Abstract:
A shaker separates components of a slurry. The shaker has a screen with a pressure differential applied to the screen to remove a portion of a slurry. The pressure differential across the screen can be toggled or pulsed. Generally, various types of separators are used to separate liquids and solids. For example, oil-field drilling operations use separators with screens to remove solids from a slurry. One type of apparatus used to remove solids from drilling mud is commonly referred to in the industry as a “shale shaker.”

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Generally, various types of separators are used to separate liquids and solids. For example, oilfield drilling operations use separators with screens to remove solids from a slurry. One type of apparatus used to remove solids from drilling mud is commonly referred to in the industry as a “shale shaker.” A shale shaker, also known as a vibratory separator, is a vibrating sieve-like device upon which returning used drilling mud is deposited and through which substantially cleaner drilling mud emerges. 
         [0002]    Oilfield drilling fluid, often called “mud,” serves multiple purposes in the industry. Drilling mud acts as a lubricant to cool rotary drill bits and facilitate faster cutting rates. Furthermore, the drilling mud counterbalances pressure encountered in subterranean formations. Various weighting and lubrication agents are mixed into the drilling mud to obtain the correct mixture for the type and construction of the formation to be drilled. Because the mud evaluation and/or mixture process may be time consuming and expensive, drillers and service companies prefer to reclaim and reuse the returned drilling mud. Another significant purpose of the drilling mud is to carry the cuttings away from the drill bit to the surface. In the wellbore, the cutting solids enter the drilling mud and must be removed before the drilling mud may be reused. 
         [0003]    Typically, shale shakers use filtration screens to separate drill cuttings from drilling fluid in on-shore and off-shore oilfield drilling. The separating screens have a mesh stretched across a frame. The mesh allows particles and/or fluid below a predetermined size to pass through the separating screen. One or more vibration motors are connected to the frame of the separating screen. The separating screen is vibrated while the mixture of particles and/or fluids is deposited on an input side. The vibration improves separation and conveys the remaining particles to a discharge end of the separating screen. 
         [0004]    The particles that do not pass through the mesh may be introduced to additional processing equipment, such as dryers, hydrocyclones, centrifuges and/or thermal desorption systems. Additionally, particles that do not pass through the mesh are collected in a bin and/or a pit. The particles and/or fluid that pass through the mesh are collected in a pan and/or a sump below the separating screen. 
         [0005]    The slurry is poured onto a back end of the vibrating screen, flowing toward the discharge end of the basket. Large particles that are unable to move through the screen remain on top of the screen and move toward the discharge end of the basket where they are collected. The fluids flow through the screen and collect in a reservoir beneath the screen. 
         [0006]    A continuing desire exists for shakers having increased fluid capacity, increased fluid flow-through rates across the screens, and/or improved fluid removal efficiencies. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]      FIG. 1  is a perspective view of a shaker according to embodiments disclosed herein. 
           [0008]      FIG. 2A  is a schematic diagram of a shaker basket and a sump according to embodiments disclosed herein. 
           [0009]      FIG. 2B  is a schematic diagram of a shaker and a pressure differential device according to embodiments disclosed herein. 
           [0010]      FIG. 3  is a schematic diagram of a system having a pressure differential device for use in a shaker according to embodiments disclosed herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Embodiments disclosed herein are applicable to separation devices that may be utilized in numerous industries. While specific embodiments may be described as utilized in the oilfield industry, such as use with shale shakers, the device may be applicable in other industries where separation of liquid-solid, solid-solid and other mixtures may require separation. The embodiments, for example, may be utilized in the mining, pharmaceutical, food, medical or other industries to separate such mixtures. 
         [0012]    In the following detailed description, reference is made to accompanying drawings, which form a part hereof. In the drawings, similar symbols or identifiers typically identify similar components, unless context dictates otherwise. The illustrative embodiments described herein are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, may be arranged, substituted, combined and designed in a wide variety of different configurations, all of which are explicitly contemplated and form part of this disclosure. 
         [0013]      FIG. 1  illustrates one embodiment of a shaker  20 , preferably a vibratory shaker. The shaker  20  may have screens  24 A,  24 B,  24 C and  24 D mounted in a basket  22  for separating solids from a slurry. As used herein, a slurry refers to a mixture of at least two components, such as fluid and solid.  FIG. 2B  also illustrates the shaker  20 . The shaker  20  may include any number of screens.  FIG. 2B  shows the shaker  20  with four screens,  24 A,  24 B,  24 C and  24 D. A vibrator  26  may be mounted to the shaker  20  for vibrating the screens  24 A,  24 B,  24 C and  24 D. The vibrator  26  may be any device capable of imparting acceleration and force on the basket  22  of the shaker  20 . The vibrator  26  may comprise a plurality of motors or other devices capable of imparting a desired motion and acceleration on the basket  22 . The shaker  20  may include a sump  28 , as shown in  FIGS. 2A and 2B , mounted below screens  24 A,  24 B,  24 C and  24 D for collecting fluid that passes therethrough. 
         [0014]    An inlet end  30  of the shaker  20  may be positioned at one end of the basket  22 . A discharge end  32  of the shaker  20  may be positioned at an opposite end and may receive material from the sump  28  for discharge. Material not passing through the screens  24  may be discharged off the end of the screen  24  and collected. The material flows across screens  24 D,  24 C,  24 B and  24 A in that order, flowing from the inlet end  30  toward the discharge end  32 . As depicted in  FIGS. 1 and 2B , flow across the screen plane is from right to left. At the discharge end  32 , material not passing through the ends may be collected for disposal and/or further processing. Fluid that may have passed through the screens  24 A,  24 B,  24 C and  24 D as the mud may move along the screens  24 A,  24 B,  24 C and  24 D may be collected in the sump  28  and/or may be sent for further processing and/or re-use. 
         [0015]    A pressure differential device  50  (shown in  FIGS. 2B and 3 ) may be provided to create a pressure differential between the space above and below the screens  24 A,  24 B,  24 C and  24 D. The pressure differential device  50  may cause fluid to flow through the screens  24 A,  24 B,  24 C and  24 D and to the sump  28 . The sump  28  may be fluidly connected to a tank, such as an accumulator, which may be positioned between the pressure differential device  50  and the sump  28 . In such an embodiment, the pressure differential device  50  may pull gas, such as air, or fluid from the tank or accumulator to create a pressure differential through the screens  24 A,  24 B,  24 C and  24 D. As a non-limiting example, the pressure differential device  50  may be connected to an accumulator or tank (not shown) that, in turn may be connected to the sump  28 . In such an embodiment, the pressure differential device  50  can pull or otherwise remove air from the tank or the accumulator to create a pressure differential through the screens  24 A,  24 B,  24 C and  24 D such that fluid is forced into the sump  28 . Advantageously, the amount of fluid forced into the sump  28  as a result of the pressure differential can be more than the amount of fluid that would flow into the sump  28  without use of the pressure differential device  50 . 
         [0016]    The pressure differential device  50  may comprise, in an embodiment, pumps that may be used to create the pressure differential or vacuum may be, reciprocating pumps, centrifugal pumps, vacuum pumps, pneumatic pumps, electric pumps, air pumps, piston pumps, rotary piston pumps, rotary vane pumps, screw pumps, scroll pumps, liquid ring pumps, external vane pumps, Wankel pumps, Toepler pumps and/or the like. In another embodiment, the pressure differential may be created by a positive displacement pump and/or a momentum transfer pump and/or an entrapment pump. 
         [0017]    Referring now to  FIG. 3 , a subsystem  34  of the shaker  20  is shown. The subsystem  34  may have screen  24 , channels  36  that may be operatively coupled to the screen  24 , and the pressure differential device  50  fluidly connected to the channels  36 . The channels  36  may facilitate the flow of fluid, liquid, vapor and/or any other material passing through the screen  24 . For example, the amount of fluid passing through the screen  24  due to the pressure differential device  50  may be controlled by the manner and/or the amount of the pressure differential applied. 
         [0018]    In an embodiment, the screen  24  may have multiple sections  38 A,  38 B and  38 C. Alternatively, the sections  38 A,  38 B and  38 C may be portions or an entirety of individual and distinct screens, such as the screens  24 A,  24 B,  24 C and  24 D. Other embodiments may have more or fewer sections. The screen  24  may be formed from a composite material. Alternatively, the screen  24  may be formed from metal or a combination of metal and a composite material. Furthermore, the screen  24  may be flat or may utilize various surface profiles, such as a curved surface, for example. 
         [0019]    The channels  36  may be fluidly connected to the bottom of the screen  24  and to the pressure differential device  50 . Seals  40  may be provided to prevent leaks from the interface between the screen  24  and the channels  36 . The seals  40  may be an elastomer that may be overmolded to the bottom of the screen  24 . Alternatively, gaskets, o-rings, threaded connections and/or other sealing interfaces may be used to seal the screen  24  to the channels  36 . 
         [0020]    In an embodiment as depicted in  FIG. 2B , three channels  36 A,  36 B and  36 C are utilized. Each of the channels  36 A,  36 B and  36 C may be operatively connected to a respective section  38 A,  38 B and  38 C of the screen  24 . The channel  36 A is connected to the section  38 A; the channel  36 B is connected to the section  38 B; and the channel  36 C may be connected to the section  38 C. In an embodiment, multiple channels may be used with one section. The sections  38 A,  38 B and  38 C may comprise the entirety of one screen or, again, comprise a portion or entirety of different, distinct screens. 
         [0021]    The channels  36 A,  36 B and  36 C may each have a valve  42  to control flow through the channels  36 A,  36 B and  36 C. Therefore, the pressure differential across the corresponding section  38 A,  38 B and  38 C may be controlled. Each of the valves  42 A,  42 B and  42 C may be connected in-line with a respective channel  36 , such that the valve  42 A is connected to the channel  36 A, the valve  42 B is connected to the channel  36 B; and the valve  42 C is connected to the channel  36 C. In an embodiment, one of the valves  42 A,  42 B and  42 C may be provided to control the pressure differential to two or even all of the channels  36 A,  36 B and  36 C. For example, one of the valves  42 A,  42 B and  42 C may be provided upstream of each of the channels  36 A to control the pressure differential applied to each of the channels  36 A,  36 B and  36 C. In such an embodiment, the other valves  42 A,  42 B and  42 C may be eliminated, or may be provided in addition to the single valve to provide further control or manipulation of the pressure differential. 
         [0022]    The valves  42 A,  42 B and  42 C may be, for example, rotary valves, ball valves, globe valves, needle valves, butterfly valves, gate valves, plug valves, diaphragm valves, piston valves and/or the like. The valves  42 A,  42 B and  42 C may be manually operated or may be remotely actuated. 
         [0023]    The pressure differential across a section  38 A,  38 B and  38 C may be pulsed, toggled and/or intermittently interrupted by opening and closing the one or more of the valves  42 A,  42 B and  42 C. Manipulating the valves  42 A,  42 B and  42 C by opening and/or closing the valves  42 A,  42 B and  42 C at least partially, may disrupt the flow of fluid, air, and/or vapor through the sections  38 A,  38 B and  38 C to affect the pressure differential across the screen  24 . 
         [0024]    Toggling or pulsing of the pressure differential, as used herein, refers to switching the pressure differential between two or more pressure values. In an embodiment, the pressure differential may be toggled between zero pressure differential and at least a partial pressure differential. In another embodiment, the pressure differential may be toggled between a first amount of pressure differential and a second amount of pressure differential greater than the first amount of pressure differential. Positive pressure may help to dislodge solids on the screen. In yet another embodiment, the pressure differential may toggle between more than two values. 
         [0025]    Further, the amount of the pressure differential applied may be selected as desired. The amount of pressure differential applied may be a complete vacuum. The pressure differential may range from a maximum pressure differential value to a minimum pressure differential value and/or to zero. In an embodiment, the amount of pressure differential may be sufficient to stall the solids and/or the cuttings of the slurry on the screen  24 . The amount of pressure differential may be insufficient to stall the solids and/or the cuttings of the slurry on the screen  24  while still increasing fluid flowing through the screen  24  as compared to the amount of fluid that would flow without use of the pressure differential device  50 . 
         [0026]    In an embodiment, a first amount of pressure differential may be applied at one of the sections  38 A,  38 B and  38 C of the screen  24 . A second amount of pressure differential may be applied to another of the sections  38 A,  38 B and  38 C of the screen  24 . Also, the first amount of pressure differential may be applied at one of the sections  38 A,  38 B and  38 C of the screen  24 , and the second amount of pressure differential may be applied to another of the sections  38 A,  38 B and  38 C of the screen  24  at the same time or at different times. Further, the first amount of the pressure differential may be applied at one of the sections  38 A,  38 B and  38 C of the screen  24  for a specific duration of time. The second amount of pressure differential may be applied to another of the sections  38 A,  38 B and  38 C of the screen  24  for a specific duration of time that may be the same or different than the first duration of time. 
         [0027]    In an embodiment, each of the valves  42 A,  42 B and  42 C may be controlled independently. For example, any of the valves  42 A,  42 B or  42 C may open and/or close irrespective of the position of any one or more of the other valves. 
         [0028]    In an embodiment, the valves  42 A,  42 B and  42 C may open and/or close so that at least one valve is open at any given time. In another embodiment, the valves  42 A,  42 B and  42 C may be pulsed or toggled so that only one of the valves  42 A,  42 B and  42 C may be open at any given time. Various duty-cycles may be utilized with respect to the amount of time each valve is opened and/or closed. In an embodiment, a five second duty-cycle may be used, for example. 
         [0029]    One example of a valve duty-cycle may be summarized as follows: 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
               
               
                 Time 
                   
                   
                   
               
               
                 (seconds) 
                 Valve 1 
                 Valve 2 
                 Valve 3 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 0 
                 Open 
                 Closed 
                 Closed 
               
               
                 5 
                 Closed 
                 Open 
                 Closed 
               
               
                 10 
                 Closed 
                 Closed 
                 Open 
               
               
                 15 
                 Open 
                 Closed 
                 Closed 
               
               
                 20 
                 Closed 
                 Open 
                 Closed 
               
               
                 25 
                 Closed 
                 Closed 
                 Open 
               
               
                 30 
                 Open 
                 Closed 
                 Closed 
               
               
                 n 
                 . . . 
                 . . . 
                 . . . 
               
               
                   
               
             
          
         
       
     
         [0030]    Furthermore, the valves  42 A,  42 B and  42 C may be variably opened to allow a pressure differential of any level between zero and the maximum vacuum capability of the pressure differential device  50 . Further, the multiple channels  36 A,  36 B and  36 C may be connected to a single one of the sections  38 A,  38 B and  38 C, to allow the same or different pressure differentials across portions of each of the sections  38 A,  38 B and  38 C. 
         [0031]    The control and manipulation of the pressure differential across the screen  24  may create a suck and release environment whereby the cuttings or solid material is temporarily stuck due to a first amount of pressure differential and then upon changing to a second amount of pressure differential (e.g. less than the first pressure differential), the cuttings or solid material may convey along the screen  24  toward the discharge end  32  of the shaker  20 . 
         [0032]    In another embodiment, the cuttings or solid material of the slurry may continually move toward the discharge end without interruption due to the pressure differential. In any of the embodiments disclosed herein, the pressure differential can advantageously be used to permit fluid or other material from passing through the screen 24 that would not pass through without use of the pressure differential. For example, additional liquid can be removed from solid drill cuttings, reducing the amount of fluid on cuttings. Such an improvement may permit disposal of the cuttings without further processing, less processing prior to disposal, or less cutting waste required for disposal. 
         [0033]    The shaker  20  may have increased fluid capacity, increased fluid flow-through rates across the screens, and/or improved fluid removal efficiencies as a result of the system and method disclosed or readily understood by those having ordinary skill in the art based on this disclosure. In an embodiment, the pressure differential is applied only to the screen  24 A nearest the discharge end  32 . In another embodiment, the pressure differential is applied only to the screen  24 D nearest the inlet end  30 . In yet another embodiment, the pressure differential is applied to both the screen  24 A and the screen  24 D. In general, the pressure differential at the discharge end  32  can increase the dryness of the cuttings, and the pressure differential at the inlet end  30  may increase fluid capacity of the shaker  20 . For example, applying the pressure differential to the screen  24 A provides an optimal cleaning section for the material just before exiting the shaker  20 . Most of the fluid separates from the solids when the material flows through the initial screens  24 D,  24 C and  24 B located nearest the inlet end  30 . Therefore, the screen  24 A provides a final solid-removing step for the remaining material that has already passed through initial screens  24 D,  24 C and  24 B, thereby providing improved shaker performance. That said, one of ordinary skill in the art will appreciate uses of the pressure differential on any single or combination of multiple screens of a shaker. 
         [0034]    In another embodiment, for example, the pressure differential may be applied to the entirety of one or more of the screens  24 A,  24 B,  24 C and  24 D within the shaker  20 . A combination of any of the pressure differential systems may be utilized. 
         [0035]    Thus, the shaker  20  separates components of a slurry, having the screen  24  with the pressure differential to remove solids from the slurry. The pressure differential device  50  may provide a pressure differential across the screen  24  to cause fluid to flow through the screen  24 . Also, a greater amount of fluid may flow through the screen due to the pressure differential as compared to the amount of fluid that may flow through the screen  24  without any pressure differential. 
         [0036]    The screen  24  may have multiple sections  38 A,  38 B and  38 C, for example. Each section  38 A,  38 B and  38 C may have a corresponding channel  36 A,  36 B and  36 C. The pressure differential across each section  38 A,  38 B and  38 C may be independently toggled or pulsed by opening and closing the valve  42 A,  42 B and  42 C on the corresponding section  38 A,  38 B and  38 C. 
         [0037]    The pressure differential across the screen  24  may pulse or toggle between two or more pressure values. In an embodiment, the pressure differential is pulsed or toggled between zero vacuum and at least a partial vacuum. In another embodiment, the pressure differential is pulsed or toggled between a positive pressure and at least a partial vacuum. The positive pressure may help to dislodge solids on the screen. In yet another embodiment, the pressure differential may pulse or toggle between more than two values. 
         [0038]    In one embodiment, a pressure differential across a screen may be selectively applied to each of the sections  38 A,  38 B and  38 C of the screen  24  wherein the pressure differential is applied across one section  38 A,  38 B and  38 C at a time. 
         [0039]    In another embodiment, the shaker  20  has multiple screens  24 A,  24 B,  24 C and  24 D and a pressure differential is provided across at least the screen  24 A nearest the material output at the discharge end  32 . 
         [0040]    In another aspect, embodiments disclosed herein relate to a method for separating components of a slurry. The method provides a slurry to a top of the screen  24  and pulsing or toggling a pressure differential across a section  38 A,  38 B and  38 C of the screen  24 . The pressure differential across the screen  24  may be independently toggled for each of the sections  38 A,  38 B and  38 C. 
         [0041]    While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the disclosure as described herein. Accordingly, the scope of the present disclosure should be limited only by the attached claims.