Abstract:
An apparatus and method have a screen frame having a screening surface provided by an array of openings separated by transverse ribs, a scalping surface having a plurality of openings formed therethrough and a vertical base portion contacting the screen surface of the screen frame such that vertical base portion connects the scalping surface to the screen frame. A scalping surface support member is disposed vertically between the scalping surface and the vertical base portion such that the scalping surface support member spaces the scalping surface a vertical height above the screening surface of the screen frame.

Description:
[0001]    This is application is a continuation application of U.S. Ser. No. 14/407,299, filed on Dec. 11, 2014, which is a 371 application of PCT/US2013/045053, filed Jun. 11, 2013, which claims priority benefit under 35 U.S.C. §120 of U.S. Ser. No. No. 61/658,158 filed Jun. 11, 2012, the disclosures of which are all incorporated herein by reference in their entireties. 
     
    
     BACKGROUND 
       [0002]    Vibratory separators are used to separate solid particulates of different sizes and/or to separate solid particulate from fluids. Vibratory separators may be used in the oil and gas industry, in which they are often referred to as shale shakers. Shale shakers or vibratory separators 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. Vibratory separators may also be used in the food industry, cleaning industry, waste water treatment, and others. 
         [0003]    Shale shakers may have one, two, or three screening decks. In many multi-deck shakers the top deck is a scalping deck designed to remove large heavy solids from the fluid stream before the stream reaches the finer mesh screens. Scalping generally increases screen life and fluid capacity of finer screens. Increasing screen life and fluid capacity may be a large costs savings for a rig. Single deck shakers are lower in cost than multiple deck shakers and are not alone capable of scalping. Although single deck shakers can be used in series to scalp the fluid stream in one shaker before fine screening is done in separate shakers, this requires much more floor space to accommodate multiple shakers. Expensive multiple deck shakers are most often used offshore where there is limited available rig floor space. Despite many valuable contributions from the art, it would be beneficial to develop a screen capable of performing the scalping and fine screening in one deck. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0004]      FIG. 1  shows a perspective view of a screen frame in accordance with one or more embodiments of the present disclosure. 
           [0005]      FIGS. 2A-2C  show a scalping insert in accordance with one or more embodiments of the present disclosure. 
           [0006]      FIGS. 3A-3D  show perspective views of scalping inserts installed in a screen frame in accordance with one or more embodiments of the present disclosure. 
           [0007]      FIGS. 4A and 4B  show cross-section views of scalping inserts installed in a screen frame in accordance with one or more embodiments of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    The following is directed to various embodiments of the disclosure. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. In addition, those having ordinary skill in the art will appreciate that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment. This description is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. Specifically, while embodiments disclosed herein may reference shale shakers or vibratory separators used to separate cuttings from drilling fluids in oil and gas applications, one of ordinary skill in the art will appreciate that a vibratory separator (or vibratory shaker) and its component parts as disclosed herein and methods disclosed herein may be used in any industrial application. For example, vibratory separators in accordance with embodiments disclosed herein may be used in the food industry, cleaning industry, waste water treatment, and others. 
         [0009]    Embodiments disclosed herein relate generally to vibratory separators. In one aspect, embodiments disclosed herein relate to a shaker screen assembly including a screen frame having at least one slot; and at least one scalping insert disposed in the at least one slot of the screen frame. 
         [0010]    In another aspect, embodiments disclosed herein relate to a scalping insert including a scalping surface having a plurality of scalping slots therethrough; and a vertical base portion. 
         [0011]    In another aspect, embodiments disclosed herein relate to a method of processing fluid, the method including providing a flow of fluid to a shaker screen assembly and flowing the fluid through a scalping surface and a screen surface of a single shaker screen deck. In some embodiments, the fluid may be a drilling fluid, waste water fluid, or other fluids containing particulate matter therein. 
         [0012]    Certain terms are used throughout the following description and claims refer to particular features or components. As those having ordinary skill in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness. 
         [0013]    In the following discussion and in the claims, the terms “including” 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 component is coupled to a second component, that connection may be through a direct connection, or through an indirect connection via other components, devices, and connections. 
         [0014]    In one aspect, embodiments disclosed herein relate to vibratory shakers with two screening surfaces of a single screen frame or deck which are in series so that a majority of the fluid passing through the two screening surfaces of the screen frame is screened twice. The first screening surface of the shaker is a scalping deck. The scalping deck is positioned above the second screen surface, which is a finer screen deck surface of wire cloth. The scalping deck may include scalping inserts to filter out most of the large solids from a fluid stream prior to passing through the finer screen deck surface below. In one example, the vibratory separator may be an oilfield shale shaker. 
         [0015]    Referring initially to  FIG. 1 , a composite screen frame  100  in accordance with one or more embodiments of the present disclosure is shown. The composite screen frame  100  is configured to be disposed in a shaker as will be understood by one of ordinary skill in the art. The screen frame  100  is formed having an array of individual openings or cells  102  separated by transverse ribs  103 . Rib slots  104 , into which scalping inserts will be inserted, are formed in ribs  103 . In other embodiments, rib slots  104  may also be formed in ribs perpendicular to ribs  103  shown in the figures (not shown). For example, rib slots, into which scalping inserts are inserted, may be formed in any number of different manners in any number of ribs in the screening surface. Although screen frame  100  is described as a composite screen frame, one of ordinary skill in the art will appreciate that other types of screen frames may be used without departing from the scope of embodiments disclosed herein. 
         [0016]    Referring now to  FIGS. 2A-2C , a scalping insert  200  for use with a shaker screen in accordance with one or more embodiments of the present disclosure is shown. The scalping insert  200  includes a scalping surface  204  which is substantially horizontal and which has multiple scalping slots  210  through the surface. While the scalping slots  210  are shown in the figures as running lengthwise along the scalping surface  204 , it will be understood that the scalping slots  210  may also run widthwise along the scalping surface  204  (i.e., perpendicular to that shown), or diagonally across the scalping surface  204 , or any other direction, in accordance with one or more other embodiments. 
         [0017]    The scalping surface  204  has raised sidewalls  208  on each end to encourage fluid to pass through scalping slots  210  of the scalping surface  204 . Heights of the sidewalls  208  may be varied as required depending on fluid flow through the scalping surface  204 . For example, scalping inserts with higher sidewalls  208  may be used when higher fluid flow rates pass through the scalping surface  204 . Angled inner surfaces  209 , extending from the top of the sidewalls  208  down toward the scalping surface  204 , of the sidewalls  208  are configured to direct fluid toward the scalping slots  210 . In addition, the scalping surface  204  includes a center divider  206  for similar purposes (i.e., to encourage fluid to flow through scalping slots  210 ). Likewise, angled surfaces of the center divider  206  also direct fluid toward the scalping slots  210 . Scalping inserts may include a center divider  206  of varying heights (e.g., a scalping insert with a higher center divider  206  may be used for higher fluid flow rates). 
         [0018]    The scalping insert  200  further includes a vertical base portion  202  which is configured to correspond with and be inserted into slots  104  ( FIG. 1 ) of the screen frame  100 . In certain embodiments, the base portion  202  may have a rectangular cross-section. In other embodiments, the base portion  202  may have other cross-sectional geometries that correspond with geometries of the slots  104  in the screen frame  100 , such as, but not limited to polygonal, triangular, circular, and other known shapes. In further embodiments, the scalping inserts  200  may be configured having a dovetail shaped base portion that corresponds with a dovetail shaped slot in the screen surface, which would allow for horizontal installation of the scalping insert in the screen surface (rather than vertical installation shown in the figures). For example, the dovetail configuration of the scalping inserts  200  may correspond with a dovetail slot formed in the screen frame and into which the scalping inserts  200  may be installed. 
         [0019]    The scalping inserts  200  may be made of any material suitable for oilfield screens. For example, glass-filled polypropylene or glass-filled nylon may be used in certain embodiments. In other embodiments, the scalping inserts  200  may be injection molded from material that is similar to the material used for composite screen frames, such as but not limited to, high-strength plastic and glass, reinforced with high-tensile-strength steel rods. In still other embodiments, the scalping inserts  200  may be cast from metal, urethane, or other materials. In addition, steel reinforcements may be used inside the molded scalping inserts to add rigidity to their structure. 
         [0020]    The scalping surface  204  and vertical base portion  202  are at approximately a  90  degree angle to each other, and form a cross-section that resembles a T-shape. Other possible scalping insert  200  cross-section geometries formed by the scalping surface  204  and the base portion  202  include, but are not limited to, Y-shapes, U-shapes, and W-shapes. For example, the scalping insert geometries  200  may be dictated by the type of fluid being screened. For fluids with a higher content of gumbo or that are sticky, a flat or T-shape scalping insert  200  may be employed. In fluids with higher sand or other finer particle contents, a Y-shape scalping insert  200  may be used. Those skilled in the art will appreciate the various scalping insert cross-section geometries that most effectively screen various fluid contents. 
         [0021]    The scalping slots  210  in the scalping surface  204  of scalping inserts  200  may have various cross-section geometries. For example, in certain embodiments, the scalping slots  210  may have a “wedge-wire” shape, which may be defined as a generally trapezoidal cross-section having a narrower opening at a top surface of the scalping surface  204  and progressively widening toward a bottom surface. The angled walls of the slot  210  may be between 5 and 20 degrees. In other embodiments, the scalping slots  210  may have trapezoidal cross-section having a wider opening at the top surface of the scalping surface  204  and progressively narrowing toward a bottom surface. In still further embodiments, the scalping slots  210  may have rectangular cross-sections. Certain scalping surfaces  204  may have scalping slots  210  with uniform cross-sectional geometries, while other scalping surfaces  204  may have scalping slots  210  with different cross-sectional geometries, for example, wedge-wire shaped scalping slots  210  on one side of a central divider  206 , and rectangular scalping slots  210  on another side of the central divider  206 . In still further embodiments, the scalping surface  204  may have alternating slot  210  cross-section geometries along a width thereof. Those skilled in the art will appreciate any number of slot  210  cross-sectional geometry configurations may be used. 
         [0022]    The scalping insert  200  may be configured as individual screen inserts which are configured to be inserted individually into slots  104  of the screen frame  100 . In certain embodiments, individual scalping inserts  200  may be fastened or coupled together to form a larger modular unit which includes multiple individual scalping inserts  200 . For example, four individual scalping inserts  200  may be fastened together. In other embodiments, ten or more scalping inserts  200  may be combined to form a large modular unit of scalping inserts  200 . In still further embodiments, a single modular scalping unit, which includes multiple individual scalping inserts  200  coupled together, may be formed and installed onto the screen frame as a single unit. Additionally, a single scalping unit configured to cover the entire screen frame surface may be used. 
         [0023]    Referring now to  FIGS. 3A-3D , various stages of scalping inserts  200  installed in the screen frame  100  in accordance with one or more embodiments are shown. As shown in  FIG. 3A , a base portion  202  ( FIG. 2A ) is inserted into slots  104  of the screen frame  100 , such that the scalping surface  204  is set at a specified distance above a surface of the screen frame  100 . The scalping surface  204  may be spaced between 1 and 2 inches above a surface of the screen frame  100  in some embodiments. In other embodiments, the scalping surface  204  may be 2 inches or higher from a surface of the screen frame  100 . In still further embodiments, various scalping inserts  200  may be positioned at various heights across the screen surface. For example, some scalping inserts  200  may be positioned at a first height above the screen surface while other scalping inserts  200  are positioned at a second height. Moreover, still other scalping inserts  200  may be positioned at a third height, and so on. It should be appreciated that in accordance with one or more embodiments disclosed herein, scalping inserts  200  may be positioned at any number and variations of heights above the screen frame surface. 
         [0024]    The scalping insert  200  may be secured in the slots  104  in various ways. For example, the base portion  202  of the scalping insert  200  may be removably secured in the slots  104  with mechanical fasteners, adhesives, snap-locks, or other known attachment techniques. In other examples, the base portion  202  of the scalping inserts  200  may be permanently secured in the slots  104  with welds, thermal bonding, or other known permanent attachment methods. Still further, the scalping units  200  may be inserted into the slots  104  without any type of fasteners, which allows the scalping units  200  to be quickly interchangeable. As shown in  FIGS. 3B-3D , additional scalping inserts  200  may be installed in slots  104  of the screen frame  100  until an entire surface of the screen frame  100  is covered with scalping inserts  200 . 
         [0025]    Methods of using the screen with scalping inserts  200  installed are described in reference to  FIGS. 4A and 4B . A fine mesh screen  115  ( FIG. 4B ) may first be attached to a top surface of the screen frame  100  with adhesives or other known attachment techniques. The mesh screen  115  may have various size meshes to allow different particle sizes to pass through. After the mesh screen  115  is applied to the screen frame surface, the scalping inserts  200  are inserted into slots  104  of the screen frame  100  (the mesh screen  115  is cut away to allow insertion of the scalping inserts into the slots  104 ) and secured therein. Once the entire surface of the screen frame  100  has scalping inserts  200  installed, the screen may be put into use. 
         [0026]    Screen frames with scalping inserts as described in embodiments herein are used to provide a series screen method of separating particles from fluid passing through the screen. Solids and fluids fall onto the screen surface, which is primarily covered with scalping inserts  200 . In certain embodiments, there may be slight spacing ‘S’ between scalping inserts  200  through which solids may pass. The spacing is provided for visual inspection of the wire mesh  115  on the screen frame. In other embodiments however, there may be no spacing between scalping inserts  200 , where instead the scalping inserts  200  abut each other over an entire screen surface. 
         [0027]    As the fluid and solids fall onto the screen surface, most large solids stay on top of the scalping surfaces  204  ( FIG. 2A ) of the scalping inserts  200  as fluid ‘F’ passes through the scalping inserts  200 . Fluid F and smaller solids pass through the scalping surfaces  204  of the scalping inserts  200  and fall to the finer screen mesh  115  below attached to the screen frame surface. As the fluid passes through the screen mesh, a finer screening of the fluid occurs in which the smaller solids are removed from the fluid. 
         [0028]    In certain embodiments, scalping inserts  200  may be inserted into slots  104  to cover the entire screen frame  100 . In alternate embodiments, scalping inserts  200  may be inserted into slots  104  in a portion of the screen frame  100 . For example, scalping inserts  200  may be inserted in the screen frame (with wire mesh beneath) at a feed end of the screen frame  100  to handle larger and heavier solids while the remaining portion of the screen frame is covered with wire mesh. 
         [0029]    Likewise, the mesh screen size (i.e., the mesh spacing) of the finer wire mesh used on the screen frame may be determined by characteristics of the particular wellbore. For example, depending on the wellbore characteristics, a coarse mesh screen may be used for drilling a wellbore containing, for example, mostly gumbo and a fine mesh screen may be used for drilling a wellbore containing, for example higher sand content. In other embodiments, different mesh sizes (i.e., mesh screen having different size openings) may be used on different surfaces of the same screen. For example, a first mesh screen size may be used to cover an area of the screening surface nearest an inlet of the screen and a second mesh screen size may be used to cover an area of the screening surface nearest an outlet of the screen. 
         [0030]    In certain embodiments, the mesh screen may be fastened to cover the entire screening surface, i.e., all scalping inserts and the screen deck may be covered with mesh screen. The mesh screen size (i.e., the mesh spacing) may be determined by characteristics of the particular wellbore. For example, depending on the wellbore characteristics, a coarse mesh screen may be used for drilling a wellbore containing, for example, mostly gumbo and a fine mesh screen may be used for drilling a wellbore containing, for example higher sand content. In other embodiments, different mesh sizes (i.e., mesh screen having different size openings) may be used on different surfaces of the same screen. For example, a first mesh screen size may be used to cover the scalping inserts and a second mesh screen size may be used to cover the screen deck below the scalping inserts. In other embodiments, a first mesh screen size may be used to cover an area of the screening surface nearest an inlet of the screen and a second mesh screen size may be used to cover an area of the screening surface nearest an outlet of the screen. 
         [0031]    Still further, in certain embodiments, sealing mechanisms (not shown) may be installed between adjacent scalping inserts  200  to avoid leak paths between the scalping inserts. For example, seals may first be installed in the slots  104  of the screen frame  100  prior to inserting the scalping inserts  200 . Thus, when the scalping inserts  200  are installed, the seals in the slots  104  may engage the scalping inserts  200 . In other embodiments, the scalping inserts  200  may have a seal disposed around an outer periphery (e.g., the base portion  202  shown in  FIG. 2A ) which engages a wall of the slots  104  when the scalping inserts  200  are installed in the slots  104  of the screen frame  100 . Other sealing mechanisms for avoiding leak paths between the scalping inserts and the screen frame will be known to those having ordinary skill in the art. 
         [0032]    Advantageously, embodiments of the present disclosure provide a shaker screen that may provide increased screen life, fluid capacity, and lower shaker cost. When large solids and clay-like material are removed from the fluid stream before it is introduced to the finer wire cloth, there is less material to bind or clog up the wire cloth which means more fluid may be processed. In addition, by scalping the large and heavy solids the fine mesh is protected and experiences lighter solids loading which increases the life the screen. Still further, the screen frame with scalping inserts is capable of scalping and fine screening a drilling fluid in a single pass through a vibratory separator. This reduces the amount of rig floor room needed to perform both scalping and screening operations, which may be done separately. Particularly, on offshore rigs where space is at a premium, the ability to both scalp and fine screen a drilling fluid in a single pass may be beneficial. 
         [0033]    Although a few example embodiments have been 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 scope of the present application. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. 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.