You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. patent application Ser. No. 11/099,938 entitled “Flapper Opening Mechanism” filed Apr. 6, 2005 now U.S. Pat. No. 7,270,191. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates generally to the design of lubricator valves used for installing tools in a live oil or gas well on wireline while controlling fluids therethrough. 
   2. Description of the Related Art 
   During operation of live oil or gas wells, it is sometimes necessary to run a tool, such as a perforating gun, into the well. Because the well is live, it may be under pressure and, therefore, it is necessary to use a device known as a lubricator valve to allow passage of the tool while controlling the flow of pressurized fluid. Sometimes the lubricator valve is located at the surface, above the wellhead. A surface-based lubricator valve is a pressure-retaining container that is used to hold the wireline tool string before it gets deployed downhole. It is often necessary, however, to locate the lubricator valve below the surface of the well. The need to deploy longer logging tools or perforating guns, for example, is a limitation for surface lubricators due to the required height of the lubricator chamber. Applicable safety requirements specify that downhole wireline running arrangements have a minimum of two safety valves (ball or flapper type) to hold the live well pressure. The upper safety valve is closed to pressure test the wellhead pressure from above. The lower safety valve is used to hold pressure from below. The lubricator valve must facilitate pressure testing from both above and below. 
   Subsurface lubricator valves of various construction are known. U.S. Pat. No. 4,846,281, issued to Clary et al., for example, describes a dual flapper valve apparatus that is used for protecting a well during a gravel packing operation. One problem with this type of arrangement is that the flapper valves close against a valve seat that is located below the flapper valve member. As a result, the flappers open by pivoting upwardly from the closed position. In the event that there is debris atop either flapper member that has accumulated during the pressure testing process, the flapper member(s) may be difficult to open afterward. A further problem with conventional lubricator valves of this type is that the flapper-type safety valves rely solely upon a torsion spring to close the flapper element. If this torsion spring is damaged, the flapper valves within the lubricator valve will fail to close properly. 
   An additional problem with conventional lubricator valve designs is that there is no bi-directional sealing. When the flapper members are closed, there is no mechanism to secure the flappers in the closed position. Thus, pressure testing can only be accomplished from a single direction as pressurizing the valve in the opposite direction will open the flapper valves. Pressure testing in both directions is important for ensuring the safety of a lubricator valve. 
   The present invention addresses the problems of the prior art. 
   SUMMARY OF THE INVENTION 
   The invention provides an improved lubricator valve arrangement for use within a wellbore to allow the passage of tools, such as perforating guns and the like, into the wellbore while it is live. The inclusion of two, independently controllable flapper-type safety valves within the lubricator valve will permit coordinated testing of fluid pressure both above and below the lubricator valve. The upper flapper valve includes a rotational flip-flap arm arrangement to positively open and close the upper flapper valve. The lower flapper valve is equipped with an integrated poppet-style pressure equalizing valve to allow the lower flapper valve to be opened more easily. 
   The direction of opening of the flapper valves precludes or reduces the risk debris-related problems that might prevent or hinder opening of the flapper valves. Each of the flapper valves pivots from a closed position to an open position by pivoting in a downward direction away from the valve seat. As a result, any debris that has accumulated on the axial top of the flapper valve element will be dropped off of the flapper element as it opens. 
   The exemplary lubricator valve also provides a mechanism for positively securing the upper flapper element in a closed position. The flapper member is sandwiched between a flow tube and a closing sleeve, both of which are axially moveable within the lubricator valve, to retain the flapper member in its closed position, thereby allowing bi-directional sealing and testing from both axial sides. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The advantages and further aspects of the invention will be readily appreciated by those of ordinary skill in the art as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference characters designate like or similar elements throughout the several figures of the drawing and wherein: 
     FIGS  1 A- 1 E present a side, cross-sectional view of an exemplary lubricator valve constructed in accordance with the present invention and in an initial open position. 
       FIGS. 2A-2E  present a side, cross-sectional view of the valve shown in FIGS  1 A- 1 E, now with the lower flapper closed. 
       FIGS. 3A-3E  are a side, cross-sectional view of the valve shown in FIGS  1 A- 1 B now with the upper and lower flappers closed. 
       FIGS. 4A-4E  are a side, cross-sectional view of the valve shown in FIGS  1 A- 1 E with upper and lower flappers closed, and the upper flapper held closed. 
       FIG. 5  is a side, cross-sectional view of an exemplary wellbore containing a production tubing string having incorporated therein a lubricator valve that is constructed in accordance with the present invention. 
       FIG. 6  is an external isometric view of the upper flapper valve portions of the lubricator valve with the upper flapper element in the open position. 
       FIG. 7  is an external isometric view of the upper flapper valve portions of the lubricator valve shown in  FIG. 6 , now with the upper flapper element in a closed position. 
       FIG. 8  is a side cut-away view of portions of the upper flapper valve portion of the lubricator valve. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   FIGS  1 A- 1 E illustrate an exemplary downhole lubricator valve  10  that is constructed in accordance with the present invention. The valve  10  includes a valve body  12  that defines a flowbore  14  axially therethrough. Beginning at the upper end, shown in  FIG. 1A , the valve body or housing  12  has an upper valve nipple  16  with a threaded box-type connection  18 . The upper valve nipple  16  is affixed at its lower end to an upper piston sub  20 . An annular fluid chamber  22  is defined between the upper valve nipple  16  and the upper piston sub  20 . A first hydraulic “open” line  24  runs from a manifold (not shown) into the fluid chamber  22 . The fluid chamber  22  is in hydraulic communication with a piston chamber  23  that is defined within the body of the upper piston sub  20 . A hydraulic “close” line  25  extends into the lower end of the piston chamber  23 . Similar open and close lines  24 ,  25  will be associated with a lower flapper valve, as will be described shortly. 
   An annular piston  26  is moveably retained within the piston chamber  23 . Selective application of pressure is applied to either of hydraulic lines  24  or  25  to open or close the valve  10 . To open the valve  10 , the open line  24  would be pressurized and the close line  25  would be opened to drain. To close the valve  10 , with the valve  10  being held open by the pressure applied to line  24 , a counter pressure is applied to close line  25  and then open line  24  is permitted to drain. The upper end of the piston  26  presents a pressure-receiving area  28 . The lower end of the piston  26  is interconnected to a moveable actuation sleeve  30  having an orientation profile  32 . The actuation sleeve  30  is disposed within a sleeve passage  34  that is defined within a sleeve housing sub  36 . Below the actuation sleeve  30  is an orientation sleeve  38 . The orientation sleeve  38  is rotatably disposed within the sleeve passage  34  and includes an axially-directed engagement surface  40  that is shaped and sized to be complimentary to the orientation profile  32  on the actuation sleeve  30 . In the embodiment depicted, both the actuation sleeve  30  and the orientation sleeve  38  have sloped side portions  42  (on the actuation sleeve  30 ) and  44  (on the orientation sleeve  38 ) that converge to points  46 ,  48  respectively that are oriented in the downward direction. The orientation sleeve  38  features a tubular sleeve body  50  and a flip-flap arm  51  with a longitudinal slot  52  disposed therein. Additionally, a milled lug  54  extends radially inwardly into slot  56  in a surrounding upper hinge support  57 . The upper end of the orientation sleeve  38  presents a radially enlarged portion  58  that is located above a torsion spring  60 . The torsion spring  60  resists-radial rotation of the orientation sleeve  38  within the surrounding sleeve housing sub  36 . An upper closure sleeve  59  resides radially within the sleeve housing sub  36 . The closure sleeve  59  presents a lower end  61  that is sinusoidally shaped and sized to abut the upper axial side of the flapper member  64  of the upper flapper-type safety valve  62  in a flush mating relation when said flapper member  64  is in a closed position. The upper closure sleeve  59  is axially moveable within the sleeve housing sub  36  under the impetus of hydraulic fluid injected through hydraulic inlets  24 , as is known in the art. The upper closure sleeve  59  returns to its original position by application of hydraulic fluid. Meanwhile, the torsion spring  60  allows rotation of the flip-flap arm  51  during reopening, and this is done after the closure sleeve  59  has moved upwardly. 
   Located below the orientation sleeve  38  is an upper flapper-type safety valve  62  that is moveable between an open position (shown in  FIG. 1B ) and a closed position (shown in  FIG. 3B ). The valve  62  has a flapper member  64  that affixed by a hinge  66  to the surrounding upper hinge support  57 . The flapper member  64  will close against sinusoidal valve seat  61  to create a fluid seal within the valve  62 . It is noted that, when opening, the flapper member  64  will pivot downwardly away from the valve seat  61 . This feature is valuable since it allows debris that may have collected atop the flapper member  64  to fall downwardly rather than to block opening of the flapper member  64 . In addition, the flapper member  64  has an outwardly projecting pin  68  on at least one radial side. The pin  68  extends into the slot  52 . During run-in, the orientation sleeve  38  is initially positioned (see  FIG. 1B ) so that the point  48  of the engagement surface  40  is rotationally offset from the point  46  of the actuation sleeve  30 . 
   As best shown in  FIG. 8 , there is a reversible collet interconnection between the upper hinge support  57  and the surrounding sleeve housing sub  36 . The body of the hinge support  57  contains a plurality of axial slots  81  that are axially distributed about the circumference of the hinge support  57 . Raised collet ridges  83  are disposed upon the outer radial surface of the hinge support  57 . The collet ridges  83  are shaped and sized to reside within enlarged groove  85  in the housing sub  36 . This collet interconnection is useful for preventing any axial movement of the upper flapper member  64  with respect to the surrounding sleeve housing sub  36  during rotational closure of the upper safety valve  62 . Engagement of the collet ridges  83  within the groove  85  releasably secures the hinge support  57  and housing sub  36  together. During rotational closure of the flapper member  64  of the upper safety valve  62 , it is important that the flapper member  64  be moved to the closed position without axial movement. Once closed, however, additional pressure in the open line  24  acting upon the pressure receiving area  28  of the piston  26  will cause the portions of the body of hinge support  57  to deflect radially inwardly, thereby allowing the collet ridges  83  to become released from the groove  85  and permits the hinge support  57  to move axially with respect to the housing sub  36 . 
   The lower end of the sleeve housing sub  36  is affixed to an upper connector sub  70  which is, in turn, connected to a lower connector sub  72 . An upper flow tube  74  resides radially within the sleeve housing sub  36  and the connector subs  70 ,  72 . The upper flow tube  74  is axially moveable within the sleeve housing sub  36  and connector subs  70 ,  72  for controlled operation of the flapper member  64  of the upper safety valve  62 . Movement of the upper flow tube  74  is accomplished by selective injection of fluid via various hydraulic lines  24 . As such actuation is well known in the art, it is not described further herein. It is noted that the lower seat  73  presents an axial end  75  that is sinusoidally shaped and sized to abut the lower axial side of the flapper member  64  in a flush, mating relation. 
   The lower end of the connector sub  72  is secured to sequentially interconnected housing subs  76 ,  80 ,  82 ,  84  and  86 . The lower end  76  of sub  78  is secured to sub  80 . The last of these, housing sub  86 , is affixed to bottom sub  88 . Housing sub  86  houses a lower flapper valve  90  having a flapper member  92  that is secured by hinge  94  to the housing sub  86 . The lower flapper member  92  is opened and closed by pivoting movement about the hinge  94  between an open position (shown in  FIG. 1E ) and a closed position (shown in  FIG. 2E ) wherein wellbore fluid flow is blocked through the valve  90 . As with conventional flapper valves, the flapper element  92  is spring-biased toward the closed position by a torsional spring associated with the hinge  94 . 
   The flapper element  92  preferably includes an integrated pressure-relieving poppet valve  96 , which may be of the type described in U.S. Pat. No. 6,644,408 entitled “Equalizing Flapper for Down Hole Safety Valves.” U.S. Pat. No. 6,644,408 is owned by the assignee of the present invention and is herein incorporated by reference. The poppet valve  96  allows pressure to be relieved and substantially equalized across the flapper member  92  prior to opening the valve  90  by contact from a flow tube used to open the flapper valve  90 . 
   Lower flow tube  98  is retained within the housing subs  78 ,  80 ,  82  and is axially moveable therein under the impetus of hydraulic fluid injected through hydraulic lines  24 , as is known in the art. The lower flow tube  98  is used to selectively open and close the lower flapper valve  90  via contact with the flapper element  92  by the lower end  100  of the flow tube  98 . 
   In operation, the lubricator valve  10  is moved through several configurations to conduct coordinated pressure testing of the production tubing string prior to passing a tool through the production tubing string and the lubricator valve  10 . In the initial configuration, during or following run-in, the lubricator valve  10  is in the configuration depicted in  FIGS. 1A-1E , with the upper and lower flapper valves  62 ,  90  both in an open position. This configuration allows fluids to pass through the lubricator valve  10  during run-in. 
   Next, the lubricator valve  10  is moved to the configuration shown in  FIGS. 2A-2E  with the lower flapper valve  90  closed. To accomplish this, the lower flow tube  98  is moved axially upwardly within the valve  10  to allow the torsion spring (not shown) of the lower flapper valve  90  to move the flapper element  92  to its closed position. With this accomplished, the lubricator valve  10  may be pressure tested from below the valve  10 . 
     FIGS. 3A-3E  illustrate the valve  10  following the closure of the lower flapper valve  90 . The upper flow tube  74  is moved axially downwardly with respect to the housing  12 . Meanwhile, the lower flow tube  98  is moved axially upwardly with respect to the housing  12 . The actuation sleeve  30  is moved axially downwardly by selective injection of hydraulic fluid through fluid conduits  24 . The actuation sleeve  30  is rotationally locked with respect to the upper closure sleeve  59  so that the orientation profile  32  is unable to rotate within the valve  10 . As depicted in  FIGS. 3A-3E , the orientation profile  32  of the actuation sleeve  30  engages the engagement surface  40  of the orientation sleeve  38  to cam upon the engagement surface  40  and thereby rotate the orientation sleeve  38  so that the point  46  of the actuation sleeve  30  aligns with the point  48  of the orientation sleeve  38 . When fully aligned, as shown in  FIG. 3B , the lug  68  of the upper flapper element  64  will have traversed the slot  52  in the flip-flap arm  51  thereby allowing the flapper element  64  to move to its closed position to block wellbore fluid flow through the lubricator valve  10 .  FIGS. 6 and 7  help to illustrate this operation more clearly. It is noted that the closing of the upper flapper valve  62  is accomplished in a positive manner by the flip-flap arm  51  rather than merely relying upon the force of the torsion spring associated with the hinge  66  to close the flapper element  64 . This is advantageous in the case that there is debris, scales, paraffin build-up or other problems associated with the valve  62  that might preclude a complete closing of the flapper member  64 . The orientation feature also acts to prevent accidental closure of the flapper element  64  prematurely. Additionally it is noted that rotation of the orientation sleeve  38  in the opposite direction within the housing of the valve  10  will cause the flip-flap arm  51  to mechanically reopen the flapper member  64 . The lug  68  of the flapper member  64  will traverse the slot  52  in the flip flap arm  51  in the opposite (i.e., downward) direction as the counter-rotation occurs. 
   Next, the closure sleeve  59  is moved downwardly within the sleeve housing sub  36  to cause the axial end  61  to contact the upper axial side of the flapper member  64  in a flush, mating relation, as depicted in  FIG. 3B . Also, the closure sleeve  59  is moved downwardly within the valve  10  to seat the closed upper flapper member  62 / 64  against the lower seat  73  (see  FIG. 4B ). At this point, the upper flapper member  64  is closed and secured in the closed configuration by being sandwiched between the closure sleeve  59  and the lower seat  73 . This allows complete pressure testing of the upper flapper valve  62  from both above and below. 
   The lubricator valve  10  may be reopened to the position shown in FIGS  1 A- 1 E, so that both flapper valves  62  and  90  are in an open position by selective injection of hydraulic fluid through hydraulic inlets  24 . Via this selective injection, the closure sleeve  59  is moved axially upwardly and the upper flow tube  74  is moved axially upwardly within the valve  10 . 
   It is desirable to utilize a time delay during reopening to ensure that the upper flapper valve member  64  is pulled upward and off the lower flapper seat and then re-opened before the upper flow tube  74  moves upwardly to protect the upper safety valve  62 . A time delay device such as a Lee Visco jet  114  fitted to the lowermost control ‘close’ line  25  would delay the upward travel of the upper flow tube  74  so that the upper flapper member  64  is rotated to re-open and travel upwardly to move axially off of the lower seat  73  before the upper flow tube  74  moves axially upwardly. This delay prevents the upper flapper member  64  from being jammed in a partially open position by the upper flow tube  74 . A manifold (not shown), of a type known in the art, could be used to operationally interconnect both of the close lines  24  while a separate manifold (not shown) could be used to operationally interconnect both of the open lines  25  of the valve  10 . As explained previously, selective application of pressure within the open and close lines  24 ,  25  is used to open or close the valve  10 . To re-open the valve  10 , pressure equalization is preferably performed prior to reopening so that the pressure in lines  24  and  25  is substantially balanced. After pressure is equalized, the manifold associated with the lines  24  is opened to allow them to drain with a max pressure applied to close lines  25 . 
   Hydraulic fluid injection will also urge flow tube  98  axially downwardly within the valve  10  so that the axial end  100  will contact the poppet valve  96  in the lower flapper member  92  and equalize the pressure across the flapper member  92 . Additional downward movement of the flow tube  98  will cause the lower flapper member  92  to be moved to the open position shown in  FIG. 1E . 
   In operation within a wellbore, the lubricator valve  10  is disposed into a wellbore as an integrated portion of a production tubing string  102 , as illustrated in  FIG. 5 . The lubricator valve  10  is located within the production tubing string  102  above an area of interest  104  within the surrounding wellbore  106  wherein it is desired to perform some function. One example of an area of interest  104  is proximate a production zone  108  below the production tubing string  102  wherein it is desired to create additional perforations within the wellbore  106  to enhance production flow. In this case, the lubricator valve  10  is operated as described above to test pressure above and below the lubricator valve  10  and then is fully opened (upper and lower flapper valves  62 ,  90  both opened) to allow a perforating gun  110  to be lowered through the production tubing string  102  on a wireline apparatus  112 , of a type known in the art. Although a wireline running arrangement is depicted in  FIG. 5 , those of skill in the art will understand that other suitable running arrangements may be used as well, such as coiled tubing or tubing. Following perforation, the wireline apparatus  112  and perforating gun  110  are withdrawn from the production tubing string  102 . 
   The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope and the spirit of the invention.

Summary:
An improved lubricator valve arrangement for use within a wellbore to allow the passage of tools, such as perforating guns and the like, into the wellbore while it is live. The inclusion of two, independently controllable flapper-type safety valves within the lubricator valve will permit coordinated testing of fluid pressure both above and below the lubricator valve. The upper flapper valve includes a rotational flip-flap arm arrangement to positively open and close the upper flapper valve. The lower flapper valve is equipped with an integrated poppet-style pressure equalizing valve to allow the lower flapper valve to be opened more easily. The direction of opening of the flapper valves precludes or reduces the risk debris-related problems that might prevent or hinder opening of the flapper valves.