FIELD OF THE INVENTION
The field of the invention is multi-zone completions and more particularly completions that link screen sections with external shrouds mounted over connected base pipe with a single access to all the screen through a bottom isolation valve and production through all the screens with a top isolation valve.
BACKGROUND OF THE INVENTION
Multi-zone completions present conflicting design parameters that need to be considered. The need for versatility in being able to shut off individual screens has to be balanced with the resistance to flow that comes from additional tubulars associated with individual screens and the difficulty in channeling flow from one screen through small passages external to the central production flow path. Addition of tubular sections to create such communication paths between screens can also impede subsequent production by reducing the drift diameter available for such flow. The reduced drift dimension also makes access further downhole more complex or impossible in some cases.
FIG. 1-3 illustrate one such system. In FIG. 1 a port 10 on a sliding sleeve valve 12 is in the open position for taking gravel pack returns through screen 14. Arrows 16 represent the gravel slurry flow to the annular space outside screens 14, 20 and 22. Arrows 18 represent the gravel slurry return flow to the surface with the gravel 24 deposited outside screens 14, 20 and 22 as shown in FIG. 2. Because sliding sleeve valve 26 is closed all the return flow represented by arrow 18 is through ports 10 while connecting paths between screens such as 28 are closed. When it is time for production valves 12 and 26 are both opened as shown in FIG. 3. However, the path of least resistance is represented by arrows 30 and 32 as opposed to connecting paths such as 28. As a result, high velocities occur through the screens such as 14 and 22 causing erosion that can put a hole in such screens and further creating uneven flow from the formation as little flow gets to the surface through screen 20 that represents a path of higher resistance than flow coming in radially through screen 14 or 22. Apart from the above issues the presence of sleeves such as 30 to create the network of connecting passages 28 results in a smaller drift dimension for production flow and can reduce the production rate. Apart from this the assembly of such a string is fairly complex and presents many leak path opportunities. It fails to accomplish an objective of maximizing production in an even manner across the screens of the entire zone and is further expensive to construct and install into the borehole.
FIGS. 4-6 represent another prior system where perforations 32, 34 and 36 are sequentially made with a perforating gun that is not shown and the completion is assembled in the hole in stages as shown in FIGS. 4-6. Screen assemblies 36 and 38 are the same and they comprise a screen 40 covered internally by an inner pipe 42 to create an annular space 44 that is accessible by a sliding sleeve valve 46 to take returns when gravel packing. Valve 46 can then be closed when the screen that is associated with it is fully gravel packed. Further access to the annular space 44 is provided by pressure sensitive valves such as 48. These can operate in response to a pressure of a predetermined value that arms each of the similarly situated valves such as 50 and 52 such that when the pressure is released all the valves will open at the same time. The production can then ensue through screen assemblies 36 and 38 into the production string 54 that extends through production packer 56. Flow through screen assembly 58 passes through packer 60 and production packer 56 to come up around the production string 54 as represented by arrows 62. Arrows 64 represent the flow coming through screen assemblies 36 and 38 into the production string 54. The issue with this system is that once the zones are opened with valves 48, 50 and 52 the screens either cannot be closed off, or it is not economical to do so. The same valves can be inadvertently open with a pressure spike in the bottom hole assembly. The use of discrete inner tubulars such as 42 inside each screen also reduce drift diameter that can restrict production.
Also relevant to such systems are U.S. Pat. Nos. 8,511,380; 8,225,863; 6,530,431; 2004/0251033; U.S. Pat. Nos. 8,281,854; 6,776,241 and 20150034301.
The present invention seeks to overcome the shortcomings of the prior systems by using shrouds to span over a base pipe joint so as to create a continuous annular space between the screen assemblies and the base pipe so that the formation can flow more uniformly through a larger drift base pipe because the screens are coupled together. In this manner, a single valve can control return flow when gravel packing. Another valve communicating with the same exterior annular space can be used as the production valve drawing the fluid that is produced through all the screens in the screen assembly. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.
SUMMARY OF THE INVENTION
Screen sections have opposed open ends near the threaded connection of a base pipe and on opposed ends. The base pipes have premium threads for connection. A shroud is placed over the premium bases pipe connection that spans from one open ended screen section to another that is adjacent. Collectively a long annular space is created under the screens and alternating shrouds with access to within the base pipes provided preferably at opposed ends. The valve on one end takes returns during gravel packing and the other takes production to the surface.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a part section view of a prior art screen assembly with internal jumper flow paths between screens during gravel packing;
FIG. 2 is the view of FIG. 1 showing gravel deposition outside the screens and returns through a single open sliding sleeve valve;
FIG. 3 is the view of FIG. 2 showing two sliding sleeves open during production;
FIG. 4 is a schematic view of a prior art triple zone completion with the first zone completed and the second zone perforated;
FIG. 5 is the view of FIG. 4 with all three zones perforated and completed;
FIG. 6 is the view of FIG. 5 with the production string tagged into the production packer;
FIG. 7 is the assembly of the present invention during gravel packing;
FIG. 8 is the view of FIG. 7 with the well shut in;
FIG. 9 is the view of FIG. 8 with the well on production;
FIG. 10 is an end detail of a screen section showing communication openings through an end ring;
FIG. 11 is a section view along lines 11-11 of FIG. 10;
FIG. 12 is a view of two joints threaded together before the shroud is advanced to bridge adjacent screens; and
FIG. 13 is the view with a tubular jumper shroud advanced into position spanning two screen sections.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 7 an alternating assembly of base pipes 70 and couplings 72 is assembled at the surface. Each base pipe 70 has a surrounding screen 74 at a spaced relation to the base pipe 70 to define an annular space 76 that is open on opposing ends 78 and 80. Spacers 82 leave openings 84 as best seen in FIG. 10. Spacers 82 can be connected to end ring 86 at threads 88 while base pipe 70 is threaded at 90 to the spacers 82. Screen 74 can swaged onto the end ring 86 or fastened in other mechanical ways such as welding. The spacers 82 are preferably also welded to the end ring 86.
FIG. 12 illustrates the assembly method into the well. A lower screen 74′ 70 is supported on the rig floor so that the next joint above can be aligned and the coupling 72 used to connect adjacent base pipes 70 with powered tongs that are not shown in the known manner. The upper base pipe 70 has a screen secured to it in the manner described above. It also can have a seamless tubularly shaped shroud 92 that is initially over the next screen 74 being added to the string. Once the new base pipe 70 is threaded to coupling 72 the shroud is lowered into position as shown in FIG. 13 so that is spans over the threads at opposed ends of the coupling 72. The shroud can be solid or it can have openings comparable to the opening size in the adjacent screens 74 to aid in gravel distribution during gravel packing. The additional openings in the shrouds 92 allow taking fluid returns through the shrouds when gravel packing, which brings the gravel to the shrouds 92 of a denser gravel pack. The ends of the shrouds 92 can be flexible and the inside diameter of the shroud is somewhat larger than the outside diameter of the underlying screen in FIG. 12 so that the shroud 92 can be manipulated into the FIG. 13 position for attachment to the end rings 86 that appear on opposed ends of screens 74 that mark the gap to be spanned by the shroud 92. Such attachment can be with fasteners such as countersunk bolts or circular clamps or the like. It should be noted that the shroud in this case can be a seamless tube or a tube with a welded seam, although seamless is preferred for greater structural integrity and avoidance of issues with chemical reaction with seam weld materials. Alternatively, the shroud 92 can be a split cylindrical shape with a longitudinal opening to allow it to be slipped over the base pipe 70 and the opening closed up. Another variation can be with the use of a hinged connection to allow an opposite side to be opened for advancing over the base pipe 70 and then closed up to secure the longitudinal edges together over the base pipe 70. The ends of the shroud 92 can then be connected to the end rings 86 in the manner described above.
FIGS. 7-9 show the end result of this process and the valves used preferably at opposed ends to facilitate gravel packing, isolation of the formation or production from the formation. FIG. 7 shows gravel slurry represented by arrows 100 entering annular space 76 that extends from gravel pack return valve 102 preferably at the lower end 104 to production valve 106 preferably at the upper end 110. Segments 108 are open to provide fluid access for screened production fluids to reach the valve 106. Valve 106 can be of a pressure to operate type or can be opened with mechanical intervention such as with a shifting tool. When valve 102 is open flow represented by arrow 112 enters the base pipe passage 114 leaving the gravel outside the screens and shrouds of the illustrated assembly. FIG. 8 shows the well shut in after gravel packing where valve 102 is closed as is valve 106. FIG. 9 shows valve 106 open to take production flow through all the screen sections and into the long annular space 76 and then into passage 114 to go to the surface.
Those skilled in the art will appreciate several advantages of the equipment described above and the method that such equipment enables. The screens communicate with each other outside the base pipes in a continuous annular space that allows the formation to be evenly produced. The drift dimension of the base pipe can be greater than prior designs for the same outer dimension of the screen assembly. A modular system facilitates rapid assembly and a lower overall cost. A single valve controls the elongated annular space for taking returns during gravel packing or for production. The production valve can be opened or closed without intervention such as with pressure cycles. Multiple zones can be produced and could ostensibly be balanced for even flow with strategically located obstructions to flow at desired locations. The shrouds can have openings to further enhance the distribution of the gravel by creating more fluid return paths. Screen modules are either open on one end or both ends depending on their placement to create an elongated annular space that allows more even flow from the formation into the passage formed by the connected base pipes.
The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below:
Patent Grant
9988884
