Patent Publication Number: US-11649695-B2

Title: Pressure regulating check valve

Description:
BACKGROUND 
     The exploration and production of hydrocarbons sometimes involves chemically treating portions of well systems, for example, to enhance production, to prevent corrosion of equipment inserted into well systems, or to address deposit build-up issues in production tubing. In some cases, a control line can be run from the surface to an injection point to inject chemicals downhole into production tubing. Flow control valves can be used in these chemical injection systems to control fluid flow between the control line and production tubing. For example, a check valve that opens at a specific pressure prevents fluid in the production tubing from flowing into the control line should downhole pressure exceed pressure in the control line. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  illustrates a schematic diagram of an example check valve assembly in a closed position, according to various embodiments. 
         FIG.  1 B  illustrates a schematic diagram of an example check valve assembly in an open position, according to various embodiments. 
         FIG.  2 A  illustrates a schematic diagram of an example of a check valve assembly in a closed position, according to various embodiments. 
         FIG.  2 B  illustrates a schematic diagram of an example of a check valve assembly in an open position, according to various embodiments. 
         FIG.  3    illustrates a schematic diagram of an alternative example configuration for a lift check valve, according to various embodiments. 
         FIG.  4    illustrates a schematic diagram of a second example of a lift check valve, according to various embodiments. 
         FIG.  5    illustrates a schematic diagram of a third example of a lift check valve, according to various embodiments. 
         FIG.  6    illustrates a flow diagram of a method for operating a check valve assembly, according to various embodiments. 
         FIG.  7    illustrates a schematic diagram of systems and apparatuses that can be used with a check valve assembly, according to one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description refers to the accompanying drawings that show, by way of illustration and not limitation, various embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice these and other embodiments. Other embodiments may be utilized, and structural, logical, and electrical changes may be made to these embodiments. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The following detailed description is, therefore, not to be taken in a limiting sense. Flow control valves are used in the chemical injection systems to control fluid flow between the control line and production tubing. For example, a check valve that opens at a specific pressure prevents fluid in the production tubing from flowing into the control line should downhole pressure exceed pressure in the control line. Pressure can be applied from the surface to overcome a cracking pressure of the check valve. In real world applications, however, the check valve can sometimes open when pressure in the production tubing decrease relative to pressure in the control line, causing a negative pressure differential. This creates a vacuum in the control line, which can lead to unwanted leakage of fluid out of the control line and into the production tubing. The existence of the vacuum can change properties of the fluid and cause damage to the control line or check valve. In addition, immediate pressure drops as the check valve opens due to the vacuum can cause the check valve to open and close repeatedly, damaging the sealing surface of the valve. The following provides one or more solutions to this problem, such as by providing an apparatus and method for using an anti-vacuum, pressure regulating check valve assembly. 
     For example, apparatus and methods are described with respect to using check valve assemblies for regulating fluid flow and pressure in chemical injection systems. In some embodiments, the check valve assembly comprises a housing defining a fluid passage having a fluid inlet side and a fluid outlet side. A lift check valve positioned within the fluid passage oriented to restrict fluid flow from the fluid inlet side and a second check valve positioned within the fluid passage oriented to restrict fluid flow from the fluid outlet side. A flow dampener positioned within the fluid passage and between the first and second check valves. 
     In an example, the chemical injection system includes a check valve assembly having a check valve and a lift check valve that actuates in a direction opposite that of the check valve. 
       FIG.  1 A  illustrates a schematic diagram of an example check valve assembly  100  in a closed position; this assembly may be used to control fluid flow in chemical injection systems. As shown, the check valve assembly  100  includes a housing  102  defining a fluid passage having a fluid inlet side  104  and a fluid outlet side  106 . In use, the fluid inlet side  104  is oriented in the uphole direction generally indicated by the arrow U; the fluid outlet side  106  is oriented in the downhole direction generally indicated by the arrow D. 
     The housing  102  includes a check valve  108  positioned within the fluid passage and oriented to restrict fluid flow from the fluid outlet side  106 . A closing member  110  of the check valve  108  is pressed against a seat  112  of the check valve  108  by a spring  114 . Fluid pressure from downhole direction D and spring force of the spring  114  keeps the check valve  108  closed by biasing the closing member  110  into engagement with the seat  112  until a greater force is exerted upon the closing member  110  from uphole direction U. The pressure at which the check valve  108  begins to open can be referred to as the cracking pressure, representing a minimum upstream pressure (e.g., pressure coming from the uphole direction U) at which the check valve  108  will open. When the cracking pressure is reached, the check valve  108  will open. One of ordinary skill in the art will recognize that check valves can be designed and specified for any specific cracking pressure. It should also be understood that although the check valve  108  is illustrated in this example having a spring-loaded ball, this disclosure is not limited to arrangements in which the closing member is a spherical ball. For example, the closing member can comprise a poppet, a diaphragm, or any other structure suitable for check valves. 
     The housing  102  further includes a lift check valve  116  positioned within the fluid passage and oriented to restrict fluid flow from the fluid inlet side  104 . A closing member  118  of the lift check valve is pressed against seat  120  of the lift check valve  116  by a spring  122 . One of ordinary skill in the art will recognize that a lift check valve is a type of check valve where the closing member of the lift check valve “lifts” off its seat by pressure from one side, rather than being pushed off its seat by pressure from the other side. Spring  122  is retained within spring chamber  124  of the lift check valve  116 . Spring force of the spring  122  keeps the lift check valve  116  closed by biasing the closing member  118  into engagement with the seat  120  until a greater force is exerted upon the closing member  118  by fluid flow  126  coming from uphole direction U. In this example, the lift check valve  116  also includes a debris collection area  128  where debris from fluid flow  126  accumulates to prevent debris from passing through the lift check valve  116 . In the depicted embodiment, the debris collection area  128  is formed as a radial space defined in part by a circumferential surface, allowing fluid communication with fluid flow  126  in the flow passage at a relatively uphole portion of the radial space. In some embodiments, the debris collection area  128  is a U-shaped tubular that is positioned at a localized low point in the flow passage, and thus captures heavy objects or other debris present within fluid flow  126 . Solid particulates and debris are retained in the debris collection area  128  while allowing fluid flow  126  to pass to a relatively downhole portion of the radial space towards closing member  118  of the lift check valve  116 . 
     The check valve assembly  100  further includes a flow dampener  130  positioned within the housing  102 . In this example, the flow dampener  130  is positioned in the interior of the housing between check valve  108  and lift check valve  116 . 
       FIG.  1 B  illustrates a schematic diagram of an example check valve assembly  100  in an open position. As shown, pressures associated with fluid flow  126  coming from a control line (not shown) will raise the closing member  118  off seat  120 , thereby opening and permitting fluid flow  126  through a fluid passage  132 . In other words, pressure from fluid flow  126  actuates closing member  118  in the uphole direction U. The flow dampener  130  prevents an immediate pressure drop from being created as the closing member  118  of the lift check valve  116  opens. Thus, the flow dampener helps prevent opening and closing of the lift check valve  116  in rapid succession and also helps prevent cavitation that would otherwise lead to pitting of the surfaces causing the lift check valve  116  to leak. It should be noted that the cracking pressure of lift check valve  116  is not dependent on any downhole pressures. Thus, the lift check valve  116  should remain closed when a negative pressure differential exists between control line pressure (e.g., experienced at fluid inlet side  104 ) and production tubing pressure (e.g., experienced at fluid outlet side  106 ). 
     Fluid flow  126  through the fluid passage  132  and flow dampener  130  builds pressure until reaching a cracking pressure sufficient to overcome spring force of the spring  114  to push the closing member  110  off seat  112 , thereby opening and permitting fluid flow  126  through a fluid passage  134  of the check valve  108 . In other words, pressure from fluid flow  126  actuates closing member  110  in the downhole direction D. It should be noted that closing member  110  and closing member  118  actuate in opposite directions relative to each other. 
     As shown, the check valve  108  prevents flow of fluids in the uphole direction U. For example, even if production tubing pressure at the downhole, fluid outlet side  106  falls below pressures experienced at the uphole, fluid inlet side  104 , the check valve  108  can be closed as illustrated in  FIG.  1 A  via spring force. Thus, the check valve assembly  100  should not be prematurely opened merely by the encountering of low downhole pressures. Opening of the check valve assembly  100  requires sufficient pressure to be exerted from the uphole, fluid inlet side  104  to raise the closing member  118  and push closing member  110  off their respective seats. A resulting benefit is that this helps prevent the creation of a vacuum in the control line from negative pressure differentials. 
       FIGS.  2 A- 2 B  illustrate schematic diagrams of an alternative example of a check valve assembly  200  in a closed and open position, respectively.  FIG.  2 A  illustrates check valve assembly  200  in a closed position, such as to control fluid flow in chemical injection systems. As shown, the check valve assembly  200  includes a housing  202  defining a fluid passage having a fluid inlet side  204  and a fluid outlet side  206 . In use, the fluid inlet side  204  is oriented in the uphole direction generally indicated by the arrow U; the fluid outlet side  206  is oriented in the downhole direction generally indicated by the arrow D. 
     The housing  202  includes a check valve  208  positioned within the fluid passage and oriented to restrict fluid flow from the fluid outlet side  206 . A closing member  210  of the check valve  208  is pressed against a seat  212  of the check valve  208  by a spring  214 . Fluid pressure from downhole direction D and spring force of the spring  214  keeps the check valve  208  closed by biasing the closing member  210  into engagement with the seat  212  until a greater force is exerted upon the closing member  210  from uphole direction U. When the cracking pressure of check valve  208  is reached, the check valve  208  will open. 
     The housing  202  further includes a lift check valve  216  positioned within the fluid passage and oriented to restrict fluid flow from the fluid inlet side  204 . A closing member  218  of the lift check valve  216  is pressed against seat  220  of the lift check valve  216  by a spring  222 . Spring  222  is retained within spring chamber  224  of the lift check valve  216 . Spring force of the spring  222  keeps the lift check valve  216  closed by biasing the closing member  218  into engagement with the seat  220  until a greater force is exerted upon the closing member  218  by fluid flow  226  coming from uphole direction U. In this example, the lift check valve  216  also includes a debris collection area  228  where debris from fluid flow  226  accumulates to prevent debris from passing through the lift check valve  216 . In the depicted embodiment, the debris collection area  228  is formed as a radial space defined in part by a circumferential surface, allowing fluid communication with fluid flow  226  in the flow passage at a relatively uphole portion of the radial space. In some embodiments, the debris collection area  228  is a U-shaped tubular that is positioned at a localized low point in the flow passage, and thus captures heavy objects or other debris present within fluid flow  226 . Solid particulates and debris are retained in the debris collection area  228  while allowing fluid flow  226  to pass to a relatively downhole portion of the radial space towards closing member  218  of the lift check valve  216 . The check valve assembly  200  further includes a flow dampener  230  positioned within the housing  202 . In this example, the flow dampener  230  is included structurally as a portion of the closing member  210 . 
       FIG.  2 B  illustrates a schematic diagram of check valve assembly  200  in an open position. As shown, pressures associated with fluid flow  226  coming from a control line (not shown) will raise the closing member  218  off seat  220 , thereby opening and permitting fluid flow  226  through a fluid passage  232 . In other words, pressure from fluid flow  226  actuates closing member  218  in the uphole direction U. It should be noted that the cracking pressure of lift check valve  216  is not dependent on any downhole pressures. Thus, the lift check valve  216  should not be opened by a negative pressure differential between control line pressure (e.g., experienced at fluid inlet side  204 ) and production tubing pressure (e.g., experienced at fluid outlet side  206 ). 
     Fluid flow  226  through the fluid passage  232  builds pressure until reaching a cracking pressure sufficient to overcome spring force of the spring  214  to push the closing member  210  off seat  212 , thereby opening and permitting fluid flow  226  through a fluid passage  234  of the check valve  208 . In other words, pressure from fluid flow  226  actuates closing member  210  in the downhole direction D. It should be noted that closing member  210  and closing member  218  actuate in opposite directions relative to each other. Flow dampener  230  regulates the velocity of fluid flow  226  until a continuous flow is attained. This dampening effect of the check valve  208  on the downhole, fluid outlet side  206  prevents an immediate pressure drop from being created as the closing member  218  of the lift check valve  216  opens. Thus, the flow dampener  230  prevents opening and closing of the lift check valve  216  in rapid succession and prevents cavitation that would otherwise lead to pitting of the surfaces causing the lift check valve  216  to leak. 
     As shown, the check valve  208  prevents flow of fluids in the uphole direction U. For example, even if production tubing pressure at the downhole, fluid outlet side  206  falls below pressures experienced at the uphole, fluid inlet side  204 , the check valve  208  can be closed as illustrated in  FIG.  1 A  via spring force. Thus, the check valve assembly  200  should not be prematurely opened when encountering low downhole pressures. Opening of the check valve assembly  200  requires sufficient pressure to be exerted from the uphole, fluid inlet side  204  to raise the closing member  218  and push closing member  210  off their respective seats. A resulting benefit is that this helps prevent the creation of a vacuum in the control line, arising from negative pressure differentials. 
       FIG.  3    illustrates a schematic diagram of a first example of a lift check valve  300 , according to one or more embodiments. The lift check valve  300  can be used in any check valve assembly, such as check valve assemblies  100  and  200  described above. As shown, the lift check valve  300  includes a housing  302  defining a fluid passage having a fluid inlet side  304  and a fluid outlet side  306 . In use, the fluid inlet side  304  is oriented in the uphole direction generally indicated by the arrow U; the fluid outlet side  306  is oriented in the downhole direction generally indicated by the arrow D. A closing member  308  of the lift check valve  300  is pressed against seat  310  of the lift check valve  300  by a spring  312 . Spring  312  is retained within spring chamber  314  of the lift check valve  300 . Spring force of the spring  312  keeps the lift check valve  300  closed by biasing the closing member  308  into engagement with the seat  310  until a greater force is exerted upon the closing member  308  by fluid flow  316  coming from a control line (not shown). In this example, the lift check valve  300  also includes a debris collection area  318  where debris from fluid flow  316  accumulates to prevent debris from passing through the lift check valve  300 . In the depicted embodiment, the debris collection area  318  is formed as a radial space defined in part by a circumferential surface, allowing fluid communication with the flow passage at a relatively uphole portion of the radial space. In some embodiments, the debris collection area  318  is a U-shaped tubular that is positioned at a localized low point in the flow passage, and thus captures heavy objects or other debris present within fluid flow. Solid particulates and debris are retained in the debris collection area  318  while allowing fluid flow to pass to a relatively downhole portion of the radial space towards closing member  308  of the lift check valve  300 . 
     In this example, the spring chamber  314  of the lift check valve  300  includes a flow orifice  320  that permits fluid flow out of housing  302  from the spring chamber  314 . In use, for example, the spring chamber  314  of the lift check valve  300  can be ported to the annulus between well casing and borehole wall during well production. The spring chamber  314  has a primary and a redundant seal (not shown) separating annulus fluid from fluids within the housing  302 . During operation, as the closing member  308  opens, fluid is forced from the spring chamber  314  out of the housing  302  and into the annulus. The flow orifice  320  restricts fluid flow out of the spring chamber  314  according to its size and dampens opening/closing speeds of the closing member  308 . Further, pressure in the annulus will also reduce the impact of hydrostatic pressures of the fluid flow  316  on the cracking pressure of the lift check valve  300 . 
       FIG.  4    illustrates a schematic diagram of a second example of a lift check valve  400 , according to one or more embodiments. The lift check valve  400  can be used in any check valve assembly, such as check valve assemblies  100  and  200  described above. As shown, the lift check valve  400  includes a housing  402  defining a fluid passage having a fluid inlet side  404  and a fluid outlet side  406 . In use, the fluid inlet side  404  is oriented in the uphole direction generally indicated by the arrow U; the fluid outlet side  406  is oriented in the downhole direction generally indicated by the arrow D. A closing member  408  of the lift check valve  400  is pressed against seat  410  of the lift check valve  400  by a spring  412 . Spring  412  is retained within spring chamber  414  of the lift check valve  400 . Spring force of the spring  412  keeps the lift check valve  400  closed by biasing the closing member  408  into engagement with the seat  410  until a greater force is exerted upon the closing member  408  by fluid flow  416  coming from a control line (not shown). In this example, the lift check valve  400  also includes a debris collection area  418  where debris from fluid flow  416  accumulates to prevent debris from passing through the lift check valve  400 . In the depicted embodiment, the debris collection area  418  is formed as a radial space defined in part by a circumferential surface, allowing fluid communication with fluid flow  416  in the fluid passage  422  at a relatively uphole portion of the radial space. In some embodiments, the debris collection area  418  is a U-shaped tubular that is positioned at a localized low point in the fluid passage  422 , and thus captures heavy objects or other debris present within fluid flow  416 . Solid particulates and debris are retained in the debris collection area  418  while allowing fluid flow  416  to pass to a relatively downhole portion of the radial space towards closing member  408  of the lift check valve  400 . 
     In this example, the spring chamber  414  of the lift check valve  400  includes a flow orifice  420  that permits fluid flow between the spring chamber  414  and a fluid passage  422  coming from the fluid inlet side  404 . In use, for example, the spring chamber  414  of the lift check valve  400  can be ported to the injection fluid flow area coming from the control line. The spring chamber  414  has a primary and a redundant seal (not shown) separating the fluid flow  416  from the components positioned within the spring chamber  414 . During operation, as the closing member  408  opens, fluid is forced from the spring chamber  414  into the fluid passage  422  containing fluid flow  416 . The flow orifice  420  restricts fluid flow out of the spring chamber  414  according to its size and dampens opening/closing speeds of the closing member  408 . 
       FIG.  5    illustrates a schematic diagram of a third example of a lift check valve  500 , according to one or more embodiments. The lift check valve  500  can be used in any check valve assembly, such as check valve assemblies  100  and  200  described above. As shown, the lift check valve  500  includes a housing  502  defining a fluid passage having a fluid inlet side  504  and a fluid outlet side  506 . In use, the fluid inlet side  504  is oriented in the uphole direction generally indicated by the arrow U; the fluid outlet side  506  is oriented in the downhole direction generally indicated by the arrow D. A closing member  508  of the lift check valve  500  is pressed against seat  510  of the lift check valve  500  by a spring  512 . Spring  512  is retained within spring chamber  514  of the lift check valve  500 . Spring force of the spring  512  keeps the lift check valve  500  closed by biasing the closing member  508  into engagement with the seat  510  until a greater force is exerted upon the closing member  508  by fluid flow  516  coming from a control line (not shown). In this example, the lift check valve  500  also includes a debris collection area  518  where debris from fluid flow  516  accumulates to prevent debris from passing through the lift check valve  500 . In the depicted embodiment, the debris collection area  518  is formed as a radial space defined in part by a circumferential surface, allowing fluid communication with fluid flow  516  in the fluid passage  526  at a relatively uphole portion of the radial space. In some embodiments, the debris collection area  518  is a U-shaped tubular that is positioned at a localized low point in the fluid passage  526 , and thus captures heavy objects or other debris present within fluid flow  516 . Solid particulates and debris are retained in the debris collection area  518  while allowing fluid flow  516  to pass to a relatively downhole portion of the radial space towards closing member  508  of the lift check valve  500 . 
     In this example, the spring chamber  514  of the lift check valve  500  includes a first flow orifice  520  that permits fluid flow out of the housing  502  from the spring chamber  514 . In use, for example, the spring chamber  514  of the lift check valve  500  can be ported to the annulus between well casing and borehole wall during well production. The spring chamber  514  has a primary and a redundant seal (not shown) separating annulus fluid from fluids within the housing  502 . During operation, as the closing member  508  opens, fluid is forced from the spring chamber  514  out of the housing  502  and into the annulus. The flow orifice  520  restricts fluid flow out of the spring chamber  514  according to its size and dampens opening/closing speeds of the closing member  508 . Further, pressure in the annulus will also counteract and reduce the impact of hydrostatic pressures of the fluid flow  516  on the cracking pressure of the lift check valve  500 , allowing the closing member  508  to have a lower cracking pressure. 
     In this example, the spring chamber  514  of lift check valve  500  further includes a second flow orifice  524  that permits fluid flow between the spring chamber  514  and a fluid passage  526  containing fluid flow  516  coming from the fluid inlet side  504 . In use, for example, the spring chamber  514  of the lift check valve  500  can be ported to the injection fluid flow area coming from the control line. The spring chamber  514  has a primary and a redundant seal (not shown) separating the fluid flow  516  from the components positioned within the spring chamber  514 . During operation, as the closing member  508  opens, fluid is forced from the spring chamber  514  into the fluid passage  526  containing fluid flow  516 . The second flow orifice  524  restricts fluid flow out of the spring chamber  514  according to its size and dampens opening/closing speeds of the closing member  508 . 
       FIG.  6    illustrates a flow diagram of a method  600  for operating a check valve assembly, according to various embodiments. At operation  602 , the method  600  includes applying a fluid pressure to a check valve assembly. In an example, the check valve assembly comprises a housing defining a fluid passage having a fluid inlet side and a fluid outlet side. The housing includes a lift check valve positioned within the fluid passage and oriented to restrict fluid flow from the fluid outlet side. A closing member of the lift check valve is pressed against a seat of the lift check valve by a spring. Fluid pressure from and spring force of the spring keeps the lift check valve closed by biasing the closing member into engagement with the seat until a greater force is exerted upon the closing member. The pressure at which the lift check valve begins to open can be referred to as the cracking pressure, representing a minimum upstream pressure at which the lift check valve will open. When the cracking pressure is reached, the lift check valve will open. One of ordinary skill in the art will recognize that check valves can be designed and specified for any specific cracking pressure. 
     The housing further includes a second check valve positioned within the fluid passage and oriented to restrict fluid flow from the fluid inlet side. A closing member of the lift check valve is pressed against a seat of the lift check valve by a spring. The spring is retained within a spring chamber of the lift check valve. Spring force of the spring keeps the lift check valve closed by biasing the closing member of the lift check valve into engagement with the seat until a greater force is exerted upon the closing member by fluid flow. In this example, the lift check valve also includes a debris collection area where debris from fluid flow accumulates to prevent debris from passing through the lift check valve. In the depicted embodiment, the debris collection area is formed as a radial space defined in part by a circumferential surface, allowing fluid communication with fluid flow in the fluid passage at a relatively uphole portion of the radial space. In some embodiments, the debris collection area is a U-shaped tubular that is positioned at a localized low point in the fluid passage, and thus captures heavy objects or other debris present within fluid flow. Solid particulates and debris are retained in the debris collection area while allowing fluid flow to pass to a relatively downhole portion of the radial space towards closing member of the lift check valve. The check valve assembly further includes a flow dampener positioned within the housing. In one example, the flow dampener is positioned in the interior of the housing between check valve and lift check valve. In another example, the flow dampener is included structurally as a portion of the closing member of the lift check valve. 
     At operation  604 , the method  600  continues by lifting, in response to fluid pressure, the closing member off of the seat of the lift check valve to permit fluid to flow through the lift check valve. In one example, pressures associated with fluid flow coming from a control line and through the flow passage will raise the closing member off its seat, thereby opening and permitting fluid flow through the fluid passage. In other words, pressure from fluid flow actuates the closing member of the lift check valve in an uphole direction towards the fluid inlet side of the housing. The flow dampener prevents an immediate pressure drop from being created as the closing member of the lift check valve opens. Thus, the flow dampener prevents opening and closing of the lift check valve in rapid succession and prevents cavitation that would otherwise lead to pitting of the surfaces causing the lift check valve to leak. It should be noted that the cracking pressure of lift check valve is not dependent on any downhole pressures. Thus, the lift check valve cannot be opened by a negative pressure differential between control line pressure (e.g., experienced at fluid inlet side) and production tubing pressure (e.g., experienced at fluid outlet side). 
     Fluid flow through the fluid passage and flow dampener builds pressure until reaching a cracking pressure sufficient to push the closing member of the lift check valve off its seat, thereby opening and permitting fluid flow through a fluid passage of the check valve. In other words, pressure from fluid flow actuates the closing member of the lift check valve in the downhole direction D towards the fluid outlet side of the housing. It should be noted that the closing members of the two check valves actuate in opposite directions relative to each other. 
     The lift check valve is designed to prevent the flow of fluids in an uphole direction. For example, even if production tubing pressure at the downhole, fluid outlet side falls below pressures experienced at the uphole, fluid inlet side, the lift check valve can be closed via spring force. Thus, the check valve assembly should not be prematurely opened merely by encountering low downhole pressures. Opening of the check valve assembly requires sufficient pressure to be exerted from the uphole, fluid inlet side to raise the closing member of the lift check valve and push the closing member of the check valve off their respective seats. A resulting benefit is that this helps prevent the creation of a vacuum in the control line when negative pressure differentials exist. 
     In some embodiments, the method  600  further includes porting fluid flow from the spring chamber of the lift check valve out of the housing through a flow orifice. During operation, as the closing member of the lift check valve opens, fluid is forced from the spring chamber out of the housing. The flow orifice restricts fluid flow out of the spring chamber according to its size and dampens opening/closing speeds of the closing member. In another alternative example, the method  600  further includes porting fluid flow from the spring chamber of the lift check valve to a fluid passage at the fluid inlet side. During operation, as the closing member opens, fluid is forced from the spring chamber into the fluid passage containing fluid flow. The flow orifice restricts fluid flow out of the spring chamber according to its size and dampens opening/closing speeds of the closing member. 
       FIG.  7    shows an illustrative schematic of systems and apparatuses that can be used with embodiments of the check valve assemblies of the present invention to inject fluids to subterranean locations, according to one or more embodiments. As depicted in  FIG.  7   , system or apparatus  700  can include tank  702 , in which fluids (e.g., injection fluids) can be stored or formulated. In some embodiments, the tank can be a mixing tank. The fluids can be conveyed via line  704  to wellhead  706 , where the fluids enters tubular  708 , with tubular  708  extending from wellhead  708  into subterranean formation  710 . Upon being ejected from tubular  708 , the fluids can subsequently be introduced into production tubing (not shown) or penetrate into subterranean formation  710 . Pump  712  can be configured to raise the pressure of the fluids to a desired degree before its introduction into tubular  708 . It is to be recognized that system or apparatus  700  is merely exemplary in nature and various additional components can be present that have not necessarily been depicted in  FIG.  7    in the interest of clarity. In some examples, additional components that can be present include supply hoppers, valves, condensers, adapters, joints, gauges, sensors, compressors, pressure controllers, pressure sensors, flow rate controllers, flow rate sensors, temperature sensors, and the like. 
     Although not depicted in  FIG.  7   , at least part of the fluids can, in some embodiments, flow back to wellhead  706  and exit subterranean formation  710 . In some embodiments, the fluids that have flowed back to wellhead  706  can subsequently be recovered, and in some examples reformulated, and recirculated to subterranean formation  710 . 
     It is also to be recognized that the disclosed fluids and check valve assemblies can also directly or indirectly affect the operation of various downhole or subterranean equipment and tools that can come into contact with the fluids and check valve assemblies during operation. Such equipment and tools can include wellbore casing, wellbore liner, completion string, insert strings, drill string, coiled tubing, slickline, wireline, drill pipe, drill collars, mud motors, downhole motors and/or pumps, surface-mounted motors and/or pumps, centralizers, turbolizers, scratchers, floats (e.g., shoes, collars, valves, and the like), logging tools and related telemetry equipment, actuators (e.g., electromechanical devices, hydromechanical devices, and the like), sliding sleeves, production sleeves, plugs, screens, filters, flow control devices (e.g., inflow control devices, autonomous inflow control devices, outflow control devices, and the like), couplings (e.g., electro-hydraulic wet connect, dry connect, inductive coupler, and the like), control lines (e.g., electrical, fiber optic, hydraulic, and the like), surveillance lines, drill bits and reamers, sensors or distributed sensors, downhole heat exchangers, valves and corresponding actuation devices, tool seals, packers, cement plugs, bridge plugs, and other wellbore isolation devices or components, and the like. Any of these components can be included in the systems and apparatuses generally described above and depicted in  FIG.  7   . 
     For purposes of illustration, the example of  FIG.  7    shows a vertically-oriented borehole configuration. However, the apparatus and techniques described herein may also be used in other borehole configurations, such as a borehole including a horizontal penetration direction, or an oblique borehole configuration, for example. It should also be noted that while  FIG.  7    generally depicts a land-based system or apparatus, it is to be recognized that like systems and apparatuses can be operated in subsea locations as well. Embodiments of the present invention can have a different scale than that depicted in  FIG.  7   . 
     In summary, various embodiments permit the cracking pressures of check valve assemblies to be determined without overtly considering low production tubing pressure that might lead to premature opening of prior art check valve assemblies. Instead, rather than opening the check valve assembly, low pressure experienced downhole operation of the lift check valve should function to increase the pressure holding the closing member against its seat, providing an improved seal. In this way, the inadvertent creation of a vacuum in the line can be avoided. In embodiments having flow orifices serving as fluid communication ports out of the spring chamber, the flow orifices can reduce the speed at which the check valve assemblies open and close. Flow orifices between the spring chamber and the annulus permit the annulus pressure to offset hydrostatic pressures of injection fluids and keep the check valve assemblies from opening prematurely. This improves the reliability of seals when the checks are closed, reducing chances of chattering that can cause damage and leakage. By reducing leakage and subsequent vacuum creation, the lift and reliability of control lines, valves, and mandrels can be increased. 
     To better illustrate the apparatuses and methods for regulating fluid flow and pressure in chemical injection systems disclosed herein, a non-limiting list of examples is provided. The following numbered examples are illustrative embodiments in accordance with various aspects of the present disclosure. 
     1. A check valve assembly may include a housing defining a fluid passage having a fluid inlet side and a fluid outlet side; a lift check valve positioned within the fluid passage oriented to restrict fluid flow from the fluid inlet side; a second check valve positioned within the fluid passage oriented to restrict fluid flow from the fluid outlet side; and a flow dampener positioned within the fluid passage and between the first and second check valves. 
     2. The check valve assembly of example 1, in which the lift check valve further includes a debris collection area formed as a radial space defined in part by a circumferential inner surface of the fluid passage. 
     3. The check valve assembly of any of the preceding examples, in which the flow dampener is positioned within an interior of the housing between the lift check valve and the second check valve. 
     4. The check valve assembly of any of the preceding examples, in which the flow dampener is included as an integral portion of a closing member of the check valve. 
     5. The check valve assembly of any of the preceding examples, in which the lift check valve includes at least one of: a first flow orifice to permit fluid flow out of the housing from a spring chamber of the lift check valve; or a second flow orifice to permit fluid flow between the spring chamber and a fluid passage at the fluid inlet side. 
     6. The check valve assembly of any of the preceding examples, in which an actuation direction of the lift check valve is opposite that of the second check valve. 
     7. The check valve assembly of any of the preceding examples, in which the lift check valve further includes a spring that biases a closing member into engagement with a seat of the lift check valve. 
     8. The check valve assembly of any of the preceding examples, in which the lift check valve further includes a fluid passage that is selectively opened and closed by movement of a closing member of the lift check valve. 
     9. The check valve assembly of any of the preceding examples, in which the closing member is moveable in response to fluid pressure to open the fluid passage by lifting the closing member off of a seat of the lift check valve. 
     10. The check valve assembly of any of the preceding examples, in which the second check valve further includes a fluid passage that is selectively opened and closed by movement of a closing member of the second check valve. 
     11. The check valve assembly of any of the preceding examples, in which the closing member is moveable in response to fluid pressure to open the fluid passage by pushing the closing member away from a seat of the second check valve. 
     12. A method includes applying fluid pressure to a check valve assembly including a housing defining a fluid passage having a fluid inlet side and a fluid outlet side, a lift check valve positioned within the fluid passage oriented to restrict fluid flow from the fluid inlet side, and a second check valve positioned within the fluid passage oriented to restrict fluid flow from the fluid outlet side; and lifting, in response to the fluid pressure, a closing member off of a seat of the lift check valve to permit fluid to flow through the lift check valve. 
     13. The method of example 12, in which lifting the closing member includes moving the closing member towards the fluid inlet side of the housing. 
     14. The method of either of examples 12 or 13, in which fluid flowing through the lift check valve at a selected pressure will result in pushing a second closing member off a seat of the second check valve to permit fluid to flow through the second check valve. 
     15. The method of any of examples 12-14, in which pushing the second closing member includes moving the second closing member towards the fluid outlet side of the housing. 
     16. The method of any of examples 12-15, further including porting fluid flow through a flow orifice to permit fluid flow from a spring chamber of the lift check valve to out of the housing, in which fluid flow is transported out of the spring chamber as the closing member is moved. 
     17. The method of any of examples 12-16, further including porting fluid flow through a flow orifice to permit fluid flow from a spring chamber of the lift check valve to a fluid passage at the fluid inlet side, in which fluid flow is transported out of the spring chamber as the closing member is moved. 
     18. The method of any of examples 12-17, further including porting fluid flow through a first flow orifice to permit fluid flow from a spring chamber of the lift check valve to out of the housing, in which fluid flow is transported out of the spring chamber as the closing member is moved, and porting fluid flow through a second flow orifice to permit fluid flow from the spring chamber of the lift check valve to a fluid passage at the fluid inlet side, in which fluid flow is transported out of the spring chamber as the closing member is moved. 
     19. The method of any of examples 12-18, in which the closing member is biased against the seat of the lift check valve using a spring. 
     20. The method of any of examples 12-19, in which pressure holding the closing member against the seat increases as pressure on the fluid outlet side of the housing decreases. 
     The accompanying drawings that form a part hereof, show by way of illustration, and not of limitation, specific embodiments in which the subject matter may be practiced. The embodiments illustrated are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed herein. Other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. This Detailed Description, therefore, is not to be taken in a limiting sense, and the scope of various embodiments is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled. 
     Such embodiments of the inventive subject matter may be referred to herein, individually and/or collectively, by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept if more than one is in fact disclosed. Thus, although specific embodiments have been illustrated and described herein, it should be appreciated that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description. 
     The embodiments are submitted with the understanding that they will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.