Abstract:
A downhole tubing filter to remove sand and other solid particles from production fluid in a subterranean well. The downhole tubing filter includes a filter element having a perforated mandrel surrounded by at least one filter media made of a stainless steel woven mesh material to provide improved permeability and resistance to chemical and physical forces.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and is a continuation-in-part of U.S. patent application Ser. No. 13/965,998 filed Aug. 13, 2013, entitled DOWNHOLE FILTRATION TOOL, which is incorporated by reference herein in its entirety. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable. 
       NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not Applicable. 
       REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX 
       [0004]    Not Applicable. 
       STATEMENT REGARDING PRIOR DISCLOSURES BY THE INVENTOR OR A JOINT INVENTOR 
       [0005]    Not Applicable. 
       BACKGROUND OF THE INVENTION 
       [0006]    1. Field of the Invention 
         [0007]    This invention relates generally to a downhole tubing filter for use in oil, gas, and water wells, and in particular a downhole tubing filter element having a metallic mandrel surrounded by a metallic mesh filter media giving the filter improved permeability, resistance to chemical breakdown, and physical strength. 
         [0008]    2. Description of the Related Art 
         [0009]    Oil and gas wells and water wells include a wellbore extending into a well to some depth below the surface. Typically, the wellbore is lined with casing to strengthen the walls of the borehole. To further strengthen the walls of the borehole, the annular area formed between the casing and the borehole is typically filled with cement to permanently set the casing in the wellbore. The casing is then perforated to allow production fluids to enter the wellbore and be retrieved at the surface of the well. 
         [0010]    Various types of downhole equipment, such as pumps and similar devices, are used to move production fluids from within the wellbore to the surface. A typical downhole arrangement would include a string composed of a series of tubes or tubing suspended from the surface. One type of well-known pump is a downhole electrical submersible pump (ESP). The ESP either includes or is connected to a downhole motor which is sealed so that the whole assembly is submerged in the fluid to be pumped. The motor is connected to a power source at the surface and operates beneath the level of the fluid downhole in order to pump the fluid to the surface. A component is connected to the motor which prevents well fluid from entering the motor and equalizes internal motor pressure with the well annulus pressure. 
         [0011]    A number of factors may be detrimental to the production of the ESP, such as the presence of foreign solid particles, such as sand, sediment, and scale. The amount and size of sand and other solid particles in the fluid may vary widely depending on the well and the conditions encountered. In enhanced recovery operations, for example, fluids may be pumped down the well to stimulate production causing additional movement of sands and solids. The sand and other solid particles act as abrasives and, over time, are damaging to the operation of the pump. 
         [0012]    Yet another problem typically encountered in wells is an excess amount of gas or gas bubbles entering the intake of the pump causing the pump to decrease in efficiency. ESPs have dramatically lower efficiencies with significant fractions of gas, and at some point, the pump may become “gas locked” and damage to the pump and/or motor may result. 
         [0013]    Many types of filters have been designed for use with ESPs. Such filters typically include a filter element designed to screen solid particles from the pump intake; however, the filtered particulates often become entrapped in the filter element. The amount of particulate material collected on the filter element is directly proportional to the to the pressure drop that occurs across the filter element. Since an excessive pressure drop across the filter element can significantly reduce fluid flow, the filter element must be periodically changed or cleaned. Often, this is done by removing the ESP from the fluid and removing the filter element. This can be a timely and inconvenient process. Pumps with intricate backwashing systems have been designed, but these are often expensive and cannot be used to retrofit existing systems. As a result, many pumps are generally operated without any filter and therefore experience early pump failure and extensive and costly down time. 
         [0014]    A problem associated with conventional downhole tubing filters arises in high temperature and/or high pressure applications. Low gravity oils require higher well bore temperature as heavy oil has a tendency to hold the sand against the filter media causing premature failure. High downhole temperatures are generally above 200° F. and up to 450° F., while high downhole pressures are generally above 7,500 psi and up to 15,000 psi. Another problem with downhole tubing filters occurs in both high pH (e.g., more than 8.0) and low pH (e.g., less than 6.0) environments. In these extreme downhole conditions, conventional filters become ineffective and suffer from degradation. 
         [0015]    It is therefore desirable to provide an improved downhole tubing filter for use in oil, gas, and water wells. 
         [0016]    It is further desirable to provide a downhole tubing filter that is connected to and suspended from downhole equipment, such as but not limited to, a rod pump or an ESP. 
         [0017]    It is still further desirable to provide a downhole tubing filter capable of separating sand and other solid particles from production fluid from entering the pump. 
         [0018]    It is yet further desirable to provide a tubing filter element having a metallic mandrel surrounded by a metallic mesh filter media giving the downhole filter improved permeability, resistance to chemical breakdown, and physical strength. 
         [0019]    Other advantages and features will be apparent from the following description and from the claims. 
       SUMMARY OF THE INVENTION 
       [0020]    In general, in a first aspect, the invention relates to a downhole tubing filter element having a metallic mandrel, and a metallic mesh filter media. The mandrel is juxtaposed between opposing end fittings, and the opposing end fittings may include a first end fitting and a second end fitting attached to the mandrel and the metallic mesh filter media. The mandrel has a plurality of diametrical perforations and an interior chamber aligned along an axial flow passage through the downhole tubing filter. The end fittings having opposing generally planar axial open ends that are axially aligned and coaxially spaced along the flow passage. The mesh filter media circumferentially surrounds the mandrel, and includes a single layer or multiple layers of woven wire mesh and metallic fibers. 
         [0021]    The downhole tubing filter element may be encased within a perforated steel housing. The mandrel is fabricated from stainless steel or carbon steel. The filter media is fabricated from stainless steel, and the layer or layers of the filter media have a weave type selected from the group consisting of a plain wire cloth, a plain Dutch weave, a Twill Dutch weave, a Reverse Dutch Twill weave, or a reverse Dutch weave. The filter media can have a drainage layer concentrically surrounding the mandrel and a filter layer concentrically surrounding the drainage layer or a drainage and support layer concentrically surrounding the mandrel and a filter layer concentrically surrounding the drainage and support layer. Still further, the filter media can include a drainage layer concentrically surrounding the mandrel and a filter layer concentrically surrounding the drainage layer. Yet further, the filter media can have a drainage layer concentrically surrounding the mandrel, a support layer concentrically surrounding the drainage layer, a filter layer concentrically surrounding the support layer, and a protective layer concentrically surrounding the filter layer. 
         [0022]    Moreover, the filter media can have a nominal micron rating between about 80 and 150 microns or between about 115 and 150 microns. In addition, the filter media can be constructed as a monolithic structure forming an integrated filter media. 
         [0023]    In general, in a second aspect, the invention relates to a downhole filter comprising a tubing filter element having a metallic mandrel having a plurality of diametrical perforations and an interior chamber aligned along an axial flow passage through the downhole tubing filter element. The filter element also includes a monolithic mesh filter media forming an integrated filter media. The filter media circumferentially surrounds the mandrel, and the filter media is constructed from a stainless steel weave having a nominal micron rating between about 80 and 150 microns. A first end fitting and a second end fitting respectively attached to opposing terminal ends of the filter element. The tubing filter element can be removably housed within a perforated steel housing. 
         [0024]    The mandrel can be fabricated from stainless steel or an investment cast precipitation-hardening corrosion-resistant carbon steel. Moreover, the layer or layers of the filter media may have a weave type selected from the group consisting of a plain wire cloth, a plain Dutch weave, a Twill Dutch weave, a Reverse Dutch Twill weave, or a reverse Dutch weave. Additionally, the filter media can be constructed with: a drainage layer concentrically surrounding the mandrel and a filter layer concentrically surrounding the drainage layer; a drainage and support layer concentrically surrounding the mandrel and a filter layer concentrically surrounding the drainage and support layer; a drainage layer concentrically surrounding the mandrel and a filter layer concentrically surrounding the drainage layer; or a drainage layer concentrically surrounding the mandrel, a support layer concentrically surrounding the drainage layer, a filter layer concentrically surrounding the support layer, and a protective layer concentrically surrounding the filter layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is a sectional, partial cutaway view of an example of a downhole tubing filter in accordance with an illustrative embodiment of the invention disclosed herein; 
           [0026]      FIG. 2  is an exploded view of the downhole tubing filter shown in  FIG. 1 ; 
           [0027]      FIG. 3  is an elevational view of an example of a tubing filter element in accordance with an illustrative embodiment of the invention disclosed herein; 
           [0028]      FIG. 4  is a cross-sectional view along A-A of the tubing filter element shown in  FIG. 3 ; 
           [0029]      FIG. 5  is a cross-sectional view of an end fitting of the tubing filter element shown in  FIG. 4 ; 
           [0030]      FIG. 6  is a cross-sectional view of another end fitting of the tubing filter element shown in  FIG. 4 ; 
           [0031]      FIG. 7  is a cross-sectional view of an example of a metallic mesh media in accordance with an illustrative embodiment of the invention disclosed herein; 
           [0032]      FIG. 8  is a cross-sectional view of another example of a metallic mesh media in accordance with an illustrative embodiment of the invention disclosed herein; 
           [0033]      FIG. 9  is a cross-sectional view of another example of a metallic mesh media in accordance with an illustrative embodiment of the invention disclosed herein; and 
           [0034]      FIG. 10  is a cross-sectional view of another example of a metallic mesh media in accordance with an illustrative embodiment of the invention disclosed herein. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    The embodiments discussed herein are merely illustrative of specific manners in which to make and use this invention and are not to be interpreted as limiting in scope. 
         [0036]    While the invention has been described with a certain degree of particularity, it is to be noted that many modifications may be made in the construction and the arrangement of its components without departing from the scope of the invention. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification. 
         [0037]    The description of the invention is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. In the description, relative terms such as “front,” “rear,” “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly” etc.) should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the machine be constructed or the method to be operated in a particular orientation. Terms, such as “connected,” “connecting,” “attached,” “attaching,” “join” and “joining” are used interchangeably and refer to one structure or surface being secured to another structure or surface or integrally fabricated in one piece. 
         [0038]    Referring to the figures of the drawings, wherein like numerals of reference designate like elements throughout the several views, a downhole tubing filter includes a tubing filter element  10 , which as shown in  FIG. 1  may be removeably encased within a perforated steel housing  200 . The tubing filter element  10  can be used in a standalone rod pump application, with a mud anchor (not shown) in a rod pump application, in an ESP application, or in any other downhole pump application. In addition, the downhole tubing filter can be used in vertical or horizontal well applications. As such, the downhole tubing filter element  10  has a bidirectional flow passage  26 . 
         [0039]    As can be seen in  FIG. 2 , an annulus  202  is formed between the tubing filter element  10  and the steel housing  200 . The steel housing  200  includes a first terminal end  204  with an internally threaded section  206  that is connected to a connection fitting  216 , which in turn may be connected to directly or indirectly with an intake end of a downhole pump (not shown) or may be connected to other downhole equipment, such as a tubing sub (not shown). The steel housing  200  also includes a second terminal end  208  with an internally threaded section  210  that connects to a removable plug  212 . The housing  200  and the fitting  216  may be constructed of carbon steel. 
         [0040]    Referring now to  FIGS. 3 through 6 , the downhole tubing filter element  10  has a first end fitting  28 , which may be connected to either an end plug  218  as shown in  FIG. 2  or directly or indirectly to the intake end of the downhole pump or other downhole equipment. The end fitting  28  has a first terminal end with a reduced diameter neck  30  and a second terminal end with an internally threaded section  32  that receives an externally threaded section of the end plug  218  or other downhole equipment. The first terminal end with the reduced diameter neck  30  is connect to a mandrel  42 , and a continuous weld or a welding end ring  44  may be attached using one or more full penetration welds or the like. 
         [0041]    A second end of the downhole tubing filter element  10  terminates in a second end fitting  34  with a first terminal end having an externally threaded section  38  that connects to the connection fitting  216  or other downhole equipment. The second end fitting  34  also includes a second terminal end with a reduced diameter neck  40  that connects to a second terminating end of the mandrel  42 . The second end fitting  34  may be connected to the mandrel using a continuous weld or a welding end ring  46 . 
         [0042]    The mandrel  42  is connected intermediate of and juxtaposed between the first end fitting  28  and the second end fitting  34 . An interior chamber  48  within the mandrel  42  is axially aligned along the flow passage  26  through the downhole tubing filter element  10 . In addition, a central bore  50  in the first end fitting  28  and a central bore  52  in the second end fitting  34  have opposing generally planar axial or open ends that are axially aligned and coaxially spaced along the flow passage  26 . The mandrel  42  includes the first terminating end that abuts the neck  30  of the first end fitting  28  and the second terminating end that abuts the neck  40  of the second end fitting  34 . The mandrel  42  includes a plurality of diametrical perforations  54  along its length to permit fluids to pass from the well  12  into the interior chamber  98  within the mandrel  42 . The perforations  54  may be round as illustrated or may be slotted or a combination of holes and slots that are punched or drilled through the mandrel  42 . The mandrel  42  may be fabricated from stainless steel or investment cast precipitation-hardening corrosion-resistant steel, such carbon steel accompanied with upper and lower end fittings  28  and  34  constructed of a similar material. 
         [0043]    A metallic mesh filter media  100  concentrically surrounds the mandrel  42 . If the filter media  100  becomes clogged or damaged, the downhole tubing filter element  10  may be removed and replaced as necessary. In addition, the filter element  100  may be constructed as a single standalone element or as stackable elements. The filter media  100  is a stainless steel mesh media constructed to withstand very high or low pH environments as well as elevated temperatures and high pressure differentials. The filter media  100  is constructed of single or multiple layers of woven wire mesh, metallic fibers and perforated steel, which are joined together using sintering or diffusion bonding to provide a monolithic structure and forms an integrated filter media. Sintering or diffusion bonding is a high temperature process that fuses tangent metal surfaces without the addition of filter metals or bonding agents. 
         [0044]    As exemplified in  FIGS. 7 through 10 , the woven layer(s) of the filter media  100  can be a plain Dutch weave, a Twill Dutch weave, a Reverse Dutch Twill weave, a reverse Dutch weave or the like. As shown in  FIG. 7 , the filter media  100  can include a filter layer  102  and a drainage layer  104  concentrically surrounding the mandrel  42 . As shown in  FIG. 8 , the filter media  100  can be constructed as a monolithic sandwich media having a protective layer  106  concentrically surrounding the filter layer  102 , which in turn concentrically surrounds a support layer  108  and the drainage layer  104 . Additionally, the filer media  100  can be constructed from concentric woven layers of the filter layer  102  and a drainage and support layer  110 , as shown in  FIG. 9  from woven layers of the filter layer  102 , the support layer  108  and the drainage layer  104  as illustrated in  FIG. 10 . 
         [0045]    The filter media  100  can have a nominal micron layer between 60 and 250, preferably between 80 and 150, and more preferably between 115 and 125. The foregoing materials and micron ratings are merely examples that may be utilized in constructing the downhole tubing filter and other materials and micron ratings may be employed to suit the particular usage of the downhole tubing filter. 
         [0046]    Whereas, the embodiments have been described in relation to the drawings, it should be understood that other and further modifications, apart from those shown or suggested herein, may be made within the scope of this invention.