Abstract:
Disclosed herein is a safety valve with a chemical injection configuration. The device includes a hydraulic fluid pressure operated piston at the housing. The device further includes a flow tube in operable communication with the piston and a chemical injection configuration disposed within the housing. Further disclosed herein is a method of maintaining the operation of a safety valve by injecting chemical fluid through a configuration within the safety valve. Still further disclosed herein is check valve. The check valve includes a seal, a dart having a closed head and sealable against the seal, one or more flutes on the dart, and a spring applying a biasing force to the dart to a sealing position, that force being overcomeable by a fluid pressure acting in a direction opposing the spring force.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of an earlier filing date from U.S. Ser. No. 60/514,868 filed Nov. 27, 2003, the entire contents of which is incorporated herein by reference. 
     
    
     BACKGROUND  
       [0002]     Chemical injection is often used in the downhole oilfield industry in conjunction with safety valves such as tubing retrievable safety valves because a common and relentless problem is a buildup of scale, hydrates, paraffin and other undesirable solids on downhole structures. Any one or combination of these solids collecting in a safety valve, i.e., on or around a flapper, on the torsion spring, on the flow tube, the power spring, etc., can hamper the ability of the safety valve to function at optimum. Chemicals, which are selected depending upon the chemistry of the wellbore and therefore the chemistry of the solids presenting problems, can be injected down into the downhole environment to dissolve such solids. In general, with respect to tubing retrievable and other safety valves in a traditionally accepted configuration, included at an uphole end thereof via common connections such as a premium thread, a secondary chemical injection device which is connected to a surface location for application of chemicals. Chemicals are injected from the location of the injection valve above the safety valve and are calculated to migrate to the areas of the safety valve. Clearly density, turbulence, obstruction and other issues may hamper the movement of the chemical to the safety valve. In addition the chemical often does not reach inner workings of the safety valve not directly exposed to the flow area thereof.  
         [0003]     Chemical injection devices as described are expensive, cause spacing out issues and connection issues. In view of the ever increasing need for efficiency and cost effectiveness, the applicants herein have developed a new system which is more efficient, more effective, of lower cost, and beneficial to the art.  
       SUMMARY  
       [0004]     Disclosed herein is a safety valve with a chemical injection configuration. The device includes a hydraulic fluid pressure operated piston at the housing. The device further includes a flow tube in operable communication with the piston and a chemical injection configuration disposed within the housing.  
         [0005]     Further disclosed herein is a method of maintaining the operation of a safety valve by injecting chemical fluid through a configuration within the safety valve.  
         [0006]     Still further disclosed herein is a check valve. The check valve includes a seal, a dart having a closed head and sealable against the seal, one or more flutes on the dart, and a spring applying a biasing force to the dart to a sealing position, that force being overcomeable by a fluid pressure acting in a direction opposing the spring force. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     Referring now to the drawings wherein like elements are numbered alike in the several Figures:  
         [0008]      FIG. 1  is a partially cut-away view of a tubing retrievable safety valve having a chemical injection system provided therein;  
         [0009]      FIG. 2  is a cross-section expanded view of the left side of the cut-away portion in  FIG. 1 ;  
         [0010]      FIG. 3  is the same structure as that of  FIG. 2  both in a position related to the injection of chemical to the safety valve;  
         [0011]      FIG. 4  is a perspective view of a check valve in accordance with this disclosure;  
         [0012]      FIG. 5  is a perspective view of a pressure test assembly installed in a tubing retrievable safety valve;  
         [0013]      FIG. 6  is a cross-sectional view of the pressure test assembly before retainer override; and  
         [0014]      FIG. 7  is a cross-sectional view of the pressure test assembly after retainer override. 
     
    
     DETAILED DESCRIPTION  
       [0015]     Referring to  FIG. 1 , a break-away view of a tubing retrievable safety valve (TRSV), modified according to the disclosure is illustrated. The safety valve is generally indicated at  10 . One of ordinary skill in the art should recognize piston  12 , piston chamber  14 , control line  16  and flow tube  18  as common components of a TRSV. A TRSV such as Baker Oil Tools part number H826103110. The balance of the components of the TRSV are considered known to the art and not in need of discussion or illustration. In accordance with the disclosure hereof TRSV body  22  is provided with a chemical injection configuration directly in the housing thereof. A greater disclosure of the configuration is made hereunder. Also illustrated in  FIG. 1  is a secondary line  20  which is in fact a chemical injection line leading to a remote location, which may be a surface location or other downhole location, having access to a supply of chemical(s) for injection. As will be understood by one of ordinary skill in the art, different chemicals are utilized at different times for different reasons, each of which can be sent down the chemical injection line  20  as discussed further herein.  
         [0016]     Referring now to  FIG. 2 , chemical injection line  20  is connected to body  22  by conventional means utilizing a control line nut  24  threaded into a tap section  26  in TRSV body  22 . The control line  20  extends a short distance as illustrated below nut  24  to bottom on shoulder  28  of a smaller dimension conduit  30  leading to a channel  32 . The interconnection between section  30  and  32  need merely provide for sufficient volume of chemical injected fluid to be acceptable. The channel  32  leads to a larger dimension channel  34  which is configured to receive two check valves  36  and  38  to prevent wellbore fluids from moving up the chemical control line. Between check valve  36  and  38  is spacer  40 , which allows the check valves to operate properly since it provides a surface  42  against which the spring  44  of the first check valve  36  may bear and in addition provides space between surface  42  and the top of check valve  38  to avoid inhibition of fluid flow. The check valves are held in position by two nuts (in one embodiment)  46 , one of which provides a seat  48  for spring  50  and the second of which simply locks the first nut  46 . Both of the lock nuts are center drilled to create a tube  52  such that chemical injection fluid may pass therethrough and into chamber  54  whereafter the fluid will bleed in all directions around components of the safety valve. It is important to note that there are no seals between the housing  22 , the flow tube  18 , the power spring which is not shown herein but which is known to one of ordinary skill in the art, and other components of this device. One of the great advantages of the configuration as set forth herein is that the chemical injection fluid must flow through these parts in order to reach the inside dimension of the wellbore making it much more likely that the chemical injected fluid is going to reach all of the places that might otherwise have hydrate and other solid buildup. This is a significant advantage since it requires less chemical to be injected and will take less time for the chemical to reverse the solids deposition process that affected performance of the safety valve and gave rise to the need for treatment.  
         [0017]     It is important to point out that during the creation of this device the inventors concluded that check valves common in chemical injection configurations would not function properly in this device. This is because all the chemical injection valves are created to be utilized in a larger bore which allows them to have a central flow channel. This is not possible in this case due to the restricted diameter which itself is due to the thickness of the housing  22 . In order to make the device function as intended, the inventors hereof were required to design a new check valve that would allow sufficient flow to achieve the desired result while still functioning within a narrower conduit than prior art check valves.  
         [0018]      FIG. 2  provides an illustration of a cross-section of the valve itself and  FIG. 4  should be viewed contemporaneously to provide perspective.  
         [0019]     The check valve itself (see  FIG. 4 ) comprises a seal  60  which in one embodiment is a PEEK seal ring which will interact with a dart head  62 , which is in this embodiment a semi-spherical configuration. It is contemplated however that different shapes such as oval might be utilized. In the presently discussed embodiment, the semi-spherical head  62  is followed by one or more flow flutes  63  in a body portion  64 . The machining or flutes, in one embodiment, is in 90 degree increments leaving a small amount of material identified herein as rib  66  between each of the flutes. It will be appreciated that a cross-section through body portion  64  in the described embodiment will yield a plus sign (+) or an X depending on orientation. It is contemplated that different configurations might be employed such as a rib cross-section of a Y-section and others. Also, although machining has been set forth above, the flutes may be formed differently such as by molding.  
         [0020]     At the tail end of dart body  64  there is provided a recess  67  to provide a good flow area to the inside dimension of spring  44  which substantially reduces restriction in that area. The new check valve has been found to function well for its intended purpose and the TRSV as modified by the disclosure hereof will be more reliable for a longer period of working life.  
         [0021]     Referring to  FIG. 3 , arrows are provided to show flow of the injected chemical and its action on check valves  36  and  38 . As one will appreciate from this drawing, the pressurized fluid from the remote location moves into the configuration described to put pressure on head  62  of dart  58 . Upon sufficient pressure being applied to head  62 , spring  44  is compressed allowing fluid to flow past seal  60 , around head  62  and into the flutes  65  of dart  58 . This action is repeated at check valve  38  and the injected chemical is illustrated in chamber  54  and in all of the potential leak paths available to the chemical in the TRSV. Consideration should be given to the drafting method of illustrating the fluid in the cavity  54  and all the other places in this figure where that illustration method has been used. This is intended to indicate to the reader all of the leak paths of the chemical being injected.  
         [0022]     In connection with the foregoing apparatus it is further desirable to allow for integrity testing of an umbilical leading to the safety valve. The device could be adapted to test lines other than chemical injection lines as well and so may be employed with other tools.  
         [0023]     Referring to  FIG. 5 , shoulder  28 , conduit  30  and channel  32  will be recognized in TRSV body  22  from earlier introduced figures.  FIG. 5  also illustrates a line pressure tester assembly  80 . The assembly comprises a housing  82  and a cartridge  84 . A seal  86  on the outside dimension of the housing  82  cooperates with the inside dimension of bore  88  preventing leakage around the assembly  80 . Also visible in  FIG. 5  are flow slots  90 , which cooperate with flow grooves  92  (different numbers of these grooves are illustrated in different drawings and are alternatives juxtaposing strength and flow area) in cartridge  84  when the assembly is “open”. In the  FIG. 5  view the assembly is “closed”. It is maintained in this position by a retainer  94 , which in the illustrated embodiment is a shear pin extending through housing  82  and cartridge  84 . The cartridge  84  is further prevented from moving uphole (left in the drawing) by a stop  96 , which in the illustrated embodiment is a retaining ring. It will be understood that arrangements other than those illustrated for the retainer and stop are equally applicable such as but not limited to protuberances on cartridge  84  or restrictions in housing  82 . Returning to the shear pin, it will be understood that other retaining means are employable whose properties include preventing relative motion between housing  82  and cartridge  84  until a selected force is applied whereupon the cartridge is movable relative to the housing. Retainer  94  allows for resetting of the assembly  80  by replacing the shear pin. Other embodiments of retainer  94  will desirably but not necessarily be resettable. The capability of resetting allows the device to be reused while it would have to be replaced if it was not resettable.  
         [0024]     Referring to  FIGS. 6 and 7 , cross-sectional views of the assembly are illustrated to show position of the cartridge  84  in the housing  82  before and after shear, respectively. Upon exposure to these drawings one of ordinary skill in the art will immediately appreciate the relative movement between cartridge  84  and housing  82 . Upon such movement in  FIG. 6 , one of the flow slots  90  can be seen. When seal  100  which is mounted on cartridge  84  and seals the cartridge  84  to the inside dimension  102  of housing  82 , moves sufficiently downstream (right in picture) seal  100  allows fluid communication between grooves  92  and slots  90  for through passage of fluid. Seal  100  is in this moved position in  FIG. 6  although slots  90  do not happen to be visible in the figure. It will be appreciated that the pin is double sheared and the center portion  94 ′ moves downhole while the ends  94 ″ stay in the position they hold prior to shearing.  
         [0025]     In operation, the assembly is subjected to a first selected pressure to verify pressure competence of the injection system using this assembly and then to a condition calculated to override retainer  94 , which may be a higher pressure.  
         [0026]     While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.