Patent Publication Number: US-8973663-B2

Title: Pump through circulating and or safety circulating valve

Description:
BACKGROUND 
     Technical Field 
     The invention relates generally to an apparatus for testing a hydrocarbon well, and, more particularly, to a reverse circulation valve for use with pump through closure or a safety valve operated in response to annulus pressure. 
     SUMMARY OF THE INVENTION 
     The present invention provides a closure and circulation valve used in drill stem tests. The invention provides an improved annulus pressure operated closure valve and has a tubular housing with an open bore therethrough and a reverse circulation port in the wall thereof. A tubular valve mandrel assembly is axially shifted in response to annulus pressure to actuate the closure valve to close off flow through the bore. In one embodiment, the mandrel assembly blocks the circulation ports until the mandrel is shifted to close the closure valve and has ports which align with and open the reverse circulation port when the mandrel is shifted. Alternatively, the closure valve can be assembled to include a case that does not contain the recirculation ports. 
     The valve of the present invention comprises a variable volume actuation chamber to axially shift the valve mandrel in response to increasing annulus pressure. During run in of the tool, a rupture disc blocks a port communicating between the annulus and the actuation chamber. The rupture disc is designed to rupture and open the port to flow in response to pressure in the annulus. The actuation chamber is formed between the valve mandrel and interior of the tool and, when sufficient pressure is applied to the annulus, causes the valve mandrel to shift closing the closure valve and opening the recirculation valve. Redundant or dual seals are provided to seal the actuation chamber. To accommodate gases trapped behind the seals of the actuation chamber, an annular seal ring is configured to vent or act as a check valve in one direction. 
     A shoulder prevents the valve mandrel from shifting downward and shear pins prevent the valve mandrel from shifting upward. The pins shear when the desired pressure is present in the annulus, thus allowing the valve mandrel to shift upward and operate the valves. 
     In one embodiment, the closure valve is a flapper-type valve in another it is a ball-type valve. Upward shifting of the valve mandrel in these types of valves is abrupt at high pressure and, accordingly, a large shoulder is present to contact the upper end of the valve to prevent damage. 
     As used herein, the words “comprise,” “have,” “include,” and all grammatical variations thereof are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps. The terms “up” and “down” are used herein to refer to the directions along the wellbore toward and away from the well head and not to gravitational directions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The drawing is incorporated into and forms a part of the specification to illustrate at least one embodiment and example of the present invention. Together with the written description, the drawing serves to explain the principles of the invention. The drawing is only for the purpose of illustrating at least one preferred example of at least one embodiment of the invention and is not to be construed as limiting the invention to only the illustrated and described example or examples. The various inherent advantages and features of the various embodiments of the present invention are apparent from a consideration of the drawings in which: 
         FIG. 1   a - b  is a partial longitudinal section view of the improved, pump through circulating and safety circulating valve in the run position; 
         FIG. 2   a - b  is a view similar to  FIG. 1  illustrating the valve of the present invention in the circulation position; 
         FIG. 3  is an enlarged longitudinal cross-section view of the rupture disk case portion of the valve of the present invention; 
         FIG. 4  is an enlarged perspective view of a portion of the upper internal mandrel of the valve of the present invention; and 
         FIG. 5  is a partial longitudinal section view of the ball valve embodiment of the valve to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in  FIGS. 1   a  and  b  the valve assembly  10  of the present invention. The valve assembly  10  is illustrated in  FIG. 1  in the run position; that is the position in which the annulus is isolated from the interior chamber of the valve. The valve assembly  10  has an elongated tubular shape for connection into a tubing string  14  and  16 . Throughout the several views, an arrow W is used to indicate the orientation of the valve with respect to the well head with the tubing string typically extending to the well head. The valve assembly  10  is typically run installed in the well connected by threads to tubing  14  and  16  and located inside a well casing  18  shown partially in  FIG. 1   b . An annulus  20  is formed inside the casing  18  around the valve assembly  10 . The valve assembly  10  has an axially extending central passageway  12  in fluid communication with the tubing string and is positioned above (on the well head side) of a packer (not shown). The passageway  12  is full bore, allowing tools to pass therethrough. “Full bore” as used herein refers to a tool which has a minimum internal dimension (diameter in this case) or drift that substantially is no less than the internal dimension or drift of the tubing string. In this embodiment, the valve assembly has an external shape and size that is substantially the same size and shape as the tubing string. 
     The valve assembly  10  is run into the well with the valve in the run position shown in  FIGS. 1   a - b . When in position at a subterranean location, the packer is set against the well casing wall, sealing the annulus formed between the outside of the tubing string and the interior wall of the surrounding casing to prevent flow along the annulus past the packer. As will be described in detail hereinafter, when it is desired to activate the valve, pressure is raised in the annulus to move the valve into the circulation position shown in  FIGS. 2   a - b . As will be described when in the circulation position, flow from below the packer through the tubing string is prevented. In addition, recirculation port  310  formed in the wall of the ports case  300  is opened to allow circulation between the interior of the valve assembly  10  and the annulus formed between the casing and the tubing string. With the valve in this position, fluids, such as for example, drilling mud or produced hydrocarbons can be circulated or pumped out of the well either through the annulus or the interior of the tubing string. 
     The valve assembly  10  as illustrated in  FIGS. 1   a - 1   b  comprises seven (7) major subparts. These major subparts comprise: hammer case  100 ; rupture disc case  200 ; ports case  300 ; safety valve adapter  400 ; bottom adapter  500 ; upper mandrel  600 ; and a lower mandrel  700 . These subparts  100 ,  200 ,  300 ,  400  and  500  are joined together by mating threads T and form an elongated tubular body. These threaded joints T are sealed with annular seals S and with back-up rings. The joint connecting the rupture disc case  200  and ports case  300  includes two spaced parallel sets of annular seal assemblies S. As will be described, this joint is in fluid communication with the variable volume mandrel actuation chamber. The upper and lower mandrels  600  and  700  are also joined together by threads T and are axially shiftable within the valve assembly. The lower mandrel  700  has a set of circular holes H in its wall for use in threading the two mandrels together. As will be described, the mandrels  600  and  700  act as a piston for actuating the valve assembly and as a valve element for controlling fluid flow. 
     Turning to  FIG. 3 , the details of the structure utilized to shift the mandrels from the run position into the circulation position will be described. A bore or port  212  is formed in the wall of the rupture disc case  200 . The port communicates between the exterior of the tool (annulus  20 ) and a variable volume actuation chamber  214 . A rupture disc assembly  216  is mounted in the bore  212  to initially separate the chamber  214  from the exterior of the valve assembly  12 . The disc assembly  216  includes a frangible partition extending across the bore  212  and blocking the bore. The partition is supported at its periphery and fails or bursts when force on the partition due to differential pressure across the partition exceeds a set value. An annular seal  220  is mounted in the wall of bore  212  to seal around the assembly  216 . Threads mount the assembly  216  in the bore  212 . It is envisioned, of course, that the assembly  216  could be mounted in the bore by any means such as snap ring, press fitting or the like. The disc  218  is mounted to close the bore extending through the actuation port assembly  210  and is selected to rupture when a predesigned pressure differential is applied to the disc. The bottom of port  212  is angled downward. This forces the entering fluid to change direction which slows tool operation. 
     The variable volume chamber  214  is formed in the annular space between the upper mandrel  600  and rupture disc case  200 . As illustrated in  FIG. 3 , the lower end of the chamber  214  is sealed off by two sliding seal assemblies  230  located between case  200  and  300 . In the illustrated embodiment, these two seal assemblies comprise annular seals with protective back-up rings mounted in rectangular grooves in the interior wall of ports case  300 . Also, as illustrated in  FIG. 3 , the upper end of the chamber  214  is sealed by a backup ring  604  and seal  602  mounted in a groove  610  formed in the upper mandrel  600 . It should be appreciated that as the mandrel translates longitudinally in the valve, the upper and lower seals will move relative to each other varying the volume of the chamber  214 . 
     As illustrated in detail in  FIGS. 3 and 4 , the groove  610  is rectangular shaped with opposing walls and has one or more axially spaced reliefs or recesses  608  formed proximate the groove wall adjacent to and below the seal  602 . The seal preferably is a relatively elastically deformable annular seal such as an o-ring of resilient material. The seal tends to extrude into and seal the space around the mandrel. A back-up ring can be provided on the side of the seal  602  away from the reliefs. These reliefs  608  make the seal unidirectional and allow the seal  602  to function like a check valve to relieve pressure trapped in the annular chamber  612  formed above the seal  602 . If a pressure differential is present, the seal  602  moves upward against the wall of the groove and seals when the higher pressure is in the chamber  214 . If, on the other hand, the higher pressure is in chamber  612 , the seal  602  will be deformed into the reliefs  608  where it is unsupported and will allow flow from the chamber  612  into chamber  214 . By relieving pressure outside of the chamber  214 , undesirable movement of the mandrel is prevented. 
     This is useful when performing internal pressure testing prior to installation. Pressure build up during testing will be relieved. Also, when the mandrell is activated, pressure in chamber  612  will increase. When the tool is removed from the well, the seal  602  is will deform to relieve the pressure. 
     A plurality of shear pins  304  are mounted in circumferentially spaced bores  302  in the ports case  300 . Pins  304  engage an annular groove  614  (see  FIG. 4 ) in the upper mandrel  600  to prevent the upper mandrel  600  from moving. When sufficient pressure is applied to the annulus, the disc  218  will fracture and shear pins  304  will shear, allowing the upper mandrel  600  to move longitudinally axially shifting in an upward direction as shown in  FIG. 2 . The number of shear pins installed and the materials thereof can be varied to set a pressure at which the upper mandrel  600  is allowed to move. The mandrel is shaped so that it acts as a piston tending to move the mandrel upward when relative pressure in the chamber  214  is raised. 
     When the upper mandrel  600  is in the run position shown in  FIG. 3 , downward movement of the mandrel is prevented. As shown in  FIGS. 3 and 4 , an annular shoulder  616  on the upper mandrel  600  rests against an annular shoulder  306  on the ports case  300 . As illustrated in  FIG. 4 , a plurality of reliefs  618  are formed in the abutting face of shoulder  616 . The shoulder  306  is illustrated as being annular shaped; however, it is envisioned that other shoulder shapes could be used. For example, the mandrel could rest against or contact cylindrical shoulders on pins. 
     The recirculation features of the valve assembly  10  will be described by reference to  FIGS. 1 and 2 . As illustrated, a plurality of recirculation ports  310  extends through the wall of the ports case  300 . A plurality of corresponding recirculation ports  620  extends through the wall of the upper mandrel  600 . When the valve assembly  10  is in the run position as illustrated in  FIGS. 1A and 1B , the ports are axially displaced from each other, preventing flow between the passageway  12  and the annulus formed around the valve assembly  10 . When annulus pressure has been raised, the disc is fractured, and the pins are sheared, allowing the upper mandrel  600  to act as a valve element and shift axially upward until an annular shoulder  630  on the upper mandrel  600  contacts a downward facing annular shoulder  110  on the hammer case  100 . When these shoulders contact, ports  310  and  620  are axially aligned as shown in  FIGS. 2A and 2B . In this way, the mandrel acts as a valve element and the port  620  acts as a valve seat which cooperate to allow fluids to be pumped (recirculated) along the annulus  20  through the ports  310  and  620  and into the passageway  12 . In an alternate embodiment, the ports case  300  and the flapper adapter  400  are replaced by a unitary part; a no-ports case not illustrated. The no-ports case is formed without recirculation on port  300  therein whereby shifting of the upper mandrel  600  upward to the position shown in  FIG. 2 , the no-ports case does not allow flow from the passageway  12  and the annulus formed around the valve assembly  1 B. According to a particular feature of the invention, the shoulders have corresponding shapes that are not entirely transverse to the direction of the mandrel&#39;s movement. As illustrated, the shoulders are generally frusto conical-shaped with the shoulder  630  tapering outward and the shoulder  110  tapering inward. The shoulder  630  forms a bell or recess for receiving the pin-shaped shoulder  110 . This configuration reduces the tendency of the shoulders on the mandrel and hammer case from being deformed. 
     The safety valve features of the valve assembly  10  will be described by reference to  FIGS. 1 and 2 . As illustrated in  FIG. 1 , the lower mandrel  700  extends into a safety valve assembly  800 . In the present embodiment, the safety valve assembly  800  is a flapper type of valve comprising a flapper-type valve element  802  mounted on a pivot  804  to open and close against a seat  806 . As illustrated in  FIG. 1 , the lower mandrel  700  is operatively associated with the valve assembly  800 , in that, the mandrel extends through the safety valve assembly  800  to hold the flapper element  802  in an open position. As is illustrated in  FIG. 2 , when the upper mandrel  600  and lower mandrel  700  shift upward the shoulders  110  and  630  contact and the lower mandrel  700  is displaced from the flapper  802  of the safety valve  800  allowing the flapper  802  to close against the seat  86 . Typically a spring  808  is provided for to urge the flapper  802  in a direction toward the seat  806  to close the valve once the lower mandrel  700  is removed. In this configuration, flow from below the valve and through the passageway  12  is blocked in an upward direction and flow through recirculation ports  310  and  620  is permitted. 
     In an alternative configuration illustrated in  FIG. 5 , a pump through ball-type valve  900  replaces the flapper valve. In this alternate configuration, the ball valve  900  is held open by the lower mandrel  700 . The ball valve  900  is urged by spring assembly  902  toward a closed position. Once the mandrel  700  is shifted up out of the ball valve  900 , to the position shown in  FIG. 2 , the ball valve will close. Replacing the flapper valve with a ball-type valve provides an additional feature of allowing fluids to be pumped down the passageway  12  and out into the annulus through recirculation ports  310  and  620 . 
     Also, as previously described, when it is desired to utilize the valve assembly  10  solely as a safety valve; the ports case  300  and the flapper adapter  400  are replaced with a no-ports case that lacks the recirculation port  310 . In another option, the safety valve is eliminated, and only the recirculating valve is present. 
     According to one method of utilizing the present invention, the valve assembly  10  is assembled and connected in a string of tubing at a position above a packer and then run into a cased well. The packer is set to seal off the annulus around the tubing, after which well services or testing steps are performed. When it is desirable to activate the safety valve and/or or open recirculation ports  620 , pressures are raised in the annulus sufficient to rupture the disc  200  and to shear the pins  304 , forcing the mandrel to shift upward. 
     Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed herein are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art, having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is, therefore, evident that the particular illustrative embodiments disclosed above may be altered or modified, and all such variations are considered within the scope and spirit of the present invention. 
     Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an”, as used in the claims, are defined herein to mean one or more than one of the element that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent(s) or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted.