Abstract:
The present invention provides for a design and method of manufacture for a mesh-type screen to be used in subsurface well completions to prevent the production of sand.

Description:
This application claims the benefit of U.S. Provisional Application 60/399,254 filed Jul. 29, 2002. 

   BACKGROUND 
   1. Field of Invention 
   The present invention pertains to screens used in subsurface well completions, and particularly to screens using mesh media. 
   2. Related Art 
   Screens are commonly used in well completions in which the producing formation is poorly or loosely consolidated. Abrasive particulates, generally referred to as “sand” or “fines”, can cause problems if produced. For example, the formation surrounding the wellbore can erode and wash out, potentially leading to collapse of the well. Sand can damage equipment such as pumps or seals as the sand travels at high speed through the pump or past the seals. Produced sand must be disposed of, and this imposes an additional cost to the well operator. Fines can clog flow passages, disrupting production. 
   Often, to enhance filtration, a layer of particles of presorted size, commonly referred to as “gravel”, is injected between the formation (or casing) and the screen. In those cases, the screen is sized to prevent passage of the gravel. The gravel in turn prevents the passage of fines. 
   Various screen types are used to prevent the production of sand. For example, a perforated base pipe can have wire wrapped around it such that the spacing between the wire wraps limits the size of sand that can pass. Mesh material can also be used. However, manufacturing screens can be an expensive, time-consuming undertaking. Therefore, there is a continuing need for improved designs and manufacturing methods for screens. 
   SUMMARY 
   The present invention provides for a design and method of manufacture for a mesh-type screen to be used in subsurface well completions to prevent the production of sand. 
   Advantages and other features of the invention will become apparent from the following description, drawings, and claims. 

   
     DESCRIPTION OF FIGURES 
       FIG. 1  is a schematic view of a mesh screen apparatus constructed in accordance with the present invention. 
       FIG. 2  is an exploded view of the mesh screen apparatus of  FIG. 1 . 
       FIG. 3  is a schematic view of an alternate embodiment of a mesh screen apparatus constructed in accordance with the present invention. 
       FIG. 4  is a schematic view of an alternate embodiment of a mesh screen apparatus constructed in accordance with the present invention. 
   

   DETAILED DESCRIPTION 
     FIG. 1  shows a mesh screen apparatus  10  constructed in accordance with the present invention. Mesh screen apparatus  10  comprises a mesh medium  12  and a perforated base pipe  14  ( FIG. 2 ). Mesh medium  12  comprises fiber strands  16 , preferably made of metal. In one embodiment, fibers  16  are intermeshed in orthogonal directions to form a layer  17 , and multiple layers  17  are then stacked upon each other, as illustrated in  FIG. 2 . If multiple layers are used, preferably the layers are interlocked. 
   A method of producing such an interlocking, layered embodiment of mesh medium  12  is to use needles to punch through the stacked layers of fibers  16 . Needles having prongs can be pushed back and forth through the layers, interlocking fibers  16  from different layers. As illustrated in  FIG. 2 , individual fibers  16  from each layer  17  are pushed into adjacent layers  17 . If desired, the resulting blanket of mesh medium  12  can then be formed into a seamless tube, as shown in  FIG. 1 . 
   Using needles to interlace fibers  16  to make mesh medium  12  allows various porosities in mesh medium  12  to be produced. Porosities commonly range between thirty and ninety-two percent, though other porosities are possible. Fibers  16  of different diameters can also be used to vary porosity. Fiber diameters ranging from two to two hundred microns are commonly used, though the present invention is not limited to those diameter fibers. In this embodiment, as before, fibers  16  preferably interlock among layers. Larger diameter fibers  16  allow for larger porosities. Various diameter fibers  16  can be used in the same mesh medium  12  to produce a mesh medium  12  having variable porosity. 
   The thickness of mesh medium  12  generally ranges from 0.125 inches to 0.25 inches, but is not limited to that range. Optionally, to make the mesh medium  12  more resistant to collapse, one or more pieces of standard mesh  18  can be placed between certain layers of mesh medium  12 , as shown in  FIG. 1 . 
   In the embodiment shown in  FIG. 3 , mesh screen apparatus  10  surrounds only a portion of base pipe  14 . The ends of mesh medium  12  may be secured directly to base pipe  14 , or otherwise secured to cover openings  20  ( FIG. 1 ) in base pipe  14 . The partial covering is to accommodate other structures such as transport tubes  22  or control lines  24  running longitudinally along base pipe  14 . Transport tubes  22  are used to provide alternate paths for fluid used in treatments such as gravel packing, fracturing, or acidizing. Examples of control lines  24  include electrical, hydraulic, fiber optic, and combinations thereof. 
   Note that the communication provided by the control lines  24  may be with downhole controllers rather than with the surface, and the telemetry may include wireless devices and other telemetry devices such as inductive couplers and acoustic devices. In addition, control line  24  itself may comprise an intelligent completion device as in the example of a fiber optic line that provides functionality, such as temperature measurement, pressure measurement, and the like. In one example, the fiber optic line provides a distributed temperature functionality so that the temperature along the length of the fiber optic line may be determined. 
   The embodiment of  FIG. 3  also includes intelligent completion devices  26  such as gauges, sensors, valves, sampling devices, a device used in intelligent or smart well completion, temperature sensors, pressure sensors, flow-control devices, flow rate measurement devices, oil/water/gas ratio measurement devices, scale detectors, actuators, locks, release mechanisms, equipment sensors (e.g., vibration sensors), sand detection sensors, water detection sensors, data recorders, viscosity sensors, density sensors, bubble point sensors, pH meters, multiphase flow meters, acoustic sand detectors, solid detectors, composition sensors, resistivity array devices and sensors, acoustic devices and sensors, other telemetry devices, near-infrared sensors, gamma ray detectors, Hydrogen sulfide (H 2 S) detectors, carbon dioxide (CO 2 ) detectors, downhole memory units, downhole controllers, perforating devices, shape charges, firing heads, locators, and other downhole devices. In addition, control line  24  may comprise an intelligent completions device  26  as in the example of the fiber optic line that provides functionality, such as temperature measurement, pressure measurement, and the like. In one example, the fiber optic line provides a distributed temperature functionality so that the temperature along the length of the fiber optic line may be determined. 
   A base pipe  14  having structures attached thereto can also have mesh medium  12  placed such that mesh medium  12  encloses both base pipe  14  and the attached structures. 
   Mesh medium  12  can also be used to wrap and protect a piece of equipment, such as an electrical submersible pump  27  (see  FIG. 4 ). Mesh medium  12  can partially or completely enclosed pump  27 . 
   A method of manufacture of mesh screen apparatus  10  as contemplated under this invention is to slide a pre-fabricated tubular form of mesh medium  12 , produced as described above, over base pipe  14 , as indicated by the arrow in  FIG. 2 . Base pipe  14  is a conventional tubing having openings  20  such as perforations or slots, as is well known in the art. Base pipe  14  can have an inset portion  28  ( FIG. 3 ) to accommodate transport tubes  22  or control lines  24 . 
   Although only a few example embodiments of the present invention are described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. It is the express intention of the applicant not to invoke 35 U.S.C. § 112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.