Patent Publication Number: US-9840933-B2

Title: Apparatus for extending the flow range of turbines

Description:
BACKGROUND 
     This disclosure relates to turbines and, more particularly, to extending the flow range of turbines. 
     Power generation turbines and alternators are used for downhole drilling operations to supply electrical power to electronic components used for measuring, logging, or sampling while drilling. As drilling mud passes through a stationary blade row in the turbine, it generates an angular momentum, or flow swirl, in expense of the pressure differential. The downstream rotating blade row, or rotor, converts that angular momentum, as well as its own reaction, into the shaft power, and supplies it to an alternator to generate electricity. During operation, the power generation turbine has to operate within a range of flow rates and as dictated by job operating conditions. This limited range of turbine operation typically does not cover the entire rig operating flow rate range that can be expected for a particular tool size. A turbine operating below an optimal flow rate range may produce insufficient power for the electronic components. A turbine operating above an optimal flow rate range may experience relatively high thermal stresses and/or accelerated wear of attached mechanical components, thus reducing reliability and service life. Moreover, replacing a damaged or worn turbine may be time-consuming and expensive and, in some instances, may be impossible once the turbine is installed downhole. Moreover, an operator may mistakenly select a turbine that is not optimized for the particular flow rate. 
     Additionally, the mud flow in the turbine typically contains suspended solid particles, such as sand. These particles, passing at a high speed across the turbine blade rows and especially at conditions outside of the turbine&#39;s flow rate range, can cause erosion to the blades or downstream turbine components. The replacement of these eroding parts may increase overall maintenance material and supply (M&amp;S) tool costs and increase service frequency. 
     SUMMARY 
     A summary of certain embodiments disclosed herein is set forth below. It should be understood that these embodiments and associated aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that the associated aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of embodiments and aspects that may not be set forth below. 
     Embodiments of this disclosure relate to an apparatus for extending the flow range of a turbine. In some embodiments, a turbine is provided that includes a movable sleeve disposed with the turbine and axially movable between a first position and a second position in response to changes in a pressure differential between a first location in the turbine and a second location in the turbine. The movable sleeve includes an inner wall and at least a portion of the inner wall having an inner conical surface. The turbine also includes a stator blade coupled to the inner wall of the movable sleeve and a rotor blade coupled to a hub of the turbine. The movable sleeve in the first position engages the tip of the stator blade with the hub of the turbine and defines a first gap having a first width between a tip of the rotor blade and the inner conical surface of the movable sleeve. The movable sleeve in the second position defines a second gap having a second width between a tip of the stator blade and the hub of the turbine, such that the second width is greater than zero. 
     In some embodiments, a turbine is provided that includes a movable sleeve disposed within the turbine and axially movable between a first position and a second position in response to changes in a pressure differential between a first location in the turbine and a second location in the turbine. The movable sleeve includes an inner wall, at least a portion of the inner wall having an inner conical surface. The turbine includes a stator blade coupled to a hub of the turbine. A first width is defined between a tip of the stator blade and the inner conical surface of the movable sleeve. The turbine also includes a rotor blade coupled to the hub of the turbine. A second width is defined between a tip of the rotor blade and the inner conical surface of the movable sleeve. The movable sleeve in the first position engages the tip of the stator blade such that the first width is about zero. The movable sleeve in the second position increases a gap between the tip of the stator blade and the surface of the hub such that the first width is greater than zero. 
     In some embodiments, an apparatus is provided that includes a first removable sleeve disposable in a turbine and having a first inner wall. The first removable sleeve defines a first width between a tip of the stator blade and the wall and defines a second width between a tip of the rotor blade and the inner conical surface of the movable sleeve. The apparatus also includes a second removable sleeve disposable within the turbine and having a second inner wall. The second removable sleeve engages the tip of the stator blade such that the first width is about zero and is configured to decrease the second width. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments and associated aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is schematic diagram of a drilling system in accordance with an embodiment of the disclosure; 
         FIGS. 2A and 2B  are schematic diagrams of a cross-section of a turbine portion having removable sleeves in accordance with an embodiment of the disclosure; 
         FIGS. 3A and 3B  are schematic diagrams of a cross-section of a turbine portion having a movable sleeve in accordance with an embodiment of the disclosure; 
         FIGS. 4A and 4B  are schematic diagrams of a longitudinal cross-section of a turbine portion having a movable sleeve in accordance with an embodiment of the disclosure; 
         FIG. 5  is a schematic diagram of an axial cross-section of the turbine portion of  FIGS. 4A and 4B  in accordance with an embodiment of the disclosure; and 
         FIGS. 6 and 7  depict streamline plots of computational fluid dynamic (CFD) results illustrating fluid flow through a turbine in accordance with an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Described herein are various implementations related to sleeves for extending the operational flow rate range of a turbine. In some embodiments, two or more removable sleeves may be used to change the cross-sectional area of a turbine. A first removable sleeve may define a stator gap between a stator blade tip and an inner wall of the sleeve and a rotor gap between a rotor blade tip and an inner wall of the sleeve. A removable sleeve may eliminate the stator gap between a stator blade tip and an inner wall of the sleeve and decrease the rotor gap between a rotor blade tip and an inner wall of the sleeve. The first removable sleeve may increase the cross-sectional area of the turbine and allow operation of the turbine at higher flow rates. 
     In some embodiments, a movable sleeve is disposed in the turbine. The movable sleeve moves between a first position and a second position in response to changes in the pressure differential across the turbine. The movable sleeve has an inner wall with an inner conical surface that defines a stator gap between a stator blade tip and the inner conical surface of the sleeve and a rotor gap between a rotor blade tip and the inner conical surface of the sleeve. The turbine includes a stationary sleeve and a spring disposed between the movable sleeve and the stationary sleeve. The spring biases the movable sleeve to the first position such that the inner conical surface of the sleeve engages the tip of the stator blade, and the stator gap is eliminated. When the pressure differential across the turbine (e.g., between a first location in turbine and a second location in the turbine) increases above a pressure differential threshold, the spring compresses and the movable sleeve moves to the second position. In the second position, the stator gap is created between the stator blade tip and the inner conical surface of the sleeve, and the width of the rotor gap is increased. 
     In some embodiments, a movable sleeve is disposed in the turbine. The movable sleeve moves between a first position and a second position in response to changes in the pressure differential across the turbine. A stator blade is coupled to the movable sleeve such that a stator gap is defined between the tip of the stator blade and the hub of the turbine. The movable sleeve has an inner wall with an inner conical surface that defines a rotor gap between a rotor blade tip and the inner conical surface of the sleeve. The turbine includes a stationary sleeve and a spring disposed between the movable sleeve and the stationary sleeve. The spring biases the movable sleeve to the first position such that the tip of the stator blade engages the hub of the turbine, and the stator gap is eliminated. When the pressure differential across the turbine increases, the spring compresses and the movable sleeve moves to the second position. In the second position, the stator gap is created between the stator blade tip and the hub of the turbine, and the width of the rotor gap is increased. 
     These and other embodiments of the disclosure will be described in more detail through reference to the accompanying drawings in the detailed description of the disclosure that follows. This brief introduction, including section titles and corresponding summaries, is provided for the reader&#39;s convenience and is not intended to limit the scope of the claims or the proceeding sections. Furthermore, the techniques described above and below may be implemented in a number of ways and in a number of contexts. Several example implementations and contexts are provided with reference to the following figures, as described below in more detail. However, the following implementations and contexts are but a few of many. 
     More specifically, a drilling system  10  is depicted in  FIG. 1  in accordance with one embodiment. While certain elements of the drilling system  10  are depicted in this figure and generally discussed below, it will be appreciated that the drilling system  10  may include other components in addition to, or in place of, those presently illustrated and discussed. It should be appreciated that the drilling system  10  depicted in  FIG. 1  is merely one example of a system that may use the turbine sleeves described herein and other systems, such as completion systems, may also use the turbine sleeves described below. As depicted, the drilling system  10  can include a drilling rig  12  positioned over a well  14 . Although depicted as an onshore drilling system  10 , it is noted that the drilling system could instead be an offshore drilling system. The drilling rig  12  can support a drill string  16  that includes a bottomhole assembly  18  having a drill bit  20 . The drilling rig  12  can rotate the drill string  16  (and its drill bit  20 ) to drill the well  14 . 
     The drill string  16  can be suspended within the well  14  from a hook  22  of the drilling rig  12  via a swivel  24  and a kelly  26 . Although not depicted in  FIG. 1 , the skilled artisan will appreciate that the hook  22  can be connected to a hoisting system used to raise and lower the drill string  16  within the well  14 . As one example, such a hoisting system could include a crown block and a drawworks that cooperate to raise and lower a traveling block (to which the hook  22  is connected) via a hoisting line. The kelly  26  can be coupled to the drill string  16 , and the swivel  24  can allow the kelly  26  and the drill string  16  to rotate with respect to the hook  22 . In the presently illustrated embodiment, a rotary table  28  on a drill floor  30  of the drilling rig  12  can be constructed to grip and turn the kelly  26  to drive rotation of the drill string  16  to drill the well  14 . In other embodiments, however, a top drive system could instead be used to drive rotation of the drill string  16 . 
     During operation, drill cuttings or other debris may collect near the bottom of the well  14 . Drilling fluid  32 , also referred to as drilling mud, can be circulated through the well  14  to remove this debris. The drilling fluid  32  may also clean and cool the drill bit  20  and provide positive pressure within the well  14  to inhibit formation fluids from entering the wellbore. In  FIG. 1 , the drilling fluid  32  can be circulated through the well  14  by a pump  34 . The drilling fluid  32  can be pumped from a mud pit (or some other reservoir, such as a mud tank) into the drill string  16  through a supply conduit  36 , the swivel  24 , and the kelly  26 . The drilling fluid  32  can exit near the bottom of the drill string  16  (e.g., at the drill bit  20 ) and can return to the surface through the annulus  38  between the wellbore and the drill string  16 . A return conduit  40  can transmit the returning drilling fluid  32  away from the well  14 . In some embodiments, the returning drilling fluid  32  can be cleansed (e.g., via one or more shale shakers, desanders, or desilters) and reused in the well  14 . The drilling fluid  32  may include an oil-based mud (OBM) that may include synthetic muds, diesel-based muds, or other suitable muds. 
     In addition to the drill bit  20 , the bottomhole assembly  18  can also include various instruments. For example, as depicted in  FIG. 1 , the bottomhole assembly  18  can include a logging-while-drilling (LWD) module  44  and a measurement-while-drilling (MWD) module  46 . Both modules can include sensors, housed in drill collars, that can collect data and enable the creation of measurement logs in real-time during a drilling operation. The modules could also include memory devices for storing the measured data. The LWD module  44  can include sensors that measure various characteristics of the rock and formation fluid properties within the well  14 . The bottomhole assembly  18  can also include one or more additional modules  48 , which could be LWD modules, MWD modules, sampling-while-drilling modules, or some other modules. It is noted that the bottomhole assembly  18  is modular, and that the positions and presence of particular modules of the assembly could be changed as desired. Further, as discussed in detail below, one or more of the modules  44 ,  46 , and  48  can be or can include a fluid sampling tool configured to obtain a sample of a fluid from a subterranean formation and perform downhole fluid analysis to measure various properties of the sampled fluid. These properties may include an estimated density and/or optical density of the OBM filtrate, the sampled fluid, and other fluids. These and other estimated properties may be determined within or communicated to the LWD module  44 , such as for subsequent utilization as input to various control functions and/or data logs. 
     The bottomhole assembly  18  can also include other modules. As depicted in  FIG. 1  by way of example, such other modules can include a turbine generator  50 , a steering module  52 , and a communication module  54 . In one embodiment, the turbine generator  50  may be driven by the flow of drilling mud through the drill string  16 , out of the drill bit  20 , and through the annulus  38  to the return conduit  40 . As seen in  FIG. 1 , the drill string  12  is generally aligned along a longitudinal z-axis. Components of the drill string  12  may be located within the drill string at various radial distances from the z-axis, as illustrated by a radial r-axis. Certain components, such as the turbine generator  50 , may include parts that rotate circumferentially along a circumferential c-axis. The turbine generator  50  may convert the hydraulic power of the drilling fluid  32  moving through the drill string  16  into mechanical rotational power in a rotating shaft. The rotating shaft may rotate along the z-axis in the same circumferential direction of the c-axis. In other embodiments, however, the turbine generator  50  may cause the rotating axis to rotate in the opposite direction. The rotating shaft, which may also include or be referred to as a rotor, provides the mechanical power that will be used to generate electrical power. The rotation of the rotating shaft may cause an alternator to generate electrical power for the electrical components. 
     The steering module  52  may include a rotary-steerable system that facilitates directional drilling of the well  14 . The communication module  54  can enable communication of data (e.g., data collected by the LWD module  44  and the MWD module  46 ) between the bottomhole assembly  18  and the surface. In one embodiment, the communication module  54  can communicate via mud pulse telemetry, in which the communication module  54  uses the drilling fluid  32  in the drill string  16  as a propagation medium for a pressure wave encoding the data to be transmitted. 
     The drilling system  10  can also include a monitoring and control system  56 . The monitoring and control system  56  can include one or more computer systems that enable monitoring and control of various components of the drilling system  10 . The monitoring and control system  56  can also receive data from the bottomhole assembly  18  (e.g., data from the LWD module  44 , the MWD module  46 , and the additional module  48 ) for processing and for communication to an operator, to name just two examples. While depicted on the drill floor  30  in  FIG. 1 , it is noted that the monitoring and control system  56  could be positioned elsewhere, and that the monitoring and control system  56  could be a distributed system with elements provided at different places near or remote from the well  14 . 
     As noted above, the turbine generator  50  may include a turbine for generating power. A turbine generator  50  may include a turbine that may operate over a range of flow rates of the drilling fluid  32 . Existing turbines may attempt to generate the required power at a minimum flow range and below a maximum free spin velocity by varying the blade angles of the turbine blades either discretely via different turbines or automatically via variable blade angle geometry. The flow rate ranges may also be extended by alternating the cross-sectional area of the turbine. An increase in the cross-sectional area, without a blade height increase, will lead to a clearance gap increase and a reduction in volumetric efficiency. In accordance with the embodiments described herein, various apparatuses are disclosed for changing the cross-sectional area of a turbine without changing the geometry of the blades to accommodate a wider range of flow rates. In some embodiments, the cross-sectional area of a turbine may be changed using a selection of removable sleeves. In some embodiments, the cross-sectional area of a turbine may be changed using axial translation of a spring-loaded movable sleeve that moves in response to the axial force generated by the fluid flow pressure of the drilling fluid  32 . 
       FIGS. 2A and 2B  depict cross-sectional side views of a turbine portion  200  having two different removable sleeves that change the cross-sectional area of the turbine portion  200  in accordance with embodiments of the disclosure.  FIG. 2A  depicts an embodiment of a turbine portion  200  having a removable sleeve  202  in accordance with an embodiment of the disclosure. As shown in  FIG. 2A , the turbine portion  200  includes a housing  204 , a hub  206 , a stator blade  208 , and a rotor blade  210 . The housing  204  and the hub  206  may define an annulus  212  having a diameter  213 . The stator blade  208  and the rotor blade  210  may be coupled to the hub  206  and disposed within the annulus  212 , with the rotor blade  210  coupled to a rotating portion of the hub  206 . In some embodiments, any number of stator blades  208  and rotor blades  210  may be included in the turbine portion  200 . Fluid flow through the turbine portion  200  is represented by arrow  214 . 
     Various removable sleeves may be inserted into the annulus  212  to define a gap between a wall of the housing  204  and the tip of a stator blade and a rotor blade. For example, as shown in  FIG. 2A , the removable sleeve  202  may be of a thickness  216  that defines a stator gap  218  of width  220  between a wall  222  of the removable sleeve  202  and a tip  224  of the stator blade  208 . Similarly, the removable sleeve  202  may define a rotor gap  226  of width  228  between the wall  222  of the removable sleeve  202  and a tip  230  of the rotor blade  210 . The inner diameter of the removable sleeve  202  may be selected to ensure that the gaps  218  and  226  change the power output and free spin velocity to satisfy the power requirements for a specific flow rate range. For example, as compared to the removable sleeve depicted in  FIG. 2B  and described below, the removable sleeve  202  in  FIG. 2A  may satisfy free spin velocity requirements at higher flow rates by increasing the stator gap  218  and the rotor gap  226 . Thus, the removable sleeve  202  may be inserted when the turbine portion  200  is used in a relatively higher flow rate range. In some embodiments, the removable sleeve  202  may include a seal  232 . The seal  232  may be selected to eliminate leakage in the passage  233  between the removable sleeve  202  and the housing  204 . 
     To change the cross-sectional area of the annulus  212 , the removable sleeve  202  may be removed from the turbine portion  200 . In some embodiments, the turbine portion  200  may be operated without a removable sleeve. In some embodiments, other removable sleeves having different inner diameters may be inserted into the annulus  212 . For example,  FIG. 2B  depicts an embodiment of the turbine portion  200  having a second removable sleeve  234  in accordance with an embodiment of the disclosure. As shown in  FIG. 2B , the second removable sleeve  234  may have a thickness  236  and a wall  238 . The second removable sleeve  234  may also include a seal  240 . In the embodiment shown in  FIG. 2B , the thickness  236  of the second removable sleeve  234  is greater than the thickness  216  of the removable sleeve  202 . The second removable sleeve  234  may define a rotor gap  242  having a width  244  between the wall  238  and the rotor tip  230 . However, in contrast to the removable sleeve embodiment depicted in  FIG. 2A , the width  244  of the rotor gap  242  is smaller than the width  228  of the rotor gap  226  of  FIG. 2A . The second removable sleeve  234  may be selected for minimum power requirements at lower flow rates. Accordingly, the inner diameter of the second removable sleeve  234  may be selected to fully close a gap between the stator tip  224  and the wall  238  of the second removable sleeve  234  and to ensure the rotor gap  242  is at its minimum allowable value to avoid rub between the rotor blade  210  and the housing  204 . In some embodiments, a removable sleeve may modify (e.g., increase or decrease) the gap between a rotor blade and the housing without changing the gap between the stator blade and the housing. In other embodiments, a removable sleeve may modify (e.g., increase or decrease) the gap between a stator blade and the housing without changing the gap between the rotor blade and the housing. 
     In the embodiments depicted in  FIGS. 2A and 2B , one stator and one rotor may be designed since the allowable flow rate range is controlled via the selection of different inner diameters for various removable sleeves. Consequently, the same stator and rotor parts may be used across a variety of flow rate conditions, and field locations may stock different removable sleeves, thus reducing M&amp;S costs. Additionally, the inner diameters of the removable sleeves may be measured to ensure that the appropriate removable sleeve is used in a particular flow rate range if, for example, part numbers or other identifications are eroded from the sleeves. In some embodiments, a stator gap and a rotor gap may create a flow bypass, such that the fluid flow near the housing may have a reduced swirl. Moreover, due to the centrifugal force, most of the erosive particles in the drilling fluid will be concentrated near the outer circumference of the annulus. The flow bypass created by the stator gap and the rotor gap may provide a low swirl flow that shields downstream components from erosion and may increase the service life or refurbish life of such components. Moreover, it should be appreciated that  FIGS. 2A and 2B  depict an example of a single stage turbine; however, the removable sleeves may be used in other embodiments having multistage turbines. 
     In some embodiments, a movable sleeve that automatically moves in response to changes in fluid flow pressure may be used to change the cross-sectional area of a turbine and change the flow rate range of the turbine.  FIGS. 3A and 3B  depict cross-sectional side views of an embodiment of a turbine portion  300  having a movable sleeve  302  in accordance with an embodiment of the disclosure. As shown in  FIG. 3A , the turbine portion  300  includes a housing  304 , a hub  306 , a stator blade  308 , and a rotor blade  310 . The housing  304  and the hub  306  may define an annulus  312 . The stator blade  308  and the rotor blade  310  may be coupled to the hub  306  and disposed within the annulus  312 , with the rotor blade  310  coupled to a rotating portion of the hub  306 . In some embodiments, any number of stator blades  308  and rotor blades  310  may be included in the turbine portion  300 . Fluid flow through the turbine portion  300  is represented by arrow  314 . 
     The movable sleeve  302  may include an inner wall  316  having a conical surface  317  and a seal  318 . The illustrated turbine portion  300  also includes a stationary sleeve  320  having debris excluders  322  that may prevent the spring from collecting solids that could restrict movement of the spring  324 . A spring  324  may be disposed between the movable sleeve  302  and the stationary sleeve  320 , such as in a spring cavity  325 . As described further below, the movable sleeve  302  may translate axially within the annulus  312  to define (e.g., increase, decrease, or eliminate) a gap between the stator and a wall of the movable sleeve  302  and a gap between the rotor and a wall of the movable sleeve  302 . 
     As shown in  FIG. 3A , the movable sleeve  302  may be in a first position such that the spring  324  is in a preloaded state. At relatively low flow rates and as shown in  FIG. 3A , the spring  324  may bias the movable sleeve  302  in the direction indicated by arrow  327  to push the movable sleeve  302  against the stator blade  208 . Thus, in the first position illustrated in  FIG. 3A , the gap between a tip  326  of the stator blade  308  and the wall  316  of the movable sleeve  302  is eliminated, such that the tip  326  of the stator blade  308  has zero radial clearance with the conical surface  317 . In the first position, a rotor gap  328  having a width  330  may be defined between a tip  332  of the rotor blade  310  and the wall  316  of the movable sleeve  302 , such that a minimal radial clearance exists between the movable sleeve  302  and the rotor blade tip  332  to avoid rubbing during operation of the turbine including shock conditions. In some embodiments, in the first position a relatively small gap may be maintained between the stator blade tip  326  and the wall  316 . In such embodiments, a small gap in the first position may aid in minimize vibration or chattering at “lift-off” of the turbine. 
     In some embodiments, the inner conical surface  334  of the movable sleeve  302  may have a similar or equal conical angle to the meridional profiles of the rotor tip  332 , the stator tip  326 , or both. Similarly, various portions of the hub  306  may have angled surfaces that may, in some embodiments, equal the conical angle of the inner conical surface  334 , the stator tip  326 , the rotor tip  332 , or a combination thereof. In other embodiments, the movable sleeve  302  may have an inner surface having a different shape other than a conical surface. 
     As the fluid flow increases in the direction indicated by arrow  308 , the pressure differential across the turbine portion  300  (e.g., between a first location and a second location in the turbine portion  300 ) may increase, resulting in an increase in the axial force on the movable sleeve  302  in the direction indicated by arrow  342 . The movable sleeve  302  may translate axially, in the direction depicted by arrow  342 , when the pressure differential exceeds a threshold pressure.  FIG. 3B  depicts the turbine portion  300  after movement of the movable sleeve  302  in the axial direction depicted by arrow  342 . After the fluid pressure exceeds a threshold pressure, the movable sleeve  302  may move to the second position depicted in  FIG. 3B  to create or increase a gap between the stator blade  308  and the wall  316  of the movable sleeve  302 . Similarly, the movable sleeve  302  may move to the second position depicted in  FIG. 3B  to increase a gap between the rotor blade  310  and the wall  316  of the movable sleeve  302 . It should be appreciated that although  FIGS. 3A and 3B  illustrate two positions of the movable sleeve  302 , the movable sleeve  302  may move to any number of positions between the first position and the second position illustrated in  FIGS. 3A and 3B  respectively. For example, as the pressure differential changes, the movable sleeve  302  may continuously move between the positions illustrated in  FIGS. 3A and 3B  and may stop movement at an intermediate position based on the pressure differential. The movable sleeve  302  may also assist in compensating for the occurrence of multiphase flows, e.g. such as in underbalance drilling operations, with appearance of gas slugs and hence abrupt density variations. The movable sleeve  302  may be responsive to a change of the density by variation of drag force on the movable sleeve  302 , adjusting its axial position accordingly, and thus enabling continued power output of the turbine. 
     As shown in  FIG. 3B , the movable sleeve  302  in the second position defines a stator gap  344  of width  346  between the wall  316  of the movable sleeve  302  and the tip  326  of the stator blade  308 . In the second position shown in  FIG. 3B , a rotor gap  350  has a width  352  greater than the width  330  defined when the movable sleeve  302  is in the first position. The spring  324  may be selected to determine the threshold pressure at which the spring compresses and the movable sleeve  302  translates, such that the gaps  344  and  350  are gradually opened while still providing sufficient force in all positions to restrict undesired movement of the movable sleeve  302  when the turbine portion  300  is subjected to axial shocks. 
     The axial movement of the movable sleeve  302  in the direction indicated by arrow  342  is restricted by the stationary sleeve  320 , such that for a given wedge angle the movable sleeve  302  can translate a distance that opens sufficient clearance gaps for a maximum flow accommodated by the turbine portion  300 . Seals  322  may be disposed between the stationary sleeve  320  and the movable sleeve  302  to prevent fluid leakage. In some embodiments, a small clearance flow passage between sleeves  302  and  320  may be used as a fluid shock absorber. Additionally or alternatively, in some embodiments, a gap  354  between the stationary sleeve  320  and the movable sleeve  302  may serve as a fluid shock absorber. The gap  354  may be selected to provide sufficient fluid viscous damping to counteract the effects from shock, vibrations, and fluid pressure pulsations. In some embodiments, fluid may be restricted in and out from the spring cavity  325  to absorb fluid energy. 
     As shown in  FIG. 3B , the movable sleeve  302  may move to the first position in the direction indicated by arrow  356  when the fluid pressure differential decreases below a pressure differential threshold, such that the axial force exerted by the spring  324  in the direction indicated by arrow  356  moves the movable sleeve  302  in that direction. The axial movement of the movable sleeve  302  in the direction indicated by arrow  356  is restricted by the stator blade  308 , such that the movable sleeve  302  may eliminate a gap between the stator tip  326  and the inner conical surface  334 , as shown in  FIG. 3A . 
     In some embodiments, the spring  324  may be a bi-stable spring that changes position in an abrupt transition from an initial position to a second position at a specific force value applied to the spring. In such embodiments, the spring  324  may return the movable sleeve  302  back to the initial position when the applied force is reduced below the specific force value. For example, in some embodiments a buckling plate or shell may be disposed between the stationary sleeve  320  and the movable sleeve  302 . In some embodiments, the movable sleeve  302  may be moved via a different mechanism than the spring  324 . For example, in some embodiments, a hydraulic actuator may be disposed between the stationary sleeve  320  and the movable sleeve  302 , such that increases in the pressure differential result in movement of the hydraulic actuator and movement of the movable sleeve  302 . In other embodiments, other suitable mechanisms for moving the movable sleeve  302  may be used. 
     In some embodiments, the stator gap  344 , the rotor gap  350 , or both may serve as anti-jamming gaps that enable debris in the fluid to wash out from the turbine portion  300 . In such embodiments, the gaps  344  and  350  may be selected to provide sufficiently large clearances at a relatively high flow rate. In such embodiments, the relatively high flow rate may be used to open the gaps  344  and  350  to the allowable maximum width to flush out debris. In some embodiments, anti-jamming features may also include profiling the stator tip, the rotor tip, or both to form a cutting edge to cut debris into smaller pieces. 
     In the embodiments depicted in  FIGS. 3A and 3B , a single rotor, a stator, and a movable sleeve may be selected to cover an entire operational flow range. Consequently, the same stator, rotor, and sleeves may be used across a variety of flow rate conditions, thus reducing M&amp;S costs. Additionally, since no additional sleeves are installed or different turbines are used in different operating conditions, human errors related to installing appropriate sleeves or turbines may be eliminated. Additionally, in the embodiment depicted in  FIGS. 3A and 3B , the maximum free spin velocity of the turbine portion  300  will only be achieved at the maximum flow of the operational flow range. For most of the operational flow range, the turbine will operate at lower speeds, thus increasing the life of power generation components such as face seals and increasing overall reliability. As noted above, the cross-sectional area of the turbine may increase if a large object (e.g., large debris) needs to pass through, thus enabling the turbine to operate using a smaller passage area and increase its cross-sectional area to prevent (or cure) jams. Moreover, the embodiments depicted in  FIGS. 3A and 3B  may include the flow bypass features described above with regard to the embodiment depicted in  FIGS. 2A and 2B . 
     Additionally, in some embodiments, an alternator coupled to the turbine embodiments illustrated in  FIGS. 3A and 3B  may use a simplified alternator design, since the adjustment of the cross-sectional area may result in a self-regulating turbine speed that may level out alternator speed and voltage range. Moreover, it should be appreciated that although  FIGS. 3A and 3B  depict a single stage turbine embodiment, the movable sleeves may be used in other embodiments having multistage turbines. 
       FIGS. 4A and 4B  depict cross-sectional side views of an embodiment of a turbine portion  400  having a movable sleeve  402  in accordance with another embodiment of the disclosure. As depicted in  FIG. 4A , the turbine portion  400  includes a housing  404 , a hub  406 , a stator blade  408  coupled to the movable sleeve  402 , and a rotor blade  410 . The housing  404  and the hub  406  may define an annulus  412  through which fluid may flow through the turbine portion  400 . The rotor blade  410  may be coupled to the hub  406  and disposed within the annulus  412 , with the rotor blade  410  coupled to a rotating portion of the hub  406 . In contrast to the embodiment depicted in  FIGS. 3A and 3B , the stator blade  408  is coupled to the movable sleeve  402  instead of the hub  406 . In some embodiments, any number of stator blades  408  and rotor blades  410  may be included in the turbine portion  400 . Fluid flow through the turbine portion  400  is represented by arrow  414 . 
     The movable sleeve  402  may include an inner wall  416  having a conical surface  417  and a seal  418 . The illustrated turbine portion  400  also includes a stationary sleeve  420  having debris excluders  422  that may prevent the spring from collecting solids that could restrict movement of the spring  424 . A spring  424  may be disposed between the movable sleeve  402  and the stationary sleeve  420 , such as in a spring cavity  426 . As described further below, the movable sleeve  402  and the stator blade  408  may translate axially within the annulus  412  to define (e.g., increase, decrease, or eliminate) a gap between the stator blade  408  and a surface  428  of the hub  406  and a gap between the rotor blade  410  and the inner wall  416  of the movable sleeve  402 . 
     As depicted in  FIG. 4A , the movable sleeve  402  may be in a first position such that the spring  424  is in a preloaded state. At relatively low flow rates and as shown in  FIG. 4A , the spring  424  may bias the movable sleeve  402  in the direction indicated by arrow  427  to push the stator blade  408  against the hub  406 . Thus, in the first position illustrated in  FIG. 4A , the gap between a tip  430  of the stator blade  408  and the surface  428  of the hub  406  is eliminated. In the first position, a rotor gap  432  having a width  434  may be defined between a tip  436  of the rotor blade  410  and the wall  416  of the movable sleeve  402 , such that a minimal radial clearance exists between the movable sleeve  402  and the rotor blade tip  436  to avoid rubbing during operation of the turbine including shock conditions. In some embodiments, in the first position a relatively small gap may be maintained between the stator blade tip  430  and the surface  428  of the hub  406 . As noted above, in such embodiments, a small gap in the first position may aid in minimize vibration or chattering at “lift-off” of the turbine. 
     In some embodiments, the inner conical surface of the movable sleeve  402  may have a similar or equal conical angle to the meridional profiles of the rotor tip  436 , the stator tip  430 , or both. Similarly, various portions of the hub  406  may have angled surfaces that may, in some embodiments, equal the conical angle of the inner conical surface, the stator tip  430 , the rotor tip  436 , or a combination thereof. In other embodiments, the movable sleeve  302  may have an inner surface having a different shape other than a conical surface. 
     As fluid flow increases in the direction indicated by arrow  440 , the pressure differential across the turbine portion  400  (e.g., between a first location in the turbine portion  400  and a second location in the turbine portion  400 ) may increase, resulting in an increase in the axial force on the movable sleeve  402  and the stator blade  408  in the direction indicated by arrow  440 . The movable sleeve  402  may translate axially to a second position, in the direction depicted by arrow  440 , when the pressure differential exceeds a threshold pressure differential.  FIG. 4B  depicts the turbine portion  400  after movement of the movable sleeve  402  in the axial direction depicted by arrow  440 . After the fluid pressure differential across the turbine portion  400  exceeds a threshold pressure differential, the movable sleeve  402  may move up to the second position depicted in  FIG. 4B  to create or increase a gap between the stator blade  408  and the surface  428  of the hub  406 . Similarly, movement of the movable sleeve  402  up to the second position depicted in  FIG. 4B  may increase a gap between the rotor blade  410  and the wall  416  of the movable sleeve  402 . It should be appreciated that although  FIGS. 4A and 4B  illustrate two positions of the movable sleeve  402 , the movable sleeve  402  may move to any number of positions between the first position and second position illustrated in  FIGS. 4A and 4B  respectively. For example, as the pressure differential changes, the movable sleeve  402  may continuously move between the positions illustrated in  FIGS. 4A and 4B  and may stop movement at an intermediate position based on the pressure differential. In some embodiments, the movable sleeve  402  may also assist in compensating for the occurrence of multiphase flows, e.g. such as in underbalance drilling operations, with appearance of gas slugs and hence abrupt density variations. The movable sleeve  402  may be responsive to a change of the density by variation of drag force on the movable sleeve  402 , adjusting its axial position accordingly, and thus enabling continued power output of the turbine. 
     As shown in  FIG. 4B , the movable sleeve  402  in the second position defines a stator gap  442  of width  444  between the surface  428  of the hub  406  and the tip  430  of the stator blade  408 . In the second position shown in  FIG. 4B , a rotor gap  446  has a width  448  greater than the width  434  defined when the movable sleeve  402  is in the first position. The spring  424  may be selected to determine the threshold pressure at which the spring compresses and the movable sleeve  402  translates, such that gaps  442  and  446  are gradually opened while still providing sufficient force in all positions to restrict undesired movement of the movable sleeve  402  and the stator blade  408  when the turbine portion  400  is subjected to axial shocks. Since the stator blades may generate a relatively higher axial force than the movable sleeve  402  that is independent of the rotation speed of the rotor, the spring  424  may be stiffer than the spring  324  used in the embodiment depicted in  FIGS. 3A and 3B . 
     The axial movement of the movable sleeve  402  and the stator blade  408  in the direction indicated by arrow  440  is restricted by the stationary sleeve  420 , such that for a given wedge angle the movable sleeve  402  can translate a distance that opens sufficient clearance gaps for a maximum flow accommodated by the turbine portion  400 . Similar to the embodiments described above, the seals  422  may be disposed between the stationary sleeve  420  and the movable sleeve  402  to prevent fluid leakage, and a small clearance flow passage between sleeves  402  and  420  may be used as a fluid shock absorber. Additionally or alternatively, in some embodiments, a gap  450  between the stationary sleeve  420  and the movable sleeve  402  may serve as a fluid shock absorber and may be selected to provide sufficient fluid viscous damping to counteract the effects from shock, vibrations, and fluid pressure pulsations. In some embodiments, fluid may be restricted in and out from the spring cavity  426  to absorb fluid energy. 
     As illustrated in  FIG. 4B , the movable sleeve  402  and the stator blade  408  may move to the first position in the direction indicated by arrow  456  when the fluid pressure differential decreases below a pressure differential threshold. As the pressure differential decreases, the axial force exerted by the spring  424  in the direction indicated by arrow  456  moves the movable sleeve  402  and the stator blade  408  in that direction. The axial movement of the movable sleeve  402  in the direction indicated by arrow  456  is restricted by the engagement of the stator blade  408  with the hub  406 , such that the axial movement reduces and then eliminates a gap between the stator tip  430  and the hub surface  428 , as shown in  FIG. 4A . 
     In some embodiments, the spring  424  may be a bi-stable spring that changes position in an abrupt transition from an initial position to a second position at a specific force value applied to the spring. In such embodiments, the spring  424  may return the movable sleeve  402  back to the initial position when the applied force is reduced below the specific force value. For example, in some embodiments a buckling plate or shell may be disposed between the stationary sleeve  420  and the movable sleeve  402 . In some embodiments, the movable sleeve  402  may be moved via a different mechanism than the spring  424 . For example, in some embodiments, a hydraulic actuator may be disposed between the stationary sleeve  420  and the movable sleeve  402 , such that increases in the pressure differential result in movement of the hydraulic actuator and movement of the movable sleeve  402 . In other embodiments, other suitable mechanisms for moving the movable sleeve  402  may be used. 
     The movable sleeve  402  may experience a relatively high torque in the circumferential direction generated by the stator blade  408  and the other stator blades coupled to the movable sleeve  402 . In some embodiments, an anti-rotation device  454  may be installed between the movable sleeve  402  and one or more stationary components of the turbine portion  400 , such as the stationary sleeve  420 , the housing  404 , or both. For example, as shown in FIG.  4 B, the anti-rotation device  454  may include an anti-rotation slot  457  and a pin  458  that may engage the anti-rotation slot  457  to prevent rotation of the movable sleeve  402 . 
       FIG. 5  depicts a circumferential cross-section  460  of the turbine portion  400  in accordance with an embodiment of the disclosure.  FIG. 5  shows the housing  404  and the movable sleeve  402  engaged via the anti-rotation device  454 . As further shown in  FIG. 5 , the pin  458  may engage the anti-rotation slot  457  to prevent rotation of the movable sleeve  402  in the directions indicated by arrow  462  but still allow axial movement of the movable sleeve  402  as described above. In some embodiments, multiple pins and multiple slots may be installed between the housing  404  and the movable sleeve  402 . In some embodiments, a pin and a slot may additionally or alternatively be installed between the movable sleeve  402  and the stationary sleeve  420 . 
     Similar to the embodiment described in  FIGS. 3A and 3B , the embodiment depicted in  FIGS. 4A and 4B  may use a single rotor, a stator, and a movable sleeve to cover an entire operational flow range, thus reducing M&amp;S costs. As noted above, since no additional sleeves are installed or different turbines are used in different operating conditions, human errors related to installing appropriate sleeves or turbines may be eliminated. Additionally, in the embodiment depicted in  FIGS. 4A and 4B , the maximum free spin velocity of the turbine portion  400  will only be achieved at the maximum flow of the operational flow range, and the turbine will operate at lower speeds in its operational flow range, thus increasing the life of power generation components and increasing overall reliability. Moreover, the embodiments depicted in  FIGS. 4A and 4B  may include the anti-jamming capability and flow bypass features described above. 
       FIG. 6  depicts a streamline plot of computational fluid dynamic (CFD) results illustrating fluid flow through a turbine.  FIG. 6  depicts a plot  600  showing a flow field for a turbine having no stator gap and a rotor gap between the rotor tip and a housing.  FIG. 7  depicts a graph of shaft power (graph  700 ) as a function of the rotor speed based on the CFD results depicted in  FIG. 6 . As shown in  FIG. 7 , a turbine using the approximate 0 mm stator gap may accommodate a flow rate range of about 275 gpm to about 800 gpm until a free spin of approximately 10600 rpm. Moving a movable sleeve in the turbine about 0.5 inches lowers the turbine speed at the 800 gpm flow rate to about 6800 rpm. 
     Conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain implementations could include, while other implementations do not include, certain features, elements, and/or operations. Many modifications and other implementations of the disclosure set forth herein will be apparent having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the disclosure is not to be limited to the specific implementations disclosed and that modifications and other implementations are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense and not for purposes of limitation.