CA3087127A1 - Vertical access thermal wellhead - Google Patents

Abstract

A method of using a system begins with providing a wellhead having a vertical bore, a second bore, and an angled bore. The wellhead is installed at a surface of the well, and the vertical bore is in fluid communication with a downhole pump. The method further includes removing a coil tubing from the angled bore in the wellhead where the angled bore intersects with the second bore extending vertically through the wellhead. The system further includes inserting a downhole tool into the second bore, and the downhole pump remains downhole during the insertion of the downhole tool.

Description

VERTICAL ACCESS THERMAL WELLHEAD
BACKGROUND
[0001] Once a resource is discovered below the surface of the earth, an extraction system is often installed for oil production, where a thermal wellhead and drilling tools are employed to access and extract the discovered resource. Such wellheads may be located onshore or offshore depending on the location of the resource, and may include different components, such as casings, hangers, valves, fluid conduits, etc., which perform operations relevant to extraction of the resource.

[0002] In some operations, the desired resource may be found in geologic formations containing a mixture of heavy and viscous oil with sand, known as oil sands or tar sands.
The viscosity profile of the oil and sand mixture makes oil extraction difficult, calling for an additional technique to improve the efficiency of the extraction process.
For instance, additional extraction techniques, such as Cyclic Steam Stimulation (CSS), may be employed to improve the extraction process to separate the oil from the sand and to reduce the viscosity of the oil prior to the extraction. In a number of extraction systems with CSS, steam is injected into the geologic formation containing the oil sands. The well is then shut for a period of time (e.g., several months) allowing the oil to be sufficiently heated. Once the resource is heat soaked, the well is opened such that the heated oil and condensed steam may be extracted.
SUMMARY

[0003] In accordance with one or more embodiments, a system may include a wellhead having a vertical bore, a second bore, and an angled bore. The vertical bore and the second bore extend parallel to a longitudinal axis of the wellhead while the angled bore extends from the second bore at an angle with respect to the longitudinal axis of the wellhead. The system further includes a production tubing string suspended from the vertical bore and extending into a well. The system may further include a downhole pump inside the production tubing and flow control devices disposed at an interval along a tail pipe in the well. The system may further include a liner hanging from a casing in the well and a shifting tool supported through the second bore. The outer diameter of the shifting tool is Date Recue/Date Received 2020-07-17 larger than an inner diameter of the angled bore. The system may further include a spool adapter having an inclined passage, which connects the vertical bore with a wellhead top.
The angled bore meets with the second bore at an intersection located above a bottom hanger.

[0004] A wellhead in accordance with one or more embodiments may include a vertical bore, a second bore, and an angled bore. The vertical bore and the second bore extend parallel to a longitudinal axis of the wellhead while the angled bore extends from the second bore at an angle with respect to the longitudinal axis of the wellhead.
The vertical bore may be isolated from the second bore and the angled bore. The system may further include a spool adapter having an inclined passage, which may connect the vertical bore with a wellhead top. The angled bore meets with the second bore at an intersection located above a bottom hanger.

[0005] In accordance with one or more embodiments, a method of using a system may begin with providing a wellhead having a vertical bore, a second bore, and an angled bore.
The wellhead may be installed at a surface of the well, and the vertical bore may be in fluid communication with a downhole pump. The method may further includes removing a coil tubing from the angled bore in the wellhead where the angled bore intersects with the second bore extending vertically through the wellhead. The system may further include inserting a downhole tool into the second bore, and the downhole pump remains downhole during the insertion of the downhole tool. The downhole tool may be a shifting tool which may be engaged with at least one flow control devices disposed in the well.
The engagement may include adjusting the at least one of flow control devices to achieve a desired steam to oil ratio.
BRIEF DESCRIPTION OF DRAWINGS

[0006] The following is a description of the figures in the accompanying drawings. In the drawings, identical reference numbers identify similar elements or acts.
The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not necessarily drawn to scale, and some of these elements may be arbitrarily enlarged and positioned to improve drawing legibility.
Date Recue/Date Received 2020-07-17

[0007] FIG. I shows an extraction system in accordance with one or more embodiments.

[0008] FIG. 2 shows a perspective view of a wellhead in accordance with one or more embodiments.

[0009] FIG. 3 shows a side view of a wellhead in accordance with one or more embodiments.

[0010] FIG. 4 shows a cross-sectional view of a wellhead in accordance with one or more embodiments.

[0011] FIG. 5 shows a top view of a wellhead in accordance with one or more embodiments.

[0012] FIGs. 6A and 6B show a cross-sectional view of a top hanger in accordance with one or more embodiments.

[0013] FIG. 7 shows a cross-sectional view of a bottom hanger in accordance with one or more embodiments.
DETAILED DESCRIPTION

[0014] Embodiments disclosed herein relate, generally, to wellheads that may provide a vertical access for downhole tools while maintaining an independent access for a production tubing such that a downhole pump disposed inside a well remains inside the well.

[0015] In the following detailed description, certain specific details are set forth in order to provide a thorough understanding of various disclosed implementations and embodiments. However, one skilled in the relevant art will recognize that implementations and embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, and so forth. In other instances, well known features or processes associated with the safety system has not been shown or described in detail to avoid unnecessarily obscuring descriptions of the implementations and embodiments.
Date Recue/Date Received 2020-07-17

[0016] Systems disclosed herein may include a wellhead having separate access conduits for a downhole pump (e.g., an electric submersible pump (ESP)), coil tubing, and downhole tools, where the access conduits for the downhole pump and the downhole tools may be oriented to provide a vertical access through the wellhead while the access conduit for the coil tubing may be oriented at a minimum viable angle through the wellhead. By providing the separate vertical access conduits through the wellhead, downhole tools may be run into the well without undergoing any bending and without having to pull up a previously run downhole pump. Downhole tools run through the wellhead may then reach a horizontal section of the well via tubulars (also sometimes referred to as guide string), which for example, guide the downhole tools to engage with other components of the system. Other components in accordance with one or more embodiments may include flow control devices used in CSS operations.

[0017] For example, wellheads according to embodiments of the present disclosure may be useful in the CSS operations, where multiple access points through the wellhead may allow for simultaneous procedures in the CSS operation. In some CSS
operations, after a well is drilled and completed, one or more flow control devices positioned in the well may be manipulated using a shifting tool provided downhole through a vertical access point in the wellhead while a production tubing remains independent from the access point.
Instead, the production tubing is accessed through a second vertical access point, maintaining an isolation between the two vertical access points.

[0018] To illustrate, FIG. 1 shows an extraction system 50 applied in a well 110 near a resource 100 in accordance with one or more embodiments of the present disclosure. The well 110 includes casings, including a surface casing 58 and an intermediate casing 112 (and optionally additional casings), lining the wellbore wall and extending from a wellhead 60 positioned at the surface of the well 110. A perforated liner 64 may be hung from the lowermost end of the casing and extend through a horizontal section of the well 110.

[0019] In preparation for production of the resource 100, downhole tools may be sent downhole through a tubing string inside a guide string 118 where downhole tools may include equipment for monitoring well environment, borehole logging, etc., which are employed for CSS operations. A plurality of flow control devices 61 positioned along a tail pipe 114 inside the perforated liner 64 may have a generally tubular body surrounded by a moveable sleeve. The tail pipe 114 may be a tubular body that runs near the resource Date Recue/Date Received 2020-07-17 100 below the wellhead 60, thereby providing a conduit for the flow control devices 61 and improving downhole hydraulic characteristics near the resource 100.
Specifically, the flow control devices 61 may be moved to alter at least one of the amount, the direction, and position of fluid (e.g., steam) flowing through the flow control devices, and the fluid may be sent through the tail pipe 114 and out of the flow control devices 61 to penetrate through the surrounding formation of the resource 100. The tail pipe 114 (and connected flow control devices 61) may be fixed within the perforated liner 64, and the well 110 may then be shut in for a period of time to allow the fluid to sufficiently heat soak the resource 100.

[0020] After the heat soaking period, production of the heat soaked resource 100 may be initiated, where the resource 100 (and condensed fluid) may flow through the flow control devices 61 and into the well 110. A downhole pump 62 provided at the end of a production tubing string 116 may pump the fluids collected in the well through the production string 116 to the surface of the well 110 to be processed. The downhole pump in accordance with one or more embodiments may be an electronic submersible pump.

[0021] One of the main challenges in CSS operations is to achieve a desired Steam to Oil Ratio (SOR), which may be, in part, controlled through the flow control devices 61.
Placement and the number of flow control devices 61 may be determined and controlled in order to achieve a desired SOR. Once the flow control devices 61 are set in place downhole, the flow control devices 61 may be adjusted to achieve the desired SOR. The adjustment of the flow control devices 61 for the desired SOR often requires a large and rigid shifting tool to withstand a force required for the shifting operation.
For example, a shifting tool 63 may be at least 2-3/8" in overall outer diameter and between 8 and 20 feet in length, such that the shifting tool can withstand the force required to shift the flow control devices 61 (to adjust flow through the flow control device 61).
However, the shifting tool 63 may range in size, including an overall outer diameter and length, depending on the operational requirements.

[0022] In conventional wellheads for CSS, a single vertical access conduit may be provided to access a downhole pump connected via production tubing, and an angled access conduit may be provided for running coil tubing. Because shifting tools (and other downhole tools) may not bend as coil tubing bends, the size of the angled access conduit may limit the allowable size of downhole tool capable of fitting there through. If the Date Recue/Date Received 2020-07-17 shifting tool cannot fit into the angled access conduit, the downhole pump (connected to the vertical access conduit through production tubing) would need to be pulled out of the well to allow the shifting tool or other downhole tool to be lowered into the well through the single vertical access conduit. Pulling the downhole pump out of the well to clear the passage for the shifting tool to pass through may incur additional costs and downtime in the CSS operation.

[0023] According to embodiments of the present disclosure, the flow control devices 61 may be shifted within a perforated liner 64 using a shifting tool 63 without pulling the downhole pump 62 on the production string 116. For the adjustment, an instrumentation coiled tubing used to send fluid downhole may then be disconnected from the tail pipe 114 and brought back to the surface of the well to clear a passage for the shifting tool 63 to pass through.

[0024] A wellhead 60 having two vertical access conduits and an angled access conduit for coil tubing may be used in the extraction system 50 to allow a vertical access for a large shifting tool without the need to pull the downhole pump 62. Thus, an extraction system 50 in accordance with one or more embodiments may include a wellhead 60 installed on a well with both a downhole pump 62 provided on a production string 116 and other downhole tools such as a shifting tool 63 to adjust one or more flow control devices disposed inside the well. The wellhead may include a vertical bore, an angled bore, and a second bore, in which the second bore provides a conduit for a shifting tool to pass through while maintaining an independent access for the downhole pump.

[0025] One skilled in the art would appreciate how embodiments of an extraction system disclosed herein would allow adjustments of the flow control devices without pulling a downhole pump inside the well, thereby saving operational cost and improving CSS operations with an efficient SOR.

[0026] A perspective view of a wellhead 70 in accordance with one or more embodiments is shown in FIG. 2. The wellhead 70 includes a thermal spool 5, adapters 12, and an angled bore 53 that extends from the top of the thermal spool 5 at an angle with respect to the longitudinal axis of the thermal spool 5. The angled bore 53 is an independent bore, which may allow access for a coil tubing.
Date Recue/Date Received 2020-07-17

[0027] FIG. 3 shows a side view of the wellhead 70 in FIG. 2 where the wellhead includes valves 26, 37, gaskets 27, pipe fittings 28, flanges 35, nipples 36, and bull plugs 38 that are used to seal and control the fluid flow within the wellhead 70.
FIG. 3 further shows a partial cross-sectional view of the wellhead 70 where a top hanger 6 and a thermal seal 7 are disposed along an upper portion of a vertical bore 51.

[0028] To illustrate with more details, FIG. 4 shows a cross sectional view of the wellhead in FIG. 2, showing two separate vertical bores including a vertical bore 51 and a second bore 52 that both extend parallel with the longitudinal axis of the wellhead 70 inside the thermal spool 5. The vertical bore 51 and the second bore 52 may be housed within a ring gasket of the wellhead 70. A thermal spool adapter 9 may extend from the top surface of the thermal spool 5 and connect the thermal spool 5 with a top section 72 of the wellhead 70. The thermal spool adapter 9 may provide a conduit that is slightly inclined as shown in FIG. 4.

[0029] The vertical bore 51 may provide a conduit for a downhole pump to pass through, and suspends the downhole pump from production tubing using the top hanger 6 and the thermal seal 7. To illustrate the suspension mechanism, FIGs. 6A and 6B show a cross sectional view on planes AA and BB of FIG. 4, respectively. Top hanger 6 allows the suspension of the downhole pump inside the wellbore during shifting operations of flow control devices.

[0030] The second bore 52 may provide a conduit for a shifting tool or other relatively stiff downhole tool (compared with coil tubing) to pass vertically through the wellhead 70.

[0031] The angled bore 53 extends from the top surface of the thermal spool 5 at an angle with respect to the longitudinal axis of the wellhead, as shown in FIG.
4. The angled bore 53 may provide a conduit for coil tubing to pass through, and suspend the coil tubing at a coil tubing slip 14. The angled bore 53 may intersect with the second bore 52 above a bottom hanger 2. Thus, when coil tubing is run through the wellhead 70, the coil tubing may be inserted into the angled bore 53 and bend at the intersection with the second bore 52 to continue through the second bore 52 and into the well.

[0032] A guide string 118 may be hung from the bottom hanger 2 and extend into a well. In some embodiments, the guide string 118 may extend from the bottom hanger 2 through a vertical section of a well to heel of the well (where a horizontal section of the Date Recue/Date Received 2020-07-17 well begins). The guide string 118 may provide a conduit through which coil tubing or downhole tools inserted in the wellhead 70 through the second bore 52 or the angled bore 53 may be guided.

[0033] For example, in thermal well, the guide string 118 may provide an isolated bore from the surface of the well to a horizontal section of the thermal well. Coil tubing along with various downhole tools and/or instrumentation may be run through the guide string 118 to reach the horizontal section of the well, at which point the coil tubing may be held in coil tubing slips 14 provided in the angled bore 53. In an operation using a vertical or rigid tool access, the coil tubing may be pulled out of the well and out of the angled bore 53 to allow a vertical access for the downhole tool to be run though the second bore 52.
After the coil tubing is pulled out and the second bore 52 is cleared, the downhole tool (e.g., a shifting tool) may be run through the second bore 52 without ongoing bending to access a lower section of the well. Once the downhole tool operation is complete (e.g., adjusting flow control devices is complete), the downhole tool (e.g., shifting tool) may be retrieved from the well via the same second bore 52 without ongoing bending.
Coil tubing may then be run via the angled bore 53. A downhole pump suspended from the top hanger 6 around the vertical bore 51 may be left in the well during the entire process of removing coil tubing from the angled bore 53, running a downhole tool through the second bore 52, removing the downhole tool, and running coil tubing through the angled bore 53.

[0034] FIG. 5 shows a top view of the wellhead system in FIG. 2, where a top section 72 is installed above the spool 5 to direct produced fluids from a well to production lines.
FIG. 7 shows a cross-sectional view of plane CC in FIG. 4, which shows a suspension mechanism of the bottom hanger 2 for the shifting tool. Additional vent 40 may be applied at the bottom of the wellhead for additional drainage capabilities of the wellhead.

[0035] A method of using a wellhead in accordance with one or more embodiments may include installing a wellhead on a well near a resource as illustrated in FIG. 1. Once the wellhead is installed, a coil tubing disposed inside the well may be pulled out of an angled bore of the wellhead until a second bore of the wellhead is cleared. A
shifting tool may then be inserted vertically into the second bore. The shifting tool may be moved downhole (e.g., through a guide string) until the shifting tool is successfully engaged with flow control devices disposed inside the well. Once the engagement is secured, the shifting tool may perform shifting operations in order to achieve a desired SOR.
Date Recue/Date Received 2020-07-17

[0036] Such shifting operations may include, for example, placing the flow control devices along the perforated liner at an interval, adjusting the position of a sleeve around a flow control device to open/close/alter a flow passage there through, and/or activating movement of a flow control device. The shifting tool may be pulled out through the second bore vertically once the shifting operation is complete. Coil tubing including downhole tools or instrumentation capable of fitting through the angled bore 53 may be inserted back below the bottom hanger, for example, to take downhole measurements or to resume a heating operation. A downhole pump disposed inside the wellbore may remain inside the wellbore while the shifting tool completes the shifting operations by passing the shifting tool through the second bore independent from a vertical bore for the downhole pump. In the same manner, coil tubing may remain inside the well (suspended from an angled bore in the wellhead) while a downhole pump suspended from a separate vertical bore through the wellhead may be replaced.

[0037] Shifting operations may enable flow control devices positioned in a thermal well to achieve a desired steam to oil ratio, for example, by adjusting at least one of arrangement, direction of fluid (e.g., steam), and amount of the fluid of the flow control devices. One skilled in the art would appreciate how a method disclosed herein may provide a cost efficient measure to perform shifting operations for a desired steam to oil ratio by providing independent accesses to the downhole pump and the shifting tool.

[0038] While the disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate that other embodiments can be devised that do not depart from the scope of the disclosure as described. Accordingly, the scope of the disclosure should be limited only by the accompanying claims.
Date Recue/Date Received 2020-07-17

Claims (20)

10What is claimed:

1. A system comprising:
a wellhead comprising:
a vertical bore extending parallel to a longitudinal axis of the wellhead;
a second bore extending parallel to the longitudinal axis of the wellhead;
an angled bore extending from the second bore at an angle with respect to the longitudinal axis of the wellhead;
a production tubing string suspended from the vertical bore and extending into a well, the production tubing string comprising a downhole pump; and flow control devices disposed at an interval along a tail pipe in the well.

2. The system according to claim 1, further comprises a liner hanging from a casing in the well, wherein the tail pipe extends through the liner.

3. The system according to claim 1, wherein a shifting tool is supported through the second bore and extends into the well.

4. The system according to claim 3, wherein an outer diameter of the shifting tool is larger than an inner diameter of the angled bore.

5. The system according to claim 1, wherein the wellhead further comprises a spool adapter having an inclined passage and connecting the vertical bore with a wellhead top.

6. The system according to claim 1, wherein the angled bore meets with the second bore at an intersection located above a bottom hanger.

7. The system according to claim 1, wherein a top hanger is disposed proximate a top of the vertical bore while a bottom hanger is disposed at a lower portion of the second bore.

8. The system according to claim 7, further comprising a guide string suspended from the bottom hanger, wherein the coil tubing extends through the guide string.

9. The system according to claim 1, wherein a coil tubing slip is disposed at an upper end of the angled bore and configured to suspend a coil tubing.

10. A wellhead, comprising:
a vertical bore extending parallel to a longitudinal axis of the wellhead;
a second bore extending parallel to the longitudinal axis of the wellhead;
an angled bore extending from the second bore at an angle with respect to the longitudinal axis of the wellhead;
wherein the vertical bore is isolated from the second bore and the angled bore.

11. The wellhead according to claim 10 further comprises a spool adapter having an inclined passage and connecting the vertical bore with a wellhead top.

12. The wellhead according to claim 10, wherein the angled bore meets with the second bore at an intersection located above a bottom hanger.

13. The wellhead according to claim 10, wherein a top hanger is disposed proximate a top of the vertical bore while a bottom hanger is disposed at a lower portion of the second bore.

14. The wellhead according to claim 10, wherein a coil tubing slip is disposed at an upper end of the angled bore and configured to suspend a coil tubing.

15. A method of using a system in a well, the method comprising:
providing a wellhead at a surface of the well, wherein the wellhead comprises a vertical bore in fluid communication with a downhole pump;
removing a coil tubing from an angled bore in the wellhead, wherein the angled bore intersects with a second bore extending vertically through the wellhead;
inserting a downhole tool into the second bore;
wherein the downhole pump remains downhole during inserting the downhole tool.

16. The method according to claim 15, wherein the downhole tool is a shifting tool, the method further comprising engaging the shifting tool with at least one flow control device disposed in the well.

17. The method according to claim 16, wherein engaging comprises adjusting the at least one flow control device to achieve a desired steam to oil ratio.

18. The method according to claim 16, wherein the shifting operations change an arrangement of the flow control devices to target a different portion of the downhole location.

19. The method according to claim 15, wherein the coil tubing remains inside the well during replacing the downhole pump.

20. The method according to claim 15, wherein the downhole pump is an electronic submersible pump.