Abstract:
An intrawell fluid injection system is operably positionable in a well having a production zone that is in fluid isolation from a discharge zone. The system includes an electric submersible pump assembly having an electric motor and a fluid pump that is operably associated with the electric motor. The fluid pump has a fluid intake operably positionable in fluid communication with the production zone. The fluid pump is operable to pump formation fluid from the production zone in a first axial direction. The system also includes a bypass assembly that is in downstream fluid communication with the electric submersible pump assembly. The bypass assembly is operable to transport formation fluid from the electric submersible pump assembly in a second axial direction that is opposite the first axial direction. The bypass assembly has a fluid discharge operably positionable in fluid communication with the discharge zone.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. §119 of the filing date of International Application No. PCT/US2013/039951, filed May 7, 2013. 
     TECHNICAL FIELD OF THE INVENTION 
     This invention relates, in general, to equipment utilized in conjunction with operations performed in relation to subterranean wells and, in particular, to the use of an intrawell fluid injection system to inject fluid from a production zone into a discharge zone without surfacing the fluid. 
     BACKGROUND OF THE INVENTION 
     Without limiting the scope of the present invention, its background is described with reference to producing water from a hydrocarbon bearing subterranean formation, as an example. 
     Most hydrocarbon bearing subterranean formations produce a mixture of oil and/or gas together with water, usually in the form of brine which may contain large amounts of dissolved minerals or precipitates such as salts. In fact, in some wells, water and other byproducts can be the majority of the total production yield, particularly during the later stages of production. Typically, once formation fluids are produced to the surface, the produced mixture undergoes a separation process where the hydrocarbon fluids are separated from the remaining components of the mixture and subsequently delivered to a refinery for treatment. In the separation process, the water and remaining components are usually removed from the hydrocarbon fluids using one or more single phase or multi-phase separation devices. Generally, these devices operate to agglomerate and coalesce the produced hydrocarbon fluids, thereby separating them from the water and other components of the produced mixture. 
     In certain operations, once the water is processed, it may be discharged into a body of water such as a surrounding ocean, in the case of offshore production. Before the water can be discharged into the ocean or any other body of water, however, it must first be rigorously tested to make sure that it does not contain any oil or other impurities that could damage the surrounding sea life. In addition, as environmental regulations increasingly become more stringent with respect to the disposal of produced water, it is crucial to obtain accurate and timely analysis of the separated fluids to avoid undesirable fines and/or fees. 
     One method to avoid disposal of produced water into the ocean or other body of water, is to inject the separated water and other components back into the ground. For example, the separated water produced from one well may be injected into a neighboring well. This process not only replaces a portion of the liquid removed from the reservoir, but also simultaneously serves to maintain required formation pressures for efficient production rates. It has been found, however, that the reinjection of the produced water into a neighboring well still requires surface processing and testing of the produced water. In addition, reinjection of the produced water into a neighboring well requires additional surface facilities including pumping and control systems as well as the drilling of a dedicated injection well, in some cases. 
     Therefore, a need has arisen for an improved system and method for disposal of water produced from a hydrocarbon bearing subterranean formation. A need has also arisen for such an improved system and method that does not involve the disposal of produced water into a body of water. Further, a need has arisen for such an improved system and method that does not require surface processing and reinjection of the produced water. 
     SUMMARY OF THE INVENTION 
     The present invention disclosed herein is directed to an intrawell fluid injection system and method for disposal of water produced from a subterranean formation. The intrawell fluid injection system and method of the present invention does not involve the disposal of produced water into a body of water. In addition, the intrawell fluid injection system and method of the present invention does not require surface processing and reinjection of the produced water. 
     In one aspect, the present invention is directed to an intrawell fluid injection system that is operably positionable in a well having a production zone that is in fluid isolation from a discharge zone. The system includes an electric motor, a fluid pump operably associated with the electric motor and a bypass assembly in downstream fluid communication with the fluid pump. The fluid pump has a fluid intake that is operably positionable in fluid communication with the production zone. The bypass assembly has a fluid discharge that is operably positionable in fluid communication with the discharge zone. 
     In one embodiment, at least one check valve assembly may be positioned in a fluid flow path between the intake and the discharge. In this embodiment, the check valve assembly may be operable to allow fluid flow from the fluid intake to the fluid discharge and operable to prevent fluid flow from the fluid discharge to the fluid intake. In certain embodiments, a sensor assembly may be operably positioned relative to the fluid flow path to measure a fluid flowrate therethrough. In some embodiments, axial fluid flow in the bypass assembly may be in a direction opposite of axial fluid flow in the fluid pump. In one embodiment, a gas separator may be operable to separate a gas fraction from the formation fluids of the production zone upstream of the bypass assembly. In another embodiment, a sample line in fluid communication with the bypass assembly may be used to supply fluid from the bypass assembly to a surface of the well for sampling. 
     In one embodiment, the bypass assembly may include an upper manifold operably positionable uphole of the electric motor and the fluid pump, a lower manifold operably positionable downhole of the electric motor and the fluid pump, and a plurality of bypass tubes extending between the upper and lower manifolds. In this embodiment, the bypass tubes may be circumferentially distributed around the bypass assembly. Also, in this embodiment, the bypass assembly may include a discharge tubing in downstream fluid communication with the lower manifold. This discharge tubing may include the fluid discharge. In addition, a seal assembly may be operably positioned between the discharge tubing and the well to provide isolation between the production zone and the discharge zone. 
     In another aspect, the present invention is directed to an intrawell fluid injection system that is operably positionable in a well having a production zone that is in fluid isolation from a discharge zone. The system includes an electric submersible pump assembly having an electric motor and a fluid pump that is operably associated with the electric motor. The fluid pump has a fluid intake operably positionable in fluid communication with the production zone. The fluid pump is operable to pump formation fluid from the production zone in a first axial direction. The system also includes a bypass assembly that is in downstream fluid communication with the electric submersible pump assembly. The bypass assembly is operable to transport formation fluid from the electric submersible pump assembly in a second axial direction that is opposite the first axial direction. The bypass assembly has a fluid discharge operably positionable in fluid communication with the discharge zone. 
     In a further aspect, the present invention is directed to an intrawell fluid injection method. The method includes providing an intrawell fluid injection system including an electric motor, a fluid pump and a bypass assembly; disposing the intrawell fluid injection system in a well having a production zone that is in fluid isolation from a discharge zone such that the fluid pump is in fluid communication with the production zone and the bypass assembly is in fluid communication with the discharge zone; operating the electric motor; pumping formation fluid from the production zone in a first axial direction with the fluid pump; receiving the formation fluid from the fluid pump in the bypass assembly; transporting the formation fluid in a second axial direction that is opposite the first axial direction in the bypass assembly; and discharging the formation fluid from the bypass assembly into the discharge zone. 
     The method may also include preventing reverse flow through the intrawell fluid injection system with at least one check valve; measuring a fluid flowrate through the intrawell fluid injection system with a sensor assembly; and/or separating a gas fraction from the formation fluids upstream of the bypass assembly with a gas separator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which: 
         FIG. 1  is a schematic illustration of an intrawell fluid injection system positioned in a wellbore according to an embodiment of the present invention; 
         FIG. 2  is a schematic illustration of an intrawell fluid injection system positioned in a wellbore according to an embodiment of the present invention; 
         FIG. 3  is a schematic illustration of an exemplary intrawell fluid injection system according to an embodiment of the present invention; and 
         FIG. 4  is a schematic illustration of an exemplary intrawell fluid injection system according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention. 
     Referring initially to figure, an intrawell fluid injection system positioned in a well is schematically illustrated and generally designated  10 . A wellbore  12  extends through the various earth strata including formation  14  and formation  16 . A casing  18  is secured within wellbore  12 . A tubing string  20  is disposed within wellbore  12 . Tubing string  20  includes various tools for controlling fluid flow in wellbore  12  such as intrawell fluid injection system  22 . In the illustrated embodiment, intrawell fluid injection system  22  includes a fluid intake subassembly  24 , a fluid pump  26  having a fluid intake  27 , a check valve assembly  28 , a sensor subassembly  30  and a bypass assembly  32 . Bypass assembly  32  includes an upper manifold  34 , a plurality of bypass tubes  36 , a lower manifold  38 , a discharge tubing  40  and a fluid discharge subassembly  42 . Preferably, fluid intake subassembly  24  and fluid pump  26  are part of an electric submersible pump assembly  44  that also includes, in the illustrated embodiment, an electric motor  46 . Power, control signals and data may be sent between various components of electric submersible pump assembly  44  and a surface control system  48  via a cable assembly  50 . 
     As illustrated, fluid intake subassembly  24  is in fluid communication with a production zone  52  associated with formation  14 . Likewise, fluid discharge subassembly  42  is in fluid communication with a discharge zone  54  associated with formation  16 . A seal assembly  56  is positioned between discharge tubing  40  and casing  18  in a location between production zone  52  and discharge zone  54  to provide isolation between production zone  52  and discharge zone  54 . An optional seal assembly  58  is positioned between discharge tubing  40  and casing  18  downhole of discharge zone  54 . In the illustrated embodiment, tubing string  20  provides support for intrawell fluid injection system  22  but does not provide a conduit for the transportation of fluids. Fluid samples, however, may be obtained at the surface via a sample line  60  that extends from upper manifold  34  to wellhead  62 . Even though intrawell fluid injection system  22  has been described and depicted as having a particular array of components, it should be understood by those skilled in the art that other arrangements of components having a greater or lesser degree of functionality could alternatively be used without departing from the principles of the present invention. 
     When it is desired to inject fluid from formation  14  into formation  16 , for example in a water flood operation, intrawell fluid injection system  22  of the present invention may be used. Operation of intrawell fluid injection system  22  is commenced responsive to power and control provided by surface control system  48  via a cable assembly  50 . Specifically, power is supplied to electric motor  46  that is operable to turn the rotor and impeller elements in fluid pump  26 . Operation of fluid pump  26  causes fluid from formation  14 , represented by arrows  64  to enter fluid intake subassembly  24 . The production fluid is then pumped in the uphole direction, as represented by arrows  66 , by fluid pump  26 . Check valve assembly  28  allows the production fluid to travel in the uphole direction upon exit from fluid pump  26  but prevents return flow therethrough. One or more sensors in sensor subassembly  30  may monitor various parameters of the production fluid such as pressure, temperature, pH, chemical composition, impurity content, viscosity, density, ionic strength, total dissolved solids, salt content, opacity, bacteria content, combinations thereof and the like as well as the flow rate of the production fluid such that the volume of production fluid injected by intrawell fluid injection system  22  may be determined. Even though check valve assembly  28  and sensor subassembly  30  have been depicted and described as being located between fluid pump  26  and upper manifold  34 , it should be understood by those skilled in the art that check valve assembly  28 , including multiple check valves, and sensor subassembly  30  could alternatively be located at any point along the flow path between fluid intake subassembly  24  and fluid discharge subassembly  42 . 
     In the illustrated embodiment, after passing through sensor subassembly  30 , the formation fluid enters upper manifold  34  that may include various fluid paths and/or valving arrangements for redirecting the formation fluid toward bypass tubes  36 , as represented by arrows  68 . The formation fluid then travels in the downhole direction, as represented by arrows  70 , through bypass tubes  36 . After passing through bypass tubes  36 , the formation fluid enters lower manifold  38  that may include various fluid paths and/or valving arrangements for redirecting the formation fluid toward discharge tubing  40 , as represented by arrows  72 . The formation fluid, as represented by arrows  74 , then travels in the downhole direction in discharge tubing  40 . The formation fluid is discharged into discharge zone  54 , as represented by arrows  76 , and is injected into formation  16 , as represented by arrows  78 . In this manner, fluid from formation  14  can be injected into formation  16  using intrawell fluid injection system  22  of the present invention. It should be noted that intrawell fluid injection system  22  may be used to inject fluid from formation  14  into formation  16  even if the natural pressure in formation  14  is not sufficient the achieve this injection as fluid pump  26  provides the required pressure boost to enable such injection. 
     Advantageously, use of intrawell fluid injection system  22  of the present invention avoids the need to surface the production fluid, thereby avoiding the associated requirement of surface processing and testing of the produced fluid prior to disposal thereof. In addition, use of intrawell fluid injection system  22  of the present invention avoids the need for additional surface facilities required for reinjection operations as well as the need to drill dedicated injection wells. Further, use of intrawell fluid injection system  22  of the present invention prevents oxygen from entering the fluid stream thereby minimizing bacteria and scale formation. 
     Even though  FIG. 1  depicts the present invention in a vertical wellbore, it should be understood by those skilled in the art that the present invention is equally well suited for use in wellbores having other directional configurations including horizontal wellbores, deviated wellbores, slanted wells, lateral wells and the like. Accordingly, it should be understood by those skilled in the art that the use of directional terms such as above, below, upper, lower, upward, downward, uphole, downhole and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure, the uphole direction being toward the surface of the well and the downhole direction being toward the toe of the well. 
     Referring next to  FIG. 2 , an intrawell fluid injection system positioned in a well is schematically illustrated and generally designated  100 . A wellbore  112  extends through the various earth strata including formation  114  and formation  116 . A casing  118  is secured within wellbore  112 . A tubing string  120  is disposed within wellbore  112 . Tubing string  120  includes various tools for controlling fluid flow in wellbore  112  such as intrawell fluid injection system  122 . In the illustrated embodiment, intrawell fluid injection system  122  includes a fluid intake subassembly  124 , a gas separator  108 , a gas discharge subassembly  110 , a fluid pump  126 , a check valve assembly  128 , a sensor subassembly  130  and a bypass assembly  132 . Bypass assembly  132  includes an upper manifold  134 , a plurality of bypass tubes  136 , a lower manifold  138 , a discharge tubing  140  and a fluid discharge subassembly  142 . Preferably, fluid intake subassembly  124 , fluid pump  126  having a fluid intake  127 , gas separator  108  and gas discharge subassembly  110  are part of an electric submersible pump assembly  144  that also includes, in the illustrated embodiment, an electric motor  146 . Power, control signals and data may be sent between various components of electric submersible pump assembly  144  and a surface control system  148  via a cable assembly  150 . 
     As illustrated, fluid intake subassembly  124  is in fluid communication with a production zone  152  associated with formation  114 . Likewise, fluid discharge subassembly  142  is in fluid communication with a discharge zone  154  associated with formation  116 . A seal assembly  156  is positioned between discharge tubing  140  and casing  118  in a location between production zone  152  and discharge zone  154  to provide isolation between production zone  152  and discharge zone  154 . An optional seal assembly  158  is positioned between discharge tubing  140  and casing  118  downhole of discharge zone  154 . In the illustrated embodiment, tubing string  120  provides support for intrawell fluid injection system  122  but does not provide a conduit for the transportation of fluids. Fluid samples, however, may be obtained at the surface via a sample line  160  that extends from upper manifold  134  to wellhead  162 . 
     When it is desired to inject fluid from formation  114  into formation  116 , for example during coal bed degasification or gas production from a mature production zone, intrawell fluid injection system  122  of the present invention may be used. Operation of intrawell fluid injection system  122  is commenced responsive to power and control provided by surface control system  148  via a cable assembly  150 . Specifically, power is supplied to electric motor  146  that is operable to turn the rotor of gas separator  108  and the rotor and impeller elements in fluid pump  126 . Operation of fluid pump  126  causes fluid from formation  114 , represented by arrows  164  to enter fluid intake subassembly  124 . The production fluid is then processes in gas separator  108  which separates at least a portion of the gas fraction from the production fluid and discharges this gas portion via gas discharge subassembly  110 , as represented by arrows  106 . The gas portion is then produced to the surface for further processing. The remainder of the production fluid is then pumped in the uphole direction, as represented by arrows  166 , by fluid pump  126 . Check valve assembly  128  allows the production fluid to travel in the uphole direction upon exit from fluid pump  126  but prevents return flow therethrough. One or more sensors in sensor subassembly  130  may monitor various parameters of the production fluid such as pressure, temperature, pH, chemical composition, impurity content, viscosity, density, ionic strength, total dissolved solids, salt content, opacity, bacteria content, combinations thereof and the like as well as the flow rate of the production fluid such that the volume of production fluid injected by intrawell fluid injection system  122  may be determined. Even though check valve assembly  128  and sensor subassembly  130  have been depicted and described as being located between fluid pump  126  and upper manifold  134 , it should be understood by those skilled in the art that check valve assembly  128 , including multiple check valves, and sensor subassembly  130  could alternatively be located at any point along the flow path between fluid intake subassembly  124  and fluid discharge subassembly  142 . 
     In the illustrated embodiment, after passing through sensor subassembly  130 , the formation fluid enters upper manifold  134  that may include various fluid paths and/or valving arrangements for redirecting the formation fluid toward bypass tubes  136 , as represented by arrows  168 . The formation fluid then travels in the downhole direction, as represented by arrows  170 , through bypass tubes  136 . After passing through bypass tubes  136 , the formation fluid enters lower manifold  138  that may include various fluid paths and/or valving arrangements for redirecting the formation fluid toward discharge tubing  140 , as represented by arrows  172 . The formation fluid, as represented by arrows  174 , then travels in the downhole direction in discharge tubing  140 . The formation fluid is discharged into discharge zone  154 , as represented by arrows  176 , and is injected into formation  116 , as represented by arrows  178 . In this manner, fluid from formation  114  can be injected into formation  116  using intrawell fluid injection system  122  of the present invention. 
     Referring next to  FIG. 3 , an enlarged view of the intrawell fluid injection system  22  of  FIG. 1  is depicted. Intrawell fluid injection system  22  includes electric submersible pump assembly  44  positioned in the center thereof. Electric submersible pump assembly  44  has a generally tubular outer housing and includes electric motor  46 , fluid intake subassembly  24  and fluid pump  26 . Also positioned in the center of intrawell fluid injection system  22  is check valve assembly  28  and sensor subassembly  30 . As described above, check valve assembly  28  and sensor subassembly  30  could alternatively be positioned in other locations in the fluid flow path through intrawell fluid injection system  22 . Power, control signals and data may be sent between a surface control system (not pictured) and the various components of electric submersible pump assembly  44 , such as electric motor  46  and sensor subassembly  30 , via a cable assembly  50 . 
     Intrawell fluid injection system  22  also includes bypass assembly  32  that is positioned above, below and around electric submersible pump assembly  44 . In the illustrated embodiment, bypass assembly  32  includes an upper manifold  34  positioned above electric submersible pump assembly  44 , a lower manifold  38  positioned below electric submersible pump assembly  44  and a plurality of bypass tubes  36  positioned around electric submersible pump assembly  44 . As illustrated, bypass assembly  32  includes four bypass tubes  36  (only three of which are visible in  FIGS. 1 and 3 ) that extend between upper manifold  34  and lower manifold  38  and are circumferentially distributed about bypass assembly  32 . Even though  FIGS. 1 and 3  have described and depicted bypass assembly  32  as having a particular number of bypass tubes, it should be understood by those skilled in the art that a bypass assembly of the present invention may alternatively have any number of bypass tubes both greater than or less than that shown. Bypass assembly  32  includes a sample line  60  that may extend to the surface to enable fluid sampling of production fluid from intrawell fluid injection system  22 . As described above, intrawell fluid injection system  22  is operable to be connected within a tubing string such that the portion of the tubing string above intrawell fluid injection system  22  does not transport fluid while the portion of the tubing string below intrawell fluid injection system  22  transports the production fluid to the discharge zone. 
     Referring next to  FIG. 4 , an enlarged view of the intrawell fluid injection system  122  of  FIG. 2  is depicted. Intrawell fluid injection system  122  includes electric submersible pump assembly  144  positioned in the center thereof. Electric submersible pump assembly  144  has a generally tubular outer housing and includes electric motor  146 , fluid intake subassembly  124 , gas separator  108 , gas discharge subassembly  110  and fluid pump  126 . Also positioned in the center of intrawell fluid injection system  122  is check valve assembly  128  and sensor subassembly  130 . Power, control signals and data may be sent between a surface control system (not pictured) and the various components of electric submersible pump assembly  144 , such as electric motor  146  and sensor subassembly  130 , via a cable assembly  150 . 
     Intrawell fluid injection system  122  also includes bypass assembly  132  that is positioned above, below and around electric submersible pump assembly  144 . In the illustrated embodiment, bypass assembly  132  includes upper manifold  134  positioned above electric submersible pump assembly  144 , lower manifold  138  positioned below electric submersible pump assembly  144  and a plurality of bypass tubes  136  positioned around electric submersible pump assembly  144 . As illustrated, bypass assembly  132  includes four bypass tubes  136  (only three of which are visible in  FIGS. 2 and 4 ) that extend between upper manifold  134  and lower manifold  138  and are circumferentially distributed about bypass assembly  132 . Even though  FIGS. 2 and 4  have described and depicted bypass assembly  132  as having a particular number of bypass tubes, it should be understood by those skilled in the art that a bypass assembly of the present invention may alternatively have any number of bypass tubes both greater than or less than that shown. Bypass assembly  132  includes sample line  160  that may extend to the surface to enable fluid sampling of production fluid from intrawell fluid injection system  122 . As described above, intrawell fluid injection system  122  is operable to be connected within a tubing string such that the portion of the tubing string above intrawell fluid injection system  122  does not transport fluid while the portion of the tubing string below intrawell fluid injection system  122  transports the production fluid to the discharge zone. 
     While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.