Abstract:
A flow regulator includes a flow regulating part configured to receive at an inlet a working fluid at a first pressure and to release the working fluid at an outlet at a second pressure; a slide provided inside the flow regulating part and configured to move along an axis to reduce the pressure of the working fluid; a control part attached to the flow regulating part, the control part including a chamber; a spring housing provided in the chamber and connected to the slide though a shaft, the spring housing configured to move the slide along the axis; a cap provided in the chamber and facing the spring housing, the cap being configured to have plural blind holes; and plural pins extending along the axis and attached to the spring housing, the plural pins being configured to enter the plural blind holes.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    Embodiments of the subject matter disclosed herein generally relate to methods and devices and, more particularly, to mechanisms and techniques for dampening a motion of a part of a regulator. 
         [0003]    2. Discussion of the Background 
         [0004]    A blowout preventer (BOP) is a safety mechanism that is used at a wellhead of an oil or gas well. The BOP may be used for offshore drilling and also for land-based drilling. The BOP is configured to shut off the flow from the well when necessary. One such event may be the uncontrolled flow of gas, oil or other well fluids from an underground formation into the well. Such event is sometimes referred to as a “kick” or a “blowout” and may occur when formation pressure exceeds the pressure applied to it by the column of drilling fluid. This event is unforeseeable and if no measures are taken to control it, the well and/or the associated equipment may be damaged. 
         [0005]    Another event that may damage the well and/or the associated equipment is a hurricane or an earthquake. Both of these natural phenomena may damage the integrity of the well and the associated equipment. For example, due to the high winds produced by a hurricane at the surface of the sea, the vessel or the rig that powers the undersea equipment may start to drift, requiring the disconnection of the power/communication cords or other elements that connect the well to the vessel or rig. Other events that may damage the integrity of the well and/or associated equipment are possible as would be appreciated by those skilled in the art. 
         [0006]    Thus, the BOP may be installed on top of the wellhead to seal it in case that one of the above events threatens the integrity of the well. The BOP is conventionally implemented as a valve to prevent and/or control the release of pressure either in the annular space between the casing and the drill pipe or in the open hole (i.e., hole with no drill pipe) during drilling or completion operations. 
         [0007]      FIG. 1  shows a well  10  that is drilled undersea. A wellhead  12  of the well  10  is fixed to the seabed  14 . A BOP  16  is secured to the wellhead  12 . The BOP may be a ram block BOP, a blind BOP, etc. Ram-type BOPS typically include a body and at least two oppositely disposed bonnets. The bonnets partially house a pair of ram blocks. The ram blocks may be closed or opened with pressurized hydraulic fluid to seal the well. 
         [0008]      FIG. 1  shows, for clarity, the ram BOP  16  detached from the wellhead  12 . However, the BOP  16  is attached to the wellhead  12  or other part of the well. A pipe (or tool)  18  is shown traversing the BOP  16  and entering the well  10 . The BOP  16  may have two ram blocks  20  attached to corresponding rods  22 . Rods  22  move integrally with the ram blocks  20  along directions A and B to close the well  10 . 
         [0009]    As shown in  FIG. 2 , the BOP  16  may include, besides the ram block  20  and the rod  22 , an extension rod  24  that may be locked by a ram locking mechanism  26 . An elastomer  28  is attached to the front side of the ram block  20  such that when the ram block  20  is closed and presses against the pipe  18 , it ensures a substantial leakage free contact between the ram block  20  and the pipe  18 , i.e., no liquid from below the ram block  20  escapes in the space above the ram block  20 . 
         [0010]    Extension rod  24  is connected to a piston  30  that is fitted inside an enclosure  32 . Piston  30  splits the enclosure  32  into closed chamber  34  and opened chamber  36 .  FIG. 2  shows the closed chamber  34  having a maximum volume while the opened chamber  36  is squeezed to have a minimum volume and corresponds to a closed position of the ram block  20 . When pressure is provided to the opened chamber  36  and the fluid in the closed chamber  34  is vented out, piston  30  moves to the left in  FIG. 2 , thus moving the ram block  20  to an open position. 
         [0011]    The pressure to the opened chamber  36  and the closed chamber  34  is provided from, for example, accumulators  42 , which are shown in  FIG. 3 .  FIG. 3  shows a stack  40  of BOPS  16  disposed on top of each other and configured to be mounted with a flange  44  to a wellhead  12  (shown in  FIG. 1 ). Stack  40  also includes, among other things, at least a regulator  46  for adjusting a pressure release by the accumulators  42  to conform to a required pressure for the opened and closed chambers. For example, such a regulator is configured to adjust an input pressure of 5,000 psi to an output pressure of 3,000 psi. As would be appreciated by those skilled in the art, such pressures are large and appropriate structures are provided to withstand such large pressures. 
         [0012]    However, during testing of the BOP  16  for closing the ram blocks, when the pressure from accumulators  42  has been released, it has been observed that a component of the regulator  46 , which adjusts the pressure and experiences linear motion inside the regulator, significantly oscillates (chatter), which leads to the failure of the regulator. It is observed that either this moving part or a part connected to this moving part fails during the oscillation regime. 
         [0013]    The chatter is attributed to the ingress of air (or other fluid that is provided by the accumulator) in the piping of the regulator, which appears to cause excessive flow and instability. As the air compresses and expands, pressure waves are generated that react with the regulator and the regulator compensates those changes in pressure by adjusting a position of a moving part (slide) rapidly. The rapid movement of the regulator causes upstream pressure spikes, which may destroy the regulator slide in a matter of a few seconds in some cases. 
         [0014]    Accordingly, it would be desirable to provide systems and methods that effectively overcome the above-noted exemplary problems. 
       SUMMARY 
       [0015]    According to one exemplary embodiment, there is a flow regulator that includes a flow regulating part configured to receive at an inlet a working fluid at a first pressure and to release the working fluid at an outlet at a second pressure, the second pressure being smaller than the first pressure; a slide provided inside the flow regulating part and configured to move along an axis to reduce the pressure of the working fluid from the first pressure to the second pressure; a control part attached to the flow regulating part, the control part including a chamber; a spring housing provided in the chamber and connected to the slide though a shaft, the spring housing configured to move the slide along the axis; a cap provided in the chamber and facing the spring housing, the cap being configured to have plural blind holes; and plural pins extending along the axis and attached to the spring housing, the plural pins being configured to enter the plural blind holes so that a movement of the slide along the axis is damped due to a dampening fluid that is trapped between the blind holes and the pins. 
         [0016]    According to another exemplary embodiment, there is a flow regulator that includes a flow regulating part configured to receive at an inlet a working fluid at a first pressure and to release the working fluid at an outlet at a second pressure, the second pressure being smaller than the first pressure; a slide provided inside the flow regulating part and configured to move along an axis to reduce the pressure of the working fluid from the first pressure to the second pressure; a control part attached to the flow regulating part, the control part including a chamber; a spring housing provided in the chamber and connected to the slide though a shaft, the spring housing configured to move the slide along the axis; and at least one pin fixedly connected to a protrusion of the flow regulating part and configured to enter a blind hole formed in the slide such that the working fluid is trapped between the blind hole and the at least one pin. 
         [0017]    According to still another exemplary embodiment, there is a blowout preventer stack that includes a frame; at least an accumulator attached to the frame and configured to provide a working fluid under pressure; a blowout preventer fluidly connected to the accumulator and configured to close a well when the working fluid is provided to the blowout preventer; and a flow regulator interposed between the accumulator and the blowout preventer and configured to reduce a first pressure of the working fluid from the accumulator to a second pressure to be provided to the blowout preventer. The flow regulator includes a flow regulating part configured to receive at an inlet the working fluid at the first pressure and to release the working fluid at an outlet at the second pressure, a slide provided inside the flow regulating device and configured to move along an axis to reduce the pressure of the working fluid from the first pressure to the second pressure, a control part attached to the flow regulating part, the control part including a chamber, a spring housing provided in the chamber and connected to the slide though a shaft, the spring housing configured to move the slide along the axis, a cap provided in the chamber and facing the spring housing, the cap being configured to have plural blind holes, and plural pins extending along the axis and attached to the spring housing, the plural pins being configured to enter the plural blind holes so that a movement of the slide along the axis is damped due to a dampening fluid that is trapped between the plural blind holes and the plural pins. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one or more embodiments and, together with the description, explain these embodiments. In the drawings: 
           [0019]      FIG. 1  is a schematic diagram of a conventional ram BOP; 
           [0020]      FIG. 2  is a more detailed diagram of a conventional ram BOP; 
           [0021]      FIG. 3  is a schematic diagram of a BOP stack; 
           [0022]      FIG. 4  is an isomeric view of a flow regulator according to an exemplary embodiment; 
           [0023]      FIG. 5  is a schematic diagram of a flow regulator according to an exemplary embodiment; 
           [0024]      FIG. 6  is a schematic diagram of a transversal view of a flow regulator according to an exemplary embodiment; 
           [0025]      FIG. 7  is a schematic diagram of a transversal view of a flow regulator according to an exemplary embodiment; 
           [0026]      FIG. 8  is a schematic diagram of a slide of a flow regulator according to an exemplary embodiment; and 
           [0027]      FIG. 9  is a schematic diagram of a pin entering a slide of a flow regulator according to an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    The following description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to the terminology and structure of a pressure regulator. However, the embodiments to be discussed next are not limited to these systems, but may be applied to other systems that adjust a pressure of a passing fluid. 
         [0029]    Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments. 
         [0030]    According to an exemplary embodiment, a flow regulator is provided with pins and corresponding blind holes such that the pins trap a fluid inside the blind holes and squeeze the fluid while attenuating an oscillatory motion (chatter) that may appear in parts of the flow regulator. 
         [0031]    As shown in  FIG. 4 , in accordance with an exemplary embodiment, a flow regulator  50  includes a flow regulating part  52  and a control part  54  that controls the fluid flow. The flow regulating part  52  is configured to regulate a pressure of a working fluid while the control part may include a dampening fluid that is insulated from the working fluid. In one application, the flow regulator  50  may provide an output pressure between 1000 to 3000 psi for an input pressure of 5000 psi.  FIG. 4  shows an isomeric view of the flow regulator  50 . A more detailed view of the flow regulator is shown in  FIG. 5 . In this figure, the flow regulating part  52  is shown having a slide  60  configured to move along an axis  62 . The slide  60  has a hole  64  that places in flow communication, when in the appropriate position, an input  66  and an output  68  of the flow regulator  50 . 
         [0032]    The slide  60  is provided inside the flow regulating part  52  and is configured to receive the working fluid, for example, the fluid under pressure from accumulator  42  shown in  FIG. 3 . The flow regulating part  52  is also referred to as the hydraulic part. The flow regulating part  52  is fluidly insulated from the control part  54 . A movement from the flow regulating part  52  is transmitted to the control part  54  by a shaft  70 , which is configured to move along axis  62  into the control part  54 . The shaft  70  is connected to a spring housing  72  of the control part  54  via a bolt  74 . In another exemplary embodiment, the shaft  70  may be connected through other means to the spring housing  72 , for example, welding. The spring housing  72  is provided into a chamber  76  of the control part  54 . The slide  60 , shaft  70 , and spring housing  72  may be made of steel or another strong material. 
         [0033]    In one exemplary embodiment, slide  60  is connected to shaft  70  by a bolt  78 . However, as will be discussed later, the slide  60  may be removably attached to the shaft  70 . The spring housing  72  is configured to move along axis  62 . The spring housing  72  may include one or more pins  80 . Pins  80  are fixedly attached to the spring housing  72 . A cap  82  is also provided inside chamber  76 , at a side of the chamber  76  opposite to a side that is adjacent to the flow regulating part  52 . Cap  82  is fixed in position by a positioning element  84 . In one application, the cap  82  is fixed to the positioning element  84  by a bolt  86 . Positioning element  84  may be adjusted along axis  62  such that a position of the cap  82  inside chamber  76  is adjusted as desired. 
         [0034]    One or more springs  90  are provided between cap  82  and the spring housing  72  such that, when no pressure is applied to the inlet  66 , the spring  90  biases the spring housing  72 , shaft  70  and slide  60  so that fluid communication is allowed between input  66  and output  68 . However, when high pressure is applied at output  68 , the slide  60  moves to the left in  FIG. 5 , compressing the spring  90 . This position is shown in  FIG. 6 , where slide  60  has moved a distance d along axis  62 .  FIGS. 5 and 6  illustrate different views of a same flow dampening device. 
         [0035]    According to an exemplary embodiment, springs  90  may be selected such that a spring force provided on shaft  70  via spring housing  72  is balanced by a force applied by the working fluid acting on slide  60 , when the pressure of the working fluid is 3000 psi. When the pressure of the working fluid increases above 3000 psi, the force exerted by the working fluid on the shaft  70  is larger than the force exerted by the springs  90  on the shaft  70 , and thus shaft  70  moves the distance “d” to the left along axis  62 , closing the working fluid flow through slide  60 , as shown in  FIG. 6 . When the pressure in the working fluid at outlet  68  decreases below 3000 psi, the force produced by the springs  90  on the shaft  70  overcomes the force produced by the working fluid on the shaft  70 , consequently causing a movement of the slide  60  to the right, as shown in  FIG. 5 , which opens the working fluid flow. 
         [0036]    Still with regard to  FIG. 5 , it is noted that cap  82  includes blind holes  94  that match pins  80 . Blind holes  94  are defined as having an open end  94   a , that is freely to communicate with the chamber  76  when pins  80  are not inside the blind holes and another end  94   b , which is permanently closed. In this way, a dampening fluid that is present in the chamber  76 , for example, a mineral oil, may be trapped inside the blind hole  94  when a corresponding piston  80  is entering the blind hole. In this way, assuming that there is a sudden oscillation (chatter) of the slide  60  as discussed in the Background Section, this oscillation is dampened by the combination of the dampening fluid being trapped inside the blind hole  94 , the pin  80  compressing the dampening fluid inside the blind hole  94  and an internal diameter of the blind hole  94  closely matching an external diameter of the pin  80  such that a limited amount of dampening fluid escapes outside the blind hole  94  past the pin  80 . In other words, the oscillations of the slide  60  are dampened by the blind hole  94 , pin  80  and dampening fluid between them. The blind hole  94 , the pin  80  and the dampening fluid act as a dampening device. The number of the blind holes and corresponding pins depends from application to application. 
         [0037]    In one exemplary embodiment, the pin  80  is manufactured to tightly fit inside the blind hole  94 , for example, with a tolerance in the order of thousands of an inch. According to an exemplary embodiment, a seal  98  may be formed between the pin  80  and the blind hole  94  to control the leakage flow rate of the dampening fluid from the blind hole  94 . Seal  98  may be formed to partially or completely encircle pin  80 .  FIG. 5  shows seal  98  partially encircling pin  80 . 
         [0038]    According to another exemplary embodiment shown in  FIG. 7 , a dampening mechanism is formed between slide  60  and a component  100  of the flow regulating part  52 . Component  100  forms a side of the flow regulating part  52  and has a protrusion  102  that extends along axis  62 , towards the control part  54 . The protrusion  102  ends with a hollow element  104 , that forms a channel  106 . Slide  60  has a sleeve part  108  that is configured to contact the hollow element  104  and to extend channel  106 . A detailed view of the sleeve part  108 , protrusion  102  and hollow element  104  is shown in  FIG. 8 . 
         [0039]      FIG. 8  illustrates an embodiment in which the protrusion  102  includes at least one pin  110  that is configured to enter a matching blind hole  112  of the sleeve part  108 . The at least one pin  110  is attached to the protrusion  102  while the blind hole  112  is formed in the sleeve part  108  of the slide  60 . In one application, the hole may be formed in the protrusion  102  and the pin may be attached to sleeve part  108 . The working fluid may be trapped inside the blind hole  112  while the pin  110  of the protrusion  102  may be compressing the working fluid. The blind hole  112 , the pin  110  and the working fluid dampen a motion of the slide  60  similar to the blind hole  94 , pin  80  and the dampening fluid. Thus, the functional description of this dampening mechanism is omitted as being similar to the one discussed above. 
         [0040]    Pin  110  may have a smooth surface but a small tolerance with respect to the blind hole  112  such that a limited amount of working fluid leaks from the blind hole  112  when compressed by pin  110 . In another exemplary embodiment, the pin  110  may have a grooved seal  114  formed in its surface to prevent the above mentioned leakage.  FIG. 9  shows such a profile for pin  110  with grooved seal  114 . 
         [0041]    The dampening mechanism of  FIG. 8  may be used without the dampening mechanism of  FIG. 5  and vice versa. In one exemplary embodiment, the two dampening mechanisms may be used together to prevent a failure of the slide due to chatter or other oscillations. 
         [0042]    The disclosed exemplary embodiments provide a regulator dampening device and a method for reducing chatter in a movable slide inside the regulator. It should be understood that this description is not intended to limit the invention. On the contrary, the exemplary embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details. 
         [0043]    Although the features and elements of the present exemplary embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein. The methods or flow charts provided in the present application may be implemented in a computer program, software, or firmware tangibly embodied in a computer-readable storage medium for execution by a specifically programmed computer or processor. 
         [0044]    This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other example are intended to be within the scope of the claims.