Patent Publication Number: US-2021164588-A1

Title: Subsea pipeline with multiple access nodes

Description:
TECHNICAL FIELD 
     In one aspect, the presently disclosed subject matter generally relates to various embodiments of a novel subsea pipeline that comprises multiple access nodes or tie-in locations that are pre-fabricated and pre-positioned at various locations in the pipeline, wherein these access nodes may be accessed on an as-needed basis as field development evolves over time. 
     BACKGROUND 
     Typically, to produce hydrocarbon-containing fluids from a subsea reservoir, several oil and gas wells are often drilled in a pattern that spaces the wells apart from each other. Each of the wells typically comprises a Christmas or production tree that is mounted on a wellhead. The tree is coupled to a production conduit such as a flowline or a jumper at the sea floor. The production conduits from the trees are typically coupled to other components such as manifolds, pipeline end terminations (PLETs), or other subsea processing units that collect or re-distribute the hydrocarbon-containing fluids produced from the wells. 
     When initial plans are made to produce hydrocarbon-containing fluids from a subsea reservoir, field developers must make some judgments as to the future development of the reservoir or field. Such decisions may include the anticipated location of various wells to be drilled into the reservoir as well as the anticipated location of certain items of subsea equipment that will be positioned subsea, such as Christmas (production) trees, manifolds, PLETs, flowlines, jumpers, pipelines, umbilicals, etc. At the time many of the original decisions are made with respect to the location and placement of various items of subsea equipment, the developer&#39;s knowledge about the capabilities of the reservoir in terms of production is somewhat limited. As development of the reservoir continues, i.e., as additional wells are drilled into the reservoir, developers acquire more and better information as it relates to the potential and actual development of the reservoir. Unfortunately, as this additional information about the field becomes available, the original decisions regarding the location of various items of subsea equipment may, in retrospect, not be ideal in terms of the efficient and economical consumption of subsea plot space (i.e., footprints) and/or efficient and economical production of hydrocarbon-containing fluids from the reservoir. 
     Typically, various utilities that are to be supplied to subsea production equipment, such as electrical power, communication lines, chemicals, etc., are supplied to the subsea equipment via relatively large and expensive bundled umbilicals that extend from a surface location, e.g., a platform to the subsea equipment. Such umbilicals may be relatively large in size and they can be very expensive to manufacture and install. 
     The present application is directed to various embodiments of a novel subsea pipeline system and utilities that comprise multiple pre-fabricated and pre-positioned access nodes or tie-in locations that may be accessed on an as-needed basis that may eliminate or at least minimize some of the problems noted above. 
     SUMMARY 
     The following presents a simplified summary of the subject matter disclosed herein in order to provide a basic understanding of some aspects of the information set forth herein. This summary is not an exhaustive overview of the disclosed subject matter. It is not intended to identify key or critical elements of the disclosed subject matter or to delineate the scope of various embodiments disclosed herein. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later. 
     The present application is generally directed to various embodiments of a novel subsea pipeline system that comprises multiple access nodes or tie-in locations that may be accessed on an as-needed basis. In one example, the system comprises a pipeline and a plurality of access node structures axially spaced apart from one another along the pipeline, wherein each of the plurality of access node structures comprises a substantially planar upper surface. 
     In another example, a method disclosed herein comprises deploying a pipeline that comprises a plurality of future access node structures, wherein, at the time the pipeline is deployed subsea, the future access node structures prevent access to an interior of the pipeline, and wherein the plurality of access node structures comprises at least one of a tapping structure, a pressure-barrier retaining structure that is adapted to receive a pressure-barrier device and a pressure-barrier retaining structure comprised of a recess with a scored pressure-retaining bottom. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain aspects of the presently disclosed subject matter will be described with reference to the accompanying drawings, which are representative and schematic in nature and are not be considered to be limiting in any respect as it relates to the scope of the subject matter disclosed herein: 
         FIG. 1  depicts one illustrative embodiment of a subsea pipeline system disclosed herein for producing hydrocarbon-containing fluids from a subsea reservoir and/or introducing various fluids into the reservoir or various items of equipment positioned subsea; 
         FIGS. 2A and 2B  are, respectively, an end view and a cross-sectional side view of a portion of a pipeline that depicts various illustrative structures associated with an illustrative example of an access node structure that is located at a future access point on the pipeline; 
         FIGS. 3A and 3B  are, respectively, an end view and a cross-sectional side view of another embodiment of a portion of a subsea pipeline system disclosed herein wherein a thermal insulation material has been positioned around an illustrative example of an access node structure disclosed herein; 
         FIG. 4  depicts an embodiment of a subsea pipeline system disclosed herein where there is no insulation material provided around an illustrative example of an access node structure disclosed herein; 
         FIG. 5A  is an end view and  FIGS. 5B and 5C  are partial cross-sectional side views of a portion of the pipeline that generally depicts how one or more illustrative utility lines may be strapped to the pipeline; 
         FIGS. 6A-6C  are, respectively, perspective, plan and cross-sectional side views of embodiments of illustrative utilities support blocks disclosed herein that may be strapped to the pipeline; 
         FIGS. 7A and 7B  are, respectively, plan and cross-sectional side views of illustrative embodiments of a plurality of fluid tapping support blocks that may be coupled or strapped to the pipeline; 
         FIG. 7C  depicts one illustrative example of an externally threaded tapping structure that may be coupled to a fluid tapping support block; 
         FIG. 8  simplistically depicts an illustrative pipe-laying vessel that may be employed when deploying illustrative embodiments of the subsea pipeline systems disclosed herein; 
         FIGS. 9-12  depict various illustrative examples of how embodiments of the pipelines disclosed herein may be wrapped around a pipeline reel or a pipe-laying vessel; 
         FIGS. 13-22  depict one illustrative method disclosed herein for tapping a pipeline via one access node structure disclosed herein after the pipeline was deployed subsea; 
         FIGS. 23-30  depict one illustrative method for plugging a previously formed tapped opening in the subsea pipeline or, when undertaken in the reverse order depicted in  FIGS. 23-30 , an illustrative method of removing a previously installed plug for gaining access into a pipeline via one of the illustrative access node structures disclosed herein; 
         FIGS. 31-37  depict other illustrative embodiment of access node structures disclosed herein that may be employed on a subsea pipeline; and 
         FIGS. 38-39  depict one illustrative example of the flexibility provided by use of various embodiments of a pipeline system disclosed herein. 
     
    
    
     While the subject matter disclosed herein is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the disclosed subject matter to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosed subject matter as defined by the appended claims. 
     DESCRIPTION OF EMBODIMENTS 
     Various illustrative embodiments of the disclosed subject matter are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
     The present subject matter will now be described with reference to the attached figures. Various structures, systems and devices are schematically depicted in the drawings for purposes of explanation only and so as to not obscure the present disclosure with details that are well known to those skilled in the art. Nevertheless, the attached drawings are included to describe and explain illustrative examples of the present disclosure. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than that understood by skilled artisans, such a special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase. 
       FIG. 1  depicts one illustrative embodiment of a subsea pipeline system  11  disclosed herein that may be employed in performing a variety of operations as it relates to the general process of producing hydrocarbon-containing fluids  18  from a subsea reservoir  10 . In general, in one illustrative embodiment, the subsea pipeline system  11  generally comprises a pipeline  12  with a plurality of future access nodes  14  spaced along the pipeline  12 . In another embodiment, the system  11  may also comprise a plurality of utility lines  15  that are coupled, e.g., strapped to the pipeline  12 . The utility lines  15  may include a variety of different utilities, including but not limited to, electrical power lines, electrical heating lines, chemical or liquid flow lines, electrical communication lines, fiber optic lines, control lines (electrical and/or hydraulic), etc. As will be appreciated by those skilled in the art after a complete reading of the present application, in one illustrative embodiment, the pipeline  12  may be used to receive and transport production fluid from various wells positioned subsea to a production facility. In another embodiment, water may be introduced into the pipeline  12  and ultimately introduced into one or more of the wells drilled in the reservoir  10 . Thus, in the broadest sense, the pipeline  12  may be employed to receive any type of fluid (gas or liquid; single phase or multiple phase) from the reservoir  10  or from any equipment positioned subsea. Similarly, the pipeline  12  may be employed to introduce any type of fluid (gas or liquid; single phase or multiple phase) into the reservoir  10 . The utility lines  15  may be used to supply one or more utilities (e.g., any fluids, controls or electrical power) to one or more items of equipment positioned subsea. For example, various chemicals in one or more of the utility lines  15  may be introduced into the wells drilled in the reservoir  10  or into any equipment positioned subsea. 
     The discussion below will primarily focus on the situation where the pipeline  12  is employed to receive production fluid from the reservoir  10  and transmit the production fluid to a production facility. However, as noted above, the novel system disclosed herein is not to be considered to be limited to this illustrative example. Additionally, depending upon the particular application, the pipeline  12  may be accessed (via one of the access nodes  14 ) when the pipeline  12  has a relatively high internal operating pressure, i.e., when the pipeline  12  is in operation, or when the pipeline  12  is non-operational, i.e., when the internal pressure within the pipeline  12  is at, above or below hydrostatic pressure. 
     The access nodes  14  may be accessed on an as needed basis (by performing various activities described more fully below) during the course of the development of the field. That is, in one example, as additional wells are drilled into the reservoir  10  over several years, one or more of the access nodes  14  may be accessed on an as-needed basis so as to permit production fluid from the additional wells to be introduced into the pipeline  12 . The number and spacing of the access nodes  14  along the pipeline  12  may vary depending upon the particular application and a variety of factors such as, for example, the overall physical size of the reservoir  10 . The access nodes  14  may be approximately equally spaced from one another along the pipeline  12  (as depicted in  FIG. 1 ) or they may be randomly and/or unequally spaced and positioned along the pipeline  12 . The position of the access nodes  14  along the pipeline  12  may be indicated by appropriate markings, e.g., painted lines and/or painted numbers on the outside of the pipeline  12  or the insulation positioned around the pipeline  12 . Ultimately, as noted above, the hydrocarbon-containing fluids  18  produced from the reservoir  10  will flow through the pipeline  12  to a production facility, such as for example, a floating production vessel (not shown), a production facility located on a platform (not shown), an on-shore production facility (not shown) or a subsea production facility or item of equipment (not shown). 
     The physical size of the pipeline  12  may also vary depending upon the particular application. The spatial positioning of the subsea pipeline system  11  relative to the reservoir  10  may also vary depending upon the particular application and a variety of factors such as, for example, the anticipated location of various wells that will be drilled into the reservoir  10 . In the example depicted in  FIG. 1 , the subsea pipeline system  11  is positioned such that the centerline of the pipeline  12  is positioned in the approximate middle of the reservoir  10 . In other applications, the subsea pipeline system  11  may be positioned adjacent one side of the reservoir  10  or it may be positioned, in whole or part, completely outside of the area defined by the reservoir  10 . The pipeline  12  may be made of a variety of different materials that are commonly used in the production of hydrocarbon-containing fluids such as, for example, carbon steel. 
     As noted above, in the illustrative example depicted in  FIG. 1 , the subsea pipeline system  11  also comprises illustrative and schematically depicted utility lines  15  that are coupled to the pipeline  12  by straps (not shown). As will be appreciated by those skilled in the art after a complete reading of the present application, the utility lines  15  are intended to be representative of any of a variety of different utilities that may be provided to equipment positioned subsea so as to allow operation, control and monitoring of the subsea equipment so as to produce hydrocarbon-containing fluids  18  from the reservoir  10  or introduce one or more fluids into the reservoir  10  and/or any subsea equipment. As noted above, the utility lines  15  may include, among other things, electrical power lines, electrical heating lines, chemical or liquid flow lines, electrical communication lines, fiber optic lines, control lines (electrical and/or hydraulic), etc. The number, size and location of such utility lines  15  that may be part of the overall subsea pipeline system  11  may vary depending upon the particular application. However, as will be appreciated by those skilled in the art after a complete reading of the present application, in some embodiments, the utility lines  15  may be omitted from the subsea pipeline system  11 , and the utilities needed by various items of subsea equipment to produce hydrocarbon-containing fluids  18  from the reservoir  10  may be supplied by one or more traditional bundled umbilical lines (not shown) that extend from a surface structure, such as a platform, to the equipment on the sea floor. 
     In one illustrative example, the subsea pipeline system  11  may be installed or positioned above the reservoir  10  at a very early point during the process of developing the reservoir  10 . In effect, the subsea pipeline system  11 , with the plurality of access nodes  14  positioned therein, may constitute a primary pipeline or production backbone for the overall reservoir  10 . In general, the development of the reservoir  10  will likely grow or increase over the years, i.e., additional wells will be drilled into the reservoir  10  and/or additional subsea processing equipment will be positioned above or adjacent the reservoir  10  to produce all of the hydrocarbon-containing fluids  18  from the various wells drilled into the reservoir  10 . The hydrocarbon-containing fluids  18  produced from these additional wells may be tied into the pipeline  12  by accessing (using one or more of the techniques and devices described more fully below) one or more of the access nodes  14  such that the produced hydrocarbon-containing fluids  18  will flow through the pipeline  12  to the final production facility. The utilities for these additional wells and/or additional subsea equipment may also be provided by coupling to or accessing one or more of the utility lines  15  (as described more fully below) that are coupled to the pipeline  12 . 
     Still referencing  FIG. 1 , various items of subsea production equipment  16 A- 16 F (generally referenced using the numeral  16 ) that are schematically depicted in  FIG. 1  may be positioned subsea and operatively coupled to the pipeline  12  at any desired point in time by accessing one or more of the access nodes  14  on an as-needed basis. The production equipment  16  should be understood to be representative of any type of equipment that may be positioned subsea and assist in at least some manner with the production of the hydrocarbon-containing fluids  18  from the reservoir  10 . For example, the production equipment  16  may comprise, among other things, a Christmas or production tree, a flow manifold, a subsea separator vessel, the outlet of a subsea pump, the inlet of a subsea pump, another pipeline (not shown), a PLET (inline or not inline), skid mounted equipment, etc. Each schematically depicted item of subsea production equipment  16 A- 16 F should be understood to be representative of one or more items of subsea equipment. 
     In the example depicted in  FIG. 1 , the production equipment  16 A is the initial production equipment that was installed for the first well drilled in the reservoir  10 , and the subsea production equipment  16 A was installed at or about the same time as the subsea pipeline system  11  was laid or positioned above the reservoir  10 . As indicated, the subsea production equipment  16 A was directly coupled to the pipeline  12  by the schematically depicted flow line  17  via a plurality of mating flanges (not shown). That is, the initial subsea production equipment  16 A was not operatively coupled to the pipeline  12  by accessing one of the access nodes  14 , although such a situation could occur in some applications. 
     As also depicted in  FIG. 1 , one or more utilities were provided to the production equipment  16 A by accessing the utility lines  15 , as indicated by the solid curved line  19 . After the installation of the initial subsea production equipment  16 A, the additional items of subsea production equipment  16 B- 16 F were sequentially positioned above the reservoir  10  over a period of time as the development of the reservoir  10  was continued, i.e., as additional wells were drilled into the reservoir  10 . The items of subsea production equipment  16 B- 16 F are depicted in dashed lines so as to reflect the positioning of these additional items of subsea production equipment  16 B- 16 F above the reservoir  10  over time. As each of these additional items of subsea production equipment  16 B- 16 F are positioned subsea, they will be operatively coupled to the pipeline  12  by accessing the pipeline  12  via one or more of the access nodes  14 , as simplistically depicted by the dashed lines  21 . One or more utilities may be provided to each of these additional items of subsea production equipment  16 B- 16 F by accessing the utility lines  15 , as indicated by the dashed curved line  23 . 
     In general, various techniques and devices may be employed to access the pipeline  12  at the access nodes  14 . Each of the access nodes  14  comprises an access node structure  14 X that, in one embodiment, may be formed integral with the pipeline  12  prior to positioning the pipeline  12  subsea. The access node structure  14 X may take a variety of different forms and may employ different techniques and devices to gain access to the pipeline  12  via one of the access nodes  14 . In one illustrative example, the access node structure  14 X takes the form of a tapping structure  20  that is adapted to allow tapping (hot or cold) of the pipeline  12  by performing various machining activities. 
       FIGS. 2A and 2B  are, respectively, an end view and a cross-sectional side view of a portion of the pipeline  12  and an illustrative example of various structures associated with an illustrative tapping structure  20  that is positioned at one or more of the access nodes  14 . As indicated, in one illustrative embodiment, the tapping structure  20  is integrally formed with an access node section of pipe  12 A (with a centerline  12 B) of the pipeline  12 . The access node section of pipe  12 A is adapted to be coupled to (e.g., welded to) other sections  12 X,  12 Y of the pipeline  12 . The other sections  12 X,  12 Y of the pipeline  12  may or may not comprise tapping structures  20 . 
     In some applications, the access node section of pipe  12 A may be coupled to the other sections (e.g.,  12 X,  12 Y) of the pipeline at an on-shore location so as to establish a substantially continuous pipeline  12  with several of the tapping structures  20  spaced apart along the continuous pipeline  12 . At that point, as described more fully below, the substantially continuous pipeline (with the tapping structures  20 ) may be positioned on or wrapped around a reel of a pipe-laying vessel, as described more fully below. In other applications, the pipeline  12  may be substantially completely fabricated aboard a pipe-laying vessel by welding the access node sections of pipe  12 A (with the tapping structure  20  attached thereto) into position between other sections of the pipeline  12  that may or may not comprise a tapping structure  20 . In either situation—the fabrication of a substantially continuous pipeline on-shore or the fabrication of the pipeline  12  on a section-by-section basis on board a pipe-laying vessel—the pipeline  12  will be deployed into the sea and positioned on the sea floor at the desired location relative to the reservoir  10  as the sea-going pipe-laying vessel moves above the reservoir  10 . In one particular application, and as described more fully below, at the same time the pipeline  12  is being deployed off of the pipe-laying vessel into the sea, one or more utility lines  15  may be strapped to the pipeline  12  and deployed into the sea along with the pipeline  12 . The axial length  12 L of the access node section of pipe  12 A may vary depending upon the application. In one illustrative embodiment the axial length  12 L may be about 1-3 m. The tapping structure  20  may be comprised of the same material as that of the pipeline  12  or it may be made of a different material than that of the pipeline  12 . 
     Still referencing  FIGS. 2A-2B , the tapping structure  20  may take a variety of different forms or configurations, and the physical size of the tapping structure  20  may vary depending upon the particular application. In the illustrative examples depicted herein, the tapping structure  20  has a generally rectangular configuration (when viewed from above) with a lateral width  20 W and an axial length  20 L. However, it is not required that all of the tapping structures  20  on the pipeline  12  be of the same size and configuration, although that may be the case in some applications. The tapping structure  20  may be sized such that it has a relatively small projection  20 D above the outer surface of the pipeline  12 . In the depicted example, the tapping structure  20  comprises a substantially planar upper surface  22  and an alignment/coupling recess  24  defined in the body of the tapping structure  20 . In other embodiments, the alignment/coupling recess  24  may be omitted. In yet other embodiments, the tapping structure  20  may comprise a plurality of alignment/coupling recesses that are adapted to facilitate alignment of a machining tool that is to be coupled to the access node structure  14 X, wherein the machining tool is adapted to be used to machine an opening that extends through the access node structure  14 X and provides fluid access to the internal of the pipeline  12 . In one illustrative embodiment, the alignment/coupling recess  24  may have a generally circular configuration when viewed from above. The depth of the alignment/coupling recess  24  may also vary depending upon the particular application. However, the depth of the alignment/coupling recess  24  should be controlled such that there is enough material  20 M remaining below the bottom of the alignment/coupling recess  24  to withstand all anticipated forces (e.g., pressure and/or mechanical forces) to be applied to the tapping structure  20  during, for example, installation, commissioning, operation and abandonment of the pipeline  12 . 
     As indicated in  FIG. 2B , the tapping structure  20  may be sized such that the substantially planar upper surface  22  is located a desired vertical distance  20 H above the centerline  12 B of the pipeline  12 . The tapping structure  20  may be forged with a machined inner surface  20 S that matches the inner surface of the pipeline  12 , wherein the tapping structure  20  is welded into an opening cut in the pipeline  12 . In other applications, the tapping structure  20  may simply be welded into position on the outside surface of the pipeline  12 . In one embodiment, the lateral width  20 W of the tapping structure  20  may be less than the outside diameter of the pipeline  12  to facilitate wrapping a continuous pipeline  12  of a reel of a pipe-laying vessel, as described more fully below. In general, as noted above, the physical dimensions of the tapping structure  20  may vary depending upon the particular application. However, in one illustrative embodiment, the lateral width  20 W may be as small as about one-half the outside diameter of the pipe  12  but no greater than the outside diameter of the pipe  12 . In one illustrative example, the axial length  20 L of the tapping structure  20  may be about 0.5-3 m. In one illustrative embodiment, the projection  20 D may be approximately equal to the wall thickness of the pipe  12  up to about double the outside diameter of the pipe  12 . With reference to  FIG. 2A , when the pipeline  12  is positioned on the sea floor, the planar upper surface  22  will ideally be oriented substantially normal to the vertical. However, such exact precision in the orientation of the planar upper surface  22  is not required, i.e., in one illustrative embodiment, the pipeline  12  may be rotated plus or minus about 15 degrees (and preferably at most about 5 degrees) as represented by the arrows  12 Z and still function as intended. 
       FIGS. 3A and 3B  are, respectively, an end view and a cross-sectional side view of another embodiment of a portion of a subsea pipeline system  11  disclosed herein. In this example, relative to the embodiment shown in  FIGS. 2A-2B , thermal insulation material  26  has been positioned around the pipeline  12  and an illustrative tapping structure  20 . Also depicted are various utility lines  15  that have been strapped to the outside of the pipeline  12  as it was deployed into the sea. As noted above, the utility lines  15  may provide various utilities to the equipment positioned on the sea floor and/or perform various functions. For example, in the depicted example, electrical heating lines  28 , electrical power lines  30 , liquid (e.g., chemical) supply lines  32  and fiber optic communications lines  34  are strapped to the pipeline  12 . Note that, in the depicted example, there are redundant lines for the various utilities  15 . Of course, the number, size, location and functions of the various utility lines  15  strapped to the pipeline may vary depending upon the particular application. Additionally, in some embodiments, although one or more utility lines  15  are coupled to the pipeline  12 , additional utilities may be provided to subsea equipment positioned adjacent the pipeline  12  by one or more traditional umbilicals (not shown) on either a permanent or temporary basis. 
       FIG. 4  depicts an embodiment of a subsea pipeline system  11  wherein there is no insulation material  26  provided on the pipeline  12 . In this example, the utility lines  15  include the above-mentioned electrical power lines  30 , liquid (e.g., chemical) supply lines  32  and fiber optic communications lines  34  that have been strapped to the pipeline  12 . In this example, the electrical heating lines  28  have been omitted. 
       FIG. 5A  is a cross-sectional view of a portion of the pipeline  12  taken across the diameter of the pipeline  12 .  FIG. 5B  is a partial cross-sectional side view (with the tapping structure  20  omitted) taken through the centerline  12 B of the pipeline  12 . The figures will be referenced to generally describe one illustrative technique for attaching the utility lines  15  to the pipeline  12  and how the electrical power lines  30  may be accessed as equipment is periodically installed subsea so as to supply electrical power to the equipment. In this example, the subsea pipeline system  11  comprises the above-mentioned insulation material  26 , the electrical heating lines  28  and the electrical power lines  30  that were all attached to the pipeline  12  at the time the subsea pipeline system  11  was being lowered into the sea. 
     In one illustrative embodiment, at some point in time after the subsea pipeline system  11  was positioned subsea, additional equipment (not shown) was positioned subsea so as to continue the development of the reservoir  10 . For example, after the original subsea pipeline system  11  was first positioned subsea, a decision was made to drill another well into the reservoir and associated production equipment, such as a Christmas tree (i.e., a production tree) was positioned on the latest well. With reference to  FIGS. 5A and 5B , electrical power for such subsea equipment may be supplied by use of an induction coupling clamp  36  that is positioned around a portion of one of the electrical power lines  30 . The structure, function and operation of such induction coupling clamps are well known to those skilled in the art. The leads  36 A,  36 B may be coupled to the newly-added subsea equipment. To the extent that the portion of the electrical power line  30  that is to be accessed is covered by insulation material  26 , such insulation material  26  may be removed by use of an ROV. The installation of the induction coupling clamp  36  and the coupling of the leads  36 A,  36 B to the subsea equipment may also be accomplished by use of an ROV. Of course, a fiber tapping device (not shown) may be positioned around a portion of one of the fiber optic communications lines  34  (not shown in the  FIG. 5  drawings) so as to provide a communications link with the newly-added subsea equipment. 
       FIGS. 5B and 5C  depict one illustrative example of a utilities support block  38  that may be used when coupling the utility lines  15  to the pipeline  12 . In this example, the utilities support block  38  comprises an open-ended slot  38 A and a strap recess  38 B.  FIG. 5B  includes a cross-sectional view of the utilities support block  38  taken through the center of the slot  38 A in a direction parallel to the centerline  12 B of the pipeline  12 .  FIG. 5C  is a cross-sectional view of the utilities support block  38  taken through the slot  38 A in a direction that is transverse to the centerline  12 B of the pipeline  12 . After the electrical power line  30  is positioned within the slot  38 A, a band or strap  40  is wrapped about the pipeline  12  and positioned within the strap recess  38 B. In this embodiment, the strap  40  insures that the electrical power line  30  remains positioned within the slot  38 A. The strap recess  38  insures that the strap  40  remains in position above the slot  38 A. Of course, the utilities support block  38  may comprise any desired number of such slots  38 A to accommodate the desired number and size of the various utility lines  15  that are coupled to the pipeline  12 . 
       FIGS. 6A-6C  are, respectively, perspective, plan and cross-sectional side views of embodiments of the illustrative utilities support blocks  38  (with various utility lines  15  positioned therein) that may be strapped to the pipeline  12  using the depicted strap or band  40 .  FIG. 6A  depicts one illustrative utilities attachment location  41  along the pipeline  12  where three illustrative utilities support blocks  38  have been strapped to the pipeline  12  using the band or strap  40 . Of course, any desired number of such utilities support blocks  38  may be employed at each utilities attachment location  41 . The number and spacing of the utilities attachment locations  41  along the pipeline  12  may vary depending upon the particular application and a variety of factors. The utilities attachment locations  41  may be equally spaced from one another along the pipeline  12  or they may be randomly and/or unequally spaced and positioned along the pipeline  12 . The position of the utilities attachment location  41  along the pipeline  12  may be indicated by appropriate markings, e.g., painted lines and/or painted numbers on the outside of the pipeline  12  or the insulation positioned around the pipeline  12 . In this example, each of the utilities support blocks  38  comprises a plurality of open-ended slots  38 A and an above-described strap recess  38 B. Any of the above-mentioned utility lines  15 , e.g., the lines  30 ,  32 ,  34 , etc., may be positioned in the slots  38 A. In the case wherein heating elements  28  are employed, the heating elements  28  may be positioned so as to contact the outer surface of the pipeline  12  for more effective heat transfer. In such a situation, the heating elements  28  may be positioned in downward facing open-ended slots (not shown) formed in the utilities support blocks  38 . As best seen in  FIG. 6C , in this example, a hinge  39  is provided between adjacent utilities support blocks  38  so as to couple the utilities support blocks  38  to one another and to allow the group of the three utilities support blocks  38  to approximately conform to the outer surface of the pipeline  12 . 
       FIGS. 7A and 7B  are, respectively, plan and cross-sectional side views of illustrative embodiments of a plurality of fluid tapping support blocks  70  that are also adapted to be coupled or strapped to the pipeline  12  at various fluid tapping attachment locations  43  along the pipeline  12 . The fluid tapping support blocks  70  may comprise one or more openings  74  that are adapted to receive a liquid-carrying utility line  15 , e.g., the above-mentioned liquid (e.g., chemical) supply line  32 . The illustrative fluid tapping support blocks  70  (with various liquid-carrying utility lines  15  positioned therein) may be strapped to the pipeline  12  using a strap or band (not shown in the  FIG. 7  drawings) such as the above-depicted strap or band  40 . Strap recesses (not shown in the  FIG. 7  drawings) similar to the above-described strap recesses  39  may also be formed in the fluid tapping support blocks  70 . 
       FIGS. 7A-7B  depict illustrative fluid tapping attachment locations  43  along the pipeline  12  where three illustrative fluid tapping support blocks  70  have been strapped to the pipeline  12 . Of course, any desired number of such fluid tapping support blocks  70  may be employed at each fluid tapping attachment location  43 . The number and spacing of the fluid tapping attachment locations  43  along the pipeline  12  may vary depending upon the particular application and a variety of factors. The fluid tapping attachment locations  43  may be equally spaced from one another along the pipeline  12  or they may be randomly and/or unequally spaced and positioned along the pipeline  12 . The position of the fluid tapping attachment locations  43  along the pipeline  12  may be indicated by appropriate markings, e.g., painted lines and/or painted numbers on the outside of the pipeline  12  or the insulation positioned around the pipeline  12 . In this example, each of the fluid tapping support blocks  70  comprises only a single opening  74  that is drilled through the block  70 . In practice, each of the fluid tapping support blocks  70  may comprise any desired number of such openings  74 . In the depicted example, each of the fluid tapping support blocks  70  comprises a drilled and tapped opening  76  that is positioned so as to expose and provide access to a portion of the liquid-carrying utility line  15  positioned within the opening  74 . As best seen in  FIG. 7B , in this example, a hinge  72  is provided between adjacent fluid tapping support blocks  70  so as to couple the fluid tapping support blocks  70  to one another and to allow the group of the three fluid tapping support blocks  70  to approximately conform to the outer surface of the pipeline  12 . 
     In one illustrative example, a liquid-carrying utility line  15  is positioned within the opening  74  in the fluid tapping support blocks  70 . A seal may be formed between the liquid-carrying utility line  15  and the fluid tapping support blocks  70  at the ends of the opening  74 . Such a seal may be effectuated in a variety of different ways, e.g., by welding, swaging, heat-expansion, threading, etc. 
     In one illustrative embodiment, as shown in  FIG. 7C , the tapped opening  76  is adapted to threadingly receive an externally threaded tapping structure  80  (the external threads being indicated by the reference numeral  82 ). In one illustrative embodiment, the tapping structure  80  comprises a plurality of wrench flats  81  and a fluid passageway  86  that extends through the body of the tapping structure  80 . A pointed end  84  is provided at one end of the fluid passageway while a fluid outlet  88  is provided at the opposite end of the fluid passageway  86 . 
     In one illustrative process, when the combination of the fluid tapping support blocks  70  with the liquid-carrying utility line  32  positioned therein is initially strapped to the pipeline  12 , the tapping structure  80  is partially threaded into the opening  76  such that a seal is established between the tapping structure  80  and the opening  76  due to the interactions of the threads. In this initially installed position, the tapping structure  80  does not extend into the opening  76  a sufficient depth such that the pointed end  84  of the tapping structure  80  engages and penetrates the liquid-carrying utility line  32 . The combination of the pipeline  12  with the attached fluid tapping support blocks  70  is then lowered into the sea with the tapping structure  80  in this initial, non-penetrating position within the opening  76  in the fluid tapping support blocks  70 . 
     At some point later in time it may be desirable to tap the liquid-carrying utility line  32  so as to provide a fluid, e.g., a chemical, in the liquid-carrying utility line  32  to an item of subsea equipment (either recently installed or previously installed) positioned near the pipeline  12 . At that time, an ROV may be used to turn the tapping structure  80  so as to force it further into the opening  76  in the fluid tapping support blocks  70 . This process continues until such time as the pointed end  84  of the tapping structure  80  engages and penetrates the liquid-carrying utility line  32  thereby allowing fluid (as represented by the arrow  89 ) from within the liquid-carrying utility line  32  to flow into the passageway  86  and out of the fluid outlet  88 . A suitable conduit (not shown) may be provided between the fluid outlet  88  and the subsea equipment. An illustrative seal  90  is provided between the tapping structure  80  and the fluid tapping support block  70  such that a fluid tight seal is established when the tapping structure  80  is in this fully-inserted and line-penetrating position. Of course, the illustrative example of the tapping structure  80  is provided by way of example only and other forms of tapping structures may be employed such as, for example, a push-fit hydraulic snap-in connector, a banjo type fitting, etc. 
     In other embodiments, the liquid-carrying utility line  32  may be penetrated on board the pipe-laying vessel after the liquid-carrying utility line  32  has been positioned in the fluid tapping support block  70  and sealed therein. Thereafter, a simple threaded plug (not shown) may be positioned in the tapped opening  76 . The plug may be removed at a later date when access to the liquid-carrying utility line  32  is needed. 
     As indicated above, in one illustrative embodiment, the pipeline disclosed herein may take the form of a continuous pipeline  12  with several of the access nodes  14  spaced apart along the continuous pipeline  12  that is adapted to be positioned on or wrapped around a pipeline reel  64  of a pipe-laying vessel  50 .  FIG. 8  simplistically depicts an illustrative pipe-laying vessel  50  that is positioned above a body of water  52 . The vessel  50  comprises an opening  54  through which the pipeline  12  (that includes a plurality of illustrative access node structures  14 X, such as the illustrative tapping structures  20 ) may be deployed into the water. In some embodiments, the pipeline system  11  may also comprise a plurality of utility lines  15  that are attached to the pipeline  12  as the pipeline is un-reeled from the pipeline reel  64  wherein the combination of the pipeline  12  (that includes a plurality of access node structures  14 X) and the utility lines  15  attached to the pipeline  12  are deployed into the water  52  at the same time via the opening  54 . 
     In one illustrative embodiment, the pipe-laying vessel  50  comprises a structural support mechanism  56 , a pipeline straightener mechanism  58 , a pipeline tensioner mechanism  60  and a pipeline aligner mechanism  62 . As depicted, in one illustrative embodiment, the pipeline  12  (that includes a plurality of access node structures  14 X) is wrapped around the pipeline reel  64  prior to being deployed in the water  52 . In general, and as will be appreciated by those skilled in the art after a complete reading of the present application, when the pipeline  12  is initially wrapped around the pipeline reel  64 , the pipeline  12  undergoes plastic deformation such that it maintains its generally circular “as-reeled” configuration when it is positioned on the pipeline reel  64 . When the pipeline  12  is deployed or “un-wrapped” from the pipeline reel  64 , the pipeline  12  will again be plastically deformed into a substantially linear configuration as it is un-wound from the pipeline reel  64  and passes through the pipeline aligner  62 , the pipeline straightener  58  and the pipeline tensioner  60  in route to the opening  54  in the pipe-laying vessel  50 . 
     As noted above, in one illustrative embodiment, the pipeline system  11  may also comprise one or more of the above-described utility lines  15  that are positioned on or wrapped around a separate utilities reel  66 . The utilities reel  66  is also mechanically supported on the vessel  50  by various support structures (not shown). In the illustrative example where the utility lines  15  comprises one or more of the liquid (e.g., chemical) supply lines  32  with the associated fluid tapping support blocks  70 , the utility lines  15  may be wrapped around the utilities reel  66  in a manner similar to that described below with respect to the wrapping of the pipeline  12  around the pipeline reel  64 . In one particularly illustrative embodiment, all of the utility lines  15  (including those with the associated fluid tapping support blocks  70 ) that will be attached or coupled to the pipeline  12  (via strapping) are wrapped around a single utilities reel  66 . In other applications, a separate fluid-carrying utilities reel (not shown) may be provided so as to allow the wrapping of any or all of the fluid-carrying utility lines  32  (with the associated fluid tapping support blocks  70 ) around this separate fluid-carrying utilities reel. Of course, as will be understood by those skilled in the art after a complete reading of the present application, any number of loaded pipeline reels  64  (with the pipeline  12  that includes a plurality of access node structures  14 X) may be positioned on the pipe-laying vessel  50 . After a first of the loaded pipeline reels  64  is “emptied” by deploying the pipeline  12  (that includes a plurality of access node structures  14 X) into the water  52 , additional pipeline  12  (that includes a plurality of access node structures  14 X) from a second loaded pipeline reel  64  may be welded to the end of the previously deployed pipeline  12  so as to permit substantially continuous introduction of the pipeline  12  into the water  52  via the opening  54 . 
     As noted above, in one illustrative example, the pipeline system  11  may comprise one or more utility lines  15  that are adapted to be coupled to the pipeline  12  (that includes a plurality of access node structures  14 X) prior to deploying the combination of the pipeline  12  and the one or more utility lines  15  into the water  52  via the opening  54  in the vessel  50 . In one illustrative embodiment, after the pipeline  12  (that includes a plurality of access node structures  14 X) exits the pipeline tensioner  60 , workers on board the pipe-laying vessel  50  position or guide one or more of the utility lines  15  from the separate utilities reel  66  into the openings or slots  38 A in one or more of the above-described utilities support blocks  38  that have been positioned around or adjacent an exterior surface of the pipeline  12 . After positioning the utility lines  15  in the slots  38 A, workers on board the vessel  50  strap the utilities support blocks  38  into position at one of the utilities attachment locations  41  along the pipeline  12  by wrapping the above-described strap  40  around the utilities support blocks  38  so as to insure that the utility lines  15  are “trapped” or maintained within the open-ended slots  38 A within the utilities support blocks  38 . 
     In another illustrative embodiment wherein the utility lines  15  that are to be attached to the pipeline  12  comprise one or more liquid-carrying utility lines  15  (such as the chemical line  32 ), workers on board the vessel  50  may also attach the above-described fluid tapping support blocks  70  to the pipeline  12  at fluid tapping attachment locations  43  by strapping the fluid tapping support blocks  70  (with the liquid-carrying utility line  15  welded into position therein) around the pipeline  12 . In one embodiment, all of the utility lines  15  (including the liquid-carrying utility line  32 ) are positioned on the same utilities reel  66 . In other applications, due to the presence of the fluid tapping support blocks  70  on the liquid-carrying utility line  32 , the liquid-carrying utility line  32  may be wrapped around a separate reel (not shown). In one illustrative embodiment, after the pipeline  12  (that includes a plurality of access node structures  14 X) exits the pipeline tensioner  60 , workers on board the pipe-laying vessel  50  position or guide one or more of the liquid-carrying utility lines  15  (such as the chemical line  32 ) from the separate utilities reel  66  (or another separate reel) adjacent an exterior surface of the pipeline  12  and thereafter strap or secure the fluid tapping support blocks  70  into position at one of the fluid tapping attachment locations  43  along the pipeline  12  by wrapping the above-described strap  40  around the fluid tapping support blocks  70 . At that point, workers on board the pipe-laying vessel  50  may install the above-described externally threaded tapping structure  80  in its initial, non-penetrating position within the tapped opening  76  in the fluid tapping support block  70 . At that point, in this illustrative embodiment, the illustrative pipeline system  11  comprised of the combination of the pipeline  12  (that includes a plurality of access node structures  14 X), the utility lines  15  installed in the utilities support blocks  38  (as strapped to the pipeline  12 ) and the liquid-carrying utility line  15  positioned within the fluid tapping support blocks  70  (as strapped to the pipeline  12 ) are deployed as a single unit into the water  52  via the opening  54  in the pipe-laying vessel  50 . 
     Of course, as will be appreciated by those skilled in the art after a complete reading of the present application, in another illustrative embodiment, the access node structures  14 X may be omitted from the pipeline system  11 , and only the utility lines  15  may be attached to the pipeline  12  as it is deployed subsea. 
       FIGS. 9-12  depict various illustrative examples of how the continuous pipeline  12  (that includes a plurality of illustrative access node structures  14 X, such as the illustrative tapping structures  20 ) may be wrapped around the pipeline reel  64 . The pipeline reel  64  comprises flanges  64 A and the reel has a diameter of about 54 m.  FIG. 9  depicts the pipeline system  11  at a point in time wherein an initial section  12 - 1  of the pipeline  12 , a section without the access node structures  14 X, i.e., a “clean” section of the pipeline  12 , has been wrapped around the pipeline reel  64  so as to define a first layer of the pipeline  12 . As depicted, the first layer  12 - 1  of the pipeline  12  is substantially uniformly positioned around the reel  64  both in terms of lateral spacing (if any) between the laterally adjacent portion of the wrapped pipeline  12  as well as the height  12 H 1  (or radial distance) of the outermost surfaces of the portions of the pipeline  12  in this first layer  12 - 1  of wrapped pipeline  12  relative to a centerline  64 B of the pipeline reel  64 . 
       FIG. 10  depicts the pipeline system  11  at a point in time wherein another section of the pipeline, a section that includes a plurality of the illustrative tapping structures  20 , has been wrapped around the pipeline reel  64  so as to define a second layer  12 - 2  of the pipeline  12 . As depicted, the second layer  12 - 2  of the pipeline  12  is substantially uniformly positioned around the reel  64  in terms of lateral spacing (if any) between the laterally adjacent portions of the wrapped pipeline section  12 - 2 . The outer surfaces of the portions of the second layer  12 - 2  of the pipeline  12  that do not include any of the tapping structures  20  are also located a substantially uniform height or radial distance  12 H 2  from the centerline  64 B of the pipeline reel  64 . As depicted, in this illustrative example, the centerlines of the tapping structures  20  on adjacent wraps of the second layer  12 - 2  of the pipeline  12  are laterally offset from one another (as indicated by the dimension  12 L) and vertically offset from one another on adjacent wraps of the pipeline section  12 - 2  (as indicated by the dimension  12 V). The magnitude of the dimensions  12 L,  12 V may vary depending upon the particular application. In one illustrative example, where the nominal diameter of the pipe of the pipeline  12  has a diameter of about 150-450 mm, the second layer  12 - 2  of the pipeline  12  comprises eighteen of the tapping structures  20  that are axially spaced apart from one another along the pipeline  12  by about 50 m. Additional sections of pipeline  12  (not shown) that comprise the tapping structures  20  may be wrapped around the reel  64  on top of the section  12 - 2 . If needed, a steel cover (not shown) may be provided between the wrapped layers of the pipeline  12  that comprise the tapping structures  20  to smooth out the “bumps” in the reeled pipeline  12  due to the presence of the tapping structures  20 . In some cases, the very outermost sections of the pipeline  12  wrapped on the reel may be clean portions of the pipeline that do not include any tapping structures  20 . 
       FIGS. 11 and 12  depict an embodiment wherein the axial spacing of the access node structures  14 X, such as the illustrative tapping structures  20 , along the pipeline  12  is approximately the same as the reeling diameter, e.g., the outer diameter of all of the previous sections of pipeline wrapped around the reel  66 . As shown in  FIG. 11 , by taking this approach, the tapping structures  20  are positioned in a substantially continuous line or battery that is approximately parallel to the axis of the pipeline reel  64 . More specifically,  FIG. 12  depicts an embodiment wherein second layer  12 - 2  of the pipeline  12  includes a plurality of the tapping structures  20  that have an axial spacing along the pipeline of about 53.2 m. The first section of pipeline (not shown in  FIG. 11 ) is free of the tapping structures  20 .  FIG. 12  is a side view of the wrapped pipeline  12  with the flanges  64 A on the reel  64  removed after the reel  64  has been completely filled. The wrapped pipeline  12  comprises six wrapped sections  12 - 1  (the innermost section),  12 - 2 ,  12 - 3 ,  12 - 4 ,  12 - 5  and  12 - 6  (the outermost section). The sections  12 - 1  and  12 - 6  are clean sections of the pipeline  12  that are free of the tapping structures  20 . Each of the pipeline sections  12 - 2 ,  12 - 3 ,  12 - 4  and  12 - 5  comprise a plurality of the tapping structures  20 . The plurality of the tapping structures  20  in the sections  12 - 2 ,  12 - 3 ,  12 - 4  and  12 - 5  define lines  20 - 2 ,  20 - 3 ,  20 - 4  and  20 - 5 , respectively, of tapping structures  20  that are oriented substantially parallel to the centerline  64 B of the pipeline reel  64 . As indicated, the lines  20 - 2 ,  20 - 3 ,  20 - 4  and  20 - 5  of tapping structures  20  are positioned at increasing larger radial distances R 2 , R 3 , R 4  and R 5 , respectively, from the centerline  64 . Also note that the lines  20 - 2 ,  20 - 3 ,  20 - 4  and  20 - 5  of tapping structures  20  are angularly spaced from one another around the reel  64  by approximately 90 degrees. In one illustrative example, where the nominal diameter of the pipe of the pipeline  12  has a diameter of about 150-450 mm, the second section  12 - 2  of the pipeline  12  comprises eighteen of the tapping structures  20  that are axially spaced apart from one another along the pipeline  12  by about 53.2 m; the third section  12 - 3  comprises eighteen of the tapping structures  20  with an axial spacing along the pipeline of about 54 m; the fourth section  12 - 4  comprises eighteen of the tapping structures  20  with an axial spacing along the pipeline of about 54.7 m; and the fifth section  12 - 5  comprises eighteen of the tapping structures  20  with an axial spacing along the pipeline of about 55.5 m. 
       FIGS. 13-22  depict one illustrative method disclosed herein wherein the access node structure  14 X is comprised of the above-described tapping structure  20  that is adapted for tapping (hot or cold) the pipeline  12  via one of the access nodes  14  on the pipeline  12  after the pipeline  12  was deployed subsea. In this example, the pipeline is wrapped with the thermal insulation material  26 . Also note that various utility lines  15  that may, in some embodiments, also have been strapped to the pipeline  12  at the time of deployment are not depicted in these drawings. 
       FIG. 13  depicts the use of a cutting tool  100  to remove a portion of the insulating material from above the tapping structure  20  at this particular access node  14 . The cutting tool  100  may be positioned subsea and operated by use of an ROV (not shown). This process operation exposes at least the planar upper surface  22  of the tapping structure  20 . Any residual insulation material  26  within the alignment/coupling recess  24  is also removed at this time. 
       FIG. 14  depicts the pipeline  12  after a CNC machine tool  102  has been landed on the tapping structure  20  and secured in place. The tool  102  may be positioned subsea by use of one or more downlines with visual observation being provided by an ROV. The tool  102  comprises an alignment/clamping structure  104  that is adapted to be aligned with and positioned at least partially within the alignment/coupling recess  24  defined in the tapping structure  20 . Once the tool  102  is properly positioned, expandable portions (not shown) of the alignment/clamping structure  104  are expanded outward so as to secure the CNC machine tool  102  to the tapping structure  20 . Also depicted in  FIG. 14  are tools  106 ,  108  that are adapted to drill and tap openings in the upper surface  22  of the tapping structure  20  so as to facilitate the later attachment of a valve (not shown in  FIG. 14 ) as described more fully below. The tools  106 ,  108  are intended to be representative in nature of any kind of tooling necessary to drill and tap openings. Of course, the number and pattern of any such openings may vary depending upon the particular application. Also depicted in  FIG. 14  is a tool  110  that is adapted to cut a seal recess into the upper surface  22 . Note that the debris from performing these various machining operations may be readily cleaned from above the upper surface  22  as machining progresses. An ROV may be used to supervise and/or control all of the operations performed by the CNC machine tool  102 . 
       FIG. 15  depicts the pipeline  12  after the CNC machine tool  102  was operated to form simplistically depicted drilled and tapped openings  112  and a seal recess  114  in the tapping structure  20 . At that point, the CNC machine tool  102  was retrieved to the surface. 
       FIG. 16  depicts the pipeline  12  after a schematically depicted valve  116  and a schematically depicted pressure-containing tapping CNC machine tool  122  was attached to the tapping structure  20 . The combination of the valve  116  and the tool  122  may be coupled together and run to the pipeline at the same time using a running tool (not shown) or by use of one or more downlines (not shown). Also depicted in  FIG. 16  is an illustrative seal  115  positioned between the valve  116  and the tapping structure  20 . The seal  115  is positioned in the previously formed seal recess  114 . Also depicted is another seal  117  positioned between the CNC tool  122  and the valve  116 . A plurality of simplistically depicted bolts  118  are adapted to engage the drilled and tapped openings  112  so as to secure the combination of the valve  116  and the tool  122  to the tapping structure  20 . The valve  116  may be any type of valve that may, when opened, provide sufficient room to perform the machining process described below. In one illustrative example, the valve  116  may be a gate or a ball valve.  FIG. 16  indicates the valve  116  in the open condition by virtue of the valve element  116 A being non-shaded. 
     In  FIG. 17  the valve element  116 A has been omitted so as not to overly complicate the drawing. As shown in  FIG. 17 , a cutting tool  122 A (e.g., a drill) of the tapping CNC machine tool  122  was extended through the open valve  116  until such time as it engaged the bottom of the alignment/coupling recess  24 . At that time, the CNC machine tool  122  was operated to as to begin drilling through the tapping structure  20 . 
       FIG. 18  depicts the pipeline  12  after several operations were performed. First, the CNC tool  122  continued drilling until such time as an opening  128  was defined in the tapping structure  20  and or the pipeline itself. The opening  128  provides fluid communication between the inside of the pipeline  12  and the valve  116 . Thereafter, the cutting tool  122 A was retracted through the open valve  116  and into the tool  122 . 
       FIG. 19  depicts the pipeline  112  after the valve  116  was closed, as indicated by virtue of the valve element  116 A being shaded. 
       FIG. 20  depicts the pipeline  112  after the CNC tool  122  has been decoupled from the closed valve  116  and is in the process of being retrieved to the surface. 
       FIG. 21  depicts the pipeline  112  after an illustrative flowline  130  has been coupled to the closed valve  116 . 
       FIG. 22  depicts the pipeline  112  after the valve  116  was opened thereby allowing establishing a fluid flow path, as indicated by the double arrow  132  between the flowline  130  and the pipeline  12 . Fluids, such a production fluids, may flow from an item of subsea equipment, such as a production tree (not shown), into the flowline  130  and ultimately into the pipeline  12  and ultimately to a surface production facility. 
       FIGS. 23-30  depict one illustrative method of plugging the opening  128  on a permanent or temporary basis. Such plugging of the opening  128  may be required in several scenarios, e.g., the failure of the valve  116  during the initial installation process or for later repair of the valve  116 . A plug may also be installed in the opening  128  as part of a permanent abandonment process operation. 
       FIG. 23  depicts the pipeline  112  after the valve  116  was closed so as to isolate the flowline  130 . 
       FIG. 24  depicts the pipeline  12  after the flowline  130  was disconnected from the valve  116 . 
       FIG. 25  depicts the pipeline  12  after a plug installation tool  138  was coupled to the closed valve  116 . A variety of known plug installation tools may be employed for this process operation. Also depicted in  FIG. 25  is a simplistically depicted plug  140 . 
       FIG. 26  depicts the pipeline  12  after the valve  116  was opened so as to isolate the flowline  130 . 
       FIG. 27  depicts the pipeline after an arm  138 A of the plug installation tool  138  was extended through the open valve  116  so as to position the plug  140  in its final sealed position within the portion of the opening  128  that extends through the tapping structure  20 . The plug  140  comprises one or more seals  141  on its outer surface that are adapted to sealingly engage the inner surface of the portion of the opening  128  that extends through the tapping structure  20 . At the time the CNC tool  122  was used to cut the opening  128  through the tapping structure  20 , the tool  122  was also used to form a recess  20 Z in the tapping structure  20 . The recess  20 Z is adapted to receive locking lugs  142  on the plug that may be actuated by the plug installation tool  138  so as to lock the plug  140  in its final sealed position within the tapping structure  20 . 
       FIG. 28  depicts the pipeline  12  after the arm  138 A of the plug installation tool  138  was retracted through the open valve  116  and into the tool  138 . 
       FIG. 29  depicts the pipeline  12  after the valve  116  was decoupled from the tapping structure  20  and the combination of the valve  116  and the tool  138  is in the process of being retrieved to the surface. 
       FIG. 30  depicts the pipeline  12  after additional insulation material  26  has been positioned on the pipeline above the tapping structure  20  with the plug positioned therein. To the extent access is ever again needed to the pipeline  12  via the opening  128 , the valve  116  and the plug installation tool  138  may be re-attached to the tapping structure  20 . The plug installation tool  138  may then be operated so as to retract the locking lugs  142  from engagement with the tapping structure  20  and the plug may be retrieved from the opening  128  within the tapping structure  20 . 
     In another illustrative method disclosed herein, in the case where a plug has been previously installed in one of the access node structures  14 X, the steps shown in  FIGS. 23-30  could be performed in reverse order to remove the previously installed plug so as to provide fluid flow access to the pipeline  12  via the access node structure  14 X. 
       FIGS. 31 and 32  depict another illustrative embodiment of an access node structure  14 X disclosed herein. More specifically, in this example, the access node structure  14 X takes the form of a pressure-barrier retaining structure  150  that is adapted to receive a simplistically depicted removable pressure-barrier device  153 . In general, the pressure barrier retaining structure  150  comprises an opening  151  that is exposed to the interior of the pipeline  12 . As was the case with the previously described tapping structure  20 , the pressure barrier retaining structure  150  may be formed integral with the pipeline  12 . The pressure-barrier retaining structure  150  may be attached to the access node section of pipe  12 A at an on-shore facility or it may be attached to the access node section of pipe  12 A on a pipe-laying vessel as the pipeline  12  is being deployed. In one illustrative embodiment, the pressure-barrier retaining structure  150  may have approximately the same dimensions as that of the illustrative tapping structure  20  discussed above. In other applications, the pressure-barrier retaining structure  150  may be significantly smaller than the tapping structure  20  described above. The size of the opening  151  may vary depending upon the particular application. In the example depicted, only a single pressure-barrier device  153  will be positioned in the opening  151 . However, if desired, the pressure-barrier retaining structure  150  could be made of sufficient size such that multiple pressure-barrier devices  153  could be positioned within the opening  151  to provide redundant pressure barriers. As will be appreciated by those skilled in the art after a complete reading of the present application, the pressure-barrier device  153  is intended to be representative of any type of pressure retaining device that may be positioned in an opening. With reference to  FIG. 31 , in one illustrative embodiment, the pressure-barrier device  153  may be a simplistically depicted removable plug that comprises one or more elastomeric sealing elements (not separately shown) and a plurality of anchor slips  155 . Such plugs are commonly employed in various downhole operations such as, for example, fracturing operations. These types of plugs may be mechanically set in the opening  151 .  FIG. 31  depicts the plug  153  in the un-set condition, while  FIG. 32  depicts the plug  153  in the set condition wherein the sealing elements of the plug  153  have been expanded to seal against the inner surface of the opening  151  and the anchor slips  155  have been extended so as to engage the inner surface of the opening  151 . In other embodiments, the pressure-barrier device  153  may be what is generally known as a disappearing tubing hanger (or glass) plug. In this illustrative example, the pressure-barrier device  153  will be positioned in the opening  151  of the pressure-barrier retaining structure  150  and set so as to seal the opening  151  prior to the pipeline  12  being deployed into the sea. As noted above, at some point later in time, the pressure-barrier device  153  may be removed by using a device such as the above-mentioned plug installation/retrieval tool  138  and the valve  116 . In the case where the need for access to the pipeline  12  is only temporary, another pressure-barrier device  153  may be re-installed in the opening  151  at the completion of the temporary process operation. 
       FIGS. 33 and 34  depict yet another illustrative embodiment of an access node structure  14 X disclosed herein. More specifically, this example depicts one or more pressure barriers adapted to be positioned in the opening  151  of the pressure-barrier retaining structure  150 . In the depicted example, the pressure barrier is a single bursting pressure-retaining device  162  positioned in the opening  151  of the pressure-barrier retaining structure  150 . The device  162  comprise a membrane (or disc)  163  that is capable of being ruptured by increasing the pressure applied to the membrane  163  so as to gain fluid access to the interior of the pipeline  12 . As noted above, if desired, the pressure-barrier retaining structure  150  could be made of sufficient size such that multiple pressure barriers, e.g., multiple bursting pressure-retaining devices  162 , could be positioned within the opening  151  to provide redundant pressure barriers. In such a situation, access would be provided to the space between such multiple pressure barriers so as to monitor the pressure within the space between the multiple pressure barriers.  FIG. 33  depicts the bursting pressure-retaining device  162  with the membrane  163  intact and the opening  151  sealed.  FIG. 34  depicts the bursting pressure-retaining device  162  wherein the membrane  163  has been ruptured, thereby creating an opening  164  in the membrane  163  that allows access to the interior of the pipeline  12 . In this illustrative example, the bursting pressure-retaining device  162  will be positioned in the opening  151  of the pressure-barrier retaining structure  150  so as to seal the opening  151  prior to the pipeline  12  being deployed into the sea. At some point later in time, the membrane  163  of the bursting pressure-retaining device  162  may be removed by attaching the valve  116  to the pressure-barrier retaining structure  150  and coupling the valve  116  to a source of fluid, typically a liquid. At that point, the valve may be opened and the pressure of the fluid may be increased until such time as the membrane  163  ruptures, thereby providing access to the pipeline  12 . After the membrane  163  is ruptured, the bursting pressure-retaining device  162  may or may not be removed from the opening  151 . 
       FIGS. 35, 36 and 37  depict yet another illustrative embodiment of an access node structure  14 X disclosed herein. More specifically, in this example, the access node structure  14 X takes the form of a pressure-barrier retaining structure  170  having a scored or notched bottom  172  with various grooves or notches that function as stress risers so as to permit all or portions of the bottom  172  to be removed so as to gain access to the pipeline  12 .  FIG. 35  is a side view of this embodiment of the access node structure  14 X with the bottom  172  intact.  FIG. 36  is a cross-sectional view of the pressure-barrier retaining structure  170  wherein portions of the bottom  172  have been mechanically removed, thereby forming an opening  175  that allows access to the pipeline  12 .  FIG. 37  is a plan view showing the bottom  172 .  FIG. 37  also indicates where the cross-sectional view of the bottom  172  shown in  FIG. 35  is taken (the portion of the cross-sectional view in  FIG. 35  that passes through bottom  172  is laterally from the centerline  12 B of the pipe  12 A). As shown in  FIGS. 35 and 37 , a plurality of grooves  173 X and  173 Y are formed in the bottom  172 . The grooves  173 X,  173 Y may be of any desired shape or configuration. As noted above, these grooves  173 X,  173 Y are formed in the bottom  172  so that they act as stress risers that enable the removal of all or a portion of the bottom  172  by mechanical means so as to gain access to the interior of the pipeline  12 . In general, the pressure barrier retaining structure  170  comprises recess  171  and the bottom  172 . The thickness of the bottom  172  as well as the depth of the grooves  173 X,  173 Y are designed such that the bottom  172  can withstand all loads applied to the bottom  172  during installation, commissioning, operation and abandonment of the pipeline  12 . As was the case with the previously described tapping structure  20 , the pressure barrier retaining structure  170  may be formed integral with the pipeline  12 . The pressure-barrier retaining structure  170  may be attached to the access node section of pipe  12 A at an on-shore facility or it may be attached to the access node section of pipe  12 A on a pipe-laying vessel as the pipeline  12  is being deployed. In one illustrative embodiment, the pressure-barrier retaining structure  170  may have approximately the same dimensions as that of the pressure-barrier retaining structure  150  or the tapping structure  20 . The size of the opening  171  may vary depending upon the particular application In this illustrative example, access node section of pipe  12 A that contains the pressure-barrier retaining structure  170 , with the notched bottom surface  172 , will be positioned in the pipeline prior to the pipeline  12  being deployed into the sea. At some point later in time, all or part of the bottom  172  may be removed by using a hydraulic tearing device. This hydraulic tearing device could use hydraulic power to effectively push or pull on the notched or scored section to apply sufficient force to tear the material at the stress risers. In one illustrative embodiment, the hydraulic tearing device may comprise a hydraulic cylinder (similar to the hydraulic cylinder shown in  FIG. 27 ) that is adapted to be extended so as to push on the notched bottom surface  172 . In such an embodiment, a sloped face at the end of the piston rod may be provided so as to apply more force to one side of the notched bottom surface  172  to initiate the tear. As the rod continues to extend, the sloped face substantially completes the tear around the whole circumference of the notched bottom surface  172 . In another embodiment, a pilot hole (not shown) may be drilled through the bottom surface and a pull-out device (not shown) would be positioned in or through the pilot hole such that it is securely attached to or cannot be readily withdrawn from the pilot hole. In one embodiment, the pull out device may be part of or an attachment to a rod of a hydraulic cylinder, wherein the rod is in an extended position. At that time, the hydraulic cylinder may be actuated so as to retract the rod, thereby mechanically tearing the bottom surface  172 . In one particular embodiment, such a pilot hole may be drilled off-center so as to initiate the tear in an edge region of the bottom surface. After the initial tearing of the bottom surface  172 , the hydraulic cylinder would be further retracted to complete the tearing around the entire circumference of the bottom surface  172 . The hydraulic tearing device may be used in much the same manner as described above with respect to the tapping operations with the exception that a plug would not be set in the opening  175  after portions of the bottom  172  were removed. 
     As will be appreciated by those skilled in the art after a complete reading of the present application, any combination of the various access node structures  14 X disclosed herein may be employed in a single pipeline  12 . For example, a single pipeline may comprise a plurality of the tapping structures  20 , a plurality of the pressure-barrier retaining structures  150  and/or a plurality of the pressure-barrier retaining structures  170 . Of course, if desired, a single pipeline may only contain a plurality of the tapping structures  20 . Thus, the presently disclosed subject matter provides great flexibility as it relates to ongoing field development activities and the manner in which access may be had to the pipeline via the access nodes  14 . 
       FIGS. 38-39  depict one illustrative example of the flexibility provided by use of various embodiments of the pipeline system disclosed herein. In some applications, it may be desirable or necessary to expand the functionality of the subsea production equipment that was previously installed above a reservoir. For example, in the early stages of the development of a reservoir  10 , the production of hydrocarbon-containing fluid under the natural production forces of a well may be sufficient to make such a well commercially viable over a certain period of time. However, over time, the produced fluids from such a well may require the addition of extra energy to boost the flowrate of hydrocarbons. The hydrocarbon streams may be single phase, or a multiphase stream of hydrocarbon-containing fluids, i.e., a production stream that includes significant quantities of both liquid and gas hydrocarbon-containing materials. In that situation, it may be desirable to boost the energy of the fluids through the addition of further subsea processing equipment, which might include the addition of one or a combination of: a single phase pump, a multiphase pump, a separator, a compressor, etc. This is typically accomplished by adding the additional subsea processing equipment through a “tie-in” that provides fluid communication between the newly-added equipment and the pre-existing equipment, such as a subsea manifold. As the development of the reservoir  10  continues over time, it may be necessary to add further subsea equipment that serves to separate liquid and gas components of the overall produced fluid and pump the liquid portions of the produced fluid to further processing units. Such additional subsea equipment may need to be tied in to the preexisting items of equipment positioned subsea. At a further stage of the development of the reservoir  10 , existing production equipment and/or newly added production equipment may be tasked with performing the additional function of reinjecting some of the separated liquid portions of the produced fluid back into a well drilled into the reservoir. All of these modified production processes that occur over the useful life of the reservoir  10  typically involve adding additional valves, flowlines and equipment so as to provide the necessary functionality for producing hydrocarbon-containing fluids from the reservoir  10  in commercially viable quantities. 
       FIG. 38  depicts an embodiment of an illustrative pipeline  12  disclosed herein that comprises previously un-tapped access nodes  14  spaced along the pipeline  12 . As indicated, the original as-deployed pipeline  12  comprises an originally-installed valve  35 . At some point in time after the initial deployment of the pipeline  12  into the sea, additional equipment subsea must be added so as to provide additional subsea process capabilities. 
     With reference to  FIG. 39 , using the illustrative tapping method disclosed herein, an opening  196  may be formed at previously un-tapped access nodes  14  on opposite sides of the valve  35 . Thereafter, a flow line  134  may be coupled to each of the valves  116  so as to provide the desired fluid communication between the pipeline  12  and the newly added subsea equipment (not shown). The flow lines  134  provide a fluid circulation path (to and from) between the pipeline  12  and the newly added subsea equipment. 
     Accordingly, as will be appreciated by those skilled in the art after a complete reading of the present application, the provision of the un-tapped access nodes  14  in the pipeline  12  at the time the pipeline  12  is deployed into the sea provides engineers with much more flexibility as it relates to the development of the reservoir  10  and the positioning of subsea equipment above the reservoir  10  over the life of the reservoir. Additionally, in the embodiments where the utility lines  15  are strapped or coupled to the pipeline  12  at the time the overall pipeline system  11  is deployed into the sea, the use of some or all of traditional subsea umbilicals to provide various utilities, e.g., power, communication, chemicals, etc., may be eliminated. 
     The particular embodiments disclosed above are illustrative only, as the disclosed subject matter may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. For example, the process steps set forth above may be performed in a different order. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the claimed subject matter. Note that the use of terms, such as “first,” “second,” “third” or “fourth” to describe various processes or structures in this specification and in the attached claims is only used as a shorthand reference to such steps/structures and does not necessarily imply that such steps/structures are performed/formed in that ordered sequence. Of course, depending upon the exact claim language, an ordered sequence of such processes may or may not be required. Accordingly, the protection sought herein is as set forth in the claims below.