Abstract:
Operators manufacture a wellscreen by forming a wire-wrapped screen on a base pipe. Rather than stopping and restarting winding, the desired length of screen is completed along the base pipe, and then the wire screen is segmented into a plurality of screen sections as required for the various zones and details of the implementation. Operators arrange the screen sections relative to one another on the base pipe, which can have different lengths with and without perforations. On the free ends of these separate screen sections, mating split ring components fit around the free ends and the base pipes. Male edges of one split ring component mate to complementary female edges of another to form the end ring around the screen section and base pipe, and longitudinal welds made in seams along the mating edges affix the split ring components together.

Description:
BACKGROUND 
     Subterranean filters, also known as “sand screens” or “wellscreens,” have been used in the petroleum industry for years to remove particulates from production fluids. The wellscreens have a perforated inner pipe and at least one porous filter layer wrapped around and secured to the pipe. Typically, the wellscreens is deployed on a production string, produced fluid passes through the filter layer and into the perforated pipe to be produced to the surface. 
     One type of wellscreen is a wire-wrapped screen. The two typical types of wire-wrapped screens include slip-on screens and direct-wrap screens. A slip-on screen is manufactured by wrapping a screen jacket on a precisely machined mandrel. Then, the jacket is later slipped on a base pipe and the end of the jacket is attached to the base pipe, typically by welding. An example of how one type of slip-on screen is manufactured by heating and shrink fitting is disclosed in U.S. Pat. No. 7,690,097. 
     The slip-on screen may allow for precise slots to be constructed, but the screen is inherently weaker than a direct-wrap screen. Discrepancies in the slip-on screen, such as variations in the spacing between the screen jacket and the base pipe, can be problematic. For example, differential pressure usually exists across the slip-on screen when in service, and sufficient differential pressure can cause the wires and the rods to bend inwardly into contact with the base pipe. Such a collapse will result in a shifting of the coils of wire forming the screen and reduce or destroy its ability to serve its intended purpose. 
     The direct-wrap screen is constructed by wrapping the screen directly on the perforated base pipe. As expected, this results in a stronger screen because any annulus between the screen jacket and the base pipe is eliminated.  FIGS. 1A-1B  show an apparatus  5  for constructing a wire-wrapped screen in place directly on a base pipe  10 . Spaced around the outside of the base pipe  10 , a number of rods  12  extend along the pipe&#39;s outside surface. The apparatus  5  wraps the wire  14  around the pipe  10  and the rods  12  to form a screen jacket. A drum (not shown) and other wire feeding components known in the art feed the wire  14  as it is being wrapped, and these components usually hold the wire in tension to bend around the pipe  10  and the rods  12 . 
     To wrap the wire  14 , the pipe  10  and rods  12  are typically rotated relative to the apparatus  5 . At the same time, the pipe  10  and rods  12  are moved longitudinally at a speed that provides a desired spacing between the adjacent coils of wire  14 . This spacing is commonly referred to as the “slot.” Alternatively, the apparatus  5  can be moved longitudinally along the pipe  10  and rods  12  as they rotate. 
     A welding electrode  16  engages the wire  14  as it is wrapped on the rods  12  and provides a welding current that fuses the wire  14  and the rods  12 . The welding electrode  16  is disc-shaped and rolls along the wire  14 . To complete the circuit for welding, the rods  12  are grounded ahead of the wrapped wire  14  using a ground electrode assembly  18 . 
     The ground electrode assembly  18  includes a plurality of contact assemblies  20  and a mounting plate  28 . Each contact assembly  20  includes a contact  22  and a housing  24 . Proper alignment and contact is needed for good welding. Moreover, optical sensors, controls, and the like are used to ensure that proper spacing is maintained between wraps of the wire  14  and that the wire  14  is extruded properly. 
     Some wire-wrapped screens have long sections of wrapping along the base pipe  10 . For other implementations, separate sections of screen are sometimes applied to a single base pipe at various intervals. One example of a wire-wrapped screen having multiple sections is the Mazeflo™ completion screen available from Exxon Mobil Corporation and disclosed in U.S. Pat. No. 7,464,752. (MAZEFLO is a trademark of Exxon Mobil Corporation.) These screens are sand screens having redundant sand control and baffled compartments. These screens isolates mechanical failure of the screen to the local compartments of the device&#39;s maze sections, while allowing continued hydrocarbon flow through the undamaged sections. The flow paths are offset so that the flow makes turns to redistribute the incoming flow momentum. 
     When manufacturing a wire-wrapped screen having separate screen sections, the wire wrapping process has to be stopped for each new screen section so ends of the screen section can be affixed to the base pipe. This is done using welds, or end rings can be inserted over the pipe before the next section of screen can be completed. Thus, a given section of wire wrapping has to be completed on the base pipe, and the base pipe must be removed from the wrapping apparatus so the end of the screen section can be secured to the base pipe before wrapping can proceed with the next screen section. This process is repeated until all the screen sections are completed on the base pipe. As will be appreciated, this form of manufacture for a wire-wrapped screen with multiple sections is time consuming and very costly. 
     The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above. 
     SUMMARY 
     Operators manufacture a wellscreen by forming a wire-wrapped screen on a base pipe. Rather than stopping and restarting the winding operation for each section, the desired length of screen is completed along the base pipe, and then the wire screen is segmented into a plurality of screen sections as required for the various zones and details of the implementation. Operators arrange the screen sections relative to one another on the base pipe. The screen sections can have different lengths, and the base pipe can have sections with and without perforations. On the free ends of these separate screen sections, operators install mating split ring components that fit around the free ends and the base pipe. 
     If the free end of the screen section is separated by an expanse of base pipe without perforations from the next section, then the end ring can weld to the base pipe to hold the screen section in place and to prevent fluid and particulates from entering the channels of the screen section between the base pipe and end ring. 
     Alternatively, screen sections may be situated next to one another, and abutting ends of the end rings can be welded together. These abutting end rings can define internal channels that allow flow from the adjoining screen sections to pass through the abutting end rings. 
     The end ring has at least two mating split ring components. Edges of one split ring component mate to complementary edges of another of the components to form the end ring around the screen section and base pipe. Preferably, the ends have mating male and female dovetails or grooves. For permanency, longitudinal welds are made in outside seams along the mating edges to affix the split ring components together. 
     The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a partially exposed side view of an apparatus for wrapping a base pipe and rods with wire. 
         FIG. 1B  shows an end section of the apparatus of  FIG. 1A . 
         FIGS. 2A-2D  show a wire-wrapped screen with multiple sections during stages of assembly. 
         FIGS. 3A-3C  show an end ring of the present disclosure in perspective, cross-sectional, and end views. 
         FIG. 3D  shows an end ring of  FIGS. 3A-3C  disposed on a base pipe at an end of a screen section. 
         FIG. 4  shows another wire-wrapped screen with multiple sections. 
         FIGS. 5A-5C  show another end ring of the present disclosure in perspective, end, and cross-sectional views. 
         FIG. 5D  shows end rings of  FIGS. 5A-5C  disposed on a base pipe at adjoining screen sections. 
         FIG. 6  shows an alternative end ring disposed on a base pipe at adjoining screen sections. 
         FIG. 7  shows yet another alternative end ring disposed on a base pipe at adjoining screen sections. 
         FIG. 8  shows another arrangement of end rings and screen sections on a base pipe for a wellscreen. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 2A-2D  show a wire-wrapped wellscreen  50  having multiple sections during stages of assembly. The wellscreen  50  has a base pipe  60  that extends along the length of the wellscreen  50 . This pipe  50  has a number of perforations  62  formed therein for passage of production fluid. As shown in the final assembly of  FIG. 2D , screen sections  70 A,  70 B, etc. are disposed at desired intervals along the base pipe  60 . Each screen section  70 A,  70 B, etc. is fitted with end rings  100  that affix the ends of the screen sections  70 A,  70 B, etc. to the base pipe  60  to secure the assembly. Each of the end rings  100  include at least two split ring components that mate together around the base pipe  60  and affix together. Further details of these end rings  100  are discussed later. 
     Rather than assembling the multiple screen sections  70 A,  70 B, etc. of the wellscreen  50  in the prior art manner described previously, the disclosed wellscreen  50  with multiple sections is manufactured in a different manner outlined in  FIGS. 2A-2D . 
     Assembly begins with the perforated base pipe  60  as shown in  FIG. 2A , which can be manufactured and machined according to conventional practices. Preferably, the base pipe  60  has multiple sections where perforations  62  are formed, which can be separated by predetermined, imperforate expanses of base pipe  60 . Different sections of the base pipe  60  can have different number, sizes, shapes, configurations, and other aspects of the perforations  62  compared to other sections. The overall selection and layout of the perforations  62  depends on the particular implementation. 
     The rods  72  of the screen  70  are positioned around the base pipe  60  at desired spacings to form the desired longitudinal channels. Then, using a winding apparatus such as discussed previously with reference to  FIGS. 1A-1B , a suitable length of the base pipe  60  is wrapped with wire  74  to form the screen  70  in one pass as shown in  FIG. 2B . Typically, the size, shape, and spacing of the wire  74  remains relatively constant as the wire  74  is wrapped. Depending on the implementation and the different type of screen sections desired, any of these and other variables can be altered during the winding process so that the wire wrapping can change along its length. 
     As shown in  FIG. 2B , rather than stopping and restarting the winding for various sections, the wire wrapping continues along the extent of the base pipe  60  to produce enough wire-wrapped screen length as needed. Then, as shown in  FIGS. 2B-2C , desired screen lengths for the various sections  70 A,  70 B,  70 C, etc. of the screen  70  are cut from the full length to form the final screen sections  70 A,  70 B,  70 C, etc. The sections  70 A,  70 B,  70 C, etc. are the spaced out appropriately along the base pipe  60 , which may have extents  66  lacking perforations  62  in between screen sections  70 A,  70 B,  70 C, etc., as noted previously. 
     Finally, as shown in  FIG. 2D , the split end rings  100  are then fitted to ends of these separated screen sections  70 A,  70 B,  70 C, etc. to complete the assembly. As expected, this form of manufacture greatly simplifies the winding process and can improve the construction of the wellscreen  50 . 
     Turning to the end rings  100  in more detail,  FIGS. 3A-3C  show an end ring  100  of the present disclosure in perspective, cross-sectional, and end views. The end ring  100  has at least two split ring components  110 ,  150  separated along their axial direction. (Although two components  110 ,  150  are shown, more than two could be used.) One split ring component  150  has male edges  152  that mate with female edges  112  of the other split ring component  110 . Preferably, the edges  112  and  152  define dovetail or groove surfaces to hold the edges  112  and  152  together before welding. Welds made in outside seams  114  and  152  along these mating edges  112  and  152  affix the two split ring components  110  and  150  together. Being split allows the end ring  100  to be assembled together over the base pipe ( 60 ) and the end of the screen section during assembly as discussed previously. 
     Internally, the end ring  100  defines an inner passage  102  that fits over the base pipe ( 60 ) and any components at the end of the screen section ( 70 A). ( FIG. 3D  shows the end ring  100  of  FIGS. 3A-3C  disposed on the base pipe  60  at an end of a screen section  70 A.) This inner passage  102  can have a wider portion  104  to accommodate the components (rod ends, wire, etc.) of the screen section ( 70 A) and can have a narrower portion  106  for fitting more snuggly against the base pipe&#39;s outer surface. The back edge of the end ring  100  at this narrower portion  106  can be welded at ( 120 ) to the base pipe ( 60 ). 
       FIG. 4  shows another wellscreen  50  having multiple screen sections  70 A,  70 B,  70 C, etc. Assembly of this wellscreen  50  can be similar to that discussed previously. Rather than separate all of the screen sections  70 A,  70 B,  70 C, etc. from one another by an expanse of base pipe  60 , at least some or all of the screen sections  70 A,  70 B,  70 C, etc. adjoin one another end-to-end. End rings  100 , such as disclosed previously, can abut one another end-to-end between adjoining screen sections (e.g.,  70 B and  70 C). These end rings  100  can be welded together and/or to the base pipe  60 . Although two of these end rings  100  can be separate from one another as shown, an integrally formed end ring can have two ends to achieve the same results between adjoining sections of wire screen. For example, an alternative end ring  100 ′ having two ends as shown in  FIG. 6  can be used between adjoining screen sections (e.g.,  70 B and  70 C). As further shown in the example of  FIG. 6 , the perforations  62  in the base pipe  60  can be arranged in two sections  64 B and  64 C relative to the adjoining screen sections  70 B and  70 C. 
     Either way, the end rings  100  (or end ring  100 ′) separate the two screen sections  70 B and  70 C. In this way, one screen section  70 B disposed over a length of the base pipe  60  can have a same or different flow characteristic (produced by more or less perforations, different sized perforations, narrower or wider wire slot, different wire extrusions, or other differences) than the flow characteristics for the other screen section  70 C on the base pipe  60 . This can produce different properties of the wellscreen&#39;s operation along its length that can be suited for a particular implementation. 
     As another alternative to the end rings  100  (or in addition thereto), adjoining wire sections (e.g.,  70 A and  70 B) can have another form of end ring  200 . As before, these end rings  200  can abut one another between the screen sections  70 A and  70 B. Rather than isolate fluid communication between the screen sections  70 A and  70 B, these end rings  200  have internal channels  208  allowing for flow of fluid between them and the base pipe  60 . In this way, one screen section  70 A disposed over a length of the base pipe  60  can have the same or different flow characteristic than the length of base pipe  60  for the other screen section  70 B. Yet, the two sections  70 A and  70 B can have cross-flow between them, which can be beneficial in some implementations. 
     Turning to the end ring  200  in detail,  FIGS. 5A-5C  show an end ring  200  of the present disclosure in perspective, cross-sectional, and end views. The end ring  200  again has at least two split ring components  210 ,  250  separated along their axial direction similar to previous arrangements. One split ring component  250  has male edges  252  that mate with female edges  212  of the other split ring component  210 . Preferably, the edges  212  and  252  define dovetailed or grooved surfaces to hold the edges  212  and  252  together before welding. Welds made in outer seams  214  and  252  along these mating edges  212  and  252  affix the two split ring components  210  and  250  together. As before, being split allows the end ring  200  to be assembled over the base pipe ( 60 ) and screen section ( 70 ) during assembly. 
     Internally, the end ring  200  defines an inner passage  202  that fits over the base pipe ( 60 ) and any components at the end of the screen section ( 70 A). ( FIG. 5D  shows end rings  100  of  FIGS. 5A-5C  disposed on the base pipe  60  between adjoining screen sections  70 A and  70 B.) This inner passage  202  can have a wider portion  204  to accommodate the components (rod ends, wire, etc.) of the screen section (e.g.,  70 A) and can have a narrower portion  206  for fitting more snuggly against the base pipe&#39;s outer surface. The back edge of the end ring  200  at this narrower portion  106  also defines several channels  208 . Fluid flow passing through the wire ( 74 ) on the accompanying screen section ( 70 A) can flow along the base pipe ( 60 ) between the longitudinal rods ( 72 ). When reaching the end ring  200 , the flow can pass through the ring&#39;s channels  208  and pass out the end of the ring  200 . When this end ring  200  is abutting and joined to another like end ring  200  at weld ( 220 ), the flow can pass into the channels  208  of this other end ring  200  to communicate with the longitudinal space between the rods ( 72 ) of the adjoining screen section (e.g.,  70 B). To align the channels  208  on abutting ends of the rings  200 , the outer surface may be machined with a guide  209  or the like as best shown in  FIG. 5A . 
     Although shown formed uniformly around the inside of the end ring  200 , other less symmetrical arrangements of the channels  208  may be used, and the communicating channels  208  between abutting end rings  200  can cross-communicate in any desirable pattern according to the implementation. Although two of these end rings  200  can abut one another as shown, an integrally formed end ring can have two ends to achieve the same results. For example,  FIG. 7  shows an integral end ring  200 ′ with channels  208  disposed on the base pipe  60  between adjoining screen sections  70 A and  70 B. As further shown in the example of  FIG. 7 , the perforations  62  in the base pipe  60  can be arranged in two sections  64 A and  64 B relative to the adjoining screen sections  70 A and  70 B. 
     Moreover, although the end rings  200  of  FIGS. 5A-5D  abut one another between sections of wire-wrapped screen, the end rings  200  could be separated by an expanse of base pipe  60  having or not having perforations. As shown in  FIG. 8 , this separated expanse of base pipe  60  can have another type of screen material disposed thereabout, such as a mesh screen  71 . Yet, the end rings  200  may allow the screen sections  70 A and  70 B to which they are disposed communicate fluid with this intermediate screen section  71 . 
     The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.