Patent Publication Number: US-10323494-B2

Title: Hydrocarbon production system and an associated method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims priority and benefit under 35 U.S.C. § 119(e) from U.S. Provisional Application No. 62/195,814 entitled “SYSTEM AND METHOD FOR WELL PARTITION AND DOWNHOLE SEPARATION OF WELL FLUIDS”, filed on Jul. 23, 2015, which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     Embodiments of the present invention relate to a hydrocarbon production system, and more particularly, to a system and method for separation and disposal of water and a solid medium from a production fluid. 
     Non-renewable hydrocarbon fluids such as oil and gas are widely used in various applications for generating energy. Such hydrocarbon fluids are generally extracted from the hydrocarbon wells which extend below a surface of earth to a region where the hydrocarbon fluids are available. Generally, the hydrocarbon fluids are not available in a purified form and are available as a mixture of hydrocarbon fluids, water, sand, and other particulate matter together referred to as a well fluid. Such well fluids are filtered using different mechanisms to extract a hydrocarbon rich stream and a water stream. 
     Generally, well fluids are extracted from a hydrocarbon well to a surface of the earth and then separated using a separator to produce oil and water. In such an approach, water separated from the well fluids is distributed and transported to a plurality of locations for disposal. One such location may include a water disposal zone located within the hydrocarbon well. However, such a process may increase capital investment and operational costs for water disposal. Further, disposal of water including sand and other particulate matter may result in plugging of the disposal zone. Further, such a process results in increased electric power consumption by the pumps used for transferring the well fluids to the surface. Further, any damage to the pumps due to the presence of the sand and other particulate matter in the well fluids is not prevented. 
     Accordingly, there is a need for an enhanced system and method for separation and disposal of water and a solid medium from a production fluid. 
     BRIEF DESCRIPTION 
     In accordance with one exemplary embodiment, a system for separation and disposal of water and a solid medium from a production fluid is disclosed. The system includes a casing-liner, a first downhole separator, a production pump, a second downhole separator, and a tube. The casing-liner is disposed within a wellbore casing disposed in a wellbore to define an annular disposal zone between the casing-liner and the wellbore casing. The first downhole separator is disposed within the wellbore casing and is configured to receive a production fluid from a production zone and generate a hydrocarbon rich stream and a water stream including a solid medium from the production fluid. The production pump is disposed within the wellbore casing and coupled to the first downhole separator and a surface unit. The production pump is configured to pump the hydrocarbon rich stream from the first downhole separator to the surface unit via a channel. The second downhole separator is disposed above the casing-liner within the wellbore casing and coupled to the first downhole separator. The second downhole separator is configured to receive the water stream including the solid medium from the first downhole separator and separate the solid medium from the water stream to generate a separated water stream. Further, the second downhole separator is configured to dispose the solid medium to the annular disposal zone. The tube is coupled to the second downhole separator and configured to dispose the separated water stream from the second downhole separator to a water disposal zone in the wellbore. 
     In accordance with another exemplary embodiment, a method for separation and disposal of water and a solid medium from a production fluid is disclosed. The method involves transferring a production fluid from a production zone to a first downhole separator disposed within a wellbore casing disposed within a wellbore. The method further involves generating a hydrocarbon rich stream and a water stream including the solid medium, from the production fluid, using the first downhole separator disposed within the wellbore casing. Further, the method involves feeding the hydrocarbon rich stream from the first downhole separator, using a production pump to a surface unit via a channel. The production pump is disposed within the wellbore casing. The method further involves transferring the water stream including the solid medium, from the first downhole separator to a second downhole separator disposed within the wellbore casing. Further, the method involves separating the solid medium from the water stream to generate a separated water stream, using the second downhole separator. The method further involves disposing the solid medium from the second downhole separator to an annular disposal zone defined between a casing-liner and the wellbore casing. The casing-liner is disposed within the wellbore casing and below the second downhole separator. Further, the method involves disposing the separated water stream from the second downhole separator to a water disposal zone in the wellbore, via a tube. 
    
    
     
       DRAWINGS 
       These and other features and aspects of embodiments of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG. 1  is a schematic diagram of a system disposed in a hydrocarbon well for separation and disposal of water and a solid medium from a production fluid in accordance with one exemplary embodiment; and 
         FIG. 2  is a schematic diagram of a portion of the system disposed in the hydrocarbon well in accordance with the exemplary embodiment of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention discussed herein relate to a system and method for separation and disposal of water and solid medium from a production fluid. In one embodiment, the system includes a casing-liner, a first downhole separator, a production pump, a second downhole separator, and a tube disposed within a wellbore casing of a wellbore. The casing-liner is disposed within the wellbore casing to define an annular disposal zone between the casing-liner and the wellbore casing. The first downhole separator is disposed within the well bore casing configured to receive a production fluid from a production zone and generate a hydrocarbon rich stream and a water stream including a solid medium, from the production fluid. The production pump is disposed within the well bore casing and coupled to the first downhole separator and a surface unit and configured to pump the hydrocarbon rich stream from the first downhole separator to the surface unit via a channel. The second downhole separator is disposed above the casing-liner and coupled to the first downhole separator. The second downhole separator is configured to receive the water stream including the solid medium from the first downhole separator and separate the solid medium from the water stream to generate a separated water stream. The second downhole separator is further configured to dispose the solid medium to the annular disposal zone. The tube is coupled to the second downhole separator and configured to dispose the separated water stream from the second downhole separator to a water disposal zone in the wellbore. 
     In certain embodiments, the first downhole separator separates the water stream including the solid medium from the production fluid, thereby preventing pumping the production fluid including water and solid medium, to the surface unit. As a result, electric power consumption by the production pump and damage of the production pump are prevented. Further, the second downhole separator separates the solid medium from the water stream, thereby preventing disposing the water stream including the solid medium directly into the water disposal zone. As a result, plugging of the water disposal zone is reduced. The system further controls a motor used to drive the first downhole separator and a control valve coupled to the channel based on one or more signals received from a plurality of sensors. The speed of the motor and an outlet pressure of the hydrocarbon rich stream in the channel are adjusted for optimum separation of the water stream including solid medium from the production fluid. The system further includes a jumper cable coupled to the motor and a lift system including the production pump and configured to supply electric power directly from the lift system to the motor. The system further includes sand and proppant proof system disposed covering a gear train coupled to the motor and the first downhole separator. As a result, the gear train is sealed from the production fluid to avoid plugging by the solid medium. 
       FIG. 1  illustrates a schematic diagram of a system  102  disposed in a hydrocarbon well  100  in accordance with one exemplary embodiment. 
     The hydrocarbon well  100  extends below a surface  104  of earth to a region where the hydrocarbon fluids are available. The hydrocarbon well  100  is used to produce a production fluid  106  (hereinafter also referred to as “well fluid”) which is a mixture of hydrocarbon fluids, water, sand, proppant, and other particulate matter. In some embodiments, the proppant, sand and other particulate matter may be referred to as a “solid medium”. The hydrocarbon well  100  includes a wellbore  108  drilled downwards from the surface  104  of the earth. The wellbore  108  extends up to a predetermined depth, for example, about 6500 feet from the surface  104  to form a vertical leg  110 . A wellbore casing  112  is disposed within the vertical leg  110 . Cement  114  is affixed to an outer surface of the wellbore casing  112 . The hydrocarbon well  100  further includes a lateral leg  116  coupled to the vertical leg  110  via a leg junction  118 . The lateral leg  116  is used to receive the production fluid  106  from a production zone  120 . The hydrocarbon well  100  further includes a water disposal zone  122  located below the production zone  120 . 
     The system  102  includes a casing-liner  126 , a first downhole separator  128 , a production pump  130 , a second downhole separator  132 , and a tube  134 . The system  102  further includes a surface separator  136  coupled to the production pump  130  via a channel  138 . The system  102  also includes a surface unit  140  coupled to the surface separator  136  via an oil outlet manifold  142 . The system  102  further includes a first sensor  144 , a second sensor  146 , and a control unit  148 . The casing-liner  126 , the first downhole separator  128 , the production pump  130 , the second downhole separator  132 , the tube  134 , and the first sensor  144  are disposed within the wellbore casing. The surface separator  136 , the surface unit  140 , the second sensor  146 , and the control unit  148  are disposed on the surface  104  of the earth. 
     The system  102  further includes a packer  150  disposed within the wellbore casing  112  and located above the first downhole separator  128 . The packer  150  is configured to prevent flow of the production fluid  106  directly from the production zone  120  to the production pump  130 . The system  102  further includes another packer  154  coupled to a bottom end portion  156  of the casing-liner  126  and the wellbore casing  112 . The casing-liner  126  is disposed above the water disposal zone  122 . The packer  154  is configured to seal an annular disposal zone  152  formed between the casing-liner  126  and the wellbore casing  112 . Further, the system  102  includes yet another packer  158  disposed within the wellbore casing  112  and coupled to the casing-liner  126 . The packer  158  is located below the second downhole separator  132  and configured to isolate the water disposal zone  122  from the production zone  120 . 
     In the illustrated embodiment, the casing-liner  126  is disposed below the lateral leg  116  and the second downhole separator  132 . The casing-liner  126  is secured inside the wellbore casing  112  via uniformly placed spring loaded centralizer  172 . The first downhole separator  128  is disposed proximate to the leg junction  118 . In one embodiment, the first downhole separator  128  is an active separator. The system  102  further includes a tube  160  extending through the packer  150  and coupled to a first outlet  162  of the first downhole separator  128 . The production pump  130  is disposed above the packer  150  and coupled to the first downhole separator  128  and the surface unit  140 . Specifically, the production pump  130  is coupled to the surface separator  136  via a production tubing  170  and the channel  138 . The surface separator  136  is coupled to the surface unit  140  via the oil outlet manifold  142 . A control valve  176  is coupled to the channel  138 . The system  102  further includes a lift system  164  disposed above the packer  150 . The lift system  164  includes a motor  166 , a gas separator  168 , and the production pump  130 . In one embodiment, the lift system  164  is an electrical submersible pump (ESP) system. 
     The second downhole separator  132  is disposed above the casing-liner  126  and coupled to the first downhole separator  128 . The second downhole separator  132  is further coupled to the casing-liner  126  and to the tube  134 . In one embodiment, the second downhole separator  132  is a passive separator. 
     The first sensor  144  is operatively coupled to the first outlet  162  of the first downhole separator  128 . The second sensor  146  is operatively coupled to the channel  138 . In some embodiments, the first sensor  144  may be disposed in the tube  160  coupled the first outlet  162  of the first downhole separator  128 . The first sensor  144  and the second sensor  146  are further communicatively coupled to the control unit  148 . In one embodiment, the first sensor  144  is a flow sensor and the second sensor  146  is a density meter or a densometer. In some other embodiments, the first sensor  144  may be a pressure sensor. 
     The system  102  further includes a motor  174  disposed within the wellbore casing  112  and coupled to the first downhole separator  128 . The control unit  148  is further communicatively coupled to the motor  174  and the control valve  176 . The system  102  further includes a power source  180  coupled to the lift system  164  via a power cable  182 . Specifically, the power cable  182  is coupled to the motor  166  of the lift system  164 . The power source  180  is disposed at the surface  104  of the earth. The system  102  further includes a jumper cable  184  extending from the power cable  182  and coupled to the motor  174  and the lift system  164 . Specifically, the jumper cable  184  is coupled to the motor  166  of the lift system  164 . The system  102  further includes a gas outlet manifold  186  coupled to a wellhead  188  disposed at the surface  104  of the earth covering the wellbore casing  112 . 
     During operation, the wellbore  108  receives the production fluid  106  from the production zone  120 . Specifically, the production fluid  106  enters the lateral leg  116  through a plurality of perforations (not shown in  FIG. 1 ). The vertical leg  110  receives the production fluid  106  via the lateral leg  116 . The production fluid  106  in the wellbore  108  is directed to the first downhole separator  128  via a first jet pump (not shown in  FIG. 1 ) disposed within the wellbore casing  112 . The first downhole separator  128  is used to generate a hydrocarbon rich stream  190  and a water stream  192  including a solid medium  198  from the production fluid  106 . The tube  160  is used to transfer the hydrocarbon rich stream  190  from the first downhole separator  128  to a portion of the wellbore casing  112  above the packer  150 . The gas separator  168  is configured to receive the hydrocarbon rich stream  190  from the first downhole separator  128  via a plurality of inlets (not shown in  FIG. 1 ). The gas separator  168  is used to separate a gaseous medium  212  from the hydrocarbon rich stream  190  before feeding the hydrocarbon rich stream  190  to the production pump  130 . The gaseous medium  212  is then filled in the top portion of the wellbore casing  112 . The gas outlet manifold  186  is used to discharge the gaseous medium  212  collected within the top portion of the wellbore casing  112  to a discharge storage facility, a compressor, or the like via the wellhead  188 . 
     The production pump  130  is configured to pump the hydrocarbon rich stream  190  received from the first downhole separator  128  to the surface unit  140  via the gas separator  168 , the production tubing  170 , the channel  138 , and the surface separator  136 . In such embodiments, the surface separator  136  is configured to generate oil  194  and a water rich stream  196  from the hydrocarbon rich stream  190 . The oil outlet manifold  142  transfers the oil  194  from the surface separator  136  to the surface unit  140 . The water rich stream  196  in the surface separator  136  may be disposed to a plurality of disposal locations including but not limited to a well-head well (not shown in figures). 
     The second downhole separator  132  is configured to receive the water stream  192  including solid medium  198  from the first downhole separator  128  via a second jet pump (not shown in  FIG. 1 ). The second downhole separator  132  is used to separate a solid medium  198  from the water stream  192  to generate a separated water stream  200 . The second downhole separator  132  is further configured to dispose the solid medium  198  to the annular disposal zone  152 . Further, the tube  134  is used to dispose the separated water stream  200  to the water disposal zone  122 . In one embodiment, the system  102  may further include a booster pump (not shown in  FIG. 1 ) coupled to the tube  134  and configured to pressurize the separated water stream  200  and then dispose the separated water stream  200  in the water disposal zone  122 . Specifically, the wellbore casing  112  includes a plurality of perforations  202  located at the water disposal zone  122  to dispose the separated water stream  200  in the water disposal zone  122 . 
     During operation, the first sensor  144  is configured to measure a flow rate of the hydrocarbon rich stream  190  at the first outlet  162  of the first downhole separator  128 . The first sensor  144  is configured to generate a first signal  204  representative of the flow rate of the hydrocarbon rich stream  190 . Similarly, the second sensor  146  is configured to measure a density of the hydrocarbon rich stream  190  in the channel  138 . The second sensor  146  is configured to generate a second signal  206  representative of the density of the hydrocarbon rich stream  190 . The control unit  148  is configured to receive at least one of the first signal  204  and the second signal  206  from the first sensor  144  and the second sensor  146  respectively. 
     In one embodiment, the control unit  148  is configured to generate and transmit a first control signal  208  to the motor  174  to control a speed of the motor  174  based on at least one of the first signal  204  and the second signal  206 . In another embodiment, the control unit  148  is configured to determine an amount of water content in the hydrocarbon rich stream  190  based on the second signal  206 . Further, the control unit  148  is configured to generate and transmit a second control signal  210  to the control valve  176  based on at least one of the first signal  204  and the second signal  206 . In such an embodiment, the control valve  176  is used to regulate a flow rate of the hydrocarbon rich stream  190  (i.e. an outlet pressure of the hydrocarbon rich stream  190 ) through the channel  138  to the surface separator  136 . In a specific embodiment, the control unit  148  may determine the amount of water content in the hydrocarbon rich stream  190  by comparing obtained value from the second signal  206  with one or more predefined values stored in a look-up table, database, or the like. The speed of the motor  174  and the flow rate of the hydrocarbon rich stream  190  in the channel  138  are adjusted for optimum separation of the water stream including the solid medium  198  from the production fluid  106 . In one embodiment, if the obtained value is less than or equal to the predefined value, the control unit  148  may allow continuous flow of the hydrocarbon rich stream  190  through the channel  138 . In another embodiment, if the obtained value is greater than the predefined value, the control unit  148  may control an outlet pressure of the hydrocarbon rich stream  190  flowing through the channel  138  by controlling the control valve  176 . 
     In one embodiment, if the amount of water content in the hydrocarbon rich stream  190  is greater than 30 percent, the control unit  148  is configured to control the outlet pressure of the hydrocarbon rich stream  190  flowing through the channel  138  by controlling the control valve  176  based on the second signal  206 . As a result, the first downhole separator  128  disposed within the wellbore casing  112  separates the water stream  192  from the production fluid  106  more efficiently. In another embodiment, if the amount of water content in the hydrocarbon rich stream  190  is less than or equal to 30 percent, the control unit  148  may allow continuous flow of the hydrocarbon rich stream  190  through the channel  138 . 
     In one embodiment, the control valve  176  may include a hydraulic choke valve or an electronic regulator valve. The control unit  148  may be a processor-based device. In some embodiments, the control unit  148  may include a proportional-integral-derivative (PID) controller which may be integrated within the control valve  176 . In some other embodiments, the control unit  148  may be a general purpose processor or an embedded system. The control unit  148  may be operated via an input device or a programmable interface such as a keyboard or a control panel. A memory module of the control unit  148  may be a random access memory (RAM), read only memory (ROM), flash memory, or other type of computer readable memory. The memory module of the control unit  148  may be encoded with a program for controlling the control valve  176  and the motor  174  based on various conditions at which the control valve  176  and the motor  174  respectively are defined to be operable. 
       FIG. 2  is schematic diagram of a portion  214  of the system  102  disposed in the hydrocarbon well  100  in accordance with the exemplary embodiment of  FIG. 1 . 
     As discussed previously, the first downhole separator  128  is disposed within the wellbore casing  112  and proximate to the leg junction  118 . In the illustrated embodiment, the first downhole separator  128  is a rotary separator such as a centrifugal separator including a plurality of rotating elements  216 . In some other embodiments, the first downhole separator  128  may be a gravity based separator. In certain other embodiments, the first downhole separator  128  may be a heater-treater, a filtering device, a hydro cyclone based separator, or the like. The motor  174  is coupled to the first downhole separator  128  via a gear train  218  covered by the sand and proppant proof  220 . The gear train  218  is used to transfer rotary motion from the motor  174  to the first downhole separator  128 . The sand and proppant proof system  220  is used to seal the gear train  218  from the production fluid  106  and avoiding plugging of solid medium  198 . Specifically, the gear train  218  is coupled to the plurality of rotating elements  216  disposed within a casing  222  of the first downhole separator  128 . In one embodiment, the motor  174  is an electric motor driven by electric power supplied via the jumper cable  184  coupled to the lift system  164 . In some other embodiments, the motor  174  may be driven by electric power supplied via a cable extending from the surface  104  of the earth. In certain other embodiments, the motor  174  may be a hydraulic motor. The first jet pump  224  is disposed within the wellbore casing  112  and coupled to an inlet  226  of the first downhole separator  128 . Specifically, the first jet pump  224  is disposed proximate to the leg junction  118 . The first jet pump  224  includes a plurality of fixed vanes  228  located around the inlet  226  of the first downhole separator  128 . The system  102  further includes a motive fluid tube  230  disposed within the wellbore casing  112  and located downstream relative to the first jet pump  224 . Specifically, the motive fluid tube  230  is coupled to the booster pump  232  and to an inlet  231  of the first jet pump  224 . Further, the booster pump  232  is coupled to a first outlet  234  of the second downhole separator  132  via the tube  134 . Specifically, the tube  134  extends into the water disposal zone  122 . In one embodiment, the booster pump  232  is a passive pump, such as a hydro cyclone. In some other embodiments, the booster pump  232  may be an active pump, such as the ESP system driven by the electric power supplied via the jumper cable  184 . 
     The second jet pump  236  is coupled to a second outlet  238  of the first downhole separator  128  and to an inlet  240  of the second downhole separator  132 . As discussed above, the first outlet  234  of the second downhole separator  132  is coupled to the tube  134 . A second outlet  242  of the second downhole separator  132  is coupled to the casing-liner  126  via a liner hanger  244 . In one embodiment, the second downhole separator  132  is a gravity based separator device. In some other embodiments, the second downhole separator  132  may be a coalescing filter. In certain other embodiments, the second downhole separator  132  may be a media filter, a filter tube, or the like. A top end portion  246  of the casing-liner  126  is mounted below the second downhole separator  132 . The bottom end portion  156  of the casing-liner  126  is disposed above the water disposal zone  122 . 
     During operation, the first jet pump  224  directs the production fluid  106  to the first downhole separator  128 . Specifically, the plurality of fixed vanes  228  is used to generate pre-swirl to the production fluid  106  before feeding to the first downhole separator  128 . In other words, the first jet pump  224  is used to pressurize the production fluid  106  prior to introducing to the first downhole separator  128  to improve efficiency of the system  102 . Specifically, the motor  174  is configured to drive the first downhole separator  128  so as to rotate the plurality of rotating elements  216  at a predetermined speed to generate the hydrocarbon rich stream  190  and the water stream  192  from the production fluid  106 . During rotation of the first downhole separator  128 , hydrocarbons having a lower molecular weight are separated from the water and the solid medium having a higher molecular weight in the production fluid  106 . The first downhole separator  128  is further configured to discharge the water stream  192  including the solid medium  198  to the second jet pump  236  via the second outlet  238  of the first downhole separator  128 . 
     The second jet pump  236  is configured to generate pre-swirl to the water stream  192  including the solid medium  198  before feeding to the second downhole separator  132 . In other words, the second jet pump  236  is used to pressurize the water stream  192  including the solid medium  198  prior to introducing to the second downhole separator  132  to improve efficiency of the system  102 . The second downhole separator  132  is configured to separate the relatively heavier solid medium  198  from the relatively lighter separated water stream  200 . Further, the second downhole separator  132  is configured to dispose the solid medium  198  to the annular disposal zone  152  via the second outlet  242 . In one embodiment, the liner hanger  244  is configured to uniformly dispose the solid medium  198  (i.e. 360 degrees) in the annular disposal zone to avoid localized plugging of the  152  casing-liner  126 . In certain embodiments, the liner hanger  244  includes an index-able dispenser or rotatable dispenser or screw type dispenser or progressive cavity pump (PCP) dispenser. In such embodiments, the dispenser is driven by the electric power supplied via the jumper cable  184  coupled to the lift system  164 . In some other embodiments, the liner hanger  244  may include multiple sand flow lines. Additionally, the second downhole separator  132  is configured to discharge the separated water stream  200  to the tube  134  via the first outlet  234 . The booster pump  232  is used to pressurize and dispose the separated water stream  200  in the water disposal zone  122 . In such embodiments, the motive fluid tube  230  is used to transfer a portion  200   a  of the separated water stream  200  to the inlet  231  of the first jet pump  224  so as to create suction pressure at the inlet  231  of the first jet pump  224 . 
     In accordance with one or more embodiments discussed herein, an exemplary system and method discloses using a first downhole separator for separating a hydrocarbon rich stream and a water stream including solid medium from a production fluid. There is no additional cost involved for lifting the water stream and processing the water stream at the surface of earth. The exemplary system and method further discloses using a second downhole separator for separating the solid medium from the water stream to generate a separated water stream and then disposing the solid medium in an annular disposal zone and the separated water stream in a water disposal zone. As a result, plugging of the water disposal zone is prevented. Further, the exemplary system and method discloses using a jumper cable to supply power to a motor configured for driving the first downhole separator. Such a configuration prevents the need to supply power from the surface of earth using a separate cable and hence reduces the system complexity. Further, use of a sand and proppant proof system enables sealing the gear train from the production fluid. The use of sensors to determine a flow rate and density of the hydrocarbon rich stream facilitates the first downhole separator to operate at a reasonable efficiency. 
     While only certain features of embodiments have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended embodiments are intended to cover all such modifications and changes as falling within the spirit of the invention.