Patent Publication Number: US-10758848-B2

Title: High capacity filtering screen

Description:
This Application is a continuation application of U.S. patent application Ser. No. 14/892,944, which is a U.S. national stage entry under 35 U.S.C. § 371 of International Application No. PCT/2014/069604, filed Dec. 10, 2014, which claims priority to Application 61/914,224 filed on Dec. 10, 2013, in the United States. 
    
    
     BACKGROUND 
     Vibratory separators are used to separate solid particulates of different sizes and/or to separate solid particulate from fluids. Vibratory separators are used in the oil and gas industry, food industry, cleaning industry, waste water treatment, and others. For example, vibratory separators, or shale shakers, used in the oil and gas industry are used to remove cuttings and other solid particulates from drilling mud returned from a wellbore. A shale shaker is a vibrating sieve-like table upon which returning used drilling mud is deposited and through which substantially cleaner drilling mud emerges. The shale shaker may be an angled table with a generally perforated filter screen bottom. Returning drilling mud is deposited at one end of the shale shaker. As the drilling mud travels toward the opposite end, the fluid falls through the perforations to a reservoir below, thereby leaving the solid particulate material behind. 
     The size of a shaker screen may be pre-determined by the size of the shaker basket which is generally determined by the size of the shaker footprint. It may be desirable to maximize the amount of fluid capacity that a shaker has (i.e., the number of gallons/minute of drilling fluid/mud that a shaker can process). The higher fluid capacity a shaker has, the fewer shakers and screens may be used to maintain drilling operations. Because the size of the screen is often pre-determined, the screening area of a two dimensional pre-tensioned screen is generally also pre-determined. For example, the maximum screen area for a 2 foot by 4 foot screen is 8 square feet. In addition, the screen or wire mesh is bonded to the screen frame so that the area of the screen where the wire mesh is bonded becomes blocked off and the effective open or non-blanked screen area is less than 8 square feet, using the example above. The wire mesh may also decrease the non-blanked area so that the effective screening area of the 8 square foot screen may be reduced by more than 50%. Despite many valuable contributions from the art, it would be beneficial to develop systems and methods that efficiently process fluids, including oil-based and water-based return drilling fluids. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a perspective view of a filtering assembly, according to embodiments of the present disclosure. 
         FIG. 2  is a cross-sectional view of the filtering assembly of  FIG. 1 . 
         FIG. 3  is an exploded perspective view of another filtering assembly, according to embodiments of the present disclosure. 
         FIG. 4  is an assembled perspective view of the filtering assembly of  FIG. 3 . 
         FIG. 5  is a top view of the filtering assembly of  FIG. 3 . 
         FIG. 6  is a side view of the filtering assembly of  FIG. 3 . 
         FIG. 7  is a cross-sectional view of the filtering assembly of  FIG. 3 , taken through the line  7 - 7  of  FIG. 5 . 
         FIG. 8  a perspective view of another filtering assembly, according to embodiments of the present disclosure. 
         FIG. 9  is a partial perspective view of the filtering assembly of  FIG. 8 . 
         FIG. 10  is a side view of the filtering assembly of  FIG. 8 . 
         FIG. 11  is a perspective view of another filtering assembly, according to embodiments of the present disclosure. 
         FIG. 12  is a partial perspective view of the filtering assembly of  FIG. 11 . 
         FIG. 13  is a side view of the filtering assembly of  FIG. 11 . 
         FIG. 14  is a perspective view of another configuration of a filtering assembly, according to embodiments of the present disclosure. 
         FIG. 15  is a side view of the filtering assembly of  FIG. 14 . 
         FIG. 16  is a cross-sectional view of the filtering assembly of  FIG. 14 . 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Embodiments disclosed herein relate generally to vibratory separators, see for example screens disclosed in International Patent Cooperation Treaty Patent Application No. PCT/US2013/045249 filed Jun. 11, 2013, and entitled, “Vibratory Separator Screen”, and U.S. Provisional Patent Application Ser. No. 61/658,175 filed Jun. 11, 2012, and entitled, “Vibratory Separator Screen”, both of which are incorporated in their entirety by reference herein. 
     In one aspect, embodiments disclosed herein relate to a filtering assembly to be used with a vibratory separator. Specifically, the filtering assembly may provide a screening surface area greater than an area defined by a length and width of the filtering assembly. In another aspect, embodiments disclosed herein may provide a filtering assembly having at least two screening levels. In another aspect, fluid provided to the filtering assembly may be filtered once. 
     With reference to  FIGS. 1 and 2 , a filtering assembly constructed in accordance with the present teachings is illustrated and indicated by reference numeral  10 . While the filtering assembly  10  is generally described herein with respect to filtering drilling fluid or mud from an oil well, it will be appreciated that the filtering assembly  10  may be operable to filter other materials, including materials from other types of wells or material from the food industry, waste water industry, cleaning industry, etc. 
     The filtering assembly  10  includes a screen frame or housing  12 . At least one screen segment  14  may be located on the housing  12 . The housing  12  may be constructed of metal (e.g., steel, aluminum, etc.), thermoset polymeric material, thermoplastic polymeric material, a reinforced composite material, or any other suitable material within the scope of the present teachings. Accordingly, the housing  12  may be manufactured by three dimensional printing, injection molding, casting, extruding, machining or stamping. Some screen embodiments may be constructed using a reinforced composite housing, such as those described in U.S. Pat. No. 6,675,975 (incorporated herein by reference), or any other like or suitable composite designs. 
     The housing  12  may be attached to a frame of a vibratory separator (not shown) as will be understood by one of ordinary skill in the art. The housing  12  includes first and second side walls  20   a  and  20   b  and first and second end walls  18   a  and  18   b . The first and second sidewalls  20   a ,  20   b  and the first and second end walls  18   a ,  18   b  define a perimeter of the housing  12 . The first and second sidewalls  20   a ,  20   b  may span a length of the housing  12  and the first and second end walls  18   a ,  18   b  may span a width of the housing P. 
     The housing  12  also has a top face  21  and a bottom face  23 . A profile of the top and bottom faces  21 ,  23  may be planar, U-shaped (e.g., concave or convex), sinusoidal, or any other suitable configuration within the scope of the present disclosure, such that the topography of the upper and lower sides are optimum for the flow and treatment of fluid therethrough. As illustrated in  FIGS. 1 and 2 , the profiles of the top and bottom face  21 ,  23  are planar. 
     The housing  12  may include a plurality of transverse ribs collectively indicated by the reference numeral  16 . The plurality of transverse ribs  16  may be arranged in pairs such that the housing includes at least one pair of transverse ribs, for example, first transverse rib  16   a  and second transverse rib  16   b . The ribs  16  may span a width of the housing  12  such that each transverse rib  16   a ,  16   b  extends laterally between the first and second side walls  20   a ,  20   b  of the housing. Each transverse rib  16   a ,  16   b  includes an upper edge  22   a ,  22   b  and a lower edge  24   a ,  24   b . The upper edge  22  may extend to the top face  21  and the lower edge  24  may extend to the bottom face  23 . 
     Referring to  FIG. 2 , the plurality of transverse ribs  16  may be arranged such that, when viewed from a longitudinal cross section, adjacent transverse ribs, e.g., first rib  16   a  and second rib  16   b  are positioned to have opposing side-faces  17   a  and  17   b , respectively, facing each other. The opposing side-faces  17   a ,  17   b  form an acute angle α with one of the top or bottom face of the housing  12 . For example, as illustrated in  FIG. 2 , opposing side-faces  17   a  and  17   b  of two adjacent, consecutive ribs  16   a ,  16   b  form an acute angle α with the bottom face  23  of the housing  12 . Opposing side-faces  18   a  and  18   b  of the next two adjacent, consecutive ribs  16   b ,  16   a , respectively, (i.e., such that side-faces  17   b  and  18   a  are located on opposite side-faces of rib  16   b ) form an acute angle α with the top face  21  of the housing  12 . 
     On the opposite face of the housing  12  (i.e., if angle α is formed with a bottom surface  23 , the opposite surface will be the top surface  21 ) the opposing side-faces  17   a  and  17   b  will from an obtuse angle β with said opposite face of the housing  12 . For example, as illustrated in  FIG. 2 , opposing side-fades  17   a  and  17   b  of adjacent ribs  16   a ,  16   b  form an obtuse angle β with the top face  21  of the housing  12 . Opposing side-faces  18   a  and  18   b  of the next two adjacent, consecutive ribs  16   b ,  16   a , respectively, form an obtuse angle β with the top face  23  of the housing  12 . 
     This configuration may alternate for each consecutive transverse rib, as shown in  FIG. 2 . In other words, the housing  12  may include an alternating arrangement or pattern of first and second transverse ribs  16   a ,  16   b , such that two adjacent first and second transverse ribs  16   a ,  16   b  define an inverted funnel having an inverted truncated V-shape, and the next two adjacent second and first transverse ribs  16   b ,  16   a  define a funnel having a truncated V-shape. 
     In one configuration, the angle α is substantially equal to fifty degrees. It will be appreciated, however, that the angle α may be more or less than fifty degrees. For example, the angle α may be between 30 degrees and 70 degrees. The angle β may be substantially equal to the angle α, plus ninety degrees. In other embodiments, the angles α and β may be supplementary angles. For example, if the top face and bottom face of the housing  12  are planar and parallel, then the angle α and the angle β of each rib are supplementary angles. However, angle α and angle β do not have to be supplementary angles. 
     The plurality of transverse ribs  16  may define a plurality of openings. Specifically, the plurality of upper edges  22   a ,  22   b  of the first and second ribs  16   a ,  16   b , respectively, of each pair of transverse ribs may define first and third openings  26   a ,  26   b  and the lower edges  24   a ,  24   b  of the first and second ribs  16   a ,  16   b , respectively, of each pair of transverse ribs may define second and fourth openings  28   a ,  28   b . For example, a first opening  26   a  may be defined by a space located on the top face  21  of the housing  12  between the first rib  16   a  and the second rib  16   b , i.e., between the upper edge  22   a  and upper edge  22   b . A second opening  28   a  may be defined by a space located on the bottom face  23  between the first rib  16   a  and the second rib  16   b , i.e., between the lower edge  24   a  and the lower edge  24   b . Each pair of ribs is positioned such that a width of the first opening  26   a  is different from a width of the second opening  28   a . As shown in  FIG. 2 , the width of the first opening  26   a  is less than the width of the second opening  28   a . However, one skilled in the art will understand that the width of the first opening  26   a  may be greater than the width of the second opening  28   a  without departing from the scope of the present disclosure. 
     A third opening  26   b  may be defined by a space located on the top face  21  of the housing  12  between adjacent pairs of ribs, i.e., between an upper edge  22   b  of the second rib  16   b  of a first pair of ribs and an upper edge  22   a  of a first rib  16   a  of a second pair of ribs. A fourth opening  28   b  may be defined by a space located on the bottom face  23  of the housing  12  between adjacent pairs of ribs, i.e., between a lower edge  24   b  of the second rib  16   b  of a first pair of ribs and a lower edge  24   a  of a first rib  16   a  of a second pair of ribs. Each adjacent pair of ribs is positioned such that a width of the third opening  26   b  is different from a width of the fourth opening  28   b . As shown in  FIG. 2 , the width of the third opening  26   b  is greater than the width of the fourth opening  28   b . However, one skilled in the art will understand that the width of the first opening  28   a  may be greater than the width of the second opening  26   b  without departing from the scope of the present disclosure. 
     A fifth opening  26   a  may be defined by a space located on the top face  21  of the screen housing  12  defined by the by a first rib  16   a  and a second rib  16   b  of the second pair of adjacent transverse ribs. A sixth opening  28   a  may be defined by a space located on the bottom face  23  of the screen housing  12  defined by a first rib  16   a  and a second rib  16   b  of the second pair of adjacent transverse ribs. As illustrated in  FIG. 2 , the shape (including width and length) of the fifth and sixth openings  26   a ,  28   a  may correspond to the first and second openings  26   a ,  28   a , respectively, such that a width of the fifth opening is different than a width of the sixth opening. 
     According to some embodiments, a width W 1  of the first opening  26   a  may be approximately equal to a width W 4  of the fourth opening  28   b , and a width W 5  of the fifth opening. A width W 2  of the second opening  28   a  may be approximately equal to a width W 3  of the third opening  26   b  and a width W 6  of the sixth opening. In one configuration, the widths W 1 , W 4 , and W 5  may be substantially equal to four centimeters, and widths W 2 , W 3 , and W 6  may be substantially equal to eleven centimeters. It will be appreciated, however, that the widths W 1 , W 4 , and W 5 , and the widths W 2 , W 3 , and W 6 , may be more or less than four centimeters and eleven centimeters, respectively, within the scope of the present disclosure. 
     The housing  12  may include a third rib  32 . The third rib  32  may span the length of the housing  12 , such that the third rib  32  is a longitudinal rib that extends from the first rib  16   a  to the second rib  16   b , in a direction substantially parallel to the sidewalls  20   a ,  20   b . An upper edge  34  of the third rib  32  may extend to the top face  21  of the housing  12 . In one configuration, a height H 1  of the third rib  32  may be equal to one-half of a height H 2  of the first and second ribs  16   a ,  16   b , although the height of the third rib  32  is not intended to limit the scope of the present disclosure. While the third rib  32  is shown extending in a direction substantially parallel to the sidewalls  20   a ,  20   b , it will also be appreciated that the third rib  32  may extend in other directions from and between the first and second ribs  16   a ,  16   b  within the scope of the present teachings. In some embodiments, H 2  may be about equal to H 1 . As illustrated in  FIG. 2 , the housing  12  includes a plurality of third ribs  32  extending between the first and second ribs  16   a ,  16   b  of each rib pair. In some embodiments, the third rib  32  may not extend between adjacent rib pairs. 
     The housing  12  may also include a fourth rib or rib  36 . The fourth rib  36  may extend from the first rib  16   a  to the second rib  16   b , in a direction substantially parallel to the sidewalls  20   a ,  20   b , such that the fourth rib is a longitudinal rib located between adjacent pairs of ribs. A lower edge  38  of the rib  32  may extend from the top face  21  to the bottom face  23  of the housing  12 . 
     The transverse ribs and longitudinal ribs, e.g., first, second, third and fourth ribs  16   a ,  16   b ,  32 ,  36 , may be integrally formed with the first and second sidewalls  20   a ,  20   b , such that the housing  12  is a monolithic construct. The dimensions of the first, second, third and fourth ribs  16   a ,  16   b ,  32 ,  36  may be such that the non-blanked surface area of the upper side  21  of the housing  12  is greater than seventy-five percent of the total surface area of the upper side  21  of the housing  12 . 
     In an assembled configuration, the filtering assembly  10  may include a plurality of screen segments  14 . The screen segments  14  may be a mesh-like construct. The plurality of screen segments  14  may be positioned across a width between the opposing side-faces  17   a ,  17   b  of the adjacent transverse ribs  16   a ,  16   b  forming the acute angle α between each of the opposing side-face and a top and bottom face  21 ,  23 . For example, a screen segment  14  may be positioned across the second opening  28   a , the third opening  26   b , and/or the sixth opening. A screen segment  14  may also be located between each end wall  18   a ,  18   b  and an adjacent rib  16 . The screen segment  14  will be located on one of either the top or bottom face  21 ,  23  that forms the acute angle α with the rib adjacent the end wall  18   a ,  18   b . For example, the second, third and sixth openings. The at least one screen segment  14  located on the top face  21  of the housing  12  forms a first screening level and the at least one screen segment  14  located on the bottom face  23  of the housing  12  forms a second screening level, such that the filter assembly  10  includes at least two screening levels. 
     As illustrated in  FIG. 2 , with reference to the plurality of openings, at least one screen segment  14  may substantially cover the second opening  28   a  and at least one screen segment  14  may substantially cover the third opening  26   b . A screen segment  14  may cover the opening on a top surface  21  of the housing  12  between the end walls  18   a ,  18   b  and an adjacent rib. The screen segments  14  may be alternately located on the top and bottom faces  21 ,  23  of the housing  12 , as shown in  FIG. 2 . The screen segments  14  may be discrete, i.e., not continuous. While the screen segments  14  are shown as having planar configurations, it will also be appreciated that at least one of the screen segments  14  may be provided in a corrugated configuration on the top and/or bottom faces  21 ,  23  of the housing  12 . 
     With reference to  FIGS. 3-7 , another configuration of a filtering assembly  100  is shown. The filtering assembly  100  may include a first housing  112   a  and a second housing  112   b . The first housing  112   a  may be substantially similar to the housing  12 , except as otherwise provided herein. For example, the first housing  112   a  may include two sidewalls and two end walls, defining a first perimeter with a first length and a first width, a top face, and a bottom face. The first housing  112   a  may also include a plurality of transverse ribs spanning the first width extending from the top face  21  to the bottom face  23  of the first screen housing  112   a . The plurality of transverse ribs  16  may be arranged such that, adjacent transverse ribs  16   a ,  16   b  have opposing side-faces  17   a ,  17   b  that are positioned such that, when viewed from a longitudinal cross-section, both opposing side-faces  17   a ,  17   b  of the adjacent transverse ribs  16   a ,  16   b  form an acute angle α between each of the opposing side-faces  17   a ,  17   b  and one of the top face  21  and the bottom face  23  of the first housing  112   a . Opposing side-faces  18   a  and  18   b  of the next two consecutive, adjacent ribs  16   b ,  16   a , respectively, (i.e., such that opposing side-faces  17   b  and  18   a  are located on opposite side-faces of rib  16   b ) form an acute angle α with the top face  21  of the first housing  112   a.    
     On the opposite face of the first housing  112   a  both opposing side-faces  17   a ,  17   b  of adjacent transverse ribs  16   a ,  16   b  form an obtuse angle β between each of the opposing side-faces  17   a ,  17   b  and said opposite face. Opposing side-faces  18   a  and  18   b  of the next two consecutive, adjacent ribs  16   b ,  16   a , respectively, form an obtuse angle β with the opposite face of the first housing  112   a . Furthermore, the description provided above with respect to the configuration of the first through fourth openings  26   a ,  26   b ,  28   a ,  28   a , is consistent between filtering assemblies  10  and  100 . Accordingly, like reference numerals will be used to describe similar features. 
     The first housing  112   a  may include at least one aperture or bore  114 . The bores  114  may be positioned along the sidewalls  20   a ,  20   b  and extend from the top face  21  to the bottom face  23  of the first housing  112   a . As illustrated, in one configuration the sidewall  20   a  includes four bores  114  and the sidewall  20   b  includes four bores  114 . The bore configuration is not intended to limit the scope of the present disclosure. 
     The second housing  112   b  may include sidewalls  116   a ,  116   b  and end walls  118   a ,  118   b . The sidewalls  116   a ,  116   b  and end walls  118   a ,  118   b  may define a second housing  112   b  having a length and a width. The housing  112   b  may also include a top face  131  and a bottom face  133 . In one configuration, the size and shape of an outer perimeter of the second housing  112   b  is generally the same as the size and shape of an outer perimeter of the first housing  112   a . The sidewalls  116   a ,  116   b  may include at least one aperture or through-bore  120 . The quantity of through-bores  120  may be equal to the quantity of bores  114  in the first housing  112   a , such that the through-bores  114  of first housing  112   a  and the through-bores  120  of second housing  112   b  align, when the second housing  112   b  is attached to the first housing  112   a.    
     The second housing  112   b  may include a plurality of transverse beams  121  extending between the sidewalk  116   a ,  116   b  and a plurality of longitudinal beams  122  extending between the end walls  118   a ,  118   b . The plurality of transverse beams  121  may be positioned to align with the plurality of transverse ribs  16  of the first housing  112   a . The transverse beams  121  may be substantially perpendicular to the longitudinal beams  122 , such that the transverse and longitudinal beams  121 ,  122  define a grid of rectangular openings  124 . The transverse beams  121  may be spaced such that a width W 5  of a first cell  124   a  is substantially equal to the width W 4  of the fourth opening  28   b  in the first housing  112   a , and a width W 6  of a second cell  124   b  is substantially equal to the width W 2  of the second opening  28   a  in the first housing  112   a.    
     The filtering assembly  100  may be assembled by securing at least one screen segment  14  to the second housing  112   b , such that the screen  14  extends between the sidewalls  116   a ,  116   b , and is substantially aligned with the second cell  124   b  and the second opening  28   a  of the first housing  112   a . The at least one screen segment may be positioned on the top face of the second housing  112   b , such that the screen segment  14  is located between the first housing  112   a  and the second housing  112   b . In the assembled configuration, the screen segment  14  may be substantially aligned with the second opening  28   a  in the first housing  112   a , and the through-bores  120  may be substantially aligned with the bores  114 . A screw, bolt or other suitable mechanical fastener (not shown) may be positioned within the bores  114  and the through bores  120  to secure the first housing  112   a  to the second housing  112   b , and thereby secure the second screen segment  14   b  between the first and second housings  112   a ,  112   b.    
     With reference to  FIGS. 8-10 , another configuration of a filtering assembly  200  is shown. The filtering assembly  200  includes a first housing  212   a  and a second housing  212   b . The first and second housings  212   a ,  212   b  may be similar to the description provided above with respect to first and second housing  112   a ,  112   b . However, in the filtering assembly  200 , at least one transverse rib  16  of the first housing  212   a  may include an extension  214  positioned along a length of a bottom edge  24  of at least one transverse rib  16 . The extension  214  may have, for example, a dovetail profile, although other interlocking profiles known in the art may be used without departing from the scope of the present disclosure. The second housing  212   b  includes a corresponding groove  216  having a profile to receive the extension  214 , such that the groove extends between first and second sidewalls  116   a ,  116   b  of the second housing  212   b . The filtering assembly  200  may be assembled by sliding the extension  214  into the groove  216 . As shown in  FIGS. 8-10 , the first housing  212   a  includes multiple extensions  214  and the second housing  212   b  includes multiples grooves  216 . Although, the extension  214  and groove  216  is described with respect to the embodiment shown in  FIGS. 8-10 , one skilled in the art will understand that any embodiment having more than one housing may include an extension  214  and groove  216 . Further, one of ordinary skill in the art will appreciate that in some embodiments, the second housing  212   b  may include the extension  214  and the first housing may include the groove  216 . 
     While the filtering assembly  200  is generally described herein as including a first housing  212   a  and a second housing  212   b , it will be appreciated that the filtering assembly  200  may include more than two housings  212 . With reference to  FIGS. 11 and 12 , in one configuration, a filtering assembly  200  includes three housings  212   a ,  212   b ,  212   c . The third housing  212   c  may have a structure substantially similar to the first housing  112   a  described with respect to  FIGS. 3 and 4 . The first housing  212   a  may be similar to the structure of the first housing  112   a , but may further include a third rib  16   c . The additional rib  16   c  may be configured substantially similar to at least one of an adjacent first rib  16   a  or second rib  16   b  (see, for example,  16   a ,  16   b , and  16   c  in  FIG. 16 ). 
     The first housing  212   a  and the third housing  212   c  may be stacked or otherwise positioned such that the top face  21  of the first housing  212   a  is opposite the bottom face  23  of the third housing  212   c . The first housing  212   a  may be positioned such that a first opening  26   a  is substantially aligned with a fourth opening  28   b  of the third housing  212   c , and a third opening  26   a  of the first housing  212   a  is substantially aligned with a second opening  28   a  of the third housing  212   c . It will be appreciated that the filtering assembly  200  may include more than three housings  212  within the scope of the present disclosure, such that each additional housing has a structure similar to the first housing  212   a.    
     With reference to  FIGS. 14-16 , another configuration of a filtering assembly  300  is shown. The filtering assembly  300  may be substantially similar to the filtering assembly  100 , except as otherwise provided herein. The filtering assembly  300  may include more than two housings  112 . In one configuration, the filtering assembly  300  includes three housings  112   a ,  112   b ,  112   c . It will be appreciated, however, that the filtering assembly  300  may include more or less than three first housings  112  within the scope of the present disclosure. In an assembled configuration, the first housing  112   a  may be stacked or otherwise positioned such that the top face  21  of the first housing  112   a  is opposite the bottom face  23  of the third housing  112   c . With particular reference to  FIG. 16 , the first and second housings  112   a ,  112   b  may be stacked or otherwise positioned such that a centerline of the second cell  124   a  in the second housing  112   b  is offset from a centerline of the fourth opening  28   b  in the first housing  112   a , and a centerline of the second opening  28   a  in the third housing  112   c  is offset from both a centerline of the second opening  26   b  of the first housing  112   a  and a centerline of the first opening  26   a  of the lower first housing  112   a.    
     Accordingly, embodiments disclosed herein provide a filtering assembly that increases an effective screening area. Specifically, embodiments disclosed herein include a screen housing having two sidewalls and two end walls, defining a perimeter with a length and a width. The screen housing also includes a top face and a bottom face. A plurality of screen segments may be positioned on the top face of the screen housing, such that the plurality of screen segments on the top face provide a screening surface area less than a total surface area of the top face. The filtering assembly also includes a plurality of screen segments disposed on the bottom face of the screen housing, such that the plurality of screen segments on the bottom face provide a screening surface area less than a total surface area of the bottom face. However, the total screening surface area of the filtering assembly is greater than the total surface area of the top face or the total surface area of the bottom face. 
     The filtering assembly may further include a plurality of transverse ribs spanning the first width extending from the top face to the bottom face of the screen housing. The plurality of transverse ribs may be arranged such that, adjacent transverse ribs  16   a ,  16   b  have opposing side-faces are positioned such that, when viewed from a longitudinal cross-section, both opposing side-faces of the adjacent transverse ribs form an acute angle α between each of the opposing side-faces and one of the top face and the bottom face of the housing. Opposing side-faces of the next two adjacent ribs form an acute angle α with the top face of the housing. On the opposite face of the first housing both opposing side-faces of adjacent transverse ribs form an obtuse angle β between each of the opposing side-faces and said opposite face. Opposing side-faces of the next two adjacent ribs form an obtuse angle β with the opposite face of the housing. 
     Furthermore, the description provided above with respect to the configuration of the first through fourth openings  26   a ,  26   b ,  28   a ,  28   a , is applicable to the above described arrangement of transverse ribs. Further, the filtering assembly may include more than one housing without departing from the scope of the present disclosure. For example, vibratory separators using screen surfaces described herein may have a single screen deck in certain embodiments. Particularly, older vibratory separators may be retrofitted with the screen surfaces described herein to increase the effective processing capacity. For example, shakers used on offshore platforms, where space on the rig floor is at a premium, may be retrofitted with the screen surfaces according to this disclosure to increase the effective screening area. Likewise, the screen surfaces may be used on shakers located at land-based rigs. In other embodiments, vibratory separators using the plurality of screen surfaces may have multiple screening decks and multiple screening surfaces. In certain embodiments, the vibratory separator may include a first screening deck, such as a top screening deck, with a first screen, and a second screening deck, such as a bottom screening deck, with a second screen positioned beneath the top screening deck. Further, those of ordinary skill in the art will appreciate that other screening decks, such as a third and/or a fourth screening deck, may be included within the vibratory separator without departing from the scope of the present disclosure. These arrangements are useful in methods of treating fluids. 
     In another aspect, embodiments disclosed herein may include a screen housing having two sidewalls and two end walls, defining a perimeter with a length and a width, a top face and a bottom face. The screen housing may further include a first pair of ribs disposed within the perimeter, spanning the width of the screen housing and each rib extending from the top face to the bottom face of the screen housing. The first pair of ribs may define a first opening located on the top face of the screen housing located between a first rib and a second rib of the first pair of ribs. The first pair of ribs may also define a second opening located on the bottom face of the screen housing located between the first rib and the second rib of the first pair of ribs, wherein a width of the first opening is different from a width of the second opening. 
     Accordingly, filtering assemblies described herein may filter a fluid once. For example, with reference to  FIG. 3 , fluid provided to filtering assembly  10  may be filtered by a screen segment  14  located on a top face  21  or a bottom face  23 . For example, fluid may be filtered by the screen segment  14  disposed across the third opening  26   b  and exit the filtering assembly through the fourth opening  28   b . Fluid that bypasses the third opening  26   b  may be filtered by the screen segment  14  disposed across the second opening  28   a  and exit the filtering assembly. 
     Filtering assemblies provided with more than two screening levels may also filter a fluid once. For example, with reference to  FIG. 16 , fluid provided to filtering assembly  16  may be filtered by screen segment  14  disposed across the third opening  26   b  of the third housing  112   c . Fluid that bypasses the screen segment  14  disposed in the third housing  112   c  may be filtered by a screen segment  14  disposed across the third opening  26   b  of the first housing  112   a . Fluid that bypasses both the third housing  112   c  and the first housing  112   a  will be filtered by screen segment  14  disposed in the second opening  28   a  of the second housing  112   b.    
     Filtering assemblies disclosed herein may be manufactured by forming a first screen housing having two first sidewalls and two first end walls, which define a first perimeter. The first screen housing has a first length and a first width, a top face, and a bottom face, and at least one pair of ribs spanning a width of the first screen housing. Once the screen housing is formed, a first screen segment may be attached between a first rib and second rib of each pair of ribs on at least one of the top face or the bottom face of the screen housing. Next, a second screen segment may be attached between the at least one pair of ribs and an adjacent pair of ribs the screen housing and/or the two first sidewalls on a at least one of the top face or the bottom face of the screen housing, such that the top face and the bottom face each have a first or second screen segment disposed thereon. Screen segments may be attached to the screen housing as separate discrete segments or a screen spanning the first length and width of the screen housing may be attached to the screen housing, and the first and screen segments may be cut out from the screen. One skilled in the art will understand that the aforementioned method may be modified in view of the various embodiments disclosed herein, for example, the method may be expanded to include forming a second housing. 
     In some embodiments, screens as disclosed herein may be used in methods of treating fluids, where the screens are positioned in a vibratory separator at or near the feed end of the separator while a single level or conventional screen is disposed proximate the discharge end of the separator. The screening surfaces may also be placed adjacent one another and have staggered relative heights. One of ordinary skill in the art will appreciate that, depending on the configuration of a given vibratory separator, one or more two-tier (or multi-tier) screens may be used in various positions on one or more decks off the vibratory separator. 
     Embodiments of the present disclosure provide a shaker screen with an increased open screening area, and thus greater overall fluid capacity. The increased screening area may improve fluid capacity of the screen. For example, for a screen that has 5.5 square feet of non-blanked area, a screen in accordance with this disclosure may increase the non-blanked area by 40% to 7.7 square feet or by 60% to 8.8 square feet. In a shaker with four screens, this would provide an increase of 8.8 square feet from 22 to 30.8 square feet or 13.2 square feet to 35.2 square feet. One of ordinary skill in the art will appreciate that the screening area of a screen as disclosed herein may increase by any other amount, including less than 40 percent, greater than 60 percent or between 40 and 60 percent based on the configuration of the screen. The horizontal screening surfaces may have a higher effective screening area and allow more fluid to pass through, thereby providing increased effective processing capacity of the screen. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.