Abstract:
A system for and method of supplying an injection fluid to a well assembly so that the injection fluid flows at a substantially constant flow rate. The fluid can be injected at a single site in the well assembly or multiple sites. A flow control regulator is included that attaches to the well assembly and provides a self adjusting flow control for the fluid being injected. The regulator includes a slidable floating sleeve having an orifice through which the fluid flows. The sleeve includes an inlet port that can register with a fluid supply port to allow the injection fluid to make its way into the sleeve. The fluid exits the sleeve through the orifice to generate a pressure differential across the orifice that in turn exerts a sliding force onto the sleeve. Moving the sleeve misaligns the inlet port and fluid supply port thereby throttling flow through the regulator to a predetermined flow rate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application relates to U.S. provisional application 61/107,247 filed on Oct. 21, 2008, the entire specification of which being herein incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates in general to oil and gas production, and in particular to a multi-ported flow regulator used for injecting fluid into a wellbore. 
         [0004]    2. Description of Related Art 
         [0005]    Oil and gas production involves extracting hydrocarbons from a subterranean formation in which they are entrained. The hydrocarbons, either in liquid (oil) or gas form, flow to the surface within a wellbore that intersects the formation. Other fluids, such as water, CO 2 , N 2 , and H 2 S, may be included in the formation with the hydrocarbons. An injection fluid, which is typically different from the produced fluid, is sometimes used during the production of fluids from subterranean formations. The injection fluid(s) can be added at a wellhead mounted on top of the wellbore, within the wellbore, or into the formation, the injection location depends on why the injection fluid is being used. 
         [0006]    Often, the fluids that are injected into the formation or deep in the wellbore are to enhance production. For example, a lower viscosity fluid can be injected into the produced fluid, in the formation or production tubing in the wellbore, to decrease the viscosity of the fluid being produced and reduce flow drag. A lower density fluid can be injected to reduce production fluid density thereby increasing its flow rate. Injection fluids can also be used to treat the formation for enhancing flow. Certain injection fluids can etch the formation and increase flow capacity through pores in the formation. Other injection fluids can aid in the separation of polar and non-polar compounds and aid in the extraction of the produced fluids from the formation. Formation pressure can be maintained or increased by injecting a higher pressure fluid into the formation. In some instances, increasing formation pressure can enhance flow of produced fluids from the formation. Examples of injection fluids include rust inhibitors, chemical treatments, surfactants, steam, water, grease, natural gas, brine, and alcohol. 
         [0007]    Fluid injection may occur at more than one location in the well, where the different locations are at different pressures. Additionally, the flow rate of fluid injection at each location may differ. Individual supply lines may be provided that extend from the surface directly to each injection point. This may be problematic due to space limitations within the wellbore and at the wellhead. 
       SUMMARY OF THE INVENTION 
       [0008]    Disclosed herein is a method of injecting fluid into a well that includes isolating first and second formations in a well from one another, extending conduit from a wellhead assembly into the well, the conduit having a first port in fluid communication with the first formation and a second port in fluid communication with the second formation, pumping fluid down the conduit and to the ports, and controlling flow through each of the ports so that the flow rates through each of the ports is substantially constant as the pressure difference between the conduit and the first and second formations vary. Fluid discharged from the first port and from the second port can be at different pressures. Each port can have a flow control device with a variable flow area that varies in inverse proportion to the pressure in the conduit. The method can further include setting a packer between the first and second formations as well as mounting a flow control device in each of the ports on the exterior of the conduit. The injection fluid can be acid, water, steam, gas, brine, surfactants, rust inhibitors, scale treatment fluids, alcohol, or combinations thereof. In one example, the injection fluid is maintained at a subcritical condition. 
         [0009]    A fluid injection system for injection into a subterranean well is also described herein. In one example the fluid injection system includes a fluid source, a fluid supply line in fluid communication with the fluid source, a first flow control regulator in fluid communication with the fluid supply line and having a discharge in pressure communication with a first location within subterranean well, so that when the fluid source supplies fluid to the fluid supply line, the fluid exits from the discharge to the first location within the subterranean well at a constant flow rate, and a second flow control regulator in fluid communication with the fluid supply line and having a discharge in pressure communication with a second location within the subterranean well that has a pressure different from the first location, so that when the fluid source supplies fluid to the fluid supply line, the fluid exits from the discharge to the second location within the subterranean well at a constant flow rate. The location in the subterranean well can include a wellhead housing, a production tree, an annulus between wellbore tubulars, and within production tubing. The fluid can exit from the discharge at a constant flow rate over a range of pressures in the fluid supply line and the locations in the subterranean well. The flow control regulators can include a flow path with a selectively changeable flow area. In an alternative example, the flow control device has an inlet, a fixed sleeve in fluid communication with the inlet, a fixed port formed through a side of the fixed sleeve, a floating sleeve coaxial and slidable with respect to the fixed sleeve, a floating port formed through a side of the floating sleeve and selectively registerable with the fixed port, a restriction orifice on an end of the floating sleeve in fluid communication with the floating port, and a compressible resilient member in contact with the restriction orifice on a side of the restriction orifice opposite the fixed sleeve, so that when injection fluid is directed to the inlet of the flow control device, the fluid flows to the fixed sleeve, through the registered fixed and floating ports, and through the restriction orifice to generate a pressure differential across the restriction orifice that creates a force to slide the floating sleeve away from the fixed sleeve misalign the floating port and fixed port that in turn reduces the flow area through the flow control device. The injection fluid can be acid, water, steam, gas, brine, surfactants, rust inhibitors, scale treatment fluids, alcohol, or combinations thereof. 
         [0010]    Included with the present disclosure is a method of treating a well assembly with an injection fluid that includes providing a constant flow valve made up of, an inlet, a discharge, a flow path between the inlet and discharge, a passage in the flow path, a slidable sleeve having a side wall adjacent and normal to the passage, an orifice in the flow path attached to an end of the slidable sleeve, so that when fluid flows through the orifice a resultant force is produced that can slide the sleeve in a first direction that moves the side wall of the sleeve over a portion of the passage. The method of this embodiment further includes applying a limiting force on the sleeve in a second direction that is opposite the first direction, providing fluid communication between the discharge and a location in the well assembly, and delivering a pre-selected amount of injection fluid to the well assembly and at a substantially constant flow rate by supplying an injection fluid to the inlet 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0011]    Some of the features and benefits of the present disclosure having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
           [0012]      FIG. 1  is side perspective view of an embodiment of a flow regulator constructed in accordance with the present invention. 
           [0013]      FIG. 2  is a partial sectional view of the flow regulator of  FIG. 1 . 
           [0014]      FIG. 3  is a schematic view of an alternative embodiment of a constant flow valve. 
           [0015]      FIG. 4  is a partial sectional view of a flow regulator on tubing. 
           [0016]      FIG. 5  is a partial sectional side view of a wellhead assembly that includes a flow regulator. 
           [0017]      FIG. 6  is a sectional view of an example of a constant flow valve within the flow regulator. 
           [0018]      FIG. 7  is a partial sectional view of a flow regulator for regulating flow into tubing. 
       
    
    
       [0019]    While the subject device and method will be described in connection with the preferred embodiments but not limited thereto. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the present disclosure as defined by the appended claims. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be through and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. 
         [0021]    It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. Accordingly, the improvements herein described are therefore to be limited only by the scope of the appended claims. 
         [0022]      FIG. 1  illustrates a perspective view of an embodiment of a flow regulator  10  as described herein. The flow regulator  10  includes a generally tubular body  12  having an opening  14  on one end and a threaded connection  20  on its opposite end. On the body  12  are optional wrench flats  16  having a generally planar surface locally altering the cylindrical surface of the body  12 . The flats  16  can be arranged around the body  12  circumference to provide a surface for engagement by a wrench or other hand tool for tightening or loosening the flow regulator  10 . As will be described in more detail below, the opening  14  of the flow regulator  10  is attachable to a fluid source. Fluid from the fluid source can enter the opening  14  and flow through the body  12 ; the fluid can be selectively regulated to a specified pressure or pressure range. Fluid within the body  12  can exit through exit ports  18  shown on the outer surface of the body  12 . 
         [0023]    A partial section view of the flow regulator  10  is shown in perspective view in  FIG. 2 . As shown, a bore  22  in the body  12  extends from the opening  14  and has a closed end at the exit ports  18 . An arrow provided in the bore  22  represents fluid flow direction within the bore  22 . Thus for the purposes of discussion herein, the arrow points in a downstream direction. Conversely, upstream is designated as being in a direction opposite that of the arrow. Thus using this convention, the opening  14  is upstream of the exit ports  18 . The bore  22  as shown includes a series of transitions that begin upstream of the wrench flats  16 , thereby narrowing the diameter of the bore  22 . In the embodiment shown, a constant flow valve  24  is housed in a narrowed portion of the bore  22 . Modular embodiments of a constant flow valve  24  are available for purchase. One example for use is a Flosert™ valve from The Lee Company, USA, Pettipaug Rd, P.O. Box 424, Westbrook, Conn., 06498-0424. 
         [0024]    An alternate example of a constant flow valve  24 A is shown in a side sectional view in  FIG. 3 . The constant flow valve  24 A includes a tubular body  54  with an inlet  56  formed through an end of the body  54 . Shown coaxially anchored within the body  54  is an annular fixed sleeve  58  with an open end facing the inlet  56  and an inner diameter less than the diameter of the inlet  56 . The sleeve  58  is closed on the end opposite the inlet  56 . The connection anchoring the fixed sleeve  58  extends continuously from the body  54  to the open end of the fixed sleeve  58  so that any flow entering the inlet  56  is directed to within the fixed sleeve  58 . Ports  60  are shown formed radially through the fixed sleeve  58 . A floating orifice  62  is shown within the body  54  that coaxially circumscribes the fixed sleeve  58  and projects past the closed end of the sleeve  58  into a discharge annulus  63 . A sleeve portion  64  of the floating orifice  62  circumscribes the fixed sleeve  58 , ports  66  is shown radially formed through the sleeve portion  64  that register with the ports  60  in the fixed sleeve  58 . Additional ports  68  are shown provided within the sleeve portion  64 . Defined in the annular space between the sleeve portion  64  and body  54  is an annulus  70  that communicates with ports  66  and ports  68  on the outer surface of the sleeve portion  64 . Ports  68  are in communication with the discharge annulus  63  on the inner surface of the sleeve portion  64 . Thus fluid entering the constant flow valve  24 A through its inlet  56 , can flow within the fixed sleeve  58 , through the registered ports  60 ,  66 , into the annulus  70 , then through ports  68  and into the discharge annulus  63 . 
         [0025]    The floating orifice  62  includes an orifice element  72  shown disposed downstream of the ports  68  within the discharge annulus  63 . A spring  74  is coaxially disposed in the discharge annulus  63  shown partially circumscribed by a forward sleeve  76  extending axially from the orifice  72  and away from the inlet  56 . The discharge annulus  63  includes an outlet  78  at its end opposite the fixed sleeve  58 . One end of the spring  74  contacts the downstream side of the orifice  72  and the other end of the spring  74  contacts a flange  80  shown projecting radially inward from the body  54  adjacent the outlet  78 . 
         [0026]    In one example of use, fluid that enters the flow regulator  10 A is directed to the inlet  56  and to within the fixed sleeve  58 . From the fixed sleeve  58  the fluid can flow through the registered ports  60 ,  66 , the annulus  70 , and the ports  68  and into the discharge annulus  63 . Within the discharge annulus  63 , the fluid flows through the restricted diameter orifice  72  before exiting the constant flow valve  24 A. Restricting flow through the orifice  72  creates a pressure differential across the orifice  72  that translates into a force to urge the floating orifice  62  downstream and compress the spring  74 . As the floating orifice  62  is moved downstream, the ports  60 ,  66  become misaligned thereby reducing the effective flow area through the valve  24 A. The reduced flow area reduces flow through the ports  60 ,  66  that in turn decreases the pressure differential across the orifice  72 . When the pressure drop across the orifice  72  and spring force are substantially the same the floating orifice  62  will stabilize and cease to move thereby maintaining a constant flow rate of fluid through the constant flow valve  24 A. 
         [0027]    An alternative constant flow control device is illustrated in a schematic view in  FIG. 4 . In this embodiment, injection fluid from the injection fluid source flows through an inlet line  57  to a control valve assembly  59 . The inlet line  57  can connect directly to the source, the fluid supply line  50 , as well as a lead line  49 . The assembly  59  includes a flow meter  69  upstream of a control valve  71 , wherein the flow meter  69  measures the flow rate and communicates to the control valve  71  to increase or decrease the flow path (not shown) through the control valve  71 , thereby maintaining a constant flow rate of injection fluid. An exit line  61  is depicted downstream of the control valve; the exit line  61  can terminate at a base  11  located on the wellbore assembly  40 , or alternatively the control valve can couple directly to the base  11 . 
         [0028]    With reference now to  FIG. 5 , an example of a wellbore assembly  40  is depicted in a side partial sectional view. The wellbore assembly  40  includes a production tree  42  and wellhead housing  43  mounted over a wellbore  3  that intersects a subterranean formation  4 . The wellbore  3  is shown lined with casing  5  and production tubing  6  within the casing  5  to form an annulus  7  between the tubing  6  and the casing  5 . The casing  5  and tubing  6  are suspended into the wellbore  3  from the wellhead housing  43 . Packers  52 , shown in sectional view, are at locations in the wellbore  3  and extend between the tubing  6  outer diameter to the casing  5  inner surface. For the sake of illustration a single casing  5  and tubing  6  are depicted, however embodiments of the present disclosure include wellbore assemblies  40  having more than one string of casing  5  as well as more than one string of production tubing  6 . 
         [0029]    Examples of pressure regulators  10  are shown disposed within the wellbore  3  at multiple locations. The regulators  10  may be threadingly connected to a base  11  shown within the annulus  7 . An injection line  46  for transporting an injection fluid or fluids is illustrated that conveys injection fluid from an injection fluid source  45  to the production tree  42 . The injection line  46  can optionally include a flow meter  47  between the source  45  and the production tree  42 . The end of the injection line  46  opposite the fluid source is shown connected to an injection port  44  mounted in the production tree  42 . Examples of injection fluid include acid, water, steam, gas, brine, surfactants, rust inhibitors, scale treatment fluids, alcohol, and combinations thereof, to name but a few. An injection fluid supply line  50  in fluid communication with the injection port  44  is shown passing through the production tree  42  and wellhead housing  43  and into the borehole  3 . Each regulator  10  is in fluid communication with the fluid supply line  50  via lead lines  49  shown connected between the fluid supply line  50  and the opening  11  of each regulator  10 . 
         [0030]    In one mode of operation, an injection fluid is provided through line  46  where it flows through the injection port  44  and into the fluid supply line  50 . After branching into the lead lines  49  the injection fluid is introduced to the regulator  10  via the opening  14  ( FIG. 2 ). The fluid flow through the flow regulator  10  is maintained substantially constant. One of the advantages of the system described herein is the ability to provide downhole an injection flow of substantially constant flow rate, irrespective of supply pressure of the injection fluid or back pressure at the exit ports  18 . Moreover, multiple injection points, as illustrated in  FIG. 5 , can be serviced with a single injection line at a given supply pressure by tailoring each pressure regulator  10  as described above. Thus significant advantages can be realized by selectively injecting a desired injection flow while limiting the number of fluid lines within the wellbore assembly  40 . 
         [0031]    An additional advantage is the modular design of the flow regulator  10 . The constant flow valve  24  used in the flow regulator  10  described herein is readily interchangeable with a constant flow valve  24  rated for a different operating capability. Additionally, a constant flow valve  24  having a certain operating capability can be installed after being manufactured, such as on site at an oil/gas well. One example of a different operating capability includes a fluid flow rate across the constant flow valve  24 . The readily interchangeable design, or ready installation, provides flexibility to meet operating conditions that may not be known or available before the regulator  10  is manufactured or delivered for use. Multiple exit ports  18  provided on the body  12  provide another advantage since injection nozzles downhole can clog from scale buildup or other debris in wellbore fluid. The plurality of ports  18  provides redundant exit points on the regulator  10  thereby significantly reducing the chances of clogging. 
         [0032]    The pressure regulators  10  are illustrated in  FIG. 5  within the annulus  7 ; however embodiments exist where the regulators  10  are connected directly to tubing, casing, the production tree, or wellhead housing. With reference to  FIG. 6 , an example of the flow regulator  10  is shown attached to a base  11 A on the tubing  6  outer wall. The flow exiting the regulator  10  (represented by arrows) discharges into the annulus  7 . A connector  51  couples the lead line  49  to the regulator  10 . The base  11 A of  FIG. 6  can be attached to the tubing  6  or integrally formed with the tubing  6 . A receptacle having an axis shown substantially parallel to the tubing  6  is formed in the base  11 A, where the receptacle includes threads formed to mate with threads on the regulator  10  nose. A pressure gauge  65  is schematically illustrated disposed within the annulus  7  in communication with a communication link  67 . The pressure gauge  65 , which can be any type, can sense the pressure within the annulus  7  and emit a signal representative of the annulus pressure to the communication link  67 . The communication link  67  can include an electrically conductive member as well as a telemetry signal. The signal can be transmitted to the surface and used to independently evaluate the pressure drop across the regulator  10 . A controller (not shown) can be included that receives the pressure signal and adjusts the pressure and/or flow rate of the injection fluid at the surface to maintain the regulator  10  within its operating conditions. 
         [0033]      FIG. 7  illustrates an alternative embodiment of a regulator  10 A having flow exiting the regulator through its nose section. The flow is received from the lead line  49 , which is shown attached to the flow regulator  10 A with a connector  51 . The flow enters the flow regulator  10 A and is regulated with the constant flow valve  24  within. The discharge from the flow regulator  10 A is direct to a discharge passage  19  laterally formed within the base  11 B. The passage  19  conveys the injection fluid between the regulator  10 A and the tubing  6 . In this example, the injection fluid can include fluids to maintain a clean flow through the tubing  6 , for example to prevent build up of materials such as asphaltene and/or scale. A pressure gauge  65 A and communication link  67 A, which can be the same as that of  FIG. 6 , is shown provided within the tubing  6 . 
         [0034]    While the invention has been shown in only one of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention. In an alternate embodiment, devices for preventing backflow, such as a check valve, can be included within the lines  46 ,  50 ,  49  that convey injection fluid.