Abstract:
A shaker screen comprises a frame that has a plurality of opposing sides. The shaker screen also comprises a screen assembly attached to the frame. In addition, each side of the shaker screen comprises a tubular member having an inner edge, an outer edge, and defining a central axis. Further, a horizontal plane intersects the central axis, the outer edge, and the inner edge of each side.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates generally to the shale shaker screens used to filter solids out of drilling mud. 
     2. Description of Related Art 
     When drilling a well (e.g., for oil or gas), a drill bit is attached to the end of a drill string and drills a hole through the subsurface to access the oil or gas reservoir. Drilling fluid is used during drilling operations. Drilling fluid comprises, for example, a finely ground clay base material to which various chemicals and water are added to form a viscous fluid designed to meet specific physical properties appropriate for the subsurface conditions anticipated. This drilling fluid is pumped down the hollow drill pipe, through the drill bit and returned to the surface in the annular space between the drill pipe and the well bore. 
     The drilling fluid serves three main purposes. First, it aids in cooling the drill bit and thereby increasing its useful life. Second, the mud flushes the cuttings or “solids” from the well bore and returns them to the surface for processing by a solid control system. Third, the mud leaves a thin layer of the finely ground clay base material along the well bore walls which helps prevent caving in of the well bore wall. 
     Although often referred to simply as “mud,” the drilling fluid is a complex composition which must be carefully engineered and tailored to each individual well and drilling operation. The drilling fluid is costly and, thus, is cleaned and reused in a closed loop system in which a solids control system and a shaker play important roles. 
     A shaker, often referred to as a “shale shaker,” is part of a solids control system used in oil and gas drilling operations to separate the solid material (“solids”), removed from the well bore by the drilling operation, from the drilling mud. For the drilling fluid to be used and reused, it must be processed after returning from the well bore to remove the aforementioned solids and maintain its proper density, often expressed as pounds per gallon or “mud weight”, i.e., 10 lb./gal. mud or “10 lb. mud”. The first step in processing the returned drilling fluid is to pass it through a shaker. The returned drilling fluid from the flow line flows into a possum belly, a container mounted at one end of the shaker, and then flows over one or more screens. A shaker includes a support frame on which the shaker screen is mounted. One or more motors in the shaker causes the screen assemblies to vibrate or oscillate, depending on the type of motors utilized. The vibrating action of the screens over which the mud passes removes larger particle size solids (e.g., in the 200 to 700 micron size range) while allowing the drilling fluid and smaller particle size solids to pass through the screen. Solids, which are discarded from the top of the shaker screen, discharge into a pit or onto a conveyor for further treatment or disposal and the underflow drilling fluid flows into the tank below. 
     A common means to secure the screen in the shaker is through the use of a wedge block. A wedge block is typically inserted between the screen and a bracket located along the inside walls of the shaker. The wedge block is pushed further back under or into the bracket, in turn pushing the wedge downward onto the screen and onto the shaker. Two wedges are typically used per screen, but other combinations of wedges may be utilized. 
     A common means to seal the screen in the shaker is through the use of gaskets secured to the shaker at the screen interface. The gasket is typically secured to the shaker with various fasteners that wear out due to contact with the drilling fluid and solids. Thus, maintenance is required to replace worn gaskets and/or fasteners. Replacing the gaskets is time- and labor-intensive—the shaker must be taken offline, the wedge blocks removed, the screens removed, the fasteners ground off, the old gasket material removed, and the new gaskets installed with new fasteners, and then the screens and wedge blocks reinstalled. 
     Accordingly, there remains a need in the art for a shaker screen and sealing gasket capable of easy and efficient replacement, while retaining the necessary securing and sealing properties within a shaker device. 
     SUMMARY OF THE PRESENT DISCLOSURE 
     The embodiments described herein are generally directed to a means for securing and sealing a shaker screen in a shaker device. 
     In an embodiment, an assembly for securing and sealing a shaker screen in a shaker device comprises a shaker screen with tapered side members on which an elastomeric or plyable gasket is adhered. The assembly also comprises a support frame with angular channels that sealingly mate with the gaskets on the side members of the screens. The assembly further comprises a central, angular, bar anchor affixed to the shaker in between each group (upper and lower) of two shaker screens; the central, angular, bar anchor comprises an angular channel on each side, each of which retains a side member of a shaker screen. In addition, the assembly comprises a wedge block retention bracket affixed to the shaker side walls above each shaker screen. Moreover, the wedge block is insertable between the wedge block retention brackets and the shaker screens, providing forces both down onto the screen side member and laterally onto the tapered screen side member, which further presses the screen side member with a gasket into the angular channel of the central, angular, bar anchor, creating a seal. 
     Thus, embodiments described herein comprise a combination of features and advantages intended to address various shortcomings associated with certain prior devices. The various characteristics described above, as well as other features, will be readily apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments, and by referring to the accompanying drawings. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the embodiments described herein. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more detailed understanding of the preferred embodiments, reference is made to the accompanying Figures, wherein: 
         FIG. 1  is a perspective view of an embodiment of a shaker made in accordance with the principles described herein. 
         FIG. 2A  is a top view of an embodiment of a shaker screen made in accordance with the principles described herein. 
         FIG. 2B  is a side view of the screen shown in  FIG. 2A . 
         FIG. 2C  is a perspective view of a portion of the screen shown in  FIG. 2B . 
         FIG. 3A  shows a lateral cross-sectional view of the screen shown in  FIG. 2A . 
         FIG. 3B  illustrates a perspective view of the screen shown in  FIG. 3A . 
         FIG. 4A  is a view of the front face of an embodiment of a wedge block made in accordance with the principles described herein. 
         FIG. 4B  is a side view of the wedge block shown in  FIG. 4A . 
         FIG. 4C  is a perspective view of an embodiment of a wedge block installed in a shaker in accordance with the principles described herein. 
         FIG. 5A  is a perspective view of an embodiment of a shaker support frame in accordance with the principles described herein. 
         FIG. 5B  shows a lateral cross-sectional view of a portion of the support frame shown in  FIG. 5A . 
         FIG. 6A  is a perspective view of an embodiment of a central, angular, bar anchor in a shaker in accordance with the principles described herein. 
         FIG. 6B  is a partial schematic view showing an embodiment of a screen being installed in a shaker in accordance with the principles described herein. 
         FIG. 6C  is a partial schematic view showing an embodiment of a screen installed in a shaker in accordance with the principles described herein. 
         FIG. 7  is a perspective view of an embodiment of a shaker made in accordance with the principles described herein. 
     
    
    
     NOTATION AND NOMENCLATURE 
     Certain terms are used throughout the following description and claim to refer to particular system components. This document does not intend to distinguish between components that differ in name but not function. Moreover, the drawing figures are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in the interest of clarity and conciseness. 
     In the following discussion and in the claims, the term “comprises” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  depicts a shaker  500  in accordance with various embodiments. In the example of  FIG. 1 , a plurality (e.g. 4) of shaker screens  100  is secured to the shaker  500  using both a central, angular, bar anchor  530  (anchor) and a wedge block  200  with a wedge block retention bracket  540 . In other embodiments, only a single screen may be used. Though all four screens  100  and both anchors  530 ,  535  are visible, only one of the four wedge block retention brackets  540  and one of the four wedge blocks  200  are visible in the perspective view of  FIG. 1 . It should be appreciated that there are four wedge block retention brackets  540 , each with a wedge block  200 , in the illustrative shaker  500  shown in  FIG. 1 . The shaker  500  also comprises a gumbo tray  520  and a possum belly  510 . 
       FIG. 2A  illustrates a top view of a shaker screen frame  100 . In a preferred embodiment, the screen frame  100  comprises side members  105 ,  110  and a plurality of cross members  115  that extend between and are secured to side members  105 . The screen frame can further comprise a plurality of mesh screens (not shown) disposed on the cross members  115 . The type and size of mesh screen (not shown) installed on the screen frame  100  can vary and does not affect the principles relied on herein; thus, shaker screen frame  100  will hereinafter be referred to simply as shaker screen  100  or screen  100 . The cross members  115  preferably comprise square tubular members typically with smaller dimensions than the side members  105 ,  110 . The side members  105 ,  110  are comprised of tubular members that are tapered at the sides (as will be discussed below in greater detail). Welds may be used to secure each end of side members  105  to each end of side members  110 ; welds also secure each end of the cross members  115  to the side members  105 . The tapered configuration of the side members  105 ,  110  eliminates shearing weld stress on the screen  100  during shaker  500  operation. In other embodiments (not specifically illustrated) the quantity of cross members  115  may be increased or decreased from that shown in  FIG. 2A . 
     Referring now to  FIGS. 2B and 2C ,  FIG. 2B  illustrates a side view of the screen  100  shown in  FIG. 2A  and  FIG. 2C  depicts a perspective view of a portion of the screen  100  shown in  FIG. 2B . In an embodiment, the screen  100  further comprises an elastomeric gasket  120  that surrounds the outermost edge  130  of all exterior sides (indicated by dashed lines in  FIG. 2B ) of the screen  100  and a portion of the side members  105 ,  110 . The gasket  120  can be of varying thicknesses and widths and can cover equal or non-equal portions above and below the outermost edge  130  of side members  105 ,  110 . For example, the seal may be ½″ wide with a total thickness of 1/16″ and cover ¼″ above and below the outermost edge  130 . For ease of illustration of the screen  100  geometry, the gasket  120  is only depicted in  FIGS. 2B and 2C ; however, the gasket  120  can be assumed to be present but not shown in the remaining illustrated embodiments of the present disclosure. 
     As previously discussed, the side members  105 ,  110  are comprised of tubular members that are tapered at the sides, rather than square as with conventional screens. Tapered sides provide the screen  100  described herein with various benefits as explained below. The geometry of the tapered side members  105 ,  110  can be more easily understood when viewing the side members  105 ,  110  in cross section.  FIG. 3A  illustrates a lateral cross-sectional view along line  125  of  FIG. 2A  and  FIG. 3B  depicts a perspective view of same. Each side member  105  further comprises a tubular member having an inner edge  140  and outer edge  130 , a central axis  150  that runs longitudinally through the center of side member  105  and a horizontal plane  155 , which intersects the central axis  150 , the inner edge  140 , and the outer edge  130  of each side member  105 . Thus, in the cross sectional view, the side members  105  appear tapered at the outermost edge  130  and innermost edge  140 . The taper angle  160  is measured from the horizontal plane  155  to an outer planar surface of side member  105  such that the apex is outer edge  130 . It can be appreciated that a similar cross section  126 , depicted in  FIG. 2A , of side members  110  would yield a substantially similar cross-sectional view as that of cross section  125 . Though not shown, the elastomeric gasket  120  would surround the outermost edge  130  of all side members  105 ,  110 . 
     As shown in  FIGS. 4A and 4B , wedge block  200  comprises a front face  220 , back face  221 , top end  211 , bottom end  213 , first side  230 , second side  231 , and a central axis  250  that runs longitudinally through and halfway between the first side  230  and second side  231  and halfway between the front face  220  and back face  221 . Wedge block  200  also includes a bottom end  213  made up of two planar surfaces  214 ,  216 , which are tapered and intersect to form bottom edge  218 —bottom edge  218  is off center from the central axis  250  such that the bottom edge  218  is located closer to the back face  221  than to the front face  220  as can more easily be seen in  FIG. 4B . Wedge block  200  is also provided with a top end  211  that is tapered from the first side  230  and second side  231  toward the central axis  250 . 
     In an embodiment, the wedge block  200  further comprises a plurality of notches or cutouts including a notch  260  in the top end  211  such that the center of the cut out  260  aligns with the central axis  250  and the notch  260  extends from the front face  220  through the back face  221 . In different embodiments (not specifically illustrated), the cut out  260  at the top end  211  may be off center from the central axis  250 . In an embodiment, the wedge block comprises a notch  225  disposed on both the front face  220  and on the top end  211 , extending from the first side  230  through the second side  231 . Notch  225  also follows the same tapered configuration as the top end  211 , which is tapered from the first side  230  and second side  231  toward the central axis  250 . In the embodiment shown, each wedge block  200  is symmetrical along the central axis  250 , thus, allowing one wedge block  200  to be used with any screen  100 , regardless of the screen&#39;s location. 
     Referring to  FIG. 5A , an interface between screens  100  and the shaker  500  comprises a support frame  525 . The support frame  525  includes a plurality of angled support members  548 ,  549  that sealingly contact the gasket  120  on side members  105 ,  110  of the screen  100 . Referring now to  FIG. 5B , which illustrates a lateral cross-sectional view of a portion of the support frame  525  along line  534  shown in  FIG. 5A ; a partial outline of a side member  105  of screen  100  (without gasket material) is shown in a substantially installed position merely to provide context. In an embodiment, angle  533  is measured from the top surface  538  to the base  539  of support member  548 . The angle  533  of the support frame members  548 ,  549  is substantially the same as the taper angle  160  of side members  105 ,  110  as shown in  FIG. 3A . In some embodiments, the angle  533  of the support frame members  548 ,  549  may be 45 degrees, but can be a different angle in other embodiments. For example, the angle  533  of the support frame members  548 ,  549  may be less than 45 degrees. In other implementations, the angle  533  of the support frame members  548 ,  549  is greater than 45 degrees. 
     The screen  100  and wedge block  200  interface with various components of the shaker device  500 , which will be discussed herein in more detail. Referring back to  FIG. 1 , a shaker interface with screens  100  comprises a plurality of central, angular, bar anchors  530 ,  535  (anchor)—a lower anchor  530  and an upper anchor  535 . Anchors  530 ,  535  are disposed axial to the central axis  550  and substantially in the center of shaker  500  such that a screen  100  may fit between the anchor and each side wall  545  of the shaker  500 . Referring to  FIG. 6A , anchor  530  further comprises angular channels  531 ,  532  that are diametrically opposed to one another. In an embodiment, each angular channel  531 ,  532  sealingly retains one side member  105  of each screen  100 . Though only the lower anchor  530  is visible in  FIG. 6A , it should be appreciated that the upper anchor  535 , shown in  FIG. 1 , comprises angular channels  536 ,  537  and operates in substantially the same way as lower anchor  530 . 
     Referring back to  FIGS. 1 and 4C , a shaker interface with screens  100  comprises a plurality of wedge block retention brackets  540 , each configured to retain a wedge block  200  against a screen  100 . Each wedge block retention bracket  540  comprises an elongated substantially “L” shaped member disposed radially from the central axis  550  and attachably connected to the shaker side wall  545  above each shaker screen  100 . A wedge block  200  is insertable between the wedge block retention brackets  540  and the shaker screens  100  such that the back face  221  of the wedge block is flush against the shaker wall  545  and the bottom end  213  interfaces with the screen side member  105 . Though only one of the four wedge block retention brackets  540  and one of the four wedge blocks  200  are visible in the perspective view of  FIG. 1 , it should be appreciated that there are four wedge block retention brackets  540 , each with a wedge block  200 , disposed radially from the central axis  550  on the shaker side wall  545  above each shaker screen  100 . Conventional shakers typically require the use of two wedge blocks per screen; the present disclosure uses half as many wedge blocks; thus, greatly reducing installation time. 
     Further, in an embodiment, each wedge block  200  is symmetrical along the central axis  250  (see  FIG. 4A ), thus, allowing one wedge block  200  configuration to be used with any screen  100 —the wedge block  200  is simply oriented such that the back face  221  of the wedge block  200  is always flush against the shaker wall  545  while the top end  211  interfaces with the wedge block retention bracket  540  (see  FIGS. 4A and 4C ). Thus, in some embodiments, first side  230  will be inserted under a wedge block retention bracket  540  and in other embodiments, second side  231  will be inserted under a wedge block retention bracket  540 . 
     Referring to  FIG. 1 , before a shaker  500  can be used to remove solids from waste drilling fluids, shaker screens  100  must be installed in shaker  500 . Referring now to  FIG. 6A , in an embodiment, a screen  100  is installed into the shaker  500 , by first placing a side member  105  into an angular channel  531 ,  532 ,  536 ,  537  of an anchor  530 ,  535 . The mesh layers (not shown) should be facing upward when the screen  100  is installed in shaker  500 . Once the side member  105  is placed in angular channel  531 ,  532 ,  536 ,  537  (see  FIG. 6B ), the screen is essentially self-seating—the screen  100  pivots along angular channel  531 ,  532 ,  536 ,  537  and can be released to drop in place (the motion of the screen  10  generally follows arrow  600 ) because the angles  533  of the support frame angular members  548 ,  549  form an inverted pyramidal shape (i.e. a funnel) configured to align with the taper angle  160  of the screen side members  105 ,  110 . Once a screen  100  is seated in the support frame (see  FIGS. 6C and 4C ), a wedge block  200  is inserted between the wedge block retention bracket  540  and the shaker screen  100  such that the back face  221  of the wedge block is flush against the shaker wall  545 . A hammer or other suitable tool is then used to pound the wedge block further under the wedge block retention bracket  540 . 
     As previously described, certain embodiments disclosed herein comprise a gasket  120  fitted on the outer edge  130  of the screen  100  (see  FIG. 2B ). The application of a gasket  120  on the screen  100  itself removes the need to install gasket material on the support frame of the shaker  500  with the use of bolts or screws. Further, whenever a screen  100  is replaced due to normal wear and tear of the mesh layers (not shown), a new gasket  120  is automatically installed. Thus, replacing gasket material no longer requires the grinding of bolts and screws, reducing down time of the shaker  500 . 
     As previously described, in an embodiment, the bottom edge  218  of the wedge block  200  is tapered (see  FIG. 4B ), which provides a force both downward onto the screen side member  105 , but also laterally onto the tapered screen side member  105 . This lateral force further presses the side member  105  with an elastomeric gasket  120  into the angular channel  531 ,  532 ,  536 ,  537  of the central, angular, bar anchor  530 ,  535 , forming a substantially fluid tight seal. 
     Referring to  FIG. 7 , in an embodiment, the gumbo tray  520  may be rotated up along central axis  555  and into the cavity of the possum belly  510  to allow for easier access to the upper screens  100  for installation or removal.