WO2019032764A1 - Submersible pump and shroud system and installation method - Google Patents

Abstract

A technique facilitates assembly and utilization of a combined submersible pumping system and shroud, e.g. an inverted shroud. In some embodiments, an inverted shroud may be combined with an ESP system in a manner which provides a gas separator functioning to separate gas from a fluid being pumped by the ESP system. During assembly, the ESP system may be suspended at least partially in a borehole. A shroud may then be positioned over the ESP system. Once the shroud is properly positioned, the ESP system is lifted up into the shroud. The shroud is then coupled with the ESP system and the combined shroud and ESP system may be deployed down into the borehole

Description

PATENT APPLICATION

SUBMERSIBLE PUMP AND SHROUD SYSTEM AND INSTALLATION

METHOD

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present document is based on and claims priority to US Provisional

Application Serial No.: 62/543,898, filed August 10, 2017, which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] In many types of well applications, a wellbore is initially drilled and an electric submersible pumping (ESP) system is deployed downhole in the wellbore for pumping well fluids. An ESP system may comprise various types of components, such as a submersible motor, a motor protector, and a submersible pump powered by the submersible motor. A power cable is generally routed down to the submersible motor and may comprise a motor lead extension (MLE) coupled with the submersible motor to supply electrical power to the motor. Examples of other components include gas separators and shrouds. For example, an ESP system is sometimes combined with a shroud which is positioned around at least a portion of the ESP system and may be used for a variety of functions, including directing fluid flows to a pump intake. However, assembly of the combined ESP system, shroud, and power cable can present a variety of difficulties.

SUMMARY

[0003] In general, a methodology and system are provided for assembling and installing a combined submersible pumping system and shroud, e.g. an inverted shroud. In some embodiments, an inverted shroud may be combined with an ESP system in a manner which provides a gas separator functioning to separate gas from a fluid being pumped by the ESP system. During assembly, the ESP system may be suspended at least partially in a borehole. A shroud may then be positioned over the ESP system. Once the shroud is properly positioned, the ESP system is lifted up into the shroud. The shroud is then coupled with the ESP system and the combined shroud and ESP system are deployed down into the borehole.

[0004] However, many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Certain embodiments of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein, and:

[0006] Figure 1 is a schematic illustration of an example of a submersible pumping system and a shroud at a stage of assembly and deployment, according to an embodiment of the disclosure; [0007] Figure 2 is a schematic illustration of an example of the submersible pumping system and the shroud at another stage of assembly and deployment, according to an embodiment of the disclosure;

[0008] Figure 3 is a schematic illustration of an example of the submersible pumping system and the shroud at another stage of assembly and deployment, according to an embodiment of the disclosure;

[0009] Figure 4 is a schematic illustration of an example of the submersible pumping system and the shroud at another stage of assembly and deployment, according to an embodiment of the disclosure;

[0010] Figure 5 is a schematic illustration of an example of the submersible pumping system and the shroud at another stage of assembly and deployment, according to an embodiment of the disclosure;

[0011] Figure 6 is a schematic illustration of another example of a system to facilitate assembly and deployment of the submersible pumping system and the shroud, according to an embodiment of the disclosure;

[0012] Figure 7 is a schematic illustration of another example of a system to facilitate assembly and deployment of the submersible pumping system and the shroud, according to an embodiment of the disclosure;

[0013] Figure 8 is a schematic cross-sectional illustration of a pumping system assembly having an example of a shroud, according to an embodiment of the disclosure;

[0014] Figure 9 is a schematic cross-sectional illustration of a pumping system assembly having another example of a shroud, according to an embodiment of the disclosure; [0015] Figure 10 is a schematic cross-sectional illustration of a pumping system assembly having another example of a shroud, according to an embodiment of the disclosure;

[0016] Figure 11 is an orthogonal illustration of another example of a shroud, according to an embodiment of the disclosure;

[0017] Figure 12 is an orthogonal illustration of a pumping system assembly having another example of a shroud, according to an embodiment of the disclosure;

[0018] Figure 13 is a schematic cross-sectional illustration of an example of a shroud, according to an embodiment of the disclosure;

[0019] Figure 14 is a schematic cross-sectional illustration of another example of a shroud, according to an embodiment of the disclosure;

[0020] Figure 15 is a schematic illustration of an example of a pumping system assembly illustrating the flow of fluid along the shroud in a manner to facilitate a gas separating function, according to an embodiment of the disclosure;

[0021] Figure 16 is a schematic illustration of another example of a pumping system assembly illustrating the flow of fluid along the shroud in a manner to facilitate a gas separating function, according to an embodiment of the disclosure;

[0022] Figure 17 is a schematic cross-sectional illustration showing an example of an intake structure facilitating a desired routing of fluid along a shroud and pumping assembly, according to an embodiment of the disclosure; [0023] Figure 18 is a schematic cross-sectional illustration similar to that of

Figure 17 but rotated approximately 90° and taken along line 18-18 of Figure 17, according to an embodiment of the disclosure;

[0024] Figure 19 is a schematic cross-sectional illustration taken generally along line 19-19 of Figure 17, according to an embodiment of the disclosure;

[0025] Figure 20 is a schematic cross-sectional illustration taken generally along line 20-20 of Figure 17, according to an embodiment of the disclosure;

[0026] Figure 21 is a schematic cross-sectional illustration taken generally along line 21-21 of Figure 17, according to an embodiment of the disclosure;

[0027] Figure 22 is a schematic cross-sectional illustration taken generally along line 22-22 of Figure 17, according to an embodiment of the disclosure; and

[0028] Figure 23 is a schematic cross-sectional illustration of another example of a pumping system assembly having a shroud, according to an embodiment of the disclosure.

DETAILED DESCRIPTION

[0029] In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. However, it will be understood by those of ordinary skill in the art that the system and/or methodology may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible. [0030] The present disclosure generally relates to a methodology and system for facilitating assembly, installation, and utilization of a combined pumping system, e.g. ESP system, and shroud. The technique is very useful when combining an ESP system with an inverted shroud. The inverted shroud may be sealed to the ESP system at a lower point such that fluid flow around an upper end of the shroud occurs at an upper point along the ESP system. In some embodiments, the inverted shroud is constructed to provide a gas separation function as fluid, e.g. well fluid, is pumped by the ESP system.

[0031] During assembly, the ESP system may be suspended at least partially in a borehole. For example, the ESP system may be suspended from a worktable via, for example, a pump lifting clamp such that the ESP system extends down into a wellhead. Effectively, this positions a top of the ESP system at a relatively low height so the shroud may be readily positioned over the low-lying ESP system. Once the shroud is properly positioned over the ESP system, e.g. set on the worktable, the ESP system may be lifted up into the shroud. The shroud may then be coupled with the ESP system and the combined shroud and ESP system may be deployed down into the borehole.

[0032] In various embodiments, a power cable for supplying electrical power to the submersible motor of the ESP system is deployed through or along the shroud prior to or during installation of the shroud. In some embodiments, the shroud may have an opening or slot which extends its entire length and is wide enough to admit the power cable, e.g. a motor lead extension (MLE) cable. After installation of the ESP system into the shroud, the power cable may be installed into the slot. The slot may then be closed by a panel or door which fastens to a corresponding portion of the shroud.

[0033] According to another embodiment, the shroud may be formed of one or more shroud sections which may be split axially into halves. The shroud halves may be nearly equal in size or of other suitable proportions. Depending on the application, the halves may be completely separate or joined along an edge by a hinge, e.g. a piano hinge. After installation of the ESP system, the shroud halves may be closed or otherwise assembled along the exterior of the ESP system. [0034] Additionally, some embodiments may utilize a shroud formed of shroud sections joined by a non-rotating joint, e.g. splicing bars fastened with radial screws. One or more shroud sections also may be preinstalled on corresponding sections of the ESP system so they may be handled and installed as a subassembly. The subassembly may be suspended in the wellhead during further preparation of the shrouded ESP system.

[0035] The shroud may be constructed from various suitable materials, such as metal which may be in the form of sheet-metal. In some embodiments, the sheet-metal may be readily formed into multiple internal and external channels or corrugations to provide, for example, flow channels or channels for the power cable.

[0036] According to an embodiment, operation of the ESP system causes an upward flow of fluid along an outside of the shroud and then a change in direction around an upper end of the shroud as the flow direction changes, e.g. reverses, to a downward flow inside the shroud. In this manner, portions of the shroud may provide suitable flow changes to release gas, thus enabling the shroud to be utilized as a gas separator. As the flowing well fluid undergoes directional changes while flowing along the shroud to the ESP system pump intake, the directional changes cause release and separation of gas from the flowing well fluid. Various other flow changes, e.g. centrifugal flow changes, flow reversals, velocity reductions, or other directional changes can be used to facilitate the separation of gas from the flowing well fluid.

[0037] Referring generally to Figure 1, an example of a well system 30 is illustrated. In this embodiment, a submersible pumping system 32, e.g. an electric submersible pumping system, is positioned for combination with a shroud 34. Initially, the submersible pumping system 32 may be suspended at least partially in a borehole 36. For example, the submersible pumping system 32 may be positioned in or through a wellhead 38 and suspended by a pump lifting clamp 40 mounted on a worktable 42. According to the embodiment illustrated, the submersible pumping system 32 is in the form of an electric submersible pumping system 44 which may have a variety of components, such as a submersible motor 46, a motor protector 48, a submersible pump 50 powered by the submersible motor 46, and a pump intake 52.

[0038] A shroud hanger 54 also may be mounted to the external housing of the submersible pumping system 32, e.g. mounted at a location beneath the pump intake 52. Additionally, a lifting cap 56 may be coupled with a pump head 58 at an upper end of the submersible pump 50. The lifting cap 56 may comprise a lifting feature 60, e.g. a lifting eye able to accept a hook or clevis, by which the submersible pumping system 32 is selectively lifted and lowered. In some applications, the lifting cap 56 may have the same diameter as the submersible pump 50 and may be attached to the pump head 58 using a flange coupling having a suitable flange bolt pattern.

[0039] Power is provided to the submersible motor 46 via a suitable power cable

62 which is routed up along the submersible pumping system 32 and past the pump lifting clamp 40 during the stage illustrated in Figure 1. By way of example, the power cable 62 may comprise a motor lead extension 64 and may be routed along the shroud 34, e.g. through an interior of the shroud 34. The power cable 62 may be directed over a cable sheave 66 or other suitable cable handling device. In some applications, the motor lead extension 64 or other type of power cable 62 may be coupled with a rope leader 68 which is routed over the cable sheave 66 or other suitable cable handling device to facilitate handling of the power cable 62.

[0040] According to an embodiment, the ESP string may be assembled in the wellhead 38 up to and including, for example, the submersible pump 50 which is then supported at the wellhead worktable 42 by the pump lifting clamp 40. At the illustrated stage of assembly and installation, the shroud 34 may be positioned at a surface location, e.g. positioned laterally, and mounted on a suitable fixture 70, e.g. a shroud table. A shroud lifting clamp 72 may be secured to an exterior of the shroud 34 generally at a lower end of the shroud while the shroud 34 is arranged laterally at a working height. [0041] Additionally, a hoist cable 74 may be routed from a hoist 76 down through and an interior 78 of the shroud 34 from a top end through a bottom end of the shroud. The hoist cable 74 may be a dual function hoist cable utilized for lifting and otherwise handling both submersible pumping system 32 and shroud 34. The hoist cable 74 may be coupled with the shroud 34 via a shroud catcher 80 which may comprise a shroud catcher pivot bar 82. In the illustrated example, the hoist cable 74 is secured to the shroud catcher 80 but includes an additional cable section 84 which extends below the shroud catcher 80 and comprises an attachment mechanism 86, e.g. a hook 88. The hoist cable 74, hoist 76, shroud catcher 80, additional cable section 84, and attachment mechanism 86 serve as a releasable lifting mechanism which may be selectively coupled with the shroud 34 and/or submersible pumping system 32.

[0042] A subsequent stage of assembly and installation is illustrated in Figure 2.

With further reference to Figure 2, the shroud 34 is lifted via a suitable lifting

mechanism, e.g. the hoist 76, dual function hoist cable 74, and shroud catcher 80. The shroud 34 is lifted and positioned over the submersible pumping system 32. In some embodiments, the cable sheave 66 or other cable mechanism may be lifted at

approximately the same pace as the shroud 34 so as to remain above the shroud 34. After lifting the shroud, the slack in power cable 62 may be pulled up through the shroud 34 and over the cable sheave 66.

[0043] Once the shroud 34 is properly positioned above the submersible pumping system 32, the attachment mechanism 86, e.g. hook 88, may be coupled with lifting feature 60, e.g. lifting eye, and excess slack may be removed from the additional cable section 84 so as to provide support for the submersible pumping system 32, as illustrated in Figure 2. The pump clamp 40 may be lifted to a suitable working height and then released and removed.

[0044] Then, both submersible pumping system 32 and shroud 34 may be lowered until the shroud lifting clamp 72 rests on worktable 42 and shroud 34 is supported in place on the worktable 42, as illustrated in Figure 3. The submersible pumping system 32 may then be lowered farther to release shroud catcher pivot bar 82, as also illustrated in Figure 3. When shroud catcher pivot bar 82 is released, it is able to pivot so that it may be pulled up through the interior 78 of shroud 34. This allows the submersible pumping system 32, e.g. electric submersible pumping system 44, to be lifted up into the shroud 34 along interior 78, as illustrated in Figure 4.

[0045] The submersible pumping system 32 may be lifted via dual function hoist cable 74 until shroud hanger 54 engages a lower end of the shroud 34. The shroud 34 may then be secured to the submersible pumping system 32 via shroud hanger 54. For example, bolts, other threaded fasteners, other suitable latching mechanisms, and/or seals may be used to sealably join the shroud 34 and shroud hanger 54.

[0046] In some applications, lower sections of shroud may be attached to lower portions of the submersible pumping system 32 or other work string components and those lower sections of shroud may be brought up into engagement with shroud 34 and secured to shroud 34. For example, the shroud lifting clamp 72 may be used to rotate shroud 34 to, for example, align screws or rotate threads by which the shroud 34 is secured to lower sections of shroud. If additional sections of shroud are installed, an upper end of the submersible pumping system 32 may be left exposed to enable attachment of the pump clamp 40 so as to facilitate additional shroud connections.

[0047] The submersible pumping system 32 and attached shroud 34 may then be lowered until, for example, an upper end of the submersible pumping system 32 is at a working height near the worktable 42, as illustrated in Figure 5. At this point, the pump lifting clamp 40 may be reattached to the pump head 58. Subsequently, the pump lifting clamp 40 may be set down on the worktable 42 to support/suspend both the submersible pumping system 32 and the attached shroud 34. At this stage, the lifting cap 56 may be removed. Additional pump sections can be installed by repeating the sequence described above until the desired pump sections and shroud sections have been installed. Once the pumping system is completed it may be lowered into the borehole 36 via a suitable conveyance, e.g. tubing, to a desired well zone for operation. [0048] It should be noted that once the submersible pumping system 32 and attached shroud 34 are deployed at a desired location within borehole 36 and operated, an upper edge 89 of shroud 34 can serve as a gas separator. During operation of the submersible pumping system 32 fluid in the borehole is drawn upwardly along an exterior of the shroud 34 until undergoing a directional change at the top edge 89 and then flowing downwardly between submersible pumping system 32 and shroud 34 until entering pump intake 52. The directional change in fluid flow as the fluid flow transitions around the top edge 89 facilitates release of gas from the fluid as it flows to submersible pumping system 32. This type of shroud 34 may be sealed along the bottom and open along the top and may be referred to as an inverted shroud.

[0049] Referring generally to Figure 6, another embodiment is illustrated in which the dual function hoist cable 74 comprises a first branch 90 for lifting the submersible pumping system 32 and a second branch 92 for lifting the shroud 34. The first branch 90 and the second branch 92 effectively serve as a lifting mechanism which may be releasably coupled with the submersible pumping system 32 and/or shroud 34.

[0050] As illustrated in Figure 6, the shroud catcher 80 in this embodiment may comprise a shroud hook 94 attached to the second cable branch 92. The shroud catcher hook 94 may be constructed to engage a lower edge of the shroud 34 to enable controlled lifting of the shroud 34. To release the hook 94, tension in second branch 92 is released until hook 94 is able to disengage from the lower edge of shroud 34. The hook 94 may then either be passed up through the interior 78 of shroud 34 or removed from the second cable branch 92.

[0051] Referring generally to Figure 7, another embodiment of well system 30 is illustrated. In this example, the lifting mechanism comprises a separate pump hoist 96 and shroud hoist 98. This embodiment and other embodiments described herein may utilize a gooseneck 100 (or other suitable mechanism) for handling the power cable 62 and/or rope leader 68 so as to control the bending radius of the motor lead extension cable 64. In some embodiments, a separate sheave or gooseneck hoist also may be used. The pump hoist 96 and shroud hoist 98 may have separate pump hoist cable 102 and shroud hoist cable 104, respectively.

[0052] In some embodiments, a swivel shroud lifting clamp 106 may be used as illustrated in Figure 7. The swivel shroud lifting clamp 106 may comprise two portions that may be rotated in relation to each other. By way of example, a first portion 106a may be attached to the shroud 34 and a second portion 106b may be attached to the shroud hoist cable 104. The swivel clamp 106 allows the shroud 34 to rotate in the swivel clamp 106 so as to prevent twisting of the cables 102 and 104 when, for example, the shroud 34 is threaded to a shroud hanger or to another shroud section while hanging vertically. In some embodiments, the sheave 66 or gooseneck 100 may be mounted on the shroud 34 or on the shroud clamp 106, as illustrated in Figure 7, so as to avoid use of an additional hoist for the gooseneck 100 or sheave 66. As further illustrated in Figure 7, the hoist cable 104 may be attached to swivel shroud lifting clamp 106 at second portion 106b to prevent twisting of the motor lead extension 64 when the shroud 34 is rotated. Depending on the application, the power cable 62, e.g. motor lead extension 64, may be installed along the inside or outside of shroud 34.

[0053] The embodiments described above embody a principle that the

submersible pumping system 32, e.g. electric submersible pumping system 44, may be lifted from a safe working level, e.g. from a safe working level near a rig floor. The submersible pumping system 32 is lifted into the shroud 34 while the shroud 34 is suspended above the pumping system 32 with the lower end of the shroud 34 positioned at approximately a working level, e.g. a level at which a worker may physically reach the shroud 34 from a working floor. As a result, a worker may attend to assembly of the submersible pumping system 32 and shroud 34 near a working floor level rather than performing tasks at an elevated height which may increase risks, delays, and number of personnel utilized for assembly. [0054] In some embodiments, the lifting mechanism may comprise various types of mechanisms other than hoist cable 74. For example, the lifting mechanism may utilize a length of tubing in place of the hoist cable 74 or in place of portions of the hoist cable 74. In such an embodiment, the length of tubing may be inserted into the shroud 34 while it is oriented in a lateral, e.g. horizontal, position. The length of tubing and the shroud 34 may then both be lifted together to a vertical orientation. According to another embodiment, the shroud 34 may be lifted first, after which the length of tubing is lifted above the shroud and lowered down through it. During the lowering operation, additional lifting mechanism tackle, e.g. a guide or tag lines, may be used to aid insertion of the tubing into the shroud 34 from the safety of the working floor. In either version, the length of tubing may then be attached to the pumping system 32 and utilized in lifting the submersible pumping system 32 into the shroud 34. The tubing may be attached to submersible pumping system 32 via a variety of mechanisms including threaded attachment with a short tube coupled with pump head 58 (instead of using lifting cap 56).

[0055] Depending on the parameters of a given embodiment, various additional lifting tackle may be used to facilitate handling of the components being lifted. For example, one or more centralizers may be used to position the hoist cable 74 at a sufficiently central position within the shroud 34. The one or more centralizers help maintain the shroud adequately vertical when mating it to the shroud hanger 54 or to previously installed sections of shroud. Such centralizers may be fixed to or slidably attached to the hoist cable 74. In other embodiments, the centralizers may be attached to the shroud 34, e.g. threaded to an upper end of the shroud 34. In some embodiments, the shroud clamp 72 may be located at an upper end of the shroud 34 and attached to, for example, hoist cable 74 so as to facilitate vertical orientation of the shroud 34 during engagement with shroud hanger 54.

[0056] Referring again to the embodiment illustrated in Figure 7, installation of the submersible pumping system 32 and the shroud 34 may be accomplished according to a sequence similar to that described above with respect to the embodiment illustrated in Figures 1-5. For example, the submersible pumping system 32 may be assembled in the wellhead 38 up to and including the submersible pump section 50 and the pumping system string may be supported via pump lifting clamp 40. A similar lifting cap 56 may be secured to pump head 58. The swivel shroud lifting clamp 106 may be attached to an upper end of the shroud 34 while it is oriented laterally, e.g. horizontally, and at working height.

[0057] The rope leader 68 may be attached to an upper end of the motor lead extension 64 to avoid damage to the motor lead extension 64 during lifting operations. The rope leader is passed from a bottom end of the shroud 34 through a top end of the shroud and also passed over the cable sheave 66 or gooseneck 100. The pump hoist cable 102 is passed along the interior 78 of shroud 34 from the top end through the bottom end while the shroud remains generally at a lateral orientation, e.g. horizontal.

[0058] The shroud 34 is then lifted via shroud hoist cable 104 and positioned above the submersible pumping system 32. The cable sheave 66 or gooseneck 100 may be lifted at approximately the same pace to a position higher than the shroud 34. The rope leader 68 and/or motor lead extension 64 may be pulled up through the shroud 34 and over the cable sheave 66 or gooseneck 100. The pump hoist cable 102 is then attached to the lifting cap 56 and the submersible pumping system 32 is lifted slightly using the pump hoist 96. The pump lifting clamp 40 may then be removed.

[0059] The submersible pumping system 32 is then lifted up through the stationary shroud 34 while the shroud 34 rests on worktable 42 via shroud lifting clamp 72 as with the previously described embodiment. Simultaneously, the motor lead extension 64 is pulled up and over the cable sheave 66 or gooseneck 100. The shroud hoist 98 is then slacked off sufficiently to permit the shroud 34 to be easily rotated in the swivel shroud lifting clamp 106 and then secured to the submersible pumping system 32 via, for example, radial screws.

[0060] In some embodiments, the shroud 34 may be secured to the submersible pumping system 32 via previously installed shroud sections mounted along the submersible pumping system 32. For example, the shroud 34 may be secured to a previous installed shroud section via threaded engagement by rotating the shroud 34 in the swivel shroud lifting clamp 106. It should be noted the shroud sections installed up to this point may be positioned to leave the upper end of the submersible pumping system 32 exposed to enable attachment of the pump lifting clamp 40 and to facilitate subsequent connections.

[0061] The shroud hoist 98 may then be slacked off completely and maintained in the slacked condition while the submersible pumping system 32 is lowered into the wellhead 38 using the pump hoist 96. The submersible pumping system 32 may be lowered until the swivel shroud lifting clamp 106 is at a working height, thus facilitating its removal. The submersible pumping system 32 and attached shroud 34 are then lowered until the upper end of the submersible pumping system 32 is at a suitable working height near the worktable 42. The pump lifting clamp 40 may be reattached and the assembly may be set down on the worktable 42 via the pump lifting clamp 40. The pump hoist cable 102 and the lifting cap 56 may then be removed. The sequence may be repeated for the installment of additional pump sections and shroud sections if additional sections are to be added. Once the pumping system is completed it may be lowered into the borehole 36 via a suitable conveyance, e.g. tubing, to a desired well zone for operation.

[0062] Depending on the parameters of a given operation, various components and component features may be adjusted. For example, the shroud 34 may be

constructed in a variety of configurations and with many types of features. Referring generally to Figure 8, another embodiment of shroud 34 is illustrated as disposed about submersible pumping system 32 with the motor lead extension 64 routed along shroud interior 78.

[0063] In this example, the shroud 34 comprises a slot opening 110 extending along its entire length. The slot opening 110 is wide enough to admit the motor lead extension 64. After installation of the submersible pumping system 32 into the shroud 34, the motor lead extension cable 64 may be installed through the slot opening 110. The slot opening 110 is then closed by a panel 1 12, e.g. a door, which fastens to the shroud 34 by a suitable fastening mechanism 114, e.g. a plurality of screws or screws in

combination with a hinge.

[0064] To limit leakage through the seam between the main portion of shroud 34 and the panel 112 (and/or from one shroud section to the next) the seams may abut or overlap each other. In some embodiments, a sealant or gasket also may be used to seal the panel 112 to the main portion of shroud 34.

[0065] Another embodiment of shroud 34 is illustrated in Figure 9. In this example, the shroud 34 comprises shroud halves 116 which may be completely separate or joined on one edge by a hinge 118, e.g. a piano type hinge. After installation of the submersible pumping system 32, the shroud halves 116 may be assembled to the submersible pumping system 32 (or to other sections of the pumping system string). The separate shroud halves 1 16 and/or the non-hinged edges of the mated shroud halves may be joined by suitable fasteners 120, e.g. screws or other fasteners.

[0066] To limit leakage along the seam or seams between the shroud halves 116, the shroud halves 116 may be constructed to overlap each other. In some embodiments, a sealant or gasket also may be used.

[0067] The motor lead extension 64 may be installed along the submersible pumping system 32 prior to installation of the shroud halves 116 and then enclosed within the shroud 34 once the shroud halves 116 are assembled. In some applications, the motor lead extension 64 can be secured along an exterior of the shroud 34.

[0068] Referring generally to Figure 10, another embodiment of shroud 34 is illustrated. In this example, the shroud 34 comprises a channel 122 which may be located along an exterior of the shroud 34. The external channel 122 is sized to accept an externally positioned motor lead extension cable 64. After installing the submersible pumping system 32 into the shroud 34, the motor lead extension cable 64 may be installed in the external channel 122.

[0069] The depth of the channel 122 may be determined according to the desired diameter of the shroud 34 so as to apportion flow areas inside and outside of the shroud 34. The flow areas may be apportioned according to desired flow rates of the liquid and gas flowing along the exterior and interior of the shroud 34. The external channel 122 may be formed integrally with the shroud 34 or it may be a separate component attached to the main body of the shroud 34 by a suitable fastening technique, e.g. fasteners, interlocking joints, a weld 124, or other suitable fastening technique. The use of external cable channel 122 can provide greater flexibility in shroud construction which can help optimize flow areas inside and outside of the shroud 34 rather than having flow areas dictated by cable clearance.

[0070] Referring generally to Figures 11, another embodiment of shroud 34 is illustrated. In this example, the shroud 34 is not fully circular in cross-section which can render the shroud 34 impractical for forming threaded connections with other shroud sections. By way of example, shroud 34 may have a corrugated construction which forms external linear channels 126 and internal linear channels 128. If additional shroud sections are to be joined to shroud 34, they may be joined via suitable connectors, such as splicing bars 130, e.g. fish plates, that bridge the joint and are fastened to the adjacent shroud with suitable fasteners 132, e.g. flathead countersunk screws, welds, or other suitable fastening techniques. In some embodiments, the ends of the shroud sections may have complementary shoulders to form a nest without occluding flow areas. In another embodiment, the end of one shroud section fits or nests within the other shroud section and the shroud sections are joined by radial fasteners, e.g. flathead countersunk screws. The nested engagement can be sealed against leakage via, for example, a seal ring or gasket.

[0071] In some embodiments, additional shroud section(s) 134 may be preinstalled on corresponding sections of submersible pumping system 32 before installation of the submersible pumping system 32 at the wellhead, as illustrated in Figure 12. This allows certain combinations of pumping system components and shroud sections to be handled as subassemblies. The shroud 34 as well as additional shroud sections 134 may be constructed as single pieces, in halves, or in other multiple piece configurations which are attached to the corresponding system component. The shroud sections 134 may be attached to the corresponding component of submersible pumping system 32 by suitable fastening techniques, such as using threaded fasteners or by welding. Standoffs may be used to properly centralize or decentralize the shroud on the corresponding pumping system component and to support the shroud against bending during handling.

[0072] In some embodiments, adjacent shroud sections do not cover the entire length but are joined by short shroud connector sections 136. By way of example, the shroud connector section 136 may be constructed with connector halves 138 which may be joined together. The shroud connector halves 138 may be attached to the

corresponding pumping system components or to the adjacent shroud sections 34, 134 by suitable fasteners, e.g. threaded fasteners. The shroud connector halves 138 also may be of sufficient length to overlap the adjacent shroud sections 34, 134. In this type of embodiment, the motor lead extension 64 may be positioned along one of the exterior channels 126.

[0073] As further illustrated in Figure 13, the shroud 34 and/or shroud section(s)

134 may be formed of a thin material, such as a thin metal material. For example, the metal material may be in the form of sheet-metal which can be formed, e.g. bent, into the multiple external channels 126 and internal channels 128. Depending on the application, a given shroud section 134 may be bounded internally by the submersible pumping system 32 and externally by the inside diameter of a well casing 140 or by a thin metal tube 141 (see Figure 14). The motor lead extension cable 64 may be positioned in one of the external channels 126 or within one of the internal channels 128, as illustrated in Figure 14. [0074] Depending on the parameters of a given application, the outside diameter of the shroud 34 (or other shroud sections 134) may be eccentric with respect to the outside diameter of the submersible pumping system 32 to permit installation of the assembly in well casings with smaller sizes. This approach can be used as a method for optimizing flow areas inside and outside of the shroud 34. According to an embodiment, upward flow of fluid is along the external channels 126 and downward flow of fluid during pumping is along the internal channels 128. The fluid moves downwardly along the internal channels 128 until entering pump intake 52.

[0075] In some embodiments, however, the upward flow may be along the internal channels 128 and the downward flow may be along the external channels 126. In this latter type of embodiment, the inner boundary of the inner channels 128 may be formed by a thin metal tube or other structure to conduct the flow past the pump intake 52. In such an embodiment, radial flow passages or other suitable flow passages may be used to conduct the flow from the outer flow channels 126 to the pump intake 52.

[0076] With respect to fluid flow, e.g. well fluid flow, one operational example is illustrated in Figure 15 in which the shroud 34 is in the form of an inverted shroud having upper edge 89 over which fluid flow is conducted. A lower end of the shroud 34 is attached to and seals to electric submersible pumping system 44 below the pump intake 52. By way of example, the lower end of the shroud 34 may be sealed to the electric submersible pumping system 44 at a position above the submersible motor 46 such that the well fluid flow, represented by arrows 142, moves past the submersible motor 46 to facilitate cooling of the submersible motor.

[0077] In this embodiment, operation of electric submersible pumping system 44 causes well fluid to flow upwardly along the outside of shroud 34, as further indicated by arrows 142. The upward flow continues until the flow undergoes a directional change as it flows over the upper edge 89 of shroud 34 and then flows downwardly on an inside of the shroud 34, as represented by arrows 144. In this example, the upper edge 89 enables the directional change with respect to fluid flow and serves as a gas separator 146 which releases gas phase from the liquid phase of the flowing well fluid. The released gas may move upwardly along the borehole 36, as represented by arrows 148. The remaining "reduced gas" fluid flows down to pump intake 52 and is produced up through and discharged from submersible pumping system 32 as represented by arrows 149.

[0078] With additional reference to Figure 16, the gas separator 146 may incorporate other mechanisms 150 for separating gas in addition to the directional changes described above. Depending on the type of mechanism 150 employed, the arrangement of shroud 34, submersible pumping system 32, flow passages, and flow directions may be adjusted.

[0079] By way of example, the additional gas separation mechanisms 150 may utilize centrifugal separation which can be used individually or in combination with directional changes with respect to the flowing well fluid. The centrifugal separation can be induced by creating a suitable centrifugal fluid flow via, for example, fins, vanes, flow passages, or other features which induce a helical flow pattern to the flowing well fluid as it moves along shroud 34. The circumferential component of the flow vector causes the liquid phase to migrate to the outside of a flow passage from where it may be conducted to the pump intake 52 while the gas phase migrates to an inside of the flow passage where it may be conducted up along the borehole 36.

[0080] The separation mechanism 150 also may comprise additional directional changes, e.g. flow reversals over relatively sharp edges which help break bubbles out of solution by producing a localized low pressure zone. These directional changes may be accomplished by providing multiple small orifices 152 in the shroud 34 (see Figure 16) which may be slanted in a downward direction to produce an acute edge on the inlet side of each orifice 152.

[0081] In some embodiments, the orifices 152 may cover a substantial length of the shroud 34 in varying size or spacing so as to optimize the fluid velocity through the orifices in a manner which minimizes entrainment of gas. Examples of such orifices 152 include louvers in a sheet-metal shroud 34 or slanted holes in a thicker walled shroud 34.

[0082] Reduction of the downward fluid velocity below the bubble transport velocity permits gas bubbles to rise. This effect may be facilitated by extending the shroud 34 substantially above the upper end of the submersible pump 50 to a region having a smaller diameter production tubing. The larger available flow area in this region between the casing and the production tubing may be used to reduce the velocity so as to permit the gas bubbles to rise. If the downward flow of well fluid is inside the shroud 34, the inside diameter of the upper end of the shroud 34 may be maximized to maximize the area between the shroud and internal components, e.g. tubing. If, on the other hand, the downward flow of well fluid is outside of the shroud 34, the outside diameter of the upper end of the shroud 34 may be minimized so as to maximize the flow area between the shroud 34 and the surrounding wellbore wall, e.g. casing.

[0083] Referring generally to Figures 17-22, another embodiment is illustrated in which the shroud 34 accommodates upward flow along the inside of the shroud 34 and downward flow along an outside of the shroud 34. To accommodate this flow pattern, a bypass is employed to enable upward flow past the pump intake 52. An intake structure 154 facilitates the desired flow pattern while delivering fluid to the pump intake 52 (see Figures 17-18).

[0084] The intake structure 154 also facilitates optimization of three flow areas in the form of: first - an axial flow area upward through the bypass (A); second - a radial flow area from outside the shroud 34 and through shroud openings 156, e.g. radial passageways, to an antechamber 158 of the intake structure 154 (B); and third - an axial flow area upward from the antechamber 158 into intake ports 160 (C) (see Figures 19- 22). Fluid flowing through the intake ports 160 continues to flow to submersible pump 50 via, for example, intake 52. [0085] According to the embodiment illustrated, the upward bypass flow area fits within the inside diameter of the shroud 34 and an outside diameter of an intake structure shaft tube 162. As illustrated, a shaft 164 of the submersible pumping system 32 extends linearly through the shaft tube 162. The area between shroud 34 and intake shaft tube 162 may be divided by walls 166 which are placed into the first and third flow areas discussed above (see also figures 19 and 20). The walls 166 may be generally radial, planar, or curved. Additionally, the walls 166 may extend beyond the outside diameter of the submersible pumping system 32 to meet closely with an inside diameter of the shroud 34.

[0086] In the regions above and below the antechamber 158 of the intake structure 154, the walls 166 may flare from the first flow area to form a smooth transition between the first flow area and the annular area located between an inside diameter of the shroud 34 and an outside diameter of the submersible pumping system 32, thus enclosing the second flow area. Being radial, the second flow area may be optimized by specifying the length of the radial passageways 156 between the annulus outside the shroud 34 and the antechamber 158 of the intake structure 154. These passageways 156 may comprise axially elongated slots in the shroud 34 that align with corresponding slots 168 between the extensions of the walls 166, described above, and proximate intake ports 160 (see Figures 20-22).

[0087] A portion of the shroud 34 which envelops the intake structure 154 may be integral with the intake structure 154 and, in some embodiments, is able to meet with upper and lower shroud sections. In some embodiments, the shroud 34 may be continuous over the region of intake structure 154. Additionally, the shroud 34 may be constructed and combined with the intake structure 154 so as to form an external channel that runs along their outer surface(s) for receipt of the motor lead extension cable 64. The intake structure 154 may be constructed via various metal fabrication methods, including casting, forging, forming, machining, welding, soldering, threading, fasteners, interference fits, component assembly or other suitable fabrication techniques for construction and installation of the intake structure 154 with respect to the shroud 34. [0088] Referring generally to Figure 23, another embodiment is illustrated which provides a different structure for conducting fluid flows along the shroud 34. In this example, bypass tubes 170 are positioned between the submersible pumping system 32 and the shroud 34. The bypass tubes 170 may be used for conducting upward fluid flow while the area outside of the bypass tubes 170 but between submersible pumping system 32 and shroud 34 may be used for downward fluid flow.

[0089] By way of example, the bypass tubes 170 may be formed with a cross- sectional crescent shape. The crescent shaped tubes 170 may be sized to accommodate placement of the motor lead extension cable 64 between sides of the bypass tubes 170 and within the shroud 34, as illustrated. The bypass tubes 170 may be fabricated as thin- walled structures, e.g. thin metal wall structures, by joining internal and external curved sections having desired radii. The curved sections may be joined by metal melting, fasteners, or other suitable fabrication techniques.

[0090] The components, component materials, and component configurations of the well system may be changed according to well parameters and/or operational conditions. Depending on the application, various hoisting assemblies, power cable handling devices, work tables, lifting mechanisms, supporting clamps, and/or other components may be adjusted to accommodate deployment of desired types of submersible pumping systems and shrouds. Additionally, the submersible pumping system may comprise various configurations of electric submersible pumping systems or other types of pumping systems.

[0091] The shroud also may have various configurations and sizes and may be constructed as a single shroud section, as a multi-section shroud, or as part of a shroud system having additional shroud sections located along the pumping system string. Additionally, the individual or plural shroud sections may have a variety of

configurations for conducting fluid flows along, for example, the exterior and interior of the shroud. [0092] The shroud may incorporate various types of gas separators which facilitate the release of gas from the well fluid or other fluids being pumped. For example, the shroud may be constructed to facilitate release of gas via abrupt directional changes with respect to fluid flow, by inducing centrifugal fluid flow, by utilizing various mechanisms to create low pressure areas, or by other suitable gas separation techniques. In some embodiments, the submersible pumping system also may incorporate separate gas separation components. Additionally, many types of attachment mechanisms may be used for securing the shroud sections to the submersible pumping system and/or to each other.

[0093] Although a few embodiments of the disclosure have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.

Claims

CLAIMS What is claimed is:

1. A method for use with a well, comprising: suspending an electric submersible pumping system at least partially in a borehole;

positioning a shroud over the electric submersible pumping system;

lifting the electric submersible pumping system into the shroud;

securing the shroud to the electric submersible pumping system; and deploying the electric submersible pumping system with the shroud down into the borehole.

2. The method as recited in claim 1, further comprising accommodating a power cable in the shroud.

3. The method as recited in claim 2, wherein accommodating comprises running the power cable through an interior of the shroud.

4. The method as recited in claim 2, wherein accommodating comprises providing the shroud with a hinged door to admit the power cable into the shroud.

5. The method as recited in claim 2, wherein accommodating comprises using a slot formed along the shroud to protect the power cable.

6. The method as recited in claim 1, wherein suspending the electric submersible pumping system comprises suspending the electric submersible pumping system through a wellhead.

7. The method as recited in claim 1 wherein positioning comprises raising the shroud with a hoist cable and a shroud catcher.

8. The method as recited in claim 7, further comprising using the hoist cable for lifting the electric submersible pumping system into the shroud.

9. The method as recited in claim 1, wherein positioning comprises coupling a hook with the hoist cable and engaging the hook with the shroud.

10. The method as recited in claim 1, further comprising using the shroud to provide a pumped fluid flow path with directional changes to enhance release of gas from fluid pumped by the electric submersible pumping system.

11. The method as recited in claim 2, further comprising routing the power cable over a sheave while positioning the shroud.

12. The method as recited in claim 2, further comprising routing the power cable over a gooseneck while positioning the shroud.

13. A method, comprising: suspending an electric submersible pumping system into a wellhead; positioning an inverted shroud above the electric submersible pumping system;

lifting the electric submersible pumping system into the inverted shroud; and

lowering the electric submersible pumping system and inverted shroud through the wellhead.

14. The method as recited in claim 13, further comprising: operating the electric submersible pumping system to pump a well fluid; and

using the inverted shroud to route the well fluid through directional changes which enhance gas release from the well fluid.

15. The method as recited in claim 13, wherein positioning comprises positioning the inverted shroud with a lifting mechanism coupled to a hoist cable.

16. The method as recited in claim 15, wherein lifting the electric submersible

pumping system comprises lifting the electric submersible pumping system with the lifting mechanism and the hoist cable.

17. The method as recited in claim 13, further comprising routing a power cable along the shroud and using the shroud to protect the power cable.

18. A system, comprising: a submersible pumping system suspended from a worktable and extending into a wellhead while suspended from the worktable;

a shroud positioned above the wellhead; and

a lifting mechanism releasably coupled to the submersible pumping system to lift the submersible pumping system up into the shroud for attachment of the shroud to the submersible pumping system.

19. The system as recited in claim 18, wherein the lifting mechanism is configured to be releasably coupled with the shroud to enable setting of the shroud on the worktable.

20. The system as recited in claim 19, wherein the lifting mechanism is movable through an interior of the shroud via a hoist cable.