Patent Publication Number: US-2015083433-A1

Title: Gas lift valve

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Application claims the benefit of U.S. Provisional Application Ser. No. 62/001,448 filed on May 21, 2014 and U.S. Provisional Application Ser. No. 61/881,663 filed on Sep. 24, 2013. Each of the aforementioned patent applications is herein incorporated by reference. 
    
    
     BACKGROUND 
     1. Field 
     Embodiments of the present disclosure generally relate to valves capable of withstanding high injection pressures, high injection rates, or varying injection pressure, including valves for use in hydrocarbon wells configured for artificial lift operations, for example. 
     2. Description of the Related Art 
     To obtain hydrocarbon fluids from an earth formation, a wellbore is drilled into the earth to intersect an area of interest within a formation. The wellbore may then be “completed” by inserting casing within the wellbore and setting the casing therein using cement, for example. In the alternative, the wellbore may remain uncased (an “open hole” wellbore), or may be only partially cased. Regardless of the form of the wellbore, production tubing is typically run into the wellbore primarily to convey production fluid (e.g., hydrocarbon fluid, as well as water and other, non-hydrocarbon gases) from the area of interest within the wellbore to the surface of the wellbore. 
     Often, pressure within the wellbore is insufficient to cause the production fluid to rise naturally through the production tubing to the surface of the wellbore. Thus, to force the production fluid from the area of interest within the wellbore to the surface, artificial lift means are sometimes employed. Gas lift and sucker rod pumping are examples of artificial lift means for increasing production of oil and gas from a wellbore. 
     Gas lift systems are often the preferred artificial lifting systems because operation of gas lift systems involves fewer moving parts than operation of other types of artificial lift systems, such as sucker rod lift systems. Moreover, because no sucker rod is required to operate the gas lift system, gas lift systems are usable in offshore wells having subsurface safety valves that would rule out the use of sucker rod pumping. 
     Gas lift systems commonly incorporate one or more valves in side pocket mandrels of the production tubing to enable the lifting of production fluid to the surface. In a typical application, the gas lift valves allow gas from the annulus between the casing and production tubing to enter the tubing through the valves, but prevent reverse flow of production fluid from the tubing to the annulus. 
     SUMMARY 
     Embodiments of the present disclosure generally relate to a valve apparatus configured to close in response to a predetermined pressure differential across the valve apparatus. In one embodiment, the valve apparatus may be used in a gas lift operation. In use, the valve apparatus is initially in an open position, whereby fluid flow through the valve apparatus is allowed. The valve apparatus closes when a predetermined pressure differential is obtained across the valve. 
     In one embodiment, a method for performing downhole gas lift operations includes coupling a gas lift valve to a tubing, wherein the gas lift valve includes an actuator, a flow control member disposed in the actuator, and a closure member that is initially in an open position; injecting a gas downhole and exterior to the tubing; urging the gas to enter the tubing via the gas lift valve; and creating a sufficient pressure differential across the gas lift valve to move the actuator, thereby causing the closure member to close the gas lift valve. 
     In another embodiment, a valve for controlling fluid flow between an inlet and an outlet includes a housing having a bore in fluid communication with an inflow port and an outlet port; a closure member configured to close fluid communication through the bore; and a flow tube movable between an extended position and a retracted position, wherein when in the extended position, the flow tube retains the closure member in an open position, and wherein the flow tube is movable to the retracted position in response to a predetermined pressure differential across the bore. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the various aspects, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. 
         FIG. 1  is a cross-sectional view of a gas injection wellbore, in accordance with an embodiment of the present disclosure. 
         FIG. 2  illustrates an exemplary embodiment of a gas lift valve.  FIG. 2A  illustrates an exemplary partial, cross-sectional view of the gas lift valve. 
         FIGS. 3A-3G  are sequential views of an exemplary embodiment of a gas lift operation. 
         FIG. 4  illustrates another exemplary embodiment of a gas lift valve. 
         FIG. 4A  illustrates an exemplary partial, cross-sectional view of the gas lift valve. 
         FIGS. 5 and 6  illustrate an exemplary embodiment of a side pocket mandrel.  FIG. 5  depicts an exemplary gas lift valve disposed in the side pocket mandrel, and  FIG. 6  depicts the gas lift valve disposed out of the side pocket mandrel. 
         FIG. 7A  illustrates another exemplary embodiment of a gas lift valve in an open position. 
         FIG. 7B  illustrates the gas lift valve of  FIG. 7A  in a closed position. 
         FIG. 7C  illustrates an exemplary partial, cross-sectional view of the gas lift valve of  FIG. 7A . 
         FIG. 7D  illustrates an exemplary partial, cross-sectional view of the gas lift valve of  FIG. 7A . 
         FIG. 7E  illustrates an exemplary embodiment of a viscous type dampener for a gas lift valve. 
         FIG. 7F  illustrates another exemplary embodiment of a friction type dampener for a gas lift valve. 
         FIG. 7G  illustrates an exemplary embodiment of a detent device for a gas lift valve. 
         FIG. 8A  illustrates another exemplary embodiment of a gas lift valve in an open position. 
         FIG. 8B  illustrates the gas lift valve of  FIG. 8A  in a position before a detent is released. 
         FIG. 8C  illustrates the gas lift valve of  FIG. 8A  in a closed position. 
         FIG. 9A  illustrates another exemplary embodiment of a gas lift valve in an open position. 
         FIG. 9B  illustrates the gas lift valve of  FIG. 9A  in a closed position. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure provide a valve apparatus capable of withstanding high injection pressures, high injection rates or varying injection line pressure, and techniques for using the valve apparatus in various suitable applications. In one embodiment, a gas lift valve apparatus is configured to close in response to a predetermined pressure differential across the gas lift valve apparatus. 
       FIG. 1  illustrates a typical gas lift completion for hydrocarbon recovery, which may include a wellhead  112  atop a casing  114  that passes through a formation  102 . Production tubing  120  positioned in the casing  114  may have a number of side pocket mandrels  130  and a production packer  122 . To conduct a gas lift operation, operators may install gas lift valves  140  in the side pocket mandrels  130 . 
     With the valves  140  installed, compressed gas G from the wellhead  112  may be injected into the annulus  116  between the production tubing  120  and the casing  114 . In the side pocket mandrels  130 , the gas lift valves  140  are in the open position to allow injected gas and other fluids to flow from the annulus  116  into the tubing  120 . When the velocity of the gas flowing through the valve  140  is above a predetermined value, the valve  140  closes to prevent further inflow of the injected gas into the tubing  120 . 
     Alternatively, a gas lift operation may be performed to gas lift fluid in the annulus  116 . Compressed gas may be injected into the production tubing  120 . The gas lift valves  140  are in the open position to allow injected gas and other fluids to flow from the tubing  120  into the annulus  116 . When the velocity of the gas flowing through the valve  140  is above a predetermined value, the valve  140  closes to prevent further inflow of the injected gas into the annulus  116 . 
     Downhole, the production packer  122  forces upwards travel through the production tubing  120  of production fluid P entering casing perforations  115  from the formation  102 . Additionally, the packer  122  keeps the gas flow in the annulus  116  from entering the tubing  120 . 
     The injected gas G passes down the annulus  116  until it reaches the side pocket mandrels  130 . Entering the mandrel&#39;s inlet ports  135 , the gas G first passes through the gas lift valve  140  before it can pass into the production tubing  120 . Once in the tubing  120 , the gas G can then rise to the surface, lifting production fluid P in the production tubing in the process. 
       FIG. 2  illustrates an exemplary embodiment of a gas lift valve  200 .  FIG. 2A  is an enlarged, partial cross-sectional view of the gas lift valve  200 . The valve  200  may be positioned in a side pocket mandrel  130  of the gas lift completion system shown in  FIG. 1 . The valve  200  includes a valve housing  210  having one or more gas inlet ports  211  and one or more gas outlet ports  212 . As shown, the inlet ports  211  are disposed at an upper portion of the valve  200  and the outlet ports  212  are disposed at a lower portion of the valve  200 . A latch  216  is shown disposed at the upper end of the valve  200 . A sealing member  215  such as a packing stack arrangement may be disposed on each side of the inlet ports  211  to isolate the fluid in the annulus  116  from the tubing  120 . The inlet ports  211  and outlet ports  212  communicate via a bore  220  in the valve  200 . A closure member  230  is configured to selectively open or close fluid communication through the bore  220 . Exemplary closure members include a flapper, a ball and seat, a sealing head, and other suitable closure members known to a person of ordinary skill in the art. In this embodiment, a flapper  230  is positioned at an upper portion of the bore  220 . As shown, the flapper  230  is retained in an open position using an actuator such as a flow tube  240 . The flow tube  240  is shown biased in an extended position using a biasing member  245  such as a spring. The biasing member  245  is disposed in an annular area  247  between the flow tube  240  and the valve housing  210 . The biasing member  245  may engage an optional spacer member  246  coupled to the flow tube  240 . 
     A flow control member  250  is coupled to the interior of the flow tube  240 . In the embodiment shown in  FIG. 2A , the flow control member  250  is an annular ring having an opening  255  therethrough. Although the flow tube  240  is shown as formed using two connected tubulars to facilitate coupling with the flow control member  250 , it is contemplated that the flow tube  240  may be formed using a single tubular, or three or more connected tubulars. The flow control member  250  forms an effective area in the bore  220  of the flow tube  240 . The effective area may be controlled by selecting the appropriate size of the inner diameter of the opening  255  of the flow control member  250 . In this respect, injected fluid flowing in from the inlet ports  211  applies a force to the flow control member  250 , which force is opposed by the biasing force of the spring  245 . When the force applied by the injected flow is higher than the biasing force, the flow tube  240  will compress the spring  245 . As a result, the flow tube  240  is moved away from the flapper  230 , thereby allowing the flapper  230  to close the bore  220 . The closing pressure of the flapper  230  can be selected by adjusting the biasing force of the spring  245 , the inner diameter of the flow control member  250 , and combinations thereof. For example, a smaller diameter opening  255  will close the flapper  230  using a smaller pressure differential than a larger diameter opening  255  when other parameters, such as the flow rate of injected fluid, the biasing force of the spring member  245 , and the inner diameter of the bore  220 , are fixed. During operation, when the biasing force of the spring member  245 , the diameter of the opening  255  and the inner diameter of the bore  220  are fixed, an increase in the flow rate of the injected gas will cause an increase in differential pressure across the flow control member  250 , and eventually close the valve  200 . After closing, fluid from the annulus  116  is prevented from entering the tubing  120 . The flapper  230  can re-open when the casing pressure, tubing pressure, and spring force acting on the flapper dictates. In another embodiment, the valve  200  may include an optional bleed port, which may also affect the re-opening of the flapper  230 . 
     In one embodiment, valve  200  may include an optional detent mechanism  253  to retain the flow tube  240  in the retracted position. For example, at a predetermined pressure differential, the flow tube  240  is retracted sufficiently such that the detent mechanism  253  is activated, thereby retaining the flow tube  240  in the retracted position. An exemplary detent mechanism  253  is a retractable pin configured to engage a recess  254  in the flow tube  240 . Another exemplary detent mechanism is a collet. In yet another embodiment, a one-way valve  257  such as a check valve may be disposed at the lower end of the valve  200 . The one-way valve  257  may prevent fluid in the tubing  120  from entering the annulus  116  via the valve  200 . 
       FIGS. 3A-3G  illustrate an exemplary sequence during a gas lift operation using one embodiment of a gas lift completion system to unload a well  301 . Referring to  FIG. 3   a , the gas lift completion system includes a wellhead  312  disposed atop a casing  314  and a production tubing  320  positioned in the casing  314 . The production tubing  320  may have a plurality of gas lift valves  340  coupled to a respective side pocket mandrel and a production packer  322  at a lower end of the tubing  320 . 
     As shown, the system  300  includes six velocity valves  340   a - 340   f  and an orifice valve  365  coupled to the tubing  320 . In  FIG. 3A , the well  301  is loaded with completion fluid, and the gas lift valves  340   a - 340   f  are in the open position because no pressure differential exists across the valves  340   a - 340   f.    
     In  FIG. 3B , injection gas  308  is supplied to assist with unloading of the well  301 . Because the gas lift valves  340   a - 340   f  are open, the fluid in the annulus  316  is allowed to enter the tubing  320 . As more pressure is applied to the casing  314 , the fluid level  309  in the annulus  316  will drop. As shown, the fluid level  309  is above the first valve  340   a , and the injection gas  308  has not entered the first valve  340   a . It must be noted that if the gas lift valves  340   a - 340   f  are closed, the annulus fluid may enter the tubing  320  through the orifice valve  365 . 
     In  FIG. 3C , the fluid level  309  in the casing  314  has dropped to the depth of the first gas lift valve  340   a , and the injected gas  308  has begun to enter the first gas lift valve  340   a  and the tubing  320 . In this respect, the injected gas  308  in the tubing  320  will aerate the fluid column in the tubing  320 . The fluid in the casing  314  continues to enter through the orifice valve  365  and/or any of the gas lift valves  340   b - 340   f  disposed below the first valve  340   a  that are open. 
     In  FIG. 3D , gas injection pressure has increased. The injected gas  308  continues to flow in through the first valve  340   a , thereby continuing to aerate the fluid column in the tubing  320 . Also, the fluid in the casing  314  continues to enter the tubing  320  through the orifice valve  365  and/or any of the gas lift valves  340   b - 340   f  below the first valve  340   a  that are open. 
     In  FIG. 3E , the fluid level  309  has dropped to the depth of the second gas lift valve  340   b , and the injected gas  308  has begun to enter the second gas lift valve  340   b . The first valve  340   a  has closed due the pressure differential across the first valve  340   a . For example, the upstream pressure (e.g., the pressure at the inlet ports  211 ) may be at 7,000 psi while the downstream pressure (e.g., the pressure at the outlet ports  212 ) may be at 4,500 psi. The pressure differential of 2,500 psi is sufficient to overcome the biasing force of the spring  245 , thereby retracting the flow tube  240  and allowing the flapper  230 , ball and seat mechanism, a sealing head, or other suitable closure member to close. 
     In  FIG. 3F , gas injection pressure is increased. The injected gas  308  continues to flow in through the second valve  340   b , thereby continuing to aerate the fluid column in the tubing  320 . Also the fluid in the casing  314  continues to enter the tubing  320  through the orifice valve  365  and/or any of the gas lift valves  340   c - 340   f  below the second valve  340   b  that are open. 
     This process of creating a pressure differential to sequentially close an upper valve and causing the fluid level to drop so that injected gas may flow through the next, lower valve continues until injected gas reaches an optimal point of injection. The optimal point of injection is a depth in the well where the gas injection point remains stationary until the well condition makes it possible to inject gas deeper. All of the gas lift valves  340   a - 340   f  that are above the optimal point of injection have closed due to the pressure differential across the valves. 
       FIG. 4  illustrates an exemplary embodiment of a gas lift valve  400 .  FIG. 4A  is an enlarged, partial cross-sectional view of the gas lift valve  400 . The valve  400  may be positioned in a side pocket mandrel  130  of the gas lift completion system shown in  FIG. 1 . It must be noted that embodiments of the gas lift valves disclosed herein may be used with other suitable types of gas lift mandrels known to a person of ordinary skill in the art. In the embodiment shown in  FIG. 1 , the valve  400  is similar to the valve  200  of  FIG. 2  in that the valve  400  includes many of the components of the former valve  200 . One difference between the valves  200 ,  400  is the axial positions of the components of this valve  400  have been inverted with respect to the latch  416 . The valve  400  includes a valve housing  410  having one or more gas inlet ports  411  and one or more gas outlet ports  412 . As shown, the inlet ports  411  are disposed at a lower portion of the valve  400  and the outlet ports  412  are disposed at an upper portion of the valve  400 . A latch  416  is shown disposed at the upper end of the valve  400 . In this embodiment, the outlet ports  412  are formed through the latch  416 . A sealing member  415  such as a packing stack arrangement may be disposed on each side of the inlet ports  411  to isolate the fluid in the annulus  116  from the tubing  120 . The inlet ports  411  and outlet ports  412  communicate via a bore  420  in the valve  400 . A closure member  430  is configured to selectively open or close fluid communication through the bore  420 . Exemplary closure members include a flapper, a ball and seat, a sealing head, and other suitable closure members known to a person of ordinary skill in the art. In this embodiment, a flapper  430  is positioned at a lower portion of the bore  420 . The flapper  430  is retained in an open position using a flow tube  440 . The flow tube  440  is shown biased in an extended position using a biasing member  445  such as a spring. The biasing member  445  is disposed in an annular area  447  between the flow tube  440  and the valve housing  410 . The biasing member  445  may engage an optional spacer member  446  coupled to the flow tube  440 . 
     A flow control member  450  is coupled to the interior of the flow tube  440 . In the embodiment shown in  FIG. 4A , the flow control member  450  is an annular ring having an opening  455  therethrough. Although the flow tube  440  is shown as formed using two connected tubulars to facilitate coupling with the flow control member  450 , it is contemplated that the flow tube  440  may be formed using a single tubular, or three or more connected tubulars. The flow control member  450  forms an effective area in the bore  420  of the flow tube  440 . The effective area of the flow control member  450  is determined by the difference in area between the inner diameter of the bore  420  and the inner diameter of the opening  455  of the flow control member  450 . In this respect, injected fluid flowing in from the inlet ports  411  applies a force to the flow control member  450 , which force is opposed by the biasing force of the spring  445 . When the force applied by the injected flow is higher than the biasing force, the flow tube  440  will compress the spring  445 . As a result, the flow tube  440  is moved away from the flapper  430 , thereby allowing the flapper  430  to close the bore  420 . The closing pressure of the flapper  430  can be selected by adjusting the biasing force of the spring  445 , the effective area of the flow control member  450 , and combinations thereof. After closing, fluid from the annulus  116  is prevented from entering the tubing  120 . The closing pressure of the flapper  430  can be selected by adjusting the biasing force of the spring  445 , the inner diameter of the flow control member  450 , and combinations thereof. For example, a smaller diameter opening  455  will close the flapper  430  using a smaller pressure differential than a larger diameter opening  455  when other parameters, such as the flow rate of injected fluid, the biasing force of the spring member  445 , and the inner diameter of the bore  420 , are fixed. During operation, when the biasing force of the spring member  445 , the diameter of the opening  455  and the inner diameter of the bore  420  are fixed, an increase in the flow rate of the injected gas will cause an increase in differential pressure across the flow control member  450 , and eventually close the valve  400 . After closing, fluid from the annulus  116  is prevented from entering the tubing  120 . The flapper  430  can re-open when the casing pressure, tubing pressure, and spring force acting on the flapper dictates. In another embodiment, the valve  400  may include an optional bleed port, which may also affect the re-opening of the flapper  430 . Although the embodiment is described using a flapper  430 , it must be noted that a ball and seat, a sealing head, or other suitable types of closure members are contemplated. 
     In one embodiment, the valve  400  may include an optional detent mechanism  453  to retain the flow tube  440  in the retracted position. For example, at a predetermined pressure differential, the flow tube  440  is retracted sufficiently such that the detent mechanism  453  is activated, thereby retaining the flow tube  440  in the retracted position. An exemplary detent mechanism  453  is a retractable pin configured to engage a recess  454  in the flow tube  440 . Another exemplary detent mechanism is a collet. In yet another embodiment, a one-way valve  457  such as a check valve may be disposed at the lower end of the valve  400 . The one-way valve  457  may prevent fluid in the tubing  120  from entering the annulus  116  via the valve  400 . 
       FIGS. 5 and 6  illustrate an exemplary side pocket mandrel suitable for receiving a gas lift valve according to embodiments of the present invention.  FIG. 5  depicts a valve  500  disposed in the side pocket mandrel  530 , and  FIG. 6  depicts the valve  500  disposed out of the side pocket mandrel  530 . Referring to  FIG. 6 , the side pocket mandrel  530  may include external check valves disposed at the entrance of the passage into the pocket  532  of the side pocket mandrel  530 . Although two passages are shown, it is contemplated that the side pocket mandrel  530  may include a single passage or three or more passages. The pocket  532  is configured to receive the valve  500  and is in fluid communication with the tubing  120 . When the valve  530  is not installed, fluid from the tubing  120  may enter the pocket  532 , but is prevented from exiting through the passages by the respective check valves. When the valve  500  is in the pocket  530  as shown in  FIG. 5 , the pressure of the injection gas may overcome the check valves, thereby allowing the injection gas to enter the passages and flow toward the gas lift valve  500 . After entering the inlet ports of the gas lift valve  500 , the injection gas may exit through the outlet ports, flow through the pocket  532 , and flow into the tubing  120 , where the injection gas may aerate the fluid column in the tubing  120 . The injection gas may continue to enter and exit the gas lift valve  500  until the pressure differential across the gas lift valve is sufficient to overcome the biasing force of the biasing member, thereby retracting the flow tube and allowing the flapper to close. It is contemplated that other suitable types of gas lift mandrels known to a person of ordinary skill in the art may be used with embodiments of the gas lift valves disclosed herein. 
     In yet another embodiment, when the gas lift valves are used in conjunction with the orifice valve, such as a shear-orifice valve, a casing annulus test may be performed without wireline intervention. In yet another embodiment, the gas lift valve may include a dampener device to facilitate movement between the open and close position. In yet another embodiment, the flow control device of the gas lift valve may include a venturi choke to improve gas passage through the gas lift valve. 
       FIG. 7A  illustrates an exemplary embodiment of a gas lift valve  700  in an open position.  FIG. 7B  illustrates the gas lift valve  700  in a closed position.  FIG. 7C  illustrates an exemplary partial, cross-sectional view of the gas lift valve  700 . The gas lift valve  700  may be positioned in a side pocket mandrel  130  of the gas lift completion system shown in  FIG. 1 . 
     The gas lift valve  700  includes a valve housing  710 . The valve housing  710  has a bore  720 , one or more gas inlet ports  711  and one or more gas outlet ports  712 . As shown in  FIG. 7A , the inlet ports  711  are disposed at a lower portion of the gas lift valve  700  and the outlet ports  712  are disposed at an upper portion of the gas lift valve  700 . The inlet ports  711  and outlet ports  712  communicate via the bore  720 . A flow tube  740  is disposed in the valve housing  710 . A check valve  757  is disposed in the bore  720 . The check valve  757  may prevent fluid in the tubing  120  from entering the annulus  116  via the gas lift valve  700 . A latch  716  is shown disposed at the upper end of the gas lift valve  700  to allow the gas lift valve  700  be positioned in a side pocket mandrel  130 . A sealing member  715 , such as a packing stack arrangement, may be disposed on each side of the inlet ports  711  to isolate the fluid in the annulus  116  from the tubing  160 . 
     The flow tube  740  may be formed by a singular tubular or two or more connected tubular. The flow tube  740  has a sealing head  730  forming a blind end. The sealing head  730  may be formed unitarily on the flow tube  740  or attached to the flow tube  740 . One or more tube inlets  732  are formed through the flow tube  740  above the sealing head  730 . The tube inlets  732  provide fluid communication between the inlet ports  711  and the outlet ports  712  through the bore  720 . A seal member  734  is disposed inside the valve housing  710 . In one embodiment, the sealing head  730  includes an upper end  730 U connected to the fluid tube  740  and lower end  730 L extending below the upper end  730 U. The sealing head  730  may include a conical portion so that the outer diameter of the upper end  730 U is smaller than the outer diameter of the end  730 L. The conical portion forms having an inclined surface  730 S matching the seal member  734 . The sealing head  730  moves relative to the seal member  734  to selectively open or close fluid communication through the bore  720 . 
     The flow tube  740  includes a flow control member  750  coupled to the interior of the flow tube  740 . In the embodiment shown in  FIG. 7C , the flow control member  750  is an annular ring having an opening  755  therethrough. The flow control member  750  forms an effective area in the flow tube  740 . The flow tube area may be controlled by selecting the appropriate size of the inner diameter of the opening  755  of the flow control member  750 . 
     A biasing member  745  is disposed in an annular area  747  between the flow tube  740  and the valve housing  710 . The flow tube  740  is biased in an open position, as shown in  FIG. 7A , by the biasing member  745 . The biasing member  745  may be a spring. An optional spacer member  746  coupled to the flow tube  740  may engage the biasing member  745  to adjust the position of the flow tube  740  and the bias force of the biasing member  745 . The spacer member  746  may be a lock nut. 
     When the gas lift valve  700  is in the open position as shown in  FIG. 7A , injected fluid flows in from the inject ports  711 , through the tube inlets  732  to into the flow tube  740 , then through the opening  755  of the flow control member  750  and the check valve  757  to the outlet ports  712 . The injected fluid flowing in from the inlet ports  711  applies a force to the flow control member  750 , which force is opposed by the biasing force of the biasing member  745 . 
     When the force applied by the injected fluid is higher than the biasing force, the flow tube  740  will compress the biasing member  745 . As a result, the flow tube  740  moves and the sealing head  730  moves towards the seal member  734 . When pressure differential across the flow control member  750  reaches a closing pressure differential, the sealing head  730  moves to a closed position and contacts the seal member  734 , as shown in  FIG. 7B . In the closed position, a seal is formed between the sealing head  730  and the seal member  734  to close the bore  720 . 
     When the gas lift valve  700  is at the closed position, fluid from the annulus  116  is prevented from entering the tubing  120 . The sealing head  730  may move down to re-open the gas lift valve  700  when the casing pressure, tubing pressure, and spring force acting on the effective area of the flow control member  750  in the flow tube  740  dictate. 
     The closing pressure differential of the gas lift valve  700  can be adjusted by selecting the biasing force of the spring member  745 , the inner diameter of the flow control member  750 , and the combinations thereof. For example, a smaller diameter opening  755  will close the sealing head  730  using a smaller pressure differential than a larger diameter opening  755  when other parameters, such as the flow rate of injected fluid and the biasing force of the spring member  745 , are fixed. During operation, when the biasing force of the spring member  745  and the diameter of the opening  755  are fixed, an increase in the flow rate of the injected fluid will cause an increase in differential pressure across the flow control member  750 , and eventually close the valve  700 . 
     The closing pressure differential of the gas lift valve  700  can also be adjusted by manipulating the travel distance  733  of the flow tube  740 .  FIG. 7D  is a partial cross-sectional view of the gas lift valve  700  illustrating the travel distance  733  of the flow tube  740  from the open position to the closed position. The longer the travel distance  733 , the more compressed the bias member  745  is at the closed position. When the travel distance  733  is too long, the gas lift valve  700  may not close. When the travel distance  733  is too short, the gas lift valve  700  may close too quickly. Additionally, the relative position between the inlet ports  711  and the tube inlets  732  may affect the closing pressure differential. The relative positions of the tube inlets  732 , the inlet ports  711 , and the lower end  730 L of the sealing head  730 , and the biasing force of the spring  745  may be pre-set so that the closing pressure differential across the flow control member  750  moves the lower end  730  of the sealing head  730  above the inlet ports  711 . Once the sealing head  730  is positioned above the inlet ports  711 , the force applied to the large surface area of the lower end  730  by the injected fluid pushes the sealing head  730  further to enable a snap close the valve  700 . 
     In one embodiment, the gas lift valve  700  may include an optional dampener to dampen potential rapid oscillation of the flow tube  740 .  FIG. 7E  illustrates an exemplary embodiment of a dampener  760  suitable for use with the gas lift valve  700 . The dampener  760  may be a viscous type dampener disposed in the valve housing  710  under the sealing head  730 . The dampener  760  may include a cylinder  764  filled with a fluid of high viscosity, such as oil. A piston  763  having a restricted flow path is movably disposed in the cylinder  764 . A shaft  762  extends from the piston  763  out of the cylinder  764  to connect with the sealing head  730 . The motion of the flow tube  740  urges the piston  763  to move up or down in the cylinder  764 , thereby forcing the fluid in the cylinder  764  to flow through the restricted path in the piston  763 . The fluid flowing through the restricted path dampens rapid oscillation of the flow tube  740 . 
       FIG. 7F  illustrates another exemplary embodiment of a dampener  770  for the gas lift valve  700 . The dampener  770  may be a friction type dampener. The dampener  770  may include a piston  774  disposed in the valve housing  710  below the sealing head  730 . A shaft structure  772  extends from the piston  774  is coupled to the sealing head  730 . The motion of the flow tube  740  urges the piston  774  to move up or down in the valve housing  710 , thereby generating friction (between the piston  774  and the valve housing  710 ). The friction dampens oscillation of the flow tube  740 . 
     In one embodiment, the gas lift valve  700  may include an optional detent mechanism  753  to retain the flow tube  740  in a fully open or a fully closed position. The detent mechanism  753  may include a housing  754  and a spring energized ball structure  758 . The spring energized ball structure  758  may be fixedly connected to the sealing head  730  by a shaft  756 . When the flow tube  740  is at a fully open position or a fully closed position, the spring energized ball structure  758  is locked into grooves in the housing  754  to keep the flow tube  740  at the fully open position or the fully closed position. The detent mechanism  753  improves flow characteristic through the gas lift valve  700 . The detent mechanism  753  may also prevent rapid oscillation of the flow tube  740 . 
       FIG. 8A  illustrates another exemplary embodiment of a gas lift valve  800  in an open position.  FIG. 8B  illustrates the gas lift valve  800  in a position before a detent is released.  FIG. 8C  illustrates the gas lift valve  800  in a closed position. The gas lift valve  800  may be positioned in a side pocket mandrel  130  of the gas lift completion system shown in  FIG. 1 . The gas lift valve  800  includes many of the components of the gas lift valve  700 . One difference between the valves  700 ,  800  is the gas lift valve  800  includes a detent mechanism that provides valve closure not directly dependent on flow rate. 
     The gas lift valve  800  includes a valve housing  810 . The valve housing  810  has a bore  820 , one or more gas inlet ports  811  and one or more gas outlet ports  812 . The inlet ports  811  are disposed at a lower portion of the gas lift valve  800  and the outlet ports  812  are disposed at an upper portion of the gas lift valve  800 . The inlet ports  811  and outlet ports  812  communicate via the bore  820 . A flow tube  840  is disposed in the valve housing  810 . A check valve  857  is disposed in the bore  820 . The check valve  857  may prevent fluid in the tubing  120  from entering the annulus  116  via the gas lift valve  800 . A sealing member  815 , such as a packing stack arrangement, may be disposed on each side of the inlet ports  811  to isolate the fluid in the annulus  116  from the tubing  160 . 
     The flow tube  840  includes a lower flow tube assembly  880  and an upper flow tube assembly  886 . The lower flow tube assembly  880  overlaps with the upper flow tube assembly  886  in the middle section where the lower flow tube assembly  880  encases the upper flow tube assembly  886 . The lower flow tube assembly  880  and the upper flow tube assembly  886  may move relative to each other changing the length of the overlapping section. Each of the flow tube assemblies  880 ,  886  may be formed by a singular tubular or two or more connected tubular. 
     The lower flow tube assembly  880  has a sealing head  830  forming a blind end. The sealing head  830  may be formed unitarily on an end section of the lower flow tube assembly  880  or attached to the lower flow tube assembly  880 . One or more tube inlets  832  are formed through the lower flow tube assembly  880  above the sealing head  830 . The tube inlets  832  provide fluid communication between the inlet ports  811  and the outlet ports  812  through the bore  820 . A seal member  834  is disposed inside the valve housing  810 . The sealing head  830  has an inclined surface matching the seal member  834 . The sealing head  830  moves relative to the seal member  834  to selectively open or close fluid communication through the bore  820 . 
     A flow control member  850  is coupled to the interior of the upper flow tube assembly  886 . The flow control member  850  is an annular ring having an opening  855  therethrough. The flow control member  850  forms a restricted area in the flow tube  840 . The flow tube area may be controlled by selecting the appropriate size of the inner diameter of the opening  855  of the flow control member  850 . A biasing member  845  is disposed around the upper flow tube assembly  886  in an annular area  847  between the flow tube  840  and the valve housing  810 . The biasing member  845  may be a spring compressed to bias the sealing head  830  to an open position, as shown in  FIG. 8A . An optional spacer member  846  coupled to the upper flow tube assembly  886  may engage the biasing member  845  to adjust the position of the sealing head  830  and the bias force of the biasing member  845 . The spacer member  846  may be a lock nut. 
     The gas lift valve  800  also includes a detent mechanism  853  to retain the lower flow tube assembly  880  along with the sealing head  830  in a fully open position. The detent mechanism  853  may include a retractable pin  884 . The retractable pin  884  may extend through an opening in the lower flow tube assembly  880  to lock the lower flow tube assembly  880  at the open position, as shown in  FIG. 8A . The retractable pin  884  may retract from the lower flow tube assembly  880  by a release mechanism  885 . In one embodiment, the release mechanism  885  may be a protrusion on the upper flow tube assembly  886 . A detent spring  882  is compressed at the open position and biases the lower fluid tube assembly  880  towards the closed position. The detent spring  882  enables the gas lift valve  800  to snap close when the detent mechanism  853  is released. 
     When the gas lift valve  800  is in the open position as shown in  FIG. 8A , injected fluid flows in from the inject ports  811 , through the tube inlets  832 , into the lower flow tube assembly  880  and the upper flow tube assembly  886 , then through the opening  855  of the flow control member  845 , through the check valve  857 , and exits via the outlet ports  812 . The detent mechanism  853  locks the lower flow tube assembly  880  with the sealing head  830  at the open position. The injected fluid flowing in from the inlet ports  811  applies a force to the flow control member  850 , which force is opposed by the biasing force of the biasing member  845 . 
     When the flow rate increases, the pressure differential across the flow control member  850  increases, thereby moving the upper flow tube assembly  886  upwards and compressing the biasing member  845  while the lower flow tube assembly  880  remains locked by the detent mechanism  853  and the gas lift valve  800  remains in the open position, as shown in  FIG. 8B . The upper flow tube assembly  886  moves relative to the lower flow tube assembly  880  until the pressure differential across the flow control member  850  reaches a predetermined closing pressure differential, at which point the detent mechanism  853  releases the lower flow tube assembly  880  and the detent spring  882  pushes the lower flow tube assembly  880  towards the closed position, as shown in  FIG. 8C . The detent mechanism  853  provides fast valve closure and prevents the gas lift valve  800  from oscillation from fluctuation of flow rate through the gas lift valve  800 . Once the pressure below the sealing head  830  is reduced or equalized, the biasing member  845  will push the upper flow tube assembly  886  and lower flow tube assembly  880  downward to re-open the gas lift valve  800  and the detent mechanism  853  will automatically re-lock the gas lift valve  800  at the open position. 
       FIG. 9A  illustrates an exemplary embodiment of a gas lift valve  900  in an open position.  FIG. 9B  illustrates the gas lift valve  900  in a closed position. The gas lift valve  900  may be positioned in a side pocket mandrel  130  of the gas lift completion system shown in  FIG. 1 . The gas lift valve  900  is similar to the gas lift valve  700 . The difference between the gas lift valve  900  and the gas lift valve  700  is that that gas lift valve  900  includes a ball and seat closure member. 
     The gas lift valve  900  includes a valve housing  910 . The valve housing  910  has a bore  920 , one or more gas inlet ports  911  and one or more gas outlet ports  912 . As shown in  FIG. 9A , the inlet ports  911  are disposed at a lower portion of the gas lift valve  900  and the outlet ports  912  are disposed at an upper portion of the gas lift valve  900 . The inlet ports  911  and outlet ports  912  communicate via the bore  920 . A flow tube  940  is disposed in the valve housing  910 . A check valve  957  is disposed in the bore  920 . The check valve  957  may prevent fluid in the tubing  120  from entering the annulus  116  via the gas lift valve  900 . A latch  916  is shown disposed at the upper end of the gas lift valve  900  to allow the gas lift valve  900  be positioned in a side pocket mandrel  130 . 
       940 The flow tube  940  may be formed by a singular tubular or two or more connected tubular. A closure member  930  is disposed in the valve housing  910 . As shown in  FIG. 9A , the closure member  930  may be a ball having a central through hole  935  for selectively to allow fluid flow and an outer slot  933  to engage an actuator. The flow tube  940  may include one or more pins  943  positioned to engage with the closure member  930 . The one or more pins  943  may insert into the outer slot  933  of the closure member  930  so that vertical movement of the pins  943  rotates the closure member  930  to selectively open or close fluid communication through the bore  920 . 
     The flow tube  940  includes a flow control member  950  coupled to the interior of the flow tube  940  of the flow tube  940 . The flow control member  950  may be an annular ring having an opening  955  therethrough. The flow control member  950  forms a choke in the flow tube  940 . The effective area of the choke may be controlled by selecting the appropriate size of the inner diameter of the opening  955  of the flow control member  950 . 
     A biasing member  945  is disposed in an annular area  947  between the flow tube  940  and the valve housing  910 . The flow tube  940  is biased in an open position, as shown in  FIG. 9A , by the biasing member  945 . The biasing member  945  may be a spring. An optional spacer member  946  coupled to the flow tube  940  may engage the biasing member  945  to adjust the position of the flow tube  940  and the bias force of the biasing member  945 . The spacer member  946  may be a lock nut. 
     When the gas lift valve  900  is in the open position shown in  FIG. 9A , injected fluid flows in from the inject ports  911 , through the central through hole  935  of the closure member  930  into the flow tube  940 , then through the opening  955  of the flow control member  945  and the check valve  957  to the outlet ports  912 . The injected fluid flowing in from the inlet ports  911  applies a force to the flow control member  950 , which force is opposed by the biasing force of the biasing member  945 . 
     When the force applied by the injected fluid is higher than the biasing force, the flow tube  940  will compress the biasing member  945 . As a result, the flow tube  940  moves up causing the closure member  930  to rotate. When pressure differential across the flow control member  950  reaches a closing pressure differential, the closure member  930  rotates to the closed position, as shown in  FIG. 9B . 
     Embodiments of the present disclosure provide a valve apparatus configured to close when a predetermined pressure differential across the valve apparatus is reached. Because the valve apparatus does not depend on bellows, the valve apparatus may be used in high injection pressure and/or high injection rate, and/or high injection volume applications and is suitable for most deepwater applications. For example, the valve apparatus is capable of withstanding extremely high pressures, e.g., from about 1,000 psi to about 10,000 psi, from about 5,000 psi to about 10,000 psi, from about 7,000 psi to 10,000 psi, at least 7,000 psi, or at least 10,000 psi. In another example, the valve apparatus is capable of withstanding injection rates from about 0.5 to about 15 million cubic feet per day; preferably from about 7.5 to about 15 million cubic feet per day. 
     One embodiment of the present disclosure provides a method for performing downhole gas lift operations. The method includes coupling a gas lift valve to a tubing, wherein the gas lift valve comprises an actuator, a flow control member disposed in the actuator, and a closure member that is initially in an open position, injecting a gas downhole and exterior to the tubing, urging the gas to enter the tubing via the gas lift valve, and creating a sufficient pressure differential across the gas lift valve to move the actuator, thereby causing the closure member to close the gas lift valve. 
     In one or more of the embodiments described herein, the gas lift valve further includes a housing having an inlet and an outlet, andabiasing member for biasing the actuator in an extended position, wherein the closure member is configured to selectively close a bore through the housing, the actuator is movable between the extended position and a retracted position, and the actuator, when in the extended position, retains the closure member in an open position. 
     In one or more of the embodiments described herein, the actuator comprises a flow tube, and the flow control member is coupled to an interior of the flow tube. 
     In one or more of the embodiments described herein, the closure member is a sealing head disposed at one end of the flow tube. 
     In one or more of the embodiments described herein, the closure member is selected from a flapper, a sealing head on the actuator, and a ball and seat. 
     In one or more of the embodiments described herein, a plurality of gas lift valves is coupled to the tubing and axially spaced apart along the tubing. 
     In one or more of the embodiments described herein, the method further comprises sequentially closing the plurality of gas lift valves. 
     In one or more of the embodiments described herein, the method further comprises flowing the gas through a first gas lift valve and flowing a liquid through a second gas lift valve. 
     In one or more of the embodiments described herein, the method includes urging a liquid to enter the tubing via an orifice valve in fluid communication with the tubing. In one embodiment, the orifice valve is disposed below the gas lift valve. 
     In one or more of the embodiments described herein, a closing pressure differential is adjustable by adjusting a force of the biasing member and/or a travel distance of the actuator between the extended position and the open position. 
     In one or more of the embodiments described herein, the method includes increasing the pressure differential by decreasing the pressure downstream from the gas lift valve. 
     In one or more of the embodiments described herein, the actuator comprises a flow tube, and the flow control member is disposed in an interior of the flow tube. 
     In one embodiment, a method for performing downhole gas lift operations includes coupling a gas lift valve to a tubing, wherein the gas lift valve comprises an actuator, a flow control member disposed in the actuator, and a closure member that is initially in an open position, injecting a gas downhole and interior to the tubing, urging the gas to exit the tubing via the gas lift valve, and creating a sufficient pressure differential across the gas lift valve to move the actuator, thereby causing the closure member to close the gas lift valve. 
     In one embodiment, a valve for controlling fluid flow includes a housing having a bore in fluid communication with an inflow port and an outlet port, a closure member configured to close fluid communication through the bore, a flow tube movable between an extended position and a retracted position, and a flow control device disposed in the flow tube, wherein when in the extended position, the flow tube retains the closure member in an open position, and wherein the flow tube is movable to the retracted position in response to a predetermined pressure differential across the bore. 
     In one or more of the embodiments described herein, the valve further comprises a biasing member for biasing the flow tube in the extended position. 
     In one or more of the embodiments described herein, the flow control device provides an effective area for urging the flow tube toward the retracted position in response to the pressure differential. 
     In one or more of the embodiments described herein, the valve further comprises a detent mechanism for retaining the flow tube in the retracted position or the extended position. 
     In one or more of the embodiments described herein, the valve further comprises a latch member. 
     In one or more of the embodiments described herein, the outlet port is formed through the latch member. 
     In one or more of the embodiments described herein, the closure member is selected from the group consisting of a flapper, a sealing head on the flow tube, and a ball and seat. 
     In one or more of the embodiments described herein, the closure member comprises a sealing head attached to the flow tube. 
     In one or more of the embodiments described herein, the valve further comprises a seal member disposed in the housing, wherein the sealing head moves relative to the seal member to selectively open or close fluid communication through the valve. 
     In one or more of the embodiments described herein, the flow tube includes one of more tube inlets adjacent to the sealing head. 
     In one or more of the embodiments described herein, the valve further comprises a dampener attached to the sealing head. 
     In one or more of the embodiments described herein, the valve further comprises a check valve disposed adjacent the outlet port. 
     In one or more of the embodiments described herein, the valve further comprises a dampener coupled to the flow tube. 
     In one or more of the embodiments described herein, the flow control device is fixedly coupled to the flow tube. 
     In one or more of the embodiments described herein, the flow control device comprises an annular ring coupled to an interior of the flow tube. 
     In one or more of the embodiments described herein, a re-open pressure is determined by an inner diameter of the bore, an inner diameter of the flow control device, and a force of the biasing member. 
     In one or more of the embodiments described herein, the valve is configured to operate in an external pressure from about 1,000 psi and about 10,000 psi. 
     In one or more of the embodiments described herein, the valve is configured to operate with an injection gas rate from about 0.5 to about 15 million cubic feet per day. 
     While the foregoing is directed to embodiments of the present disclosure, other and further embodiments may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.