells. Example commercial scale spacings are shown in FIGS. 28 and 30 to 32. In some implementations, the spacing between the legs of the multileg horizontal well can be similar to the spacing between the rib or barb well sections, e.g., within 10%, 15%, 20%, 25% or 30%. For instance, the average spacing between some or all adjacent legs of each well could be from 20 to 60 meters, or 25 to 50 meters, or 30 and 40 meters, and the average spacing between some or all adjacent ribs/barbs could also be from 20 to 60 meters, or 25 to 50 meters. Spacing strategies can also vary depending on features the reservoir.

In some implementations, the waffle well system 10 can be provided with crossovers per area with a certain range. For example, the crossovers per area can be between 5 and 15 per 100 m²over a portion, over the majority or over the entirety of the reservoir region covered by the waffle well system 10. The crossover density can be relatively consistent over the waffle well or can vary in different regions based on reservoir characteristics, drilling methods, and other factors.

Well Completion Implementations

In some implementations, one or more of the wells is provided with a completion that facilitates or enhances operation. For example, in some implementations, at least one of the well sections is completed with a slotted liner that prevents collapse and enables fluid inflow from the reservoir. This well section can be the last section that is drilled which can both facilitated deployment of the liner and also ensure that no subsequent drilling would intersect and damage the liner. This well section can also be one that has the most and/or a high number of crossovers and intersections.

In some implementations, blank liners can be deployed in certain portions of certain well sections, notably in the areas where the formation is of lower quality. For instance, if a well section passes through a poor-quality formation region, a blank liner can be placed in that region so that the well section can still access the higher quality formation areas on either side of the poor-quality region. In another example, if a well section is drilled too far into a poor-quality region, a blank liner can be deployed to the end in that region to reduce inflow of mineral solids which could reduce the productivity of the operation.

It is noted that the completions that may be used in the waffle well can depend on the nature of the formation rock, the hydrocarbons, and the planned hydrocarbon recovery process. For instance, if fracturing is planned for the formation, the wells can be completed with equipment for fracturing, such as a cemented Liner with frac ports, a ball-drop frac system with liner, a swellable packer liner frac, or a plug and perf frac system with liner. If the formation is relatively consolidated, an open hole completion can be preferred. Other types of completions that can be deployed in at least one of the well sections are as follows: a slotted Liner completion, a perforated Liner completion, a wire-wrapped screen liner completion, or a liner completion with inflow control devices (ICDs).

In some implementations, the first well 12 is not completed in the leg well sections in a manner that would impede or be counter-productive to the drilling or operation of the crossover well 14. It is possible to leave the first well 12 as an open hole well, and the crossover well 14 is the one that is provided with one or more completions. For the crossover well 14, one or more or all of its well sections can be completed with liners and/or additional equipment.

It is also possible for one of the wells to include a completion while the other is provided as an open hole well or including completed sections and open hole sections. Both wells could also be open hole. This networked waffle well system can also facilitate the use of open hole wells since collapse issues are mitigated by the multiple paths the hydrocarbons can take for recovery.

In fracturing implementations, the operation could include drilling the waffle well system, completing certain well sections with fracturing equipment, performing the fracturing process, and then transition to production mode. While many scenarios are possible, in some implementations the fracturing is performed via one or more well sections of the crossover well 14 only and not via the first well 12. The one well section that could be used as the fracturing well could be a last well section that was drilled, but it could alternatively be another well section. Multiple well sections could also be used for fracturing in some implementations.

In some implementations, the crossover well is drilled in spaced apart relation with respect to the horizontal legs of the multileg horizontal well and the fracturing facilitates connection of the legs with the crossover well to form an interconnected well network. In this scenario, at least a section of the crossover well is spaced apart, either above or below, with respect to the legs such that fluid communication would be prevented or reduced due to the spacing between the well sections. In one example, the crossover well spans diagonally across multiple legs, preferably most or all of the legs. When the crossover well is subjected to fracturing, the fractures connect the crossover well with proximate sections of the legs over the length of the crossover well. Thus, the crossover well, the fractures, and the legs form an interconnected well network.

The vertical offset spacing between the crossover well and the horizontal legs can be provided based on various factors, such as the formation properties and the design parameters of the fracturing operation. For example, the average spacing can be up to two meters, for example, such as 0.5 to 2 meters. The spacing can be relatively constant over the length of the crossover well, or could be variable in some cases. It is also noted that for frac connectivity of the wellbore, it can be determined by a calculated frac height that may consider factors—such as pumping rates, size of frac, type of reservoir rock, type of rocks below and above reservoir—for estimate purposes.

For certain formations or situations, fracturing may be an effective and efficient way of creating and enhancing fluid connectivity between the crossover well and the legs providing overall benefits compared to providing well sections that intersect with each other as described further above. In addition, if a crossover well is drilled such that intersection with the legs is not achieved such that fluid communication is enabled between the legs and the crossover well, the crossover well can be fractured instead of providing ribs well sections to form the interconnected well network. In another optional scenario, a first crossover well with ribs could be provided to intersect with legs and a second crossover well could be provided vertically spaced apart and then fractured to provide fracture-based fluid communication. It is also possible to have a crossover well with ribs that intersect with most of the legs, and where one or more leg is not intersected the crossover well could be isolated and fractured at that location to promote fluid communication. Various combinations of fractures and intersections can be provided by combining aspects of the present description.

In some implementations, as shows for example in FIG. 37, a single crossover well can be provided and fractured to form the interconnected well network. Alternatively, more than one crossover well can be provided and fractured to cover a larger area of the horizontal legs with a fracture-enhanced well network. In some implementations, substantially all of the crossover well can overly or underly the horizontal legs, although other configurations are possible.

The fracturing operation can be performed using various methods, equipment and completions. The hydraulic fracturing can use various types of fluids and proppants, and can be conducted at operating conditions depending on the formation, well spacing, and other factors. For example, the fracturing operation can include multistage fracturing, where the stages are optionally provided based on the location of the legs (e.g., each fracturing stage corresponds to a well section proximate a corresponding leg). In alternative implementations, the fracturing operation can be performed along the entire length of the crossover well simultaneously. The fracturing can be performed using sliding sleeves operated one at a time along the well in a multistage operation. It is also noted that fracturing can be performed on certain length of the well, leaving the remaining length unfractured; the unfractured section can have a similar offset spacing as the fractured section of the crossover well, or can directly intersect the horizontal legs.

Operation of Waffle Well System

The waffle well system can be designed, drilled, completed and operated in various ways depending on the reservoir and other factors.

In terms of drilling and installation, in some implementations, the multileg horizontal well is first drilled into the reservoir and then tested for fluid production. If fluid production is below targets or has certain characteristics, then the crossover well can be drilled to provide the networked waffle well system. For example, if the first well produces too much water, produces very little oil and/or has other production problems that may be due to wellbore collapse, the crossover well can be provided in a subsequent drilling phase. During the testing phase of the multileg horizontal well, it may be determined that certain leg well sections display good productivity while others do not, in which case the fishbone well could be provided to access only the unproductive leg well areas.

While one embodiment has the crossover well drilled only after initial production is tested in the multileg horizontal well, it is also possible to forgo the testing phase and drill both the multileg horizontal well and the crossover well together prior to operating. The first well and the crossover well-in addition to any tertiary or additional wells-could be drilled in the same drilling operation using the same drilling rig prior to production. This combined drilling approach can have various advantages in terms of cost and efficiencies, and the waffle well pattern can be adapted accordingly. For example, instead of drilling a single multileg horizontal well with eight legs, one can drill a waffle well with four legs and four crossover well sections, thus providing a similar total wellbore length while facilitating a well system with increased robustness to collapse, higher recovery rate and recovery factors for the given area. In this embodiment, it is also possible to test drilling samples during the drilling of the first well to determine certain formation characteristics that can inform the specific pattern for the crossover well. For instance, if poor reservoir areas are identified, the crossover well design can be adapted to truncate the barb or rib well sections prior to the reservoir areas (see, e.g., FIGS. 30 to 32 and related example). An initial waffle well design can be based on modelling and/or planning based on reservoir characteristics garnered from seismic, exploration well samples, and the like; and the waffle well design can subsequently be modified based on drilling samples (e.g., of the multileg horizontal well and/or of the initial crossover sections) to provide a final drilling plan.

In addition, the waffle well system can be assessed in terms of intersections during or after the drilling operation. For example, the proximity of each pair of intersecting well sections can be assessed for offset to determine characteristics of the waffle well system. For example, the number of intersected well sections can be determined and can include well sections that are directly intersected, slightly offset, and separate. In some implementations, the completion equipment can be adapted based at least in part on the assessment of the crossovers. In some implementations, the assessment of crossover characteristics can be performed during the drilling process such that the drilling of the crossover well can be adapted to provide a target number of intersections in a given region and/or in the overall waffle well pattern.

In terms of operation, after an optional testing phase, the networked waffle well system can be operated to include a production stage which can optionally be complemented by pretreatment and/or injection stages. The pretreatment stage could include the injection or circulation of fluids to increase subsequent production. The injection of fluids, such as steam or hot water, could be performed as part of the pretreatment stage or alternating with production stages (e.g., cyclic steam stimulation process). Depending on the viscosity of the hydrocarbons (e.g., heavy oil or bitumen), heating may be desired to increase mobility and facilitate or enable production.

Furthermore, the waffle well system adapted for later-life hydrocarbon recovery that may include fluid injection. Water floods and other enhanced oil recovery (EOR) processes could be used in certain waffle well applications. Flow control devices (FCDs) and other equipment can be used to facilitate such EOR processes.

Regarding testing, it is also possible to test certain features during the drilling and/or operation of the wells. For example, during drilling of the crossover well, readings could be obtained to assess potential productivity of the networked waffle well system and the crossover drilling could be adapted accordingly. The testing can include gas detection and/or drilling fluid sample detection. As mentioned above, testing can be conducted in relation to the first well 12 and the drilling plan for the second well 14 can be adapted accordingly.

In one implementation, the waffle well system can be used in the context of fixing an initial well that is experiencing production problems by subsequent drilling and operation of the crossover well. However, another notable implementation is where the first well and the crossover well are drilled prior to operation of the wells as this can involve notable efficiencies.

When the well network is fracture-enhanced, the operation and testing of the well network can be provided accordingly.

Reservoir and Hydrocarbon Implementations

The method for recovering hydrocarbons using the networked well system can be implemented in various types of reservoirs and performed to recover various hydrocarbons. In some implementations, the reservoir has one or more features or properties within 10% to 25% of the example reservoir described in more detail below, although various other reservoir types can be applicable. The hydrocarbons may include oil, heavy oil, bitumen, gas, or combinations thereof, for example. The waffle well system could be preferably deployed in any reservoir that is a candidate for typical multilateral development.

EXAMPLES & RESULTS

Examples of the waffle well system were drilled and tested in the Sparky reservoir. The Sparky reservoir at Monitor is a thin, stacked, deltaic deposit, made up of delta front and prodelta deposits as well as distributary channels which crosscut the area. Facies changes within the Sparky as well as down cutting, younger Waseca channels segregate the regional pools in the area. Within Monitor, the Sparky Formation reaches 20 m gross thickness. Using cut-offs of 15% porosity, and 4 ohm-m (calculating 35% Sw) in the Sparky sandstone reservoir yields net oil pay values in the 5 m to over 10 m range. The Sparky sandstones in this area show porosities ranging from 21-30%, with permeabilities averaging 50 mD.

Referring to FIGS. 28 and 29, a first example waffle well application is illustrated. In this case, the multileg horizontal well was drilled initially and production was attempted but resulted mainly in water production. After these initial production difficulties, a jet pump cleanout process was conducted, but water production continued with little to no oil production. A drilling rig cleanout was then conducted, but little to no production was achieved. Then, the fishbone well was drilled as shown in FIG. 28 which facilitated oil production as shown in FIG. 29 (i.e., shortly after the “waffle well drill” point which represents the drilling of the fishbone well intersecting the original multileg horizontal well). This example illustrates that an intersecting fishbone well can be provided to crossover an existing well experiencing difficulties in oil production.

Referring to FIGS. 30 to 32, a second example waffle well application is shown. In this case, the multileg horizontal well was drilled and experienced initial oil production but a collapse occurred, and production ceased. The feather well was then drilled, and fluid production has resumed. FIG. 30 illustrates the initial drilling plan of the feather well, FIG. 31 shows the updated drilling plan based on information gathered regarding reservoir quality where barb well sections were truncated to focus on the higher quality regions of the pay zone, and FIG. 32 shows the final waffle well pattern as drilled. In this example, it is noted that there is a primary crossover well section that cuts across the bar well sections as well as many of the leg well sections and thus has the most intersections with other lateral well sections. The positioning of the primary crossover well section as well as the barb well sections focus on the higher quality region of the pay zone, as the western part of the area was of lower quality. In addition, the primary crossover well section was drilled last and perforated liner is placed in it given its high degree of interconnectivity with other well sections.

The second example illustrates how the secondary well (e.g., the feather well) can be planned, drilled and/or completed based partly on information obtained from drilling of the primary well (e.g., the multileg horizontal well). In this case, the drilling samples obtained during drilling of the multileg horizontal well showed poorer quality reservoir in the western region, indicating that extending the barb well sections of the feather well to reach the westernmost leg would not be required. In addition, the primary crossover well section was planned to swoop across leg and barb well sections and thus it was the last one drilled and was lubricated as well to facilitate completion with a perforated liner.

In the final drilled waffle well pattern, there are 63 crossings with the primary crossover well section having 15 of those. Almost all crossings where intersection was attempted achieved well sections that were within one meter of each other. There were eight crossings where intersection was not attempted, and they were within a few meters. About half of the crossings had intersections within half a meter.

In another example, a multileg horizontal well was provided and a crossover well was drilled off the vertical section to span diagonally across the legs, such that the crossover well was suitable for fracturing.

WAFFLE WELL PATTERN WITH NETWORKED WELLS FOR HYDROCARBON RECOVERY AND RELATED METHODS

Information

Publication Number

Date Filed

Date Published

Inventors

Original Assignees

CPC

International Classifications

Abstract

Description

Claims

Priority Claims (1)