Patent Publication Number: US-11649819-B2

Title: Pumping systems with fluid density and flow rate control

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to pumping, and more particularly to pumping systems for controlling fluid density and flow rate such for use in delivering proppant downhole for hydraulic fracturing. 
     2. Description of Related Art 
     Proppant must be pumped at pressure into downhole earth formations to produce production fluids such as oil and gas in hydraulic fracturing operations. The proppant concentrations and flow rates must be controlled to achieve the intended effect, and typically multiple pumps are used for purposes of volume and redundancy. Multiple pumps feeding the downhole formation draw from a sources of clean and/or dirty fluid. The clean fluid can, for example, be water, and the dirty fluid can, for example, be a suspension of proppant. In some hydraulic fracturing operations a single pump or a plurality of pumps can be designated to pump only clean fluid or can be switched to pump proppant instead. When one pump fails, operators can compensate by manually adjusting the remaining pumps to maintain the desire concentration and flow rate of proppant into the downhole formation. 
     The conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved pumping systems. This disclosure provides a solution for this need. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to certain figures, wherein: 
         FIG.  1    is a schematic side elevation view of an exemplary embodiment of a system constructed in accordance with the present disclosure, showing the system connected to a well head for pumping a fracturing fluid containing proppant into a downhole formation; 
         FIG.  2    is a schematic view of the system of  FIG.  1   , showing the controller, pumps, valves, and sensors for controlling downhole flow rate and concentration of proppant; 
         FIG.  3    is a schematic view of one of the pumps of the system of  FIG.  1   , schematically showing the fluid flow in the first stroke direction of the linear motor; 
         FIG.  4    is a schematic view of the pump of  FIG.  3   , schematically showing the fluid flow in the second stroke direction of the linear motor; 
         FIG.  5    is a schematic view of the pump of  FIG.  3   , showing a plunger in place of the piston. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of a system in accordance with the disclosure is shown in  FIG.  1    and is designated generally by reference character  100 . Other embodiments of systems in accordance with the disclosure, or aspects thereof, are provided in  FIGS.  2 - 4   , as will be described. The systems and methods described herein can be used for controlling flow of proppant on a continuous spectrum of flow rate and concentration, improving pump life, and providing automatic adjustment of pumps to follow a predetermined stimulation method and/or to compensate for failed pumps. 
     In a wellbore  102  through an earth formation  104 , a casing  106  can be positioned in the wellbore  102  with an annulus  108  between the casing  106  and the formation  104 . Downhole tools can be passed into the wellbore  102  through the casing  106 , and production fluids, such as oil and gas, can be conveyed to the surface within the casing  106 . The system  100  can be used to pump proppant from the surface  110  down casing  106  and ultimately into the earth formation  104 . 
     With reference now to  FIG.  2   , the system  100  includes a first plurality of pumps  112 ,  114 ,  116 , referred to herein as clean pumps, connected to draw clean fluid, e.g., water, at low pressure from a clean fluid source  118  through a clean fluid supply junction  120 . A second plurality of pumps  122 ,  124 ,  126 , referred to herein as dirty pumps, is operatively connected to a dirty fluid supply  128  that receives proppant laden fluids at low pressure from a dirty fluid source  130 , e.g., a blender. A first valve  132  is connected between the clean fluid supply junction  120  and the dirty fluid supply  128  for regulating clean fluid, e.g. water, to the dirty fluid supply  128 . A second valve  134  is connected to regulate flow of a dirty fluid from the dirty fluid source  130  to the dirty fluid supply  128 . A controller  136  is operatively connected to the first and second valves  132 ,  134 , to the clean pumps  112 ,  114 ,  116 , and to the dirty pumps  122 ,  124 ,  126 , for controlling downhole concentration and flow rate of proppant through the combination of fluids from the clean fluid source  118  and the dirty fluid source  130  at a pressure provided by the pumps  112 ,  114 ,  116 ,  122 ,  124 ,  126 . Broken lines in  FIG.  2    indicate the wired or wireless connections between the controller  136  and the pumps  112 ,  114 ,  116 ,  122 ,  124 ,  126  and valves  132 ,  134 . 
     The system  100  allows for variation of proppant concentration and flow rate across a continuous spectrum (as opposed to discrete or step-wise variation as in traditional systems where discrete or step-wise shifts of a gear transmission limit flow rate and the concentration settings are set by fluid sources and combined as high pressure fluids prior to or after entering the well head). The continuous rate spectrum of system  100  is produced by the pumps  112 ,  114 ,  116 ,  122 ,  124 ,  126 . The continuous concentration spectrum (ranging from clean to pure proppant and carrier fluid, i.e., dirty) is produced by the valves  132 ,  134  and the pumps  112 ,  114 ,  116 ,  122 ,  124 ,  126 . In  FIG.  2   , to supply pure dirty fluid to the casing  106  (which would be set by the blend of proppant), valve  132  can be closed and operation of cleans pumps  112 ,  114 ,  116  can cease. To supply pure clean fluid to casing  106 , valve  134  can be shut (the valve  132  can be either open or closed and the dirty side pumps  122 ,  124 ,  126  can either run or not). In split flow types of operations as in traditional pumping systems, a proppant laden carrier fluid (dirty fluid) combines with the clean fluid after leaving the pumps and prior to going down hole as the fracturing fluid. In such traditional systems, the pump rates are adjusted and the concentration of fluid in the blender is changed to achieve desired down hole properties. Such traditional techniques produce the step-wise adjustments in flow and concentration of proppant, because (among other things) the traditional systems lack the continuous spectrum from the low pressure side valves (e.g. the valves  132  and  134  in  FIG.  2   ). The traditional systems allow for changing the concentration by adjusting the mixture of proppant in the blender, which does not allow for a continuous spectrum of adjustment to downhole flow rates and proppant concentrations as in the present disclosure. 
     A plurality of sensors  138 ,  140 ,  142 ,  144  are operatively connected to the controller, as indicated by broken lines in  FIG.  2   , for feedback to control the downhole proppant concentration and flow rate on the fly. A first volume flow meter  138  is upstream of the clean fluid supply junction  120  for measuring total flow Q c1  of clean water into the clean and dirty pumps  112 ,  114 ,  116 ,  122 ,  124 ,  126 . A second volume flow meter  140  is included in a flow path fluidly connecting the clean fluid supply junction  120  to the clean pumps  112 ,  114 ,  116  for measuring flow Q c2  of clean water into the clean pumps  112 ,  114 ,  116 . A third volume flow meter  142  is included just downstream (or optionally just upstream) of the second valve  134  for measuring flow Q d  of dirty fluid into the dirty fluid supply  128 . The plurality of sensors includes a densometer  144  included in series downstream of the dirty fluid supply  128  and upstream of the dirty pumps  122 ,  124 ,  126  for measuring the fluid density and in-turn the concentration p of proppant. The controller  136  is connected to control each of the pumps  112 ,  114 ,  116 ,  122 ,  124 ,  126  individually, and is operatively connected to receive feedback from the first, second, and third volume flow meters  138 ,  140 ,  142  and the densometer  144  for closed-loop control of the pumps  112 ,  114 ,  116 ,  122 ,  124 ,  126 . 
     Consider that Q 3  is the flow rate of clean water from the clean fluid supply junction  120  to the dirty fluid supply  128 , and that the flow of Q 3  carries a concentration of proppant C 1  and Q d  (the flow through flow meter  142 ) carries a proppant concentration C 2  of fluid then the measured concentration ρ is:
 
( Q   3   *C   1   +Q   d   *C   2 )/( Q   3   +Q   d )=ρ
 
     However, since the proppant concentration C 1  is zero for clean fluid, then this relation reduces to: 
     
       
         
           
             
               
                 ( 
                 
                   
                     Q 
                     d 
                   
                   ⁢ 
                   
                     C 
                     2 
                   
                 
                 ) 
               
               
                 
                   Q 
                   3 
                 
                 + 
                 
                   Q 
                   d 
                 
               
             
             = 
             ρ 
           
         
       
     
     To achieve a maximum concentration of proppant for the system, then the valve at Q 3  could restrict flow to achieve: 
     
       
         
           
             
               
                 
                   Q 
                   d 
                 
                 ⁢ 
                 
                   C 
                   2 
                 
               
               
                 Q 
                 d 
               
             
             = 
             
               
                 C 
                 2 
               
               = 
               ρ 
             
           
         
       
     
     Or a mass flow rate of proppant out of the dirty side of the system  100 :
 
 {dot over (m)}=ρ*Q   d  
 
     Thus the downhole concentration is: 
                 ρ   ⁢           ⁢     Q   d           Q   d     +     Q     c   ⁢           ⁢   2           =     C   downhole           
With the same mass flow rate m. The calculated concentration ρ is actively compared to the concentration measured at the densometer  144  for feedback control of concentration.
 
     The parallel pumps  122 ,  124 ,  126  in series with the supply share the flow rate load according to:
 
 Q   d   =Q   pump4   +Q   pump5   +Q   pump6 ,
 
for the dirty side, and:
 
 Q   c2   =Q   pump1   +Q   pump2   +Q   pump3 ,
 
for the clean side.
 
     Through this example, it becomes apparent how the system  100  can be used to set a mass flow rate of proppant and overall fluid volume flow rate to achieve desired pressures and fluid concentrations. As further discussed below, system  100  can ensure that Qa and Qc2 are always achieved if a pump system fails or is added. This allows system  100  to adjust proppant concentration and flow rate downhole during the pumping operation to an infinite degree through adjusting the motor speed (described further below), valves  132 ,  134 , or any combination. 
     The controller  136  is configured, e.g., with machine readable instructions, to compare a desired downhole volume flow rate and mass flow rate of proppant laden fluid (the fracturing fluid) to the actual produced fracturing fluid based on the feedback from the first, second, and third volume flow meters  138 ,  140 ,  142  and the densometer  144 . The controller  136  is configured, e.g., with machine readable instructions, to adjust individual flow rates of the clean and dirty pumps  112 ,  114 ,  116 ,  122 ,  124 ,  126  and to adjust the valves  132 ,  134  to make the actual downhole flow concentration and flow rate of proppant match the desired downhole concentration and flow rate of proppant. 
     With reference now to  FIG.  3   , each of the pumps  112 ,  114 ,  116 ,  122 ,  124 ,  126  includes an electric motor  146 , e.g., a linear electric motor (LEM), a linear induction motor (LIM), or a rotary electric motor connected to a transmission for converting rotary to linear motion. While  FIG.  4    only shows one pump  112  for sake of clarity, those skilled in the art will readily appreciate that pumps  114 ,  116 ,  122 ,  124 ,  126  can all be configured similar to pump  112 . The motor  146  includes a rod  148  that is connected to a respective pump piston  150  that is slidingly engaged in piston chamber  152 . The cross-sectional view of  FIG.  3    can represent a single section of a pump with one or more similar parallel sections to form a duplex, triplex, quintuplex, or the like. 
     With continued reference to  FIG.  3   , each of the pumps  112 ,  114 ,  116 ,  122 ,  124 ,  126  is a double acting pump. This allows the pump to perform pumping work in both directions, reducing the number of strokes for a given volume of flow and extending the pump life. The pump piston  150  divides the piston chamber  152  into a first end  154  and a second end  156 . A first one-way suction valve  158  is in fluid communication with the first end  154  of the piston chamber, configured to admit fluid into the first end  154  of the piston chamber  152  therethrough. A first one-way discharge valve  160  is in fluid communication with the first end  154  of the piston chamber  152 , configured to discharge fluid from the first end  154  of the piston chamber  152  therethrough. A second one-way suction valve  162  is in fluid communication with the second end  156  of the piston chamber  152 , configured to admit fluid into the second end of the piston chamber therethrough. A second one-way discharge valve  164  is in fluid communication with the second end  164  of the piston chamber  152 , configured to discharge fluid from the second end  156  of the piston chamber  152  therethrough. 
     The suction valves  158  and  162  can both draw fluid from a common source, e.g., connecting to the source through a y-connection. The discharge valves  160  and  164  can both feed into the same destination, e.g., connecting through another y-connection.  FIG.  3    shows the motor stroking in a first direction, indicated by the large right-facing arrow. In this stroke direction, the piston pushes fluid out of the second end  156  of the piston chamber  152  through discharge valve  164  and draws fluid through the suction valve  158  into the first end  154  of the piston chamber  152  as indicated in  FIG.  3    by the large vertical arrows. In the reverse stroke direction, shown with the large left pointing arrow in  FIG.  4   , the piston  150  drives fluid out of the first end  154  of the piston chamber  152  through discharge valve  160 , and draws fluid into the second end  156  of the piston chamber  152  through the suction valve  162 , as indicated by the large vertical arrows. Due to the presence of the rod  148  in the first end  154  of the piston chamber  152 , the piston  150  should travel at a different speed in the first stroke direction of  FIG.  3    than in the second stroke direction of  FIG.  4    to maintain a given flow rate through the pump  112 . The need to actuate the piston at two different speeds depending on which direction the piston is traveling is readily accommodated by the fact that the motor  146  is electric. Those skilled in the art will readily appreciate that a non-electric engine/transmission/crankshaft can be used to produce differing speeds in the two directions without departing from the scope of this disclosure; however an electric motor can advantageously produce this motion in a straightforward manner. The pump  112  in  FIGS.  3 - 4    includes a piston  150 , however as shown in  FIG.  5   , the piston  150  can be replaced with a plunger  250  for a plunger pump configuration, which otherwise operates similar to the piston pump configuration of  FIGS.  3 - 4   . 
     While shown and described in the exemplary context of double acting single piston pumps, those skilled in the art will readily appreciate that any suitable type of pump such as double acting plunger pumps, single acting plunger pumps including but not limited to triplex pumps, quintuplex pumps, centrifugal pumps, progressive cavity pumps, or any assortment or combination of the foregoing, can be used without departing from the scope of this disclosure. While electric linear motors are advantageous, those skilled in the art will readily appreciate that with lag expected, any other suitable type of drive such as standard engines, transmissions, gears, crankshafts, connecting rod drives, and the like, can be used without departing from the scope of this disclosure, although some set ups may limit the range of adjustment to discrete steps. 
     With reference again to  FIG.  2   , the controller  136  can include machine readable instructions configured to cause the controller  136  to follow a programmed stimulation method that varies downhole proppant flow rate and/or concentration as a function of time. The programmed stimulation method can be supplied as a program or sequence of commands to be executed by the controller. In addition to or in lieu of following programmed input, the controller  136  can receive on-the-fly user input for changing the desired downhole proppant flow rate and concentration. Programmed and/or user input to the controller  136  is indicated in  FIG.  2    with the arrow  166 . Regardless of whether the desired downhole flow rate and concentration of proppant are from a predetermined stimulation program or from on-the-fly user input, the controller  136  adjusts the pumping of the pumps  112 ,  114 ,  116 ,  122 ,  124 ,  126  to match the actual downhole flow rate and concentration of proppant (indicated in  FIG.  2    with the large arrow  168 ) with the desired flow rate and concentration. The controller  136  can determine actual downhole concentration and flow rate of proppant based on measurements from the first, second, and third volume flow meters  138 ,  140 ,  142  and the densometer  144 . Adjusting to match an actual downhole flow rate and concentration of proppant with a desired flow rate and concentration of proppant includes the controller  136  varying electrical power to at least one of the respective motors  146  (shown in  FIGS.  2 - 4   ) to adjust pumping rates and/or adjusting valves  132 , 134  to adjust proppant concentration. 
     If one or more of the pumps  112 ,  114 ,  116 ,  122 ,  124 ,  126  fails, the controller  136  can automatically adjust the remaining pumps  112 ,  114 ,  116 ,  122 ,  124 ,  126  that are still operational to maintain the desired flow rate and concentration of proppant without requiring user input. The desired flow properties can be maintained by adjusting any remaining operational pumps  112 ,  114 ,  116 ,  122 ,  124 ,  126  and/or the valves  132 ,  134  which can include adjusting pump speed for a given operation pump  112 ,  114 ,  116 ,  122 ,  124 ,  126  and/or valve position of the valves  132 ,  134 . If one clean pump, e.g., pump  112 , has failed, the controller  136  can increase and balance flow among operational clean pumps, e.g., pumps  114  and  116 . Similarly, if one of the dirty pumps, e.g., pump  122 , fails, the controller  136  can increase and balance flow among operation dirty pumps, e.g., pumps  124  and  126 . 
     Dedicating some pumps to be clean pumps  112 ,  114 ,  116  and some pumps to be dirty pumps  122 ,  124 ,  126  ensures that at least the clean pumps  112 ,  114 ,  116  will be isolated from proppant. The clean pumps  112 ,  114 ,  116  will therefore have extended service lives between servicing, and fluid end consumables costs and whole fluid end costs are reduced. While shown and described in the exemplary context of having three clean pumps  112 ,  114 ,  116  and three dirty pumps  122 ,  124 ,  126 , those skilled in the art will readily appreciate than any suitable number of clean and dirty pumps can be used without departing from the scope of this disclosure. 
     Systems and methods as disclosed herein do not rely on user monitoring to check pump performance or to orchestrate pump rates to follow a stimulation method for a given hydraulic fracturing job. Placing pumps in a control system where each pump self-regulates and communicates with the collective regulation, if a pump were to fail, allows the other pumps to immediately react and adjust with no downtime. If a pump is swapped during a job, or another pump is sitting on standby, as soon as a replacement enters service, the pumps can automatically return to their original parameters. If used with accelerometers to measure excessive pump movement and/or with a system to monitor cavitation, any problematic pump can decrease output to a safe level with the other pumps compensating for the duration of the job. This can prevent unnecessary pump failure as a result of less than ideal pumping conditions, while keeping the job running uninterrupted, and without requiring human input. Using electric motor driven pumps in combination with the valve arrangement to regulate the mixture of clean and dirty flows to the dirty side of the pumping system, there is an infinite number of pressure, flow rate, and proppant concentration combinations for a single system in a single job (as opposed to being limited to discrete combinations as in traditional systems). Using electric motors to drive the pumps can eliminate the need for transmission, gear sets, and roller bearings, as they would otherwise be supplanted with the drive mechanism specific to the electric motor. 
     Accordingly, as set forth above, the embodiments disclosed herein may be implemented in a number of ways. For example, in general, in one aspect, the disclosed embodiments relate to a system. The system includes a first plurality of pumps connected to draw from a clean fluid supply junction. A second plurality of pumps is operatively connected to a dirty fluid supply. The dirty fluid can be sourced from a connected container holding a premixed proppant suspension or a blender, for example. A first valve is connected between the clean fluid supply junction and the dirty fluid supply for supplying clean fluid to the dirty fluid supply to create a particular fluid mixture. A second valve is connected to feed a dirty fluid to the dirty fluid supply. A controller is operatively connected to the first and second valves and to the first and second pluralities of pumps for controlling downhole concentration and flow rate of proppant from the dirty fluid supply, wherein downhole concentration and flow rate are varied across a continuous spectrum. 
     In general, in another aspect, the disclosed embodiments relate to a method. The method includes controlling downhole concentration and flow rate of proppant, wherein downhole concentration and flow rate are varied across a continuous spectrum. 
     In accordance with any of the foregoing embodiments, a plurality of sensors can be operatively connected to the controller for feedback to control the downhole concentration and flow rate during the pumping operation. The plurality of sensors can include a first volume flow meter upstream of the clean fluid supply junction for measuring total flow of clean water into the first and second pluralities of pumps, a second volume flow meter in a flow path fluidly connecting the clean fluid supply junction to the first plurality of pumps for measuring flow of clean water into the first plurality of pumps, a third volume flow meter downstream of the second valve for measuring flow of dirty fluid into the dirty fluid supply, and a densometer in series with the dirty fluid supply upstream of the second plurality of pumps for measuring concentration of proppant. The controller can be connected to control each of the pumps in the first and second pluralities of pumps individually, and can be operatively connected to receive feedback from the first, second, and third volume flow meters and the densometer for closed-loop control of the pumps. 
     The controller can be configured to compare a desired downhole flow concentration and flow rate of proppant mixed with a water mixture to actual downhole flow concentration and flow rate of proppant mixed with water mixture based on the feedback from the first, second, and third volume flow meters and the densometer. The controller can be configured to adjust individual flow rates of the first and second pluralities of pumps and/or to adjust the first and second valves to make the actual downhole flow concentration and flow rate match the desired downhole concentration and flow rate. 
     In accordance with any of the foregoing embodiments, each of the pumps in the first and second plurality of pumps can include an electric motor. The electric motor can be connected to produce a linear motion in the respective pump and/or the electric motor can be a linear motor. The linear motor can include a rod that is connected to a respective pump piston slidingly engaged in piston chamber, wherein the pump piston divides the piston chamber into a first end and a second end. A first one-way suction valve can be in fluid communication with the first end of the piston chamber, configured to admit fluid into the first end of the piston chamber therethrough. A first one-way discharge valve can be in fluid communication with the first end of the piston chamber, configured to discharge fluid from the first end of the piston chamber therethrough. A second one-way suction valve can be in fluid communication with the second end of the piston chamber, configured to admit fluid into the second end of the piston chamber therethrough. A second one-way discharge valve can be in fluid communication with the second end of the piston chamber, configured to discharge fluid from the second end of the piston chamber therethrough. 
     In accordance with any of the foregoing embodiments, the controller can include machine readable instructions configured to cause the controller to follow a programmed stimulation method that varies downhole proppant flow rate and/or concentration as a function of time. 
     In accordance with any of the foregoing embodiments, controlling downhole concentration and flow rate can include receiving sensor feedback into a controller from a plurality of sensors to control a first plurality of pumps operatively connected to a clean fluid supply junction and a second plurality of pumps operatively connected to a dirty fluid supply to adjust to match an actual downhole flow rate and concentration of proppant with a desired flow rate and concentration of proppant. Receiving sensor feedback can include receiving sensor feedback from a first, second and third flow meter, and from a densometer as described above. The method can include determining actual downhole concentration and flow rate of proppant based on measurements from the first, second, and third volume flow meters and the densometer. Adjusting to match an actual downhole flow rate and concentration of proppant with a desired flow rate and concentration of proppant can include the controller varying electrical power to at least one of the respective motors. 
     In accordance with any of the foregoing embodiments, each pump in the first and second pluralities of pumps can be a double acting pump and wherein the electric motor is connected to produce linear motion in the respective pump. Controlling a first plurality of pumps operatively connected to a clean fluid supply junction and a second plurality of pumps operatively connected to a dirty fluid supply can include pumping fluid from each pump in the first and second pluralities of pumps in both linear directions of the respective linear motor. Pumping fluid from each pump in the first and second pluralities of pumps in both linear directions of the respective linear motor can include actuating the respective motor at a first rate in a first stroke direction and actuating the respective motor at a different rate in a second stroke direction reverse of the first stroke direction. 
     In accordance with any of the foregoing embodiments, matching an actual downhole flow rate and concentration of proppant with a desired flow rate and concentration of proppant can include matching a desired flow rate that changes as governed by a programmed stimulation method that varies downhole proppant flow rate and/or concentration as a function of time. It is also contemplated that the method can include receiving user input for on-the-fly desired flow rate and concentration of proppant, wherein matching an actual downhole flow rate and concentration of proppant with a desired flow rate and concentration of proppant includes matching a desired flow rate that changes as governed by a the on-the-fly desired flow rate and concentration of proppant. 
     In accordance with any of the foregoing embodiments, if one or more of the pumps in the first and second pluralities of pumps fails, the method can include automatically adjusting remaining operational pumps in the first and second pluralities of pumps to maintain the desired flow rate and concentration of proppant without requiring user input. Adjusting remaining operational pumps can include at least one of adjusting pump speed and/or adjusting a pump valve or choke. 
     In accordance with any of the foregoing embodiments, the method can include balancing flow among operational pumps in the first plurality of pumps with one another, and balancing flow among operation pumps in the second plurality of pumps with one another. 
     The methods and systems of the present disclosure, as described above and shown in the drawings, provide for pumping proppant into downhole formations with superior properties including controlling flow of proppant on a continuous spectrum of flow rate and concentration, improved pump life, and automatic adjustment of pumps to follow a predetermined stimulation method and/or to compensate for failed pumps. While the apparatus and methods of the subject disclosure have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure.