Patent Publication Number: US-2019186236-A1

Title: A flow control system for power generation

Description:
BACKGROUND 
     This section is intended to provide background information to facilitate a better understanding of the described embodiments. Accordingly, it should be understood that these statements are to be read in this light and not as admissions of prior art. 
     Downhole electrical generators and batteries, among others, are often used to generate and supply energy power to downhole equipment, including flow control devices, telemetry devices, sensors, and packers. However, a generator located in a downhole environment includes several limitations including restricting tubing or interfering with fluid flow through a wellbore or annulus of the wellbore. As an alternative to downhole generators, conditions occurring during operations can generate kinetic, mechanical, rotational, and thermal energy, among others types of energy. The generated energy can be converted into electrical energy to supply power to downhole drilling equipment and devices. For instance, power generated by a high-velocity fluid can drive a downhole generator where the kinetic energy of the fluid is converted into mechanical/rotational energy as it flows through a motor. The fluid flow causes a rotor within the motor to rotate a motor shaft. The rotation of the motor shaft generates electricity that can be used to power various downhole drilling equipment, such as a rotating valve sleeve. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a detailed description of the embodiments of the invention, reference will now be made to the accompanying drawings in which: 
         FIG. 1  is a schematic view of the example oilfield environment including a fracturing system, according to one or more embodiments; 
         FIG. 2  is a perspective view of an example valve assembly, according to one or more embodiments; 
         FIGS. 3A  is a front perspective view of an example valve assembly for internal power generation, according to one or more embodiments; 
         FIG. 3B  is a cross-sectional view of the valve assembly, according to one or more embodiments; 
         FIG. 3C  is a detailed cross-sectional view of the valve assembly, according to one or more embodiments; 
         FIG. 4  is a cross-sectional view of an example valve assembly, according to one or more embodiments; and 
         FIG. 5  is a schematic view of a power generation system, according to one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure describes a method and system for internal and external power generation in an oilfield environment using a downhole flow control system. In a downhole environment, multiple components, including valves, sensors, and downhole tools, often use a source of energy to operate at full capacity. Yet, rather than relying on power from an above-ground source, a flow control system of the embodiments uses rotational and fluid energy generated during downhole operations to generate and supply electrical energy. 
       FIG. 1  is a schematic view of the example oilfield environment  100 , including a multi-zone or fracturing system  142 , according to one or more embodiments. As shown in  FIG. 1 , a completion string  114  located in a wellbore  118  further extends through a subsurface formation  120 . A number of valves  130 , such as sliding sleeve-operated valves, are mounted on the completion string  114  to control fluid flow through the string  114  and into selected zones of the subsurface formation  120 . 
     The wellbore  118  includes a casing  144  that is cemented in place or otherwise secured to a wall of the wellbore  118  or a previously hung casing. The wellbore  118  may include several cased sections or the wellbore  118  may not contain any casing, often referred to as an “openhole”. In one or more embodiments, perforation tunnels  146  can be formed in the subsurface formation  120 , as well as, the casing  144  using a perforation tool (not shown) such as a perforating gun, hydro-jetting, or other tools as known in the art. The perforation tunnels  146  can be formed in one or more zones of the subsurface formation  120  based on formation characteristics (e.g., formation type, density, resistivity, porosity, etc.) surrounding the wellbore  118 . One or more annular sealing devices  148  are mounted on the completion string  114  between the valves  130 . The annular sealing devices  148  can include mechanically, hydraulically, electromechanically, chemically, or temperature-activated packers, plugs, or other isolation devices to isolate the zones of the subsurface formation  120  or other sections of the wellbore  118 . 
     The multi-zone or fracturing system  142  can produce or deliver a fluid to and/or from one or more downhole locations and into the perforation tunnels  146 , including both new and existing perforation tunnels  146 . The injected fluid can include a fracturing fluid, a completion fluid, a treatment fluid, formation sand, and the like, that is stored in a storage unit  154 , for example, a tank, pipeline, or the like. The perforation tunnels  146 , which may be formed deep into the subsurface formation  120 , also increase the surface area for produced hydrocarbons to flow from a zone(s) of the subsurface formation  120  and into the wellbore  118  and/or an annulus area  138  of the wellbore  118 . 
     The valves  130  receive and regulate the flow of the fluid as it flows downward or upward through the completion string  114 . Additionally, during operations, the valves  130  can supply electrical power to various equipment located in the wellbore  118 . Specifically, the flow of the fluid through the valves  130  is converted to rotational energy to rotate magnetic components within the valve  130 , thereby, generating a varying magnetic field. An electrical conductor, such as a wire, is located in the valves  130  to receive and convert the varying magnetic field into electrical energy. The generated electrical energy can be used to power downhole devices, components, and the like, attached to and/or located near the completion string  114 . Accordingly, the valves  130  provide a downhole power source and eliminate the need of an electrical control line(s) extending from a surface  156  and into the wellbore  118  to deliver downhole power. 
     Various types of valves  130  may be used along the length of the completion string  114 . Further, the configuration and the number of valves  130  positioned in the wellbore  118  for power generation will vary depending on power requirements and the availability of other power sources, among other considerations. 
     Note, the oilfield environment  100  of  FIG. 1  is merely exemplary in nature and that various additional components may be present that have not necessarily been illustrated in the interest of clarity. For example, additional components that may be present include, but are not limited to, supply hoppers, adapters, joints, gauges, sensors, compressors, pressure controllers, pressure sensors, flow rate controllers, flow rate sensors, temperature sensors, and the like. 
       FIG. 2  is a perspective view of an example valve assembly  230 , according to one or more embodiments. The valve assembly  230  is configured to receive and control a flow of a fluid  202  as it flows through a hollow passageway  204  of a tubular string  214  located in a wellbore  218 . The valve assembly  230  includes a hollow body  208  to receive the flow of the fluid  202  which can flow into or out of the valve assembly  230  depending on the characteristics of a well, e.g., a producer well or an injector well. 
     The valve assembly  230  includes a valve element, such as a rotatable sliding sleeve  217  to regulate the flow of the fluid  202  as it flows through the hollow body  208 . As the fluid  202  flows across the valve assembly  230 , a pressure differential is created to cause the sleeve  217  to rotate to configure a port(s)  256 , formed in the hollow body  208 , into an open or closed position. To provide an open port position, the sleeve  217  rotates to expose the openings of the port  256  so that the fluid  202  flows through the port  256  and into an annular area  238  located between the tubular string  214  and an inner wall of the wellbore  218 . In a closed port position, the sleeve  217  may rotate to cover the openings of the port  256 , and thus, prevent fluid flow through the port  256  and into the annular area  238 . As the fluid  202  enters and exits the valve assembly  230 , a velocity of the fluid  202  rotates a rotor assembly  222  attached to the sleeve  217 . The rotating motion of the rotor assembly  222  provides a rotatable, turbine effect to generate energy, as will be further explained. 
     In the embodiments, the rotor assembly  222  includes a rotatable bearing  224  with one or more openings  226 . For the convenience of this discussion, the rotor assembly  222  will be described as including multiple openings  226 . In the embodiments, the openings  226  are arranged longitudinally within and spaced along a circumference of the rotatable bearing  224 . The openings  226  are formed at an angled orientation with respect to the direction of fluid flow and may be in the form of a hole, oval, slot, or any other type of opening capable of receiving the fluid  202 . As the fluid flows across the rotatable bearing  224 , the openings  226  receive the fluid  202  and cause the rotor assembly  202 , including the rotatable bearing  224 , to rotate. 
     The openings  226  are designed to convert the energy created by the velocity of the fluid  202  into mechanical/rotational energy to provide torque to other downhole equipment and devices. As will be further discussed, the mechanical/rotational energy generated by the rotational motion of the rotatable bearing  224  is used in conjunction with one or more electric lines or conductors (not shown) disposed within the valve assembly  230  to provide a power generation system. 
     Depending on the parameter conditions associated with the fluid  202 , the rotational speed of the rotatable bearing  224  can correspond with the rotational speed of the sleeve  217 . As depicted in  FIG. 2 , the sleeve  217  is assembled to and forms part of the valve assembly  230 . In some embodiments, the sleeve  217  may be configured as a separate component from the valve assembly  230 . For instance, the sleeve  217  may be disposed in various areas along the longitudinal axis of tubular string  214 , such as, above or below the valve assembly  230 . It would be understood that the valve assembly  230  may include components other than a sleeve, such as a plug, to control and regulate fluid flow within the tubular string  214 . 
       FIGS. 3A  is a front perspective view of an example valve assembly  330  for internal power generation, according to one or more embodiments. The valve assembly  330  includes a rotor assembly  322  composed of a rotatable bearing  324  and internal openings  326 , among other components further described with respect to  FIG. 3B . In one or more embodiments, the one or more openings  326  formed within the rotatable bearing  324  include angled openings arranged in a pattern. The design and arrangement of the openings  326  are configured to rotate the rotatable bearing  324  upon passage of a fluid through the openings  326  and through an internal passageway  332  of the valve assembly  330 . 
       FIG. 3B  is a cross-sectional view of the valve assembly  330 , according to one or more embodiments. In addition to the rotor assembly  322 , the valve assembly  330  includes a sliding sleeve  317  and one or more magnets  310  rotatably mounted and/or embedded within the rotatable bearing  324 . Due to the angle of the openings  326 , the force of a fluid  302  flowing into the valve assembly  330  is used to rotate the rotatable bearing  324  as the fluid flows through the openings  326 . As the rotatable bearing  324  rotates continuously or intermittently, the magnet(s)  310  also rotates. The sleeve  317  may be connected with the rotatable bearing  324  such that rotation of the rotatable bearing  324  also rotates the sleeve  317 . 
       FIG. 3C  is a detailed cross-sectional view of the valve assembly  330 , according to one or more embodiments. It will be appreciated that the valve assembly  330  can be used as a power generating structure to generate and supply power to other components located in a wellbore. 
     One or more electrical conductors  328 , depicted as dashed lines, are located in a groove  334  of a stator  336  to be protect from the fluid  302  flowing into and across the valve assembly  330 . In particular, the electrical conductors  328  are displaced at a relative distance from the magnet(s)  310 . In embodiments, the conductors  328  and the magnets  310  may be distributed circumferentially about a central axial flow path of the fluid  302  as it flows into the valve assembly  330 . As the magnet(s)  310  located in the rotatable bearing  324  rotates, a varying magnetic field is created where the conductors  328  convert the varying magnetic field into an electric current to generate internal electrical power. In this regard, electrical power is created without the need for a passageway-restricting power generator located in the internal passageway  332  of the valve assembly  330 . 
     It will be appreciated that the electrical energy generated internally within the valve assembly  330  by rotation of the rotatable bearing  324  is available for use and/or stored for downhole use. In one more embodiments, the electrical energy provides an electric current to form a downhole power generator circuit (DPG) and/or can be stored as power in a battery on or near the valve assembly  330 . As an example, the stored electrical power can power a downhole valve actuation/monitoring system, gauges, or the like. 
     In some applications, the force and pressure of the fluid  302  causes damage and/or failure to the valve assembly  330  and/or other downhole components. For example, the force at which the fluid  302  enters the valve assembly  330  can impinge on and damage the sleeve  317 . Accordingly, the rotating motion of the rotor assembly  322  can minimize erosion of the flowing fluid  302  by dissipating the flow energy of the fluid  302  across the opening (i.e., circumference) of the bearing  324  and not just the area exposed to the slots. 
       FIG. 4  is a cross-sectional view of an example valve assembly  430  for external power generation, according to one or more embodiments. The valve assembly  430  includes an outer body housing  410  and an inner body housing  412  where an annular area  438  is formed therebetween. The valve assembly  430  further includes a rotor assembly  422  located in the annular area  438  and a sliding sleeve  417 . 
     The rotor assembly  422  is made of multiple magnetic rotor blades  423 . The housing  410  is configured to protect the blades  423 , for example, while running a tubular string into a well with the valve assembly  430  mounted thereon. In other embodiments, the valve assembly  430  is run without the housing  410  and the actual casing of the well acts as the housing  410 . In this way, an outer diameter of the housing  410  that is equal to or slightly larger than the rotor blades  423  is run into the well to ensure the blades  423  are centered and protected either before and/or after installation of the blades  423 . In the examples, the rotor blades  423  are made of magnetic materials and/or one or more magnets or magnetic material (not shown) is embedded within the structure of the rotor blades  423 . As the fluid  402  enters the annular area  438 , the sleeve  417  directs the flow of the fluid  402  pass the rotor blades  423  where the velocity of the fluid  202  rotates the blades  423  to create a varying magnetic field. 
     As shown in  FIG. 4 , a stator  436  is located beneath the rotor blades  423  and includes one or more openings  440  to accommodate an electrical conductor  428 , depicted as a dashed line. In examples, the openings  440  can also act as control line feed-through ports formed therein to feed a control line, e.g., hydraulic or electrical, into a next zone of the valve assembly  430 , used to actuate additional downhole devices and equipment. The openings  440  allow the electric conductor  428  and/or a control line to bypass the components of the valve assembly  430 , such as the rotor blades  423 , thus, protecting the physical integrity of the conductor  428  and/or the control line. As the rotor blades  423  rotate, a varying magnetic field is created where the conductor  428  converts the varying magnetic field into an electric current to generate electrical power. In the embodiments, the conductor  428  can be coiled (not shown) around the inner body housing  412  and/or located inside of the stator  436  to maximize energy harvesting. The valve assembly  430  generates external electrical power since the rotor blades  423  are located outside of the inner body housing  412  of the assembly  430 . Accordingly, electricity is generated downhole without the need for generating power using electrical control lines located at a surface location. The electrical energy generated downhole is available for present use and/or can be stored at a downhole location. For example, the electrical energy can provide an electric current to form a downhole power generator circuit (DPG) and/or can be stored as power in a battery on or near the valve assembly  430 . 
     It should be understood that the embodiments are not limited to the particular embodiments as shown in  FIG. 4 , but any other combination, number, configuration, and the like of rotors, stators, openings, and electrical conductors may be used. 
     The valve assemblies depicted in  FIGS. 3A-3C  and  FIG. 4  separately provide individual power generation both internally and externally, respectively. Additionally, the embodiments of  FIGS. 3A-3C  and  FIG. 4  can be combined to provide two-stage serial power generation that simultaneously allows for additional pressure drop across a tubular wellbore string and for power generation. 
       FIG. 5  is a schematic of a power generation system  500 , according to one or more embodiments. The power generation system  500  can be used to provide power in varied operations including, drilling, completing, fracturing, and production, among others. As previously described, a varying magnetic field generated by a valve assembly  330 ,  430  can be converted into electrical energy to form a DPG  507  and/or the energy can be stored, for example, in a rechargeable battery array (RBA)  508 . In one or more embodiments, the DPG  507  can serve as a power supply to power other downhole components within a tubular string  514 , such as valves, sensors, and downhole tools. 
     In embodiments, the electrical power generated in the valve assembly  530  can be used to operate and power an onboard computer (CPU)  510  that can interface with and provide power to other components within the power generation system  500  as well as other downhole components located along the tubular string  514 . As an example, the onboard CPU  510  may interface with and power a master CPU  512  to control one or more valves  530  located along a length of the tubular string  514 . In this configuration, the master CPU  512  controls operation of the valves  530  by sending logic and rules in the form of control signals to the onboard CPU  510 . Accordingly, the onboard CPU  510  may indirectly control the valves  530  autonomously based on the logic and rules received. The use of the onboard CPU  510  with the master CPU  512  provides redundancy during malfunctioning or failure of the onboard CPU  510 . In one or more embodiments, the rules and logic include instructions for optimizing the inflow characteristics of the valve  530  or actuating the valves  530 , among other actions. For example, the onboard CPU  510  may be instructed to maintain a constant window of flow differential through the valves  530  (e.g., 1000±50 psi (6.8×10 4  Pascal) at a 20% choke open position) for a set period of time. Further, the onboard CPU  510  may be instructed to shut-in the valves  530  in the event of a catastrophic event. In the preferred embodiments, the master CPU  512  may hold complete override privileges related to the operation of the valves  530 . In some cases, where manual input is not possible due to a lack of human intervention, the onboard CPU  510  can make a pre-programmed decision to provide autonomous control (i.e., without outside control from other components) of the valves  530 . 
     In the embodiments, the valves  530  may include any hydraulically operated valve, including a safety valve. The valves  530  can be equipped with a Hydraulic Module (HM)  516  which has a measured amount of hydraulic fluid that can operate the valve  530  from a fully open position to a fully closed position. In preferred embodiments, the HM  516  may interface with the onboard CPU  510  and thus, is powered and controlled by the onboard CPU  510  based on specific logic and rules programmed at the master CPU  512 . 
     In the embodiments, a position of the valves  530  can be controlled using a valve mounted configurable gauge (VCG)  518  that is configured to interface with the onboard CPU  510 . The VCG  518  can perform other functions including capturing and measuring data within the tubular string  514  in real-time. The real-time data may include, but is not limited to, position feedback, temperature and pressure, and water cut in production. Since the VCG  518  interfaces with the onboard CPU  510 , the real-time data of the VCG  518  can be monitored against the logic and rules programmed at the master CPU  512 . Accordingly, the onboard CPU  510  can provide real-time decisions to autonomously control the valves  530 . Optionally, a tubing mounted permanent downhole gauge system (PDG)  520  can interface with and provide the onboard CPU  510  with measurable parameter data related to the tubular string  514 . 
     The power generated at the valves  530  is used to create a DPG  507 , power the onboard CPU  510 , and various other modules that may interface with the onboard CPU  510 . In the described embodiments, the master CPU  512 , the HM  516 , the VCG  518 , and the PDG  520  may rely on the onboard CPU  510  as a source of power to form the interdependent power generation system  500 . It would understood that the modules of the power generation system  500  including, but not limited to, the DPG  507 , the RBA  508 , the onboard CPU  510 , the master CPU  512 , the HM  516 , and the VCG  518 , may be located within the tubular string  514  and in close proximity to the valves  530 . In the embodiments, the master CPU  512  may include a surface computer located, for example, in a control room. In other embodiments, the master CPU  512  may be located in a downhole environment and remotely controlled from a remote location, e.g., the control room. It should be further understood that although the power generation system  500  is illustrated as providing power to downhole components, the system  500  could additionally power above ground surface components. 
     In addition, to the embodiments described above, many examples of specific combinations are within the scope of the disclosure, some of which are detailed below: 
     Example 1. A valve assembly for use in controlling flow of a fluid in a wellbore, comprising a housing including an internal passageway, a conductor located adjacent to the internal passageway, a rotor assembly located outside of the internal passageway and comprising a magnet having a magnetic field and rotatable with the rotor assembly, and a flow path to receive a flow of the fluid therethrough to rotate the rotor assembly, herein rotation of the rotor assembly and the magnet relative to the conductor produces electrical energy in the conductor. 
     Example 2. The valve assembly of Example 1, wherein the magnet is embedded within a rotatable bearing of the rotor assembly to produce internal electrical energy. 
     Example 3. The valve assembly of Example 1, wherein the magnet is embedded within a blade of the rotor assembly to generate external electrical energy. 
     Example 4. The valve assembly of Example 1, further comprising a central processing unit (CPU) powered by the electrical energy. 
     Example 5. The valve assembly of Example 1, further comprising a battery configured to store the electrical energy. 
     Example 6. The valve assembly of Example 5, wherein the battery further comprises a rechargeable battery array configured to be rechargeable by the electrical energy. 
     Example 7. The valve assembly of Example 1, wherein the rotatable assembly configured to rotate continuously or intermitted to change the magnetic field of the magnet. 
     Example 8. A control system for downhole applications, comprising, a valve assembly configured to control a flow of a fluid in a wellbore, comprising, a housing including an internal passageway, a conductor located adjacent to the internal passageway, a rotor assembly located outside of the internal passageway comprising a magnet having a magnetic field and rotatable with the rotor assembly, and a flow path to receive a flow of the fluid therethrough to rotate the rotor assembly, wherein rotation of the rotor assembly and the magnet relative to the conductor produces electrical energy in the conductor, and a central processing unit (CPU) configured to control one or more valves, wherein the electrical energy is used to power the CPU. 
     Example 9. The control assembly of Example 8, further comprising a master central processing unit (CPU) configured to interface with and to provide control signals to the CPU and wherein the CPU supplies power to the master CPU. 
     Example 10. The control assembly of Example 9, wherein the control signals comprise logic to actuate the one or more valves. 
     Example 11. The control assembly of Example 9, wherein the control signals comprise logic to optimize flow characteristics of the one or more valves. 
     Example 12. The control assembly of Example 8, wherein the CPU is a slave to a master CPU and wherein the master CPU directly controls the one or more valves. 
     Example 13. The control assembly of Example 8, wherein the CPU autonomously controls the one or more valves via a pre-programmed signal when a master CPU is inoperable. 
     Example 14. The control assembly of Example 8, wherein the CPU monitors real-time downhole parameter data against a control signal of a master CPU. 
     Example 15. The control assembly of Example 8, further comprising a gauge system configured to measure parameters for the downhole applications and to provide real-time downhole parameter data. 
     Example 16. The control assembly of Example 8, wherein the CPU is configured to power and control one or more components attached to the one or more valves. 
     Example 17. A method for operating a valve assembly, comprising maintaining ports of the valve assembly in an open position to permit a fluid to flow through an internal passageway of the valve assembly, flowing the fluid through an opening of a rotor assembly located outside of the internal passageway to rotate the rotor assembly, wherein the rotation rotates a magnet attached to the rotor assembly to vary a magnetic field of the magnet, and exposing a conductor located adjacent to the rotor assembly to the varying magnetic field to produce electrical energy in the conductor. 
     Example 18. The method of Example 17, further comprising supplying the electrical energy to a central processing unit (CPU) to control a function of a valve located in a downhole environment. 
     Example 19. The method of Example 18, further comprising interfacing a master CPU with the CPU, wherein the CPU supplies power to the master CPU. 
     Example 20. The method of Example 17, further comprising storing the electrical energy in a battery for further use in a downhole environment. 
     This discussion is directed to various embodiments of the present disclosure. The drawing figures are not necessarily to scale. Certain features of the embodiments may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. It is to be fully recognized that the different teachings of the embodiments discussed may be employed separately or in any suitable combination to produce desired results. In addition, one skilled in the art will understand that the description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment. 
     Certain terms are used throughout the description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function, unless specifically stated. In the discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. In addition, the terms “axial” and “axially” generally mean along or parallel to a central axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to the central axis. The use of “top,” “bottom,” “above,” “below,” and variations of these terms is made for convenience, but does not require any particular orientation of the components. 
     Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present disclosure. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. 
     Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims.