Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority to U.S. Provisional Application 61/734,694 filed Dec. 7, 2012, the entirety of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]    Aspects of the present disclosure generally relate to fluid flow control. More specifically, aspects of the present disclosure relate to controlling the flow of fluid such as formation fluid and/or borehole fluid within a downhole tool. 
       BACKGROUND INFORMATION  
       [0003]    Underground formation testing is performed during drilling and geotechnical investigation of underground formations. The testing of such underground formations is important as the results of such examinations may determine, for example, if a driller proceeds with drilling and/or extraction. Since drilling operations are expensive on a per day basis, excessive drilling impacts the overall economic viability of drilling projects. 
         [0004]    Multi-valve well testing tools use multiple valves configured in a circuit. Toggling of one of the valves typically sets the other valves into motion as well. The well testing tools disclosed in U.S. Pat. No. 4,553,598 to Meek entitled “Full Bore Sampler Valve Apparatus”, and in U.S. Pat. No. 4,576,234 to Upchurch entitled “Full Bore Sampler Valve”, are mechanical in nature. One valve is disposed in the tool and is mechanically linked to another valve disposed in the tool. To open one valve, an operator at the well surface, upon opening the valve, must expect the other valve to open or close, since the two valves are mechanically linked together. Therefore, the operation of one valve is not independent of the operation of the other valve. When one valve in the tool is opened, other valves disposed in the tool must be opened or closed in a specific predetermined sequence. 
         [0005]    More recent multi-valve well testing tools use other arrangements for toggling valves. For example, semi-passive valves are referenced in U.S. Pat. No. 7,577,070 to Brennan, III et al., the entirety of which is incorporated herein by reference. Brennan, III et al. disclose valves that are partially passive wherein the flow of fluid through the valve assists in toggling the valve. Hydraulics are only used in the referenced system to assist in returning the valve-state to its original position. The hydraulic valve systems of the prior art do not use hydraulics to initially set the valve or valves into motion. Moreover, the valve systems are not fully active. That is, all aspects of valve movement are not controlled by hydraulics. To provide a valve system that is fully active, a solenoid is required for each individual valve. Space is limited in a downhole tool, and each solenoid requires a relatively large amount of space. 
         [0006]    Therefore, a need exists for providing a system and/or method that uses hydraulic pressure to toggle valve state while minimizing size and/or the number of solenoids required. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0007]      FIGS. 1 and 2  are schematic views of a prior art wireline-conveyed downhole tool with which one or more aspects of the present disclosure may be used. 
           [0008]      FIGS. 3A ,  3 B,  4 A and  4 B are schematic views of a prior art fluid pumping system. 
           [0009]      FIGS. 5A and 5B  show an active mud check valve with two hydraulic lines in accordance with one or more aspects of the present disclosure. 
           [0010]      FIG. 6  shows an active mud check valve with four hydraulic lines in accordance with one or more aspects of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION  
       [0011]    Certain examples are shown in the above-identified figures and described in detail below. In describing these examples, like or identical reference numbers are used to identify common or similar elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic for clarity and/or conciseness. 
         [0012]    The example valves described herein may be used on a downhole tool to sample fluids in a subterranean formation. More specifically, the example valves described herein may route dirty fluid between the displacement unit and inlet or outlet flowline portions of a testing tool. 
         [0013]      FIGS. 1 and 2  illustrate a prior art downhole tool which may be suspended from a rig  5  by a wireline  6  and lowered into a well bore  7  for the purpose of evaluating surrounding formations I. Details relating to tool A are described in U.S. Pat. Nos. 4,860,581 and 4,936,139, both to Zimmerman et al., the entireties of which are hereby incorporated by reference. The downhole tool A has a hydraulic power module C, a packer module P, and a probe module E. The hydraulic power module C includes a pump  16 , a reservoir  18 , and a motor  20  which controls operation of the pump  16 . A low oil switch  22  also forms part of the control system and is used to regulate the operation of the pump  16 . 
         [0014]    The hydraulic fluid line  24  is connected to the discharge of the pump  16  and runs through hydraulic power module C and into adjacent modules for use as a hydraulic power source. In the embodiment shown in  FIG. 1 , the hydraulic fluid line  24  extends through the hydraulic power module C into the probe modules E and/or F depending upon which configuration is used. The hydraulic loop is closed by virtue of the hydraulic fluid return line  26 . As shown in  FIG. 1 , the hydraulic fluid return line  26  extends from the probe module E to the hydraulic power module C where the hydraulic fluid return line  26  terminates at the reservoir  18 . 
         [0015]    The tool A further includes a pump-out module M, as shown in  FIG. 2 , which can be used to dispose of unwanted samples by pumping fluid through the flow line  54  into the borehole, or may be used to pump fluids from the borehole into the flow line  54  to inflate the straddle packers  28  and  30 , as shown in  FIG. 1 . Furthermore, the pump-out module M may be used to draw formation fluid from the borehole via the probe module E or F, and then pump the formation fluid into the sample chamber module S against a buffer fluid therein. In other words, the pump-out module may be used for pumping fluids into, out of, and through the downhole tool A. 
         [0016]    A piston pump  92 , energized by hydraulic fluid from a pump  91 , may be aligned in various configurations, e.g., to draw from the flowline  54  and dispose of the unwanted sample though flowline  95 . Alternatively, the pump  92  may be aligned to pump fluid from the borehole into the flowline  54 . The pump-out module M can also be configured where the flowline  95  connects to the flowline  54  such that fluid may be drawn from the downstream portion of the flowline  54  and pumped upstream or vice versa. The pump-out module M has the necessary control devices to regulate the piston pump  92  and to align the fluid line  54  with the fluid line  95  to accomplish the pump-out procedure. 
         [0017]    Referring to  FIGS. 3A ,  3 B,  4 A and  4 B, a particular embodiment of the pump-out module M may use four reversible mud check valves  390 , also referred to as CMV 1 -CMV 4 , to direct the flow of the fluid being pumped. These reversible mud check valves  390  allow the pump-out module M to pump either up or down, or in or out, depending on the tool configuration. The reversible mud check valves  390  may utilize a spring-loaded ceramic ball  391  that seals alternately on one of two O-ring seats  393   a,    393   b  to allow fluid flow in only one direction. The O-ring seats  393   a,    393   b  are mounted in a sliding piston-cylinder  394 , also called a check valve slide or a piston slide. 
         [0018]      FIGS. 3A and 3B  show the respective first stroke and second stroke of the two-stroke operation of the piston pump  392  with the pump-out module M configured to “pump-in” mode, where fluid is drawn into the module M through a port  346  for communication via a flowline  354 . Thus, the solenoids SI, S 2  are energized in  FIGS. 3A and 3B  to direct hydraulic fluid pressure to shift the piston slides  394  of the check valves CMV 1  and CMV 2  upwardly and shift the piston slides  394  of the check valves CMV 3  and CMV 4  downwardly. The fluid pressure causes the upper springs  395   a  of the check valves CMV 1  and CMV 2  to bias the respective balls  391  against the lower seal seats  393   b,  and the lower springs  395   b  of check valves CMV 3  and CMV 4  to bias the respective balls  391  against the upper seal seats  393   a.  The biasing of the balls  391  allows fluid to flow upwardly through the check valve CMV 2  and downwardly through the check valve CMV 4  under movement of the piston  392   p  to the left, as indicated by the directional arrows of  FIG. 3A . Similarly, the biasing of the balls  391  allows fluid to flow upwardly through the check valve CMV 1  and downwardly through valve CMV 3  under movement of the piston  392   p  to the right, as indicated by the directional arrows of  FIG. 3B . Sufficient fluid-flowing pressure may be needed to overcome the respective spring-biasing forces. Solenoid S 3  is provided to selectively move the pump piston  392   p  from the position in  FIG. 3A  to the position in  FIG. 3B  and back. The solenoid S 3  may also be linked to solenoids S 1  and S 2  to synchronize the timing therebetween. 
         [0019]      FIGS. 4A and 4B  show a respective first stroke and second stroke of the two-stroke operation of the piston pump  392  with the pump-out module M configured to “pump-out” mode, where fluid is discharged from the flowline  354  through the port  346  into the borehole. Thus, the solenoids S 1 , S 2  have been de-energized in  FIGS. 4A and 4B  to direct hydraulic pressure to shift the piston slides  394  of the check valves CMV 1  and CMV 2  downwardly and shift the piston slides  394  of the check valves CMV 3  and CMV 4  upwardly. This shifting results in the lower springs  395   b  of the check valves CMV 1  and CMV 2  biasing the respective balls  391  against the upper seal seats  393   a.  Further, the shifting results in the upper springs  395   a  of the check valves CMV 3  and CMV 4  biasing the respective balls  391  against the lower seal seats  393   b.  The biasing of the balls  391  allows fluid to flow downwardly through the check valve CMV 1  and upwardly through the check valve CMV 3  under movement of the pump piston  392   p  to the left, as indicated by the directional arrows of  FIG. 4A . Similarly, the biasing of the balls  391  allows fluid to flow downwardly through the check valve CMV 2  and upwardly through the check valve CMV 4  under movement of the pump piston  392   p  to the right, as indicated by the directional arrows of  FIG. 4B . Sufficient fluid-flowing pressure may be needed to overcome the respective spring-biasing forces. 
         [0020]    In each of the  FIGS. 3A ,  3 B,  4 A and  4 B, the check valves having no directional flow arrows are configured such that their respective balls  391  are subjected to fluid pressure that compresses each ball against an o-ring seat to maintain a seal. Conversely, when the direction of fluid flow opposes the spring-biasing forces, a gap is opened between the ball and the seat so as to permit the fluid flow indicated by the three directional arrows. The valves open to balance the pressure differential across the opening with the biasing forces provided by the respective springs. 
         [0021]    The fluid pumped through the tool A, flows directly past the o-ring seats  393   a,    393   b  at various intervals during the two-stroke pumping cycles. Since this fluid may be formation fluid or borehole fluid laden with impurities varying from fine mud particles to abrasive debris of various sorts, such flow may produce accelerated wear of the o-ring seats. The wear can shorten the life of the o-ring and may lead to frequent failure of the seals. The following are examples of failures that may occur: 1) the o-ring is gradually worn during the pumping process until the o-ring will no longer seal; 2) debris gets trapped between the ball and one or both of the O-ring seats; 3) fine particles settle in the valve cavity and may gradually build up to the point where the particles prevent the ball from sealing against the seat; and 4) filters that are typically used with such valves are susceptible to plugging. The failure of any one of the four reversible mud check valve seals may reduce the output of the pump  392 , and the loss of two seals may completely disable the pump  392 . 
         [0022]    The present disclosure illustrates a system and method for pumping formation fluid through a downhole tool using controlled mud check valves. The system and/or method may use one or more springs to assist in opening and closing the valves. The mud check valves may operate using only hydraulic pressure with the assistance of the springs. Furthermore, a reduced number of solenoids are required to open and close the valves. 
         [0023]    In accordance with the present disclosure, a valve  590  is described to exhibit a non-limiting example of an embodiment of the application. Referring now to the drawings wherein like numerals refer to like parts,  FIGS. 5A and 5B  show schematic views of a flow control valve  590  in respective closed and open positions according to one or more aspects of the present disclosure. 
         [0024]    The valve  590  combines two mud check valves  591 ,  592  in one port, thus saving tool space and reducing flowline dead volume. The valve  590  may be used as a check valve, e.g., as a replacement for the check valve CMV 1  (also referenced as  390 ) of  FIGS. 3A ,  3 B,  4 A and  4 B within a downhole tool, such as tool A of  FIGS. 1 and 2 . The downhole tool is adapted for use in a borehole environment. Accordingly, the check valve  590  includes a body  510  having a fluid passageway  512  therethrough and a first flowline  514  and a second flowline  516 . Each of the flowlines  514 ,  516  is adapted for receiving or discharging fluid from the passageway  512 . The first flowline  514  may communicate fluid with another portion of the tool, such as, for example, a lower module of the tool. The second flowline  516  may communicate fluid with another portion of the tool, such as, for example, an upper module of the tool. A third flowline  515  may be provided extending from the valve  590 . The third flowline  515  may be in communication with a displacement unit, such as the displacement unit  392  shown in  FIGS. 3A ,  3 B,  4 A and  4 B. 
         [0025]    A piston  518  may be slidably disposed in the passageway  512  between the first flowline  514  and the second flowline  516  of the body  510 . The piston  518  may have a conduit portion  520  that defines a bore therethrough for conducting fluid through the passageway  512 . The piston  518  may have the third flowline  515  extending therefrom. The piston  518  may also be referred to as a sliding cylinder, a check valve slide, or simply a piston slide. 
         [0026]    A pair of annular seals  528 ,  530  may seal the first flowline  514  and the second flowline  516 , respectively. The annular seals  528 ,  530  may be elastomeric o-rings, or various other materials, as dictated by the operating temperatures and pressures in the downhole environment. The annular seals  528 ,  530  may have a metal cone sealable against a donut elastomer. Furthermore, the annular seals  528 ,  530  may be face seals or shear seals. The annular seals  528 ,  530  are adapted for sealably engaging inner walls  524 ,  526  upon translatory movement of the piston  618  relative to the body  510 .  FIG. 5A  shows the annular seal  530  engaging the inner wall  524  to close the first flowline  514 . Outer flanged portion  521 ,  522  are affixed at the ends of the piston  518  for abutting the inner walls  524 ,  526 . 
         [0027]    The valve body  510  may also have a first hydraulic line  532  and a second hydraulic line  534  extending therefrom. The hydraulic lines  532 ,  534  may be in communication with the directional unit, a pump, and/or any other device for creating differential pressure. Accordingly, differential pressure across the hydraulic lines  532 ,  534  such as that provided by pressurized hydraulic fluid in a known manner, induces reciprocal translatory movement of the piston  518  within the passageway  512  of the body  510 .  FIG. 5A  shows the valve system with the first flowline  514  in an open position, and the second flowline  516  in a closed position. Thus, in the position shown in  FIG. 5A , the first hydraulic line  532  has a higher pressure than the second hydraulic line  534 , resulting in the piston  518  being pressed against the first inner wall  524 . Thus, the position of the piston  518  may be controlled by the hydraulic lines  532 ,  534  by increasing and decreasing the pressure within the lines. Thus, the valve  590  does not rely on pressure from formation fluid and/or the displacement unit to be toggled. 
         [0028]    The valve  590  may further include a pair of coil springs  544 ,  546  slidably disposed at least partially around a portion of the piston  518 . The coil springs  544 ,  546  yieldably limit translatory movement of the piston  512  within the passageway  512 . Thus, increasing the pressure of the first hydraulic line  532  above that of the second hydraulic line  534  induces translatory movement of the piston  518  within the passageway  512  of the body  510  to one of two stop positions. In the stop position of  FIG. 5A , the outer flanged portion  522  of the piston  518  abuts a portion of the inner wall  526  of the valve body  510 . One having ordinary skill in the art will appreciate that, due to the spring loading on the piston  518 , the piston  518  may be positioned in the “no flow” condition. In “no flow” condition one of the annular seals  528 ,  530  engage the inner walls  514 ,  516  to close both the first flowline  514  and the second flowline  516 . 
         [0029]    From the position of  FIG. 5A , the inner wall  526  constrains movement towards the coil spring  546 . Such movement occurs when the piston  518  is energized by the pressure of fluid provided to the hydraulic line  532 . The fluid pressure is increased on the first side  591  of the valve  590  until sufficient force is developed to overcome the bias of the coil spring  546 . In other words, the hydraulic pressure may move the plug  526  from the position of  FIG. 5A  to the position of  FIG. 5B  by compressing the coil spring  544  so that the coil spring  544  yields to such movement. The inner walls  524 ,  526  may act as hard limits on the range of translatory movement by the piston  518 , and thus limit the range of yielding by the coil springs  544 ,  546 . It will, therefore, be appreciated by one having ordinary skill in the art that a function of the coil springs  544 ,  546  is to bias the piston  518  towards a position where one of the annular seals  528 ,  530  engages the inner walls  524 ,  526 . When the annular seals  528 ,  530  engage the inner walls  524 ,  526  the flowlines  514 ,  516  close and prevent fluid flow through the valve passageway  512 . 
         [0030]      FIG. 6  shows an embodiment of an active valve  690  with four hydraulic lines. As illustrated, this embodiment has four hydraulic lines  631 ,  632 ,  633 , and  634  on each side  691 ,  692  of the piston  618 . Fluid may enter or exit the valve  690  through a first flowline  614  and/or a second flowline  616 . Fluid may also be communicated to a displacement unit via a third flowline  615 . Fluid may travel through a passageway  612  bored inside of the piston. Thus, fluid entering through the first flowline  614  may flow past a first inner wall  624  and the first end of the piston  618  into the passageway  612  of the piston  618 . From there, the fluid may exit the valve  690  through the third flowline  615 . 
         [0031]    Movement of the piston  618  may be dictated by the increasing and/or decreasing of pressure in the hydraulic lines  631 ,  633 . For example, hydraulic pressure may be increased in the hydraulic lines  631 ,  633  to bias the piston towards an inner wall  626  to seal a second flowline  616 . A vacuum cavity  650  may be defined between the piston  618  and a body  610  of the valve  690 . The hydraulic lines  631 ,  632 ,  633 ,  634  may be fluidly connected to the cavity  650  such that an increase and/or a decrease of pressure via the hydraulic lines  631 ,  632 ,  633 ,  634  causes the piston  621  to move within the cavity  650 . 
         [0032]    Elastomer donuts  628 ,  630  may be provided on the inner walls  624 ,  626  to engage end portions  621 ,  622  of the piston  618 . Alternatively, a cone-shaped opening in the end portions  621 ,  622  may engage a cone-shaped elastomer (not shown) extending from the inner walls  624 ,  626  of the valve  690 . 
         [0033]    Coil springs  644 ,  646  may be provided within the valve  690  to aid in biasing the piston  618 . The coil springs  644 ,  646  may act to move the piston  618  to an original position after the piston  618  has been moved to one side or another due to hydraulic pressure. 
         [0034]    The preceding description has been presented with reference to present embodiments. Persons skilled in the art and technology to which this disclosure pertains will appreciate that alterations and changes in the described structures and methods of operation can be practiced without meaningfully departing from the principle and scope of the disclosure. Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope. 
         [0035]    In one example embodiment, a valve is disclosed comprising: a body defining a volume; at least two mud check valves in the body, a fluid passageway connecting the at least two mud check valves, a first flowline configured to transport a first portion of a fluidl, a second flowline configured to transport a second portion of the fluid, wherein each of the first and second flowlines are configured to receive and discharge fluid from the passageway wherein the first flowline is configured to transfer the first portion of the fluid to a first portion of a downhole tool and wherein the second flowline is configured to transfer the second portion of the fluid to a second portion of the downhole tool. 
         [0036]    In another example embodiment a valve for transporting a fluid, comprising: a body, a flowline, at least four hydraulic lines in the body, the hydraulic lines configured to transport the fluid, and a piston configured to move according to at least one of an increasing and decreasing pressure in two of the hydraulic lines, wherein the piston is configured to transport to a position to allow the fluid to exit the valve via the flowline. 
         [0037]    Although exemplary systems and methods are described in language specific to structural features and/or methodological acts, the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms of implementing the claimed systems, methods, and structures.

Technology Category: 4