The present invention relates to a method of installing a pump string assembly in an oil and gas well, particularly to a method of installing an ESP bypass assembly.

Background to the Invention

Electrical submersible pump (ESP) systems are a well-known type of artificial lift system that can be deployed in the bore of oil and gas wells to improve and control the flow of fluids from the downhole formation to the surface. Many oil and gas wells employ some form of artificial lift at some point during the life of the well, typically to compensate for low reservoir pressure in mature wells, and ESP systems in particular provide the benefits of variable power and flow control, allowing operators to control extraction rates. ESP systems are also well-suited to pumping fluids with high gas content.

ESP systems are typically assembled as a string of sections, usually including at least a motor, a seal protector and a pump, and can be installed alongside a bypass tubing string which provides continuity of the production tubing above the ESP system, so that, for example, wireline accessibility through the bore of the production tubing to the reservoir below is maintained through the bypass tubing string. In this case the length of the complete ESP system must be accurately calculated in advance of installation to ensure that the lowermost ESP section is clamped at the correct position on the lowermost bypass tubing joint, so that the top of the assembled ESP system corresponds with the top of the uppermost bypass tubing joint, allowing both the ESP system and bypass tubing string to be connected to the production tubing above. The sections of the ESP system and corresponding joints of the bypass tubing string are then assembled simultaneously and run into the bore of the well alongside each other. Typically, the first bypass tubing joint is inserted partway into the well, and then a safety clamp fitted to hold the joint at the correct height above a work table for the first ESP section to be attached to the joint with a bypass clamp. The next bypass tubing joint is then made up to the first joint, the safety clamp removed, and the first ESP section and bypass tubing joints lowered further into the well until the lift clamp at the top of the first ESP section lands on the work table. Further ESP sections and bypass tubing joints are added alternately in this manner until the ESP system is complete. If the ESP system has been assembled accurately, the uppermost end of the ESP system will closely correspond to the uppermost end of the bypass tubing string, and both can be connected to the production tubing above the ESP bypass system, usually through a flow diverter valve assembly such as a Y-tool.

Summary

According to the present invention, there is provided a method of assembling a pump string assembly in an oil or gas well, the pump string assembly comprising a pump string and a bypass string connected by a flow diverter at an upper end of the pump string and the bypass string, the pump string comprising pump sections connected together to form the pump string extending for a first length from the flow diverter and the bypass string comprising tubing joints connected together to form the bypass string, the method comprising: connecting multiple tubing joints of the bypass string in end to end relationship, and inserting the tubing joints of the bypass string into the well, the connected multiple tubing joints of the bypass string inserted in the well having a greater length than the first length; subsequently connecting a first section of the pump string to the connected tubing joints of the bypass string that are assembled in the well, and sliding the first section of the pump string relative to the assembled connected tubing joints of the bypass string in an axial direction along the bypass string and into the well; connecting a second section of the pump string to the first section of the pump string; and sliding the connected first and second sections of the pump string relative to the bypass string in an axial direction along the bypass string and into the well; and subsequently connecting the bypass string and pump string to the flow diverter at the upper end of the pump string and the bypass string.

Optionally the bypass string extends for a second length from the flow diverter. Optionally the second length of the bypass string is greater than the first length of the pump string. Optionally the multiple tubing joints (optionally all of the tubing joints) of the bypass string are connected in end to end relationship before being inserted into the well. Optionally each tubing joint of the bypass string is connected to the bypass string already inserted into the well, and optionally the bypass string is then lowered into the well before connecting the next tubing joint of the bypass string. Optionally the first and second sections of the pump string are connected to the bypass string before sliding the connected sections of the pump string into the well. Optionally at least one further section of the pump string can be connected to the first and second sections of the pump string, optionally before the connected first, second and further sections of the pump string slide relative to the bypass string into the well. Optionally two, three, four, five or more sections of the pump string can be connected to the first section of the pump string, optionally before the connected sections of the pump string slide relative to the bypass string into the well. Optionally at least one further section of the pump string is connected to the second section of the pump string after the second section of the pump string is connected to the first section of the pump string. Optionally at least one further section of the pump string is connected to the second section of the pump string before the second section of the pump string is connected to the first section of the pump string, optionally at a location removed from the bypass string and the first section of the pump string.

Optionally each section of the pump string is connected to the bypass string with a coupling device, which is optionally adapted to form a rigid fit with the first and second sections of the pump string and a sliding fit with the bypass string, optionally to permit axial movement of the first and second sections of the pump string relative to the bypass string.

Optionally the pump string is an ESP (electrical submersible pump) assembly, and optionally the first and second sections are sections (e.g. consecutive sections) of an ESP assembly, optionally a motor section, optionally a seal protector section, optionally a gas separator section, optionally a pump section. Optionally the pump string incorporates one or more sections which are not ESP sections. Optionally the non-ESP sections of the pump string can comprise filtration devices, optionally sand screens or traps, optionally comprising a blind ended bore or annulus with an upwardly facing opening. Optionally the non-ESP sections of the pump string can be disposed at an upper axial end of the pump string, optionally closest to the surface when the pump string assembly is operational, optionally adjacent to the flow diverter connected to the pump string and the bypass string. Optionally a sand screen or trap can be disposed immediately above a section of the pump string, optionally the uppermost section. Optionally a coupling device is attached between the first section of the pump string and the bypass string before the first section of the pump string is supported at the surface of the well.

Optionally the outer surface of the first section (and optionally of the second and/or further sections) of the pump string comprises a recessed portion, optionally disposed adjacent to an axial end of the first and second sections, which optionally has a reduced outer diameter relative to the outer surface of the first and second and/or further sections. Optionally the outer surface of the recessed portion is not arcuate, and optionally has at least one flat to enable application of torque to the surface. In one example, the outer surface of the recessed portion has a polygonal profile, optionally comprised of a plurality of (optionally adjacent) planar surfaces, optionally identical planar surfaces, and optionally one or more of the planar surfaces is perpendicular to a radius of the section of the pump string.

Optionally the bypass tubing string is assembled (optionally completely assembled) before the pump string is assembled. The method of assembling the bypass string optionally includes the steps of inserting a first bypass tubing joint partway into the well; supporting the first bypass tubing joint at the surface of the well; connecting a second bypass tubing joint to the first bypass tubing joint; inserting the first and second bypass tubing joints partway into the well; and supporting the second bypass tubing joint at the surface of the well. Optionally an uppermost bypass tubing joint of the bypass tubing string (e.g. the final bypass tubing joint of the bypass tubing string that is directly connected to the flow diverter), which is optionally shorter than at least some of the other bypass tubing joints of the bypass tubing string, and is optionally shorter than a pump leg of the flow diverter, is connected to the flow diverter before being connected to the bypass tubing joints that are already assembled in the well, and is optionally connected to the bypass tubing string after the flow diverter is connected to the pump string. Optionally the uppermost bypass tubing joint is connected to the bypass tubing string after the pump string is assembled.

Optionally the connections between the bypass tubing joints are flush joints, optionally having an outer diameter substantially equal to the outer diameter of the bypass tubing joints. Optionally the outer diameter of the bypass string is substantially constant, and is optionally smaller than the outer diameter of the pump string. Optionally the outer surface of the bypass string has a low-friction surface, and is optionally coated with a lubricant, optionally with a dry lubricant.

Optionally the first section of the pump string is supported (optionally suspended), optionally above the surface of the well, after the first section of the pump string slides along the bypass string in an axial direction into the well. Optionally the second and optionally further sections of the pump string are supported (optionally suspended), optionally above the surface of the well, after the first and second and optionally further sections of the pump string slide along the bypass string in an axial direction into the well.

Optionally the first section, and optionally the first, second and optionally further sections of the pump string are supported by a support structure at the surface of the well, optionally by a moveable support structure, optionally by a work table. Optionally the support structure comprises a surface, optionally a planar surface, which is optionally perpendicular to the axis of the pump string. Optionally the planar surface comprises a slot. Optionally the width of the slot is sufficient to allow the pump string to pass through the planar surface in an axial direction relative to the bypass string.

Optionally the width of the slot does not permit a shoulder of the first and second sections of the pump string, optionally disposed at an axial end of the first and second sections, to pass through the planar surface. Optionally the outer diameter of the shoulder is greater than the outer diameter of the first and second sections of the pump string. Optionally the shoulder of the first and second sections of the pump string comprises a removable shoulder, optionally a collar, optionally a lift clamp. Optionally the first and second sections of the pump string are supported by the support structure when the shoulder of the first or second section is in contact with (optionally landed on, optionally suspended from) the planar surface of the support structure.

Optionally the outer diameter of each coupling device is greater than the width of the slot in the planar surface. Optionally a coupling device is connected between the pump string and the bypass string at a location above the planar surface. Optionally the slot in the planar surface does not permit the coupling device to pass through the planar surface in an axial direction. Optionally the support structure can be removed from the pump string to permit movement of the pump string in an axial direction relative to the bypass string when axial movement of the pump string is otherwise prevented by the coupling device not passing through the slot in the planar surface of the support structure. Optionally the coupling device is connected between the pump string and the bypass string at a location below the planar surface, which optionally permits movement of the pump string in an axial direction relative to the bypass string without removing the support structure from the pump string.

Optionally the bypass string is suspended in the well, optionally from a fixed point above the surface of the well, optionally from a hoist.

Optionally the bypass string is supported, optionally by a support structure at the surface of the well, which optionally also supports the pump string. Optionally the support structure comprises first and second surfaces, optionally planar surfaces, which are optionally perpendicular to the axes of the bypass string and the pump string. Optionally the pump string is supported on the first planar surface, and optionally the bypass string is supported on the second planar surface. Optionally the second planar surface is spaced from the first planar surface in the direction of the axes of the bypass string and the pump string, and optionally the second planar surface for supporting the bypass string is above (optionally vertically above) the first planar surface for supporting the pump string. Optionally the second planar surface is removable from the support structure.

Optionally the first and second planar surfaces comprise slots with respective first and second widths. Optionally the width of the slot in the second (e.g. upper) planar surface is narrower than the width of the slot in the first (e.g. lower) planar surface. Optionally the width of the slot in the first (e.g. lower) planar surface permits the coupling device attached to the second section of the pump string to pass through the first planar surface in an axial direction relative to the bypass string. Optionally the width of the slot of the first (e.g. lower) planar surface and second (e.g. upper) planar surface is sufficient to receive the bypass string, but not sufficient for a shoulder at an axial end of the bypass string to pass through the slot of the second planar surface. Optionally the outer diameter of the shoulder of the bypass string is greater than the outer diameter of the bypass string. Optionally the shoulder of the bypass string comprises a removable shoulder, optionally a collar, optionally a lift nubbin, optionally a safety clamp. Optionally the bypass string is supported by the support structure when the shoulder of the bypass string is in contact with, optionally landed on, optionally suspended from, the second planar surface (optionally the first planar surface) of the support structure.

Optionally the support structure comprises a moveable plate with a slot. Optionally the width of the slot in the moveable plate is narrower than the width of the slot in the first (e.g. lower) planar surface of the support structure. Optionally the moveable plate is a C-plate. Optionally the moveable plate can be placed on the first planar surface of the support structure, optionally with the slot in the moveable plate aligned with (optionally superimposed on) the slot in the first planar surface, in order to narrow the width of the slot in the first planar surface. Optionally the width of the slot in the moveable plate does not permit the coupling device attached to the second section of the pump string to pass through the first planar surface in an axial direction, but does permit the pump string to pass through the first planar surface. Optionally the moveable plate can be removed from the first planar surface of the support structure to permit the coupling device attached to the second section of the pump string to pass through the first planar surface in an axial direction.

Optionally the coupling device is a clamping device, optionally a bypass clamp. Optionally the clamping device comprises first and second apertures. Optionally the inner diameter of the first aperture is adjustable, and optionally the inner diameter of the second aperture is fixed. Optionally the coupling device attaches to the second section of the pump string (or optionally to the first section of the pump string) adjacent to an axial end of the pump string section, optionally adjacent to the connection of the second section of the pump string to the first section, optionally at the recessed portion of the outer surface of the second section of the pump string.

Optionally the first aperture of the coupling device is adapted to extend partway around (optionally to surround) the second section (or optionally the first section) of the pump string. Optionally the radial dimension of the first aperture can be adjusted to be equal to an outer diameter of the second section of the pump string, optionally equal to the outer diameter of the recessed portion of the second section. Optionally the first aperture of the coupling device clamps or grips the second section (or optionally the first section) of the pump string, and optionally substantially prevents axial (and optionally rotational) movement of the coupling device relative to the second section (or optionally the first section) of the pump string.

Optionally the second aperture of the coupling device is adapted to extend partway around the bypass string. Optionally the second aperture has an inner diameter, which optionally has a fixed radial dimension that is larger than the outer diameter of the bypass string. Optionally the inner diameter of the second aperture can be adjusted to be larger than the outer diameter of the bypass string. Optionally the inner diameter of the second aperture can be adapted for use with more than one outer diameter of bypass string, optionally by adding an insert to the second aperture, which optionally decreases the inner diameter of the second aperture of the coupling device. Optionally the radial dimension of the second aperture of the coupling device permits movement of the coupling device in an axial direction, and optionally in a rotational direction, relative to the bypass string, but substantially prevents movement of the coupling device in a radial direction relative to the bypass string. Optionally the inner surface of the second aperture of the coupling device has a low-friction surface, and is optionally coated with a lubricant, optionally with a dry lubricant. Optionally the second aperture is formed by opposing arms which extend circumferentially around the bypass string from the coupling device so that the arms extend around more than 180 degrees of the bypass string, but less than 360 degrees, for example, from 200 to 340 degrees, optionally from 230-310 degrees, optionally from 270-300 degrees of the bypass string, with a sliding clearance between the outer surface of the bypass string at its widest point and the inner surface of the second aperture.

Optionally the method of assembling the pump string is preceded by the steps of : lifting (optionally suspending) a first section of the pump string into proximity with the bypass string, optionally into parallel alignment with the bypass string, optionally above the surface of the well; attaching a coupling device between the first section of the pump string and the bypass string, optionally adjacent to a first axial end of the first section of the pump string, optionally at a recessed portion of the outer surface of the first section; lowering the first section of the pump string in an axial direction relative to the bypass string, optionally partway into the well; and supporting, optionally landing, an opposing second axial end of the first section of the pump string on the support structure. Optionally the method includes holding the pump string in an axially stationary position while lowering the bypass string into the well, wherein the axial position of the pump string is unchanged after sliding a final section of the pump string along the bypass string into the well. Optionally the method includes holding the bypass string in an axially stationary position while lowering the flow diverter assembly and connected pump string into the well.

Optionally the method of assembling the first and second (and optionally further) sections of the pump string is repeated for adjacent pairs (or other multiples) of sections of the pump string, and optionally for the final sections of the pump string. Optionally the final section of the pump string and optionally the final joint of the bypass string are connected to a flow diverter valve assembly, optionally a Y-tool assembly, after the penultimate and final sections of the pump string have been assembled. Optionally a first conduit of the flow diverter valve assembly is connected to the pump string. Optionally a second conduit of the flow diverter valve assembly is connected to the bypass string. Optionally the first and second conduits of the flow diverter valve assembly have different lengths, and optionally the lengths of the first and second conduits are fixed. Optionally the first and second conduits are integrated with the flow diverter valve assembly, and optionally the pump string and the bypass string connect directly to the flow diverter valve assembly.

Optionally the bypass string is lowered, optionally in an axial direction, into the well relative to the pump string before the first conduit of the flow diverter valve assembly is connected to the pump string. Optionally the upper end of the bypass string is axially spaced from the upper end of the pump string by a distance less than (optionally equal to) the difference in length of the first and second conduits of the flow diverter valve assembly. Optionally the flow diverter valve assembly and the pump string are lowered into the well, optionally in an axial direction, relative to the bypass string after the flow diverter valve assembly is connected to the pump string, optionally before the flow diverter valve assembly is connected to the bypass string. Optionally the uppermost bypass tubing joint of the bypass tubing string (directly connected to the flow diverter) is connected to the flow diverter valve assembly before the flow diverter valve assembly and pump string are lowered into the well. Optionally connecting the uppermost bypass tubing joint to the flow diverter assembly (optionally to a swivel of the flow diverter valve assembly) reduces the distance by which the flow diverter valve assembly is lowered into the well.

Optionally the final section of the pump string is supported (optionally suspended), optionally by the support structure, before the final section of the pump string is connected to the flow diverter valve assembly. Optionally the final section of the pump string is released from the support structure, optionally by removing a lift clamp attached to the final section, after the final section is connected to the flow diverter valve assembly. Optionally the pump string is suspended from the flow diverter valve assembly after the flow diverter valve assembly is connected to the pump string. Optionally the bypass string is supported (optionally suspended), optionally by the support structure, before the bypass string is connected to the flow diverter valve assembly. Optionally the bypass string is released from the support structure, optionally by removing a safety clamp attached to the bypass string, optionally by removing the support structure, after the bypass string is connected to the flow diverter valve assembly. Optionally the bypass string is suspended from the flow diverter valve assembly after the flow diverter valve assembly is connected to the bypass string.

Optionally the pump string can be made up of more than two sections, and this will normally be the case in most examples. Optionally the final section to be added to the pump string at the top of the suspended pump string will be connected to the flow diverter valve assembly as outlined above.

According to another aspect of the present invention, there is provided a method of installing a pump string assembly in an oil or gas well, the pump string assembly comprising a pump string and a bypass string connected by a flow diverter at an upper end of the pump string and the bypass string, the pump string comprising at least first and second sections, the first and second sections having an axis, the second section being adapted to be connected to the first section, wherein the pump string extends for a first length from the flow diverter, wherein the method comprises: assembling the bypass string and installing the bypass string to a length greater than the first length in the well; subsequently supporting the first section of the pump string at the surface of the well; connecting the second section of the pump string to the first section; attaching a coupling device between the second section of the pump string and the bypass string that is assembled in the well, wherein the coupling device is adapted to form a rigid fit with the second section of the pump string and a sliding fit with the bypass string, to permit axial movement of the first and second sections of the pump string relative to the bypass string; and inserting the first and second sections of the pump string into the well in an axial direction relative to the bypass string and supporting the second section of the pump string at the surface of the well.

According to a further aspect of the present invention, there is provided a method of installing a first string of tubulars in an oil or gas well, the first string of tubulars comprising at least first and second tubulars, the first and second tubulars having an axis, the second tubular being adapted to be connected to the first tubular, wherein the first string of tubulars extends for a first length into the well, wherein the method comprises: assembling a second string of tubulars and installing the second string of tubulars to a length greater than the first length in the well; subsequently supporting the first tubular at the surface of the well; connecting the second tubular to the first tubular; attaching a coupling device between the second tubular and the second string of tubulars that is assembled in the well, wherein the coupling device is adapted to form a rigid fit with the second tubular and a sliding fit with the second string of tubulars, to permit axial movement of the first and second tubulars relative to the second string of tubulars; and inserting the first and second tubulars into the well in an axial direction relative to the second string of tubulars and supporting the second tubular at the surface of the well.

According to another aspect of the present invention, there is provided a pump string assembly for an oil or gas well, the pump string assembly comprising a pump string and a bypass string connected by a flow diverter at an upper end of the pump string and the bypass string, the pump string comprising pump sections connected together to form the pump string extending for a first length from the flow diverter and the bypass string comprising tubing joints connected together to form the bypass string, wherein the pump string assembly is assembled by: connecting multiple tubing joints of the bypass string in end to end relationship, and inserting the tubing joints of the bypass string into the well, the connected multiple tubing joints of the bypass string inserted in the well having a greater length than the first length; subsequently connecting a first section of the pump string to the assembled connected tubing joints of the bypass string that are assembled in the well, and sliding the first section of the pump string relative to the assembled connected tubing joints of the bypass string in an axial direction along the bypass string and into the well; connecting a second section of the pump string to the first section of the pump string; sliding the connected first and second sections of the pump string relative to the bypass string in an axial direction along the bypass string and into the well; and subsequently connecting the bypass string and pump string to the flow diverter at the upper end of the pump string and the bypass string.

Optionally a section of the pump string (optionally the final section of the pump string to be assembled) is connected to a flow diverter assembly, optionally to a first conduit of the flow diverter assembly, optionally a Y-tool assembly. Optionally a tubing joint of the bypass string (optionally the uppermost tubing joint) is connected to the flow diverter assembly, optionally to a second conduit of the flow diverter assembly. Optionally the first and second conduits of the flow diverter valve assembly have different lengths, and optionally the lengths of the first and second conduits are fixed. Optionally the axial spacing between the upper end of the pump string and the upper end of the bypass string after the pump string and the bypass string are connected to the flow diverter assembly is equal to the difference in length of the first and second conduits of the flow diverter assembly.

According to a further aspect of the present invention, there is provided a pump string assembly for an oil or gas well, the pump string assembly comprising a pump string and a bypass string connected by a flow diverter assembly at an upper end of the pump string and the bypass string, the pump string comprising pump sections connected together to form the pump string extending for a first length from the flow diverter and the bypass string comprising tubing joints connected together to form the bypass string, the connected tubing joints of the bypass string having a greater length than the first length, wherein the pump sections of the pump string are each adapted to be slidably connected to the assembled connected tubing joints of the bypass string after the bypass string has been inserted into the well; and wherein the uppermost section of the pump string and the uppermost tubing joint of the bypass string are directly connected to respective conduits of the flow diverter assembly. Connecting directly to the flow diverter assembly optionally avoids the requirement for telescopic joints between the flow diverter assembly and the sections or joints of the pump string and the bypass string.

The various aspects of the present invention can be practiced alone or in combination with one or more of the other aspects, as will be appreciated by those skilled in the relevant arts. The various aspects of the invention can optionally be provided in combination with one or more of the optional features of the other aspects of the invention. Also, optional features described in relation to one aspect can typically be combined alone or together with other features in different aspects of the invention. Any subject matter described in this specification can be combined with any other subject matter in the specification to form a novel combination.

Various aspects of the invention will now be described in detail with reference to the accompanying Figures. Still other aspects, features, and advantages of the present invention are readily apparent from the entire description thereof, including the Figures, which illustrates a number of exemplary aspects and implementations. The invention is also capable of other and different examples and aspects, and its several details can be modified in various respects, all without departing from the spirit and scope of the present invention. Accordingly, each example herein should be understood to have broad application, and is meant to illustrate one possible way of carrying out the invention, without intending to suggest that the scope of this disclosure, including the claims, is limited to that example. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. In particular, unless otherwise stated, dimensions and numerical values included herein are presented as examples illustrating one possible aspect of the claimed subject matter, without limiting the disclosure to the particular dimensions or values recited. All numerical values in this disclosure are understood as being modified by "about". All singular forms of elements, or any other components described herein are understood to include plural forms thereof and vice versa.

Language such as "including", "comprising", "having", "containing", or "involving" and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term "comprising" is considered synonymous with the terms "including" or "containing" for applicable legal purposes. Thus, throughout the specification and claims unless the context requires otherwise, the word “comprise” or variations thereof such as “comprises” or“comprising” will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Any discussion of documents, acts, materials, devices, articles and the like is included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention.

In this disclosure, whenever a composition, an element or a group of elements is preceded with the transitional phrase "comprising", it is understood that we also contemplate the same composition, element or group of elements with transitional phrases "consisting essentially of”, "consisting", "selected from the group of consisting of”,“including”, or "is" preceding the recitation of the composition, element or group of elements and vice versa. In this disclosure, the words“typically” or “optionally” are to be understood as being intended to indicate optional or non- essential features of the invention which are present in certain examples but which can be omitted in others without departing from the scope of the invention.

References to directional and positional descriptions such as upper and lower and directions e.g. “up”, “down” etc. are to be interpreted by a skilled reader in the context of the examples described to refer to the orientation of features shown in the drawings, and are not to be interpreted as limiting the invention to the literal interpretation of the term, but instead should be as understood by the skilled addressee. References to“up” or“down” will be made for purposes of description with the terms "above", "up", "upward", "upper", or "upstream" meaning away from the bottom of the well and toward the surface, and "below", "down", "downward", "lower", or "downstream" meaning toward the bottom of the well and away from the surface and deeper into the well, whether the well being referred to is a conventional vertical well or a deviated well and therefore includes the typical situation where a rig is above a wellhead, and the well extends down from the wellhead into the formation, but also horizontal wells where the formation may not necessarily be below the wellhead.

In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawings are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in the interest of clarity and conciseness. The present invention is susceptible to embodiments of different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present invention with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce the desired results.

Brief Description of the Drawings

In the accompanying drawings :

Figures 1a, 1 b and 1c are respectively a side elevation view of an example of an installed pump string assembly, and detailed side elevation and perspective views of a bypass clamp and motor base plug;

Figures 2a and 2b are respectively top section and top elevation views of a bypass clamp, used for installing the pump string assembly shown in Figure 1a;

Figures 2c and 2d are respectively perspective views of first and second examples of a work table, used for installing the pump string assembly shown in Figure 1a;

Figures 3a to 3f are side elevation views of the pump string assembly shown in Figure 1a which illustrate the initial stages of running in the bypass tubing and attaching the first section of the pump string;

Figures 4a to 4d are side elevation views of the pump string assembly shown in Figure 1a which illustrate the repeated sequence of running in the subsequent sections of the pump string; Figures 5a to 5f are side elevation views of the pump string assembly shown in Figure 1a which illustrate the final stages of attaching a Y-tool assembly to the bypass and pump strings and running in of the complete pump string assembly; and Figures 6a to 6d are side elevation views of a second example of a pump string assembly which illustrate the repeated sequence of running in the subsequent sections of the pump string using a second example of a work table.

Detailed Description

Referring now to the drawings, a pump string assembly 1 installed in accordance with the invention is shown in Figure 1a. In this example the pump string assembly 1 comprises an electrical submersible pump (ESP) pump string 10 and a bypass tubing string 20, both connected to a Y-tool 41 below a rotary table 5, but in other examples the pump string assembly 1 may be installed below a wellhead.

In this example the pump string 10 incorporates three sections : a motor section 14 and associated motor base plug 12, a seal protector section 16 and a pump section 18, but in other examples, the pump string 10 may incorporate other different sections, or incorporate more than one of a particular section e.g. two or more motor sections 14, depending upon the power requirements of the pump section 18 to develop the required flowrate or output pressure of fluids from the well. In further examples, the pump string 10 may incorporate one or more other sections whose function is not related to pumping, such as filtering devices and / or sand screens. Typically such pump string sections are positioned at the upper end of the pump string, for example between the pump section 18 and pump leg 42 of the Y-tool 41 shown in Figure 1a, ideally immediately above the uppermost pump section. Also in this example, the base of each section of the pump string 10 comprises a neck, or recessed portion, which is disposed adjacent to a bolted flange connection at the lowermost axial end of each section of the pump string, but in other examples, the connections at each axial end of the pump string sections may comprise any suitable mechanical connection means.

The motor base plug 12 of this example is shown in Figure 1c, and comprises a neck or recess 13 disposed intermediate two axially-facing shoulders 13a, 13b. The outer surface of the recess 13 in this example is not arcuate, but comprises a plurality of flats, or in other words contiguous identical planar surfaces, around the circumference of the motor base plug 12, set in diametrically opposed pairs, with each planar surface disposed perpendicular to a radius of the motor base plug 12. In this example, the outer surface of the recess 13 comprises sixteen contiguous planar surfaces, with each planar surface set an angle of approximately 157.5 degrees to the adjacent planar surfaces on either side, but in other examples the outer surface of the recess may comprise fewer or more planar surfaces. Furthermore, the planar surfaces need not be identical or contiguous. For example, the outer surface may be substantially arcuate, with only two, or four, or any other number of non-contiguous flats or planar surfaces, optionally set in diametrically opposed pairs. In other words, the outer surface of the recess 13 has a polygonal profile.

Also in this example the bypass tubing string 20 comprises three bypass tubing joints 22a, 22b, 22c, which in this example all have equal length, but in other examples, each bypass tubing joint 22 may be a different length. In this example, the three bypass tubing joints 22a, 22b, 22c are approximately equal in length to API 5CT Range 2 tubing, that is between 28 and 32 feet (8.53 and 9.75 metres) in length. The joints between the three bypass tubing joints 22a, 22b, 22c are flush joints, such that the outer diameter of the joints is equal to the outer diameter of the bypass tubing joints, and therefore the outer diameter of the bypass tubing string 20 is constant over its entire length.

Furthermore in this example, the bypass tubing string 20 also incorporates a bell- type wireline entry guide 24 at the lowermost end of the first bypass tubing joint 22a, but in other examples the lowermost end of the bypass tubing string may be a crossover sub e.g. for connection to an additional tailpipe section, or an alternative wireline entry guide such as a self-aligning guide shoe.

The pump string 10 and bypass tubing string 20 are connected to each other by four bypass clamps 30a, 30b, 30c, 30d, as best seen in Figure 1b, and in further detail in Figures 2a and 2b. In this example each bypass clamp 30 comprises two symmetrical halves 31a, 31 b joined by hinges 32a, 32b which allow the clamp to move between an open configuration and a closed configuration. In the open configuration, the halves 31a, 31b of the bypass clamp 30 are separated from each other, allowing the bypass clamp to be fitted around the outer surfaces of the pump string 10 and bypass tubing string 20. In the closed configuration, the two halves 31a, 31 b of the bypass clamp contact each other at faces 39a, 39b and are secured together by a restraining bolt 38 disposed in a threaded bore extending through the bodies of the two halves of the bypass clamp. When in the closed configuration, the bypass clamp 30 forms a closed first aperture 34, and arms 37a, 37b form a slot or open second aperture 35. In this example the open second aperture 35 has an inner diameter of slightly more than 2 7/8 inches (0.073 metres), while the inner diameter of the closed first aperture 34 is approximately equal to the outer diameter of the neck at the base of each section of the pump string 10, and can be reduced by adjusting the radial position of jaws 36a, 36b.

The uppermost ends (e.g. the ends closest to the surface) of the pump string 10 and bypass tubing string 20 are joined respectively to the pump leg 42 and bypass leg 44 of Y-tool assembly 40. In this example the pump leg 42 is longer than the bypass leg 44, and both have a fixed length. Also in this example the pump leg 42 has a flanged connection 43 for connection to the uppermost end of the pump 18 of the pump string 10, and the pump leg 42 is therefore fixed rotationally relative to both the pump 18 and Y-tool 41. The bypass leg 44 comprises a swivel 45 which rotates relative to the bypass tubing string 20 in order to make up the threaded connection at the upper end of the uppermost bypass tubing joint 22c. In this example the swivel 45 is a rotational lock swivel which is locked after being made up to the bypass tubing joint 22c, to prevent any further rotation of the bypass tubing string 20, but in other examples a standard non-locking swivel can be used if the bypass clamp at the uppermost end of the pump string 10 is a standard clamp which forms a rigid fit with both the pump string 10 and bypass tubing string 20.

In this example a work table 50, shown in Figure 2c, is used to support the partially assembled sections of the pump string 10 in the bore of the well while the next section is added to the pump string. A second example of a work table 150 is depicted in Figure 2d, and will be described later. The work table 50 comprises two surfaces 52a, 52b which in this example are planar and parallel to one another, each surface having a respective pocket or slot 53a, 53b in a first edge of each surface which extends toward an opposing second edge of each surface. In this example the surface 52b is disposed vertically above the surface 52a, and is spaced from the surface 52a by approximately 30 inches (0.762 metres), but in other examples the surface 52b may be spaced from the surface 52a by any appropriate distance that provides a reasonable working height for the surface 52b. The slots 53a, 53b are vertically aligned with each other, and face corresponding edges of the surfaces 52a, 52b, and in this example the width of both slots is approximately 7 inches (0.178 metres), but in other examples, the width of the (lower) slot 53a may be greater than the width of the (upper) slot 53b e.g. the width of the (lower) slot 53a may be approximately 9 inches (0.229 metres). When the work table 50 is placed, for example, on the rotary table 5 seen in Figure 1a, both surfaces 52a, 52b are perpendicular to the axes of the pump string 10 and bypass tubing string 20. Therefore, the work table 50 can be moved or lifted in a radial direction toward a portion of either the pump string 10 or bypass tubing string 20 that is supported (e.g. suspended) partway through the rotary table 5, and receive the pump string or bypass tubing string into the slots 53a, 53b. In other words, after being moved radially toward either the pump string 10 or bypass tubing string 20, the surfaces 52a, 52b will partially surround the pump string or bypass tubing string. If the pump string 10 is fitted with a shoulder or collar, for example a lift clamp 11 (seen in Figures 3e and 3f), which has an outer diameter greater than the width of the slot 53b, the pump string can be lowered through the slots 53a, 53b until the shoulder or collar contacts the surface 52b, at which point further axial movement of the pump string will be prevented, and the pump string will be supported by (or in other words suspended from) the work table 50.

The assembly sequence of the pump string assembly 1 is shown generally in Figures 3a to 3f, Figures 4a to 4d and Figures 5a to 5f. The steps depicted in Figures 3a to 3d are typically carried out once prior to assembly of the sections of the pump string 10, then the steps in Figures 4a to 4d are repeated typically for each section (but in some examples for two or more sections at a time) of the pump string 10, for as many times as is needed, depending on the number of sections in the pump string 10. Finally the steps shown in Figures 5a to 5f complete the installation of the pump string assembly 1. In this example, a single section of the pump string 10 is added in the sequence of steps shown in Figures 4a to 4d, but in other examples, at least one further section e.g. more than one section of the pump string 10 may be added in each sequence of steps shown in Figures 4a to 4d, as will be described in more detail below. Prior to assembly of the pump string assembly 1 , the total length of the pump string 10 is calculated, to determine the number of bypass tubing joints 22 that will be required for the particular pump string assembly 1 , which will depend on the length of the pump string 10. Preferably the length of the bypass tubing string 20 should exceed the length of the pump string 10 by typically 15 feet (4.57 metres), and by at least 8 to 10 feet (2.44 to 3.05 metres), to provide clearance between the wireline entry guide 24 (which typically has a greater outer diameter than the bypass tubing string 20) and the pump string 10, and also to allow for deflection of the portion of the bypass tubing string 20 which extends below the lowermost end of the pump string 10, while minimising corresponding deflection of the pump string. Therefore, the total length of the pump string, plus 15 feet (4.57 metres), is divided by the made-up length of each bypass tubing joint 22, and the result rounded up to the next integer to determine the total number of bypass tubing joints 22 required.

As shown in Figure 3a, the first step of the assembly sequence in this example is to attach a hoist coupling 26, such as a swivel lift nubbin, to a first bypass tubing joint 22a, and to lower the bypass tubing joint from a hoist (not shown in the Figures) through the rotary table 5 and partway into the well. In other examples the first bypass tubing joint 22a may be lowered into the well by other means, such as with an elevator. The bypass tubing joint 22a is then held in the rotary table 5 by slips 6, the hoist coupling 26 removed, and a second bypass tubing joint 22b made up to the first bypass tubing joint 22a, as seen in Figure 3b. While the second bypass tubing joint 22b is still suspended, the slips 6 are removed, the second joint 22b lowered partway into the well, and the slips 6 replaced. In this example, a third bypass tubing joint 22c is then added to the bypass tubing string 20 in the same manner as just described to complete the bypass tubing string 20 as shown in Figure 3d. In other examples, fewer or more bypass tubing joints 22 can be added. As best seen in Figure 5a, the length of the bypass tubing string 20 exceeds the calculated length of the pump string 10 by at least 15 feet (4.57 metres). In some examples, the uppermost bypass tubing joint of the bypass tubing string 20 can be retained and connected to the swivel 45 of the Y-tool 41 , for example to allow an alternative working height when making up the final connections between the pump and bypass strings 10, 20 and the pump and bypass legs 42, 44 of the Y-tool assembly 40. In these examples, the uppermost bypass tubing joint is typically shorter than bypass tubing joints that are assembled and inserted into the well before connecting sections of the pump string 10. For example, the length of the uppermost bypass tubing joint can be approximately equal to, or optionally less than, the axial distance between the upper end of the bypass string 20 and the lower end of the bypass leg 44 shown in Figure 5b. In either case, the overall length of the bypass tubing string 20 inserted into the well before connecting sections of the pump string 10 exceeds the length of the pump string, as described previously. In such examples, the uppermost bypass tubing joint can optionally be connected to the flow diverter of the Y-tool assembly 40 before being connected to the multiple joints of bypass tubing that have already been connected and assembled in the well.

Once the bypass tubing string 20 has been assembled and is suspended from the hoist coupling 26 attached to the last bypass tubing joint 22c, the bypass tubing string is lowered through the rotary table 5 until, in this example, approximately 10 feet (3.05 metres) of the bypass tubing string remains above the rotary table, as best seen in Figure 3d. The slips 6 are removed from the rotary table 5, and the bypass tubing string 20 moved to one side of the aperture through the rotary table 5, as also shown in Figure 3d, while still suspended by the hoist coupling 26.

Before assembling the pump string 10 by repeating the steps shown in Figures 4a to 4d, the first section of the pump string to enter the well (e.g. the lowermost section in the assembled pump string assembly 1), which in this example is the motor section 14 and corresponding motor base plug 12, is first coupled to the bypass tubing string 20. The joints of the bypass tubing string are already assembled and the lower end of the bypass tubing string is already inserted in the well, leaving only the upper end of the upper joint protruding from the rotary table 5. A lift clamp 11 is attached to the opposite axial end of the motor section 14 from the motor base plug 12, and the motor section 14 and motor base plug 12 lifted, in this example by a second hoist (also not shown in the Figures), toward the portion of the bypass string 20 above the rotary table 5, as shown in Figure 3e. A first bypass clamp 30a is then attached between the motor base plug 12 and the bypass string 20, as seen in Figure 3f.

In this example the bypass clamp 30a is opened by removing the restraining bolt 38, and the two hinged halves 31a, 31b of the bypass clamp are then placed around the recess 13 of the motor base plug 12, and around the bypass tubing string 20. As the bypass clamp 20 is closed and the two hinged halves 31a, 31b approach each other, the recess 13 of the motor base plug 12 is contained within the first aperture 34 of the bypass clamp, and the bypass tubing string 20 is contained within the second aperture 35 of the bypass clamp. The bypass clamp 20 is fully closed when the two hinged halves 31a, 31b come into contact with each other at faces 39a, 39b, and the restraining bolt 38 is replaced and tightened to secure the halves 31a, 31b of the bypass clamp together. When the restraining bolt 38 is fully tightened, the hinged halves 31a, 31 b of the bypass clamp 30a extend around both the motor base plug 12 and bypass tubing string 20, but do not compress or grip either the pump string 10 or the bypass tubing string 20. In other words, after the restraining bolt 38 is tightened, but before the jaws 36a, 36b are adjusted, the bypass clamp 30a is free to move in a rotational direction relative to the motor base plug 12, and in both axial and rotational directions relative to the bypass tubing string 20. The bypass clamp 30a is prevented from moving in an axial direction relative to motor base plug 12 by the axially-facing shoulders 13a, 13b of the motor base plug 12. The jaws 36a, 36b are then moved radially into the first aperture 34 of the bypass clamp 30 until they contact and compress against the recess 13 of the motor base plug 12, forming a rigid fit between the bypass clamp and the motor base plug. In other words, the jaws 36a, 36b grip against the polygonal profile of the recess 13 to prevent both axial and rotational movement of the bypass clamp 20 relative to the pump string 10. In this example the inner diameter of the second aperture 35 is fixed, and is slightly larger than the outer diameter of the bypass tubing string 20, such that the arms 37a, 37b form a sliding fit with the bypass tubing string 20. Therefore, the bypass clamp 30 permits both axial and rotational movement of the bypass clamp relative to the bypass tubing string 20, and so the pump string 10 can move axially and rotationally relative to the bypass tubing string 20. During operation of the motor and pump sections 14, 18 of the pump string 10, torque developed by the motor section 14 is typically controlled by gradually increasing or decreasing of the speed of the motor, which in many examples is a variable drive motor specifically adapted to allow operation of the pump string 10 across a wide range of pumping capacities and flow rates.

The pump string 10 is then assembled by repeating the steps shown in Figures 4a to 4d for each remaining section of the pump string, which in this example includes the seal protector section 16 and pump section 18. As seen in Figure 4a, a first section of the pump string 10, still suspended above the rotary table 5 from lift clamp 11 , is lowered partway through the rotary table and into the well. The work table 50 is then moved onto the rotary table 5 such that the bypass tubing string 20 and pump string

10 are received into the slots 53a, 53b. The first pump string section is lowered further until the lift clamp 11 lands upon the surface 52b of the work table 50, as shown in Figure 4a. In this example a second pump string section of the pump string 10, for example seal protector 16, fitted with another lift clamp 11 , is then lifted toward the portion of the bypass string 20 above the rotary table 5, as shown in Figure 4b, and the bolted flange connection of the second pump section is made up to the end of the first pump section. In other examples, at least one further section of the pump string 10, for example pump section 18, can also be connected to the first section of the pump string before the first section of the pump string is lowered into the well. In other words, while the sequence of steps shown in Figures 4a to 4d illustrate only a single section of pump string 10 being connected to a preceding pump section, in other examples, particularly if the available working height above the rotary table 5 is relatively unrestricted and free of obstructions, two or more further sections of the pump string 10 may be assembled away from the bypass string 20 and then lifted toward the bypass string 20 above the rotary table 5, and connected to the end of the first pump section. Alternatively, a second pump string section may be connected to the first pump string section, and then a third pump string section connected to the second pump string section, before the first section of the pump string is lowered into the well as described below.

As also shown in Figure 4b, once the bolted flange joint between the first and second pump sections has been made up, the first pump section is supported by (e.g. suspended from) the second pump section, and the lift clamp 11 supporting the first pump section on the work table 50 can be removed. In this example, as seen in Figure 4c another bypass clamp 30 is attached between the bypass tubing string 20 and the neck of the second pump section, in the same manner as the bypass clamp 30a attached to the first motor base plug 12 section of the pump string 10. The work table 50 is then removed from the rotary table 5, optionally by sliding the work table radially so that the axes of the pump and bypass tubing strings 10, 20 move out of the slots 53a, 53b, in order to allow the bypass clamp 30 on the second pump section to be lowered into the well, and then the work table 50 is replaced and the first and second pump string sections are lowered further until the second lift clamp

11 lands upon the surface 52b of the work table 50, as shown in Figure 4d. In other examples, the steps of attaching the bypass clamp 30 and lowering the first and second pump sections into the well can be reversed, so that the pump sections are first lowered slightly to allow the bypass clamp to be attached between the bypass tubing string 20 and the second pump section below the surface 52b of the work table 50. In examples of the work table 50 where the width of the (lower) slot 53a is greater than the width of the (upper) slot 53b, the first and second pump sections, with the bypass clamp 30 attached, can then be lowered into the well without removing the work table 50 from the rotary table 5. This sequence is then repeated for all remaining sections of the pump string 10.

When all sections of the pump string 10 have been assembled and with the lift clamp 11 of the last pump section still landed on the surface 52b of the work table 50, the bypass tubing string 20 is lowered relative to the pump string 10, and a safety clamp 21 is fitted to the bypass tubing string above the surface 52b of the work table 50, as shown in Figure 5a. The hoist coupling 26 is also removed from the uppermost end of the bypass tubing string 20.

In this example, the Y-tool assembly 40, comprising Y-tool 41 , pump leg 42 and bypass leg 44 is then picked up and suspended above the worktable 50 and the upper ends of the complete pump string 10 and bypass tubing string 20, as shown in Figure 5b. The pump leg 42 is aligned with the pump string 10, and the Y-tool assembly 40 lowered until the pump leg 42 is at the correct height for making up the flanged connection 43 between the pump leg 42 and the last pump section 18 of the pump string 10. Once the pump leg 42 has been connected to the pump section 18, the lift clamp 11 supporting the pump string 10 on the work table 50 can be removed, as the pump string 10 is now suspended from the Y-tool assembly 40.

The Y-tool assembly 40, along with the connected pump string 10, is then lowered into the well until the bypass leg 44 of the Y-tool assembly is at the correct height for making up the swivel 45 of the bypass leg to the threaded connection at the top of the bypass tubing string 20, as shown in Figure 5c. Once the bypass leg 44 has been connected to the bypass tubing string 20, the safety clamp 21 supporting the bypass tubing string on the work table 50 can also be removed. The whole Y-tool assembly 40, with attached pump and bypass tubing strings 10, 20, is then raised a short distance out of the well until the flanged connection between the pump leg 42 and the pump string 10 is again at a suitable working height, as best seen in Figure 5d.

The final bypass clamp 30d between the pump leg 42 and the bypass tubing string 20 is then attached, as shown in Figure 5e, which completes installation of the Y-tool assembly 40. The complete pump string assembly 1 is then run into the well, as seen in Figure 5f, with further production tubing joints being added above the Y-tool assembly 40 as required.

A second example of the installation of a pump string assembly 101 in accordance with the present invention is shown in Figures 6a to 6d. The second example is generally similar to the first example described above, and equivalent parts are numbered similarly, but the reference numbers are increased by 100. In the second example, the installed pump string assembly 101 is identical to the installed pump string assembly 1 in the first example, and the pump string 110, bypass tubing string 120, bypass clamps 130 and Y-tool assembly 140 are all similar in form and in function to the corresponding parts described previously in the first example.

In the second example, the work table 150 is also similar in form to the work table 50 of the first example, and also comprises two lower surfaces 152a, 152b which in this example are planar and parallel to one another, with the lower surface 152b disposed vertically above the lower surface 152a, as shown in Figure 2d. Each lower surface 152a, 152b has a respective pocket or slot 153a, 153b in a first edge of each lower surface which extends toward an opposing second edge of each lower surface. In this example, the width of the slots 153a, 153b is approximately 9 inches (0.229 metres). The work table 150 further comprises a removable C-plate 154 with a pocket or slot 155, similar to the slots 153a, 153b, but which in this example is approximately 7 inches (0.178 metres) wide, as also shown in Figure 2d. The removable C-plate 154 can be placed upon the lower surface 152b, with the slot 155 of the C-plate aligned with the slot 153b of the lower surface, in order to reduce the effective width of the slot 153b from approximately 9 inches (0.229 metres) to approximately 7 inches (0.178 metres). Also in this example, the work table 150 further comprises an upper surface 156 disposed vertically above the lower surfaces 152a, 152b, as also shown in Figure 2d. The upper surface 156 is parallel to the lower surfaces 152a, 152b and is spaced from the lower surface 152b by approximately 48 inches (1.219 metres), and also has a slot 157 which is vertically aligned with the slots 153a, 153b of the lower surfaces 152a, 152b. In this example the slot 157 of the upper surface 156 is approximately 3 inches (0.076 metres) wide. Therefore, in a similar manner to that of the work table 50 of the first example, the work table 150 in this example can be moved or lifted in a radial direction toward a portion of either the pump string 110 or bypass tubing string 120 that is supported (e.g. suspended) partway through the rotary table 105, and receive the pump string or bypass tubing string into the slots 153a, 153b. If the upper end of bypass tubing string 120 is above the level of the upper surface 156, the bypass tubing string is also received into the slot 157, but in this example, the width of the slot 157 is too narrow to receive the pump string 110. If either the pump string 110 or bypass tubing string 120 is fitted with a shoulder or collar, for example a lift clamp 111 or hoist coupling 126, which has an outer diameter greater than the width of either the slot 153b or slot 157, the pump string and bypass tubing string respectively can be lowered through the slots 153a, 153b, 157 until the shoulder or collar contacts either the surface 152b or surface 157, at which point further axial movement of the pump string or bypass tubing string will be prevented, and the pump string or bypass tubing string will be supported by (or in other words suspended from) the work table 150.

The assembly sequence of the pump string assembly 101 of this example is generally the same as the assembly sequence of the pump string assembly 1 of the first example. During the initial steps shown in Figures 3a to 3f of the first example, the work table 150 is moved onto the rotary table 105 and the bypass tubing string 120 received into the slots 153a, 153b and 157 of the lower and upper surfaces 152a, 152b, 156 of the work table. The bypass tubing string 120 is then lowered until the hoist coupling 126 lands on the upper surface 156 of the work table 150, as seen in Figure 6a, and the hoist coupling is then detached from the hoist used to lift the final bypass tubing joint 122c onto the bypass tubing string 120. Therefore, in this example, a single hoist can be used to assemble both the bypass tubing string 120 and the pump string 110.

The pump string 110 is then assembled by repeating the steps shown in Figures 6a to 6d for each section of the pump string. The C-plate 154 is initially placed on the lower surface 152b of the work table 150, and a first section of the pump string 110 is lowered through the rotary table and into the well until the lift clamp 111 attached to the first section of the pump string lands on the surface of the C-plate 154, as shown in Figure 6a. A second pump string section fitted with another lift clamp 111 is then lifted toward the portion of the bypass string 120 between the upper and lower surfaces 156, 152b of the work table 150, as shown in Figure 6b, and the bolted flange connection of the second pump section is made up to the end of the first pump string section. As described previously in the first example, in the second example, more than one pump string section may be lifted toward and connected to the first pump string section supported on the surface of the C-plate 154. As best seen in Figure 6c, once the bolted flange joint between the first and second pump sections has been made up, the first pump section is supported by (e.g. suspended from) the second pump section, and the lift clamp 111 supporting the first pump section on the C-plate 154 of the work table 150 can be removed. Another bypass clamp 130 is attached between the bypass tubing string 120 and the neck of the second pump section. The C-plate 154 is then removed from the work table 150 in order to expose the full width of the slot 153b of the lower surface 152b, which is sufficient to allow the bypass clamp 130 to pass through the slot 153b (and slot 153a), allowing the pump string 110 to be lowered in an axial direction relative to the bypass tubing string 120. Once the bypass clamp 130 has been lowered through the rotary table 105 and into the well, the C-plate 154 is replaced on the lower surface 152b of the work table 150, and the second pump string section lowered further until the second lift clamp 111 fitted to the second pump section lands on the C-plate, as shown in Figure 6d. This sequence is then repeated for all remaining sections of the pump string 110.