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You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates generally to the design of circulating valves used in wellbores.  
         [0003]     2. Description of the Related Art  
         [0004]     Circulating valves are used to provide fluid communication between the central flowbore and the annulus. The typical circulating valve has a sliding sleeve that is movable to selectively cover several ports that allow fluid flow between the annulus and the flowbore. These valves are important during an operation to run a device into a wellbore. They allow fluid to be circulated into the flowbore from the annulus (fill up), or from the flowbore out into the annulus (circulation). They also ensure that pressure is equalized between the flowbore and the annulus. A typical application for a circulating valve would be running in and setting an inflatable packer on coiled tubing. The circulating valve would be open during the run in. When the packer reaches the depth at which it will be set, the circulating valve must be closed in order to set the packer. In conventional designs, surface intervention is necessary to close the valve. Normally, this is accomplished by dropping a closing ball into the flowbore. The ball lands on a ball seat within the valve. Fluid pressure is increased behind the ball, and the sleeve is then shifted closed. On many occasions, including the setting of an inflatable packer, it is undesirable to drop a closing ball to close the sleeve. The operation can be time consuming and detrimental to the operation of tools below the ball. Thus, it is desired to have an alternative method of selectively closing the circulation valve.  
         [0005]     The present invention addresses the problems of the prior art.  
       SUMMARY OF THE INVENTION  
       [0006]     The invention provides systems and methods for operating a circulation valve such that the valve will automatically close without the need for a ball to be dropped or other intervention from the surface. The circulation valve is autonomous and will preferably be actuated from an open to a closed position by a power screw or another suitable motive force mechanism. In one embodiment, the valve is actuated by a timer such that it will close after a predetermined period of time has passed. In further embodiments, the valve is associated with a sensor to detect certain wellbore conditions, such as flow, pressure or temperature or a combination of conditions. When a predetermined condition or set of conditions is detected, the valve closes. In accordance with still further embodiments, an accelerometer or position sensor is associated with the circulating valve to determine when the packer or other tool has reached its desired depth. At that time, the valve is closed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a side, cross-sectional view of a running arrangement wherein an inflatable bridge plug is being run into a wellbore on coiled tubing having a circulation valve constructed in accordance with the present invention.  
         [0008]      FIG. 2  is a closer side, cross-sectional view of the arrangement shown in  FIG. 1  now with the circulation valve having been closed in preparation to set the bridge plug.  
         [0009]      FIG. 3  is a side, cross-sectional view of the arrangement shown in  FIGS. 1 and 2  now with the bridge plug having been set.  
         [0010]      FIG. 4  is a one-quarter cross-sectional view of an exemplary circulation valve constructed in accordance with the present invention and in an open, circulating configuration.  
         [0011]      FIG. 5  is a one-quarter cross-sectional view of the circulation valve shown in  FIG. 4 , now in a closed configuration.  
         [0012]      FIG. 6  illustrates one embodiment for a control module used with the circulation valve of  FIGS. 4 and 5 .  
         [0013]      FIG. 7  illustrates an alternative embodiment for a control module used with the circulation valve of  FIGS. 4 and 5 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]      FIGS. 1 and 2  illustrate an exemplary slim hole-style wellbore  10  that has been drilled through the earth  12 . The wellbore  10  has been lined with steel casing  14 . Two separate hydrocarbon-bearing formation layers  16 ,  18  are present in the earth  12  and separated by an interval  20  of relatively impermeable rock. Perforations  22 ,  24  have been previously created through the casing  14  and into layers  16  and  18 , respectively, to allow fluid communication from the formations  16 ,  18  into the wellbore  10 . In this illustration, it is desired to run in and set an inflatable bridge plug packer device within the wellbore  10  between the upper perforations  22  and the lower perforations  18 . This might be done because, for example, the lower formation  18  has suffered from water infiltration or the like so that it is no longer desirable to produce from the lower formation  18 .  
         [0015]     A wellhead  26  is located at the surface  28 . An exemplary coiled tubing running arrangement, generally indicated at  30 , is shown being run into the wellbore  10  through the wellhead  26 . Coiled tubing  32  is dispensed from spool  34  and injected into the wellhead  26  by a coiled tubing injector apparatus  36  of a type known in the art. Those of skill in the art will understand that while coiled tubing  32  is a continuous string of tubing, the coiled tubing running arrangement  30  will actually contain a number of connectors and tools incorporated into it, but will define a central flowbore along its length. The lower end of the coiled tubing running arrangement  30  carries an inflatable bridge plug  38 . Also included in the coiled tubing running arrangement  30  is a nipple profile locator  40  that is designed to locate and latch into landing nipple  42  in the casing  14 . The coiled tubing running arrangement  30  also includes an autonomous circulating valve  44 , which is constructed in accordance with the present invention. The structure and function of the circulation valve  44  will be described in greater detail shortly. It is noted that the details of surface valving and fluid pressurization of the coiled tubing are not shown in  FIG. 1  or described in detail herein, as such details are well understood by those of skill in the art.  
         [0016]      FIGS. 2 and 3  illustrate the components associated with the downhole portions of the coiled tubing running arrangement  30  in greater detail. In  FIG. 2 , the nipple profile locator  40  has been landed into landing nipple  42 . The circulation valve  44 , which can be seen to have lateral fluid ports  48 , is moved from its open configuration to a closed position. The bridge plug  38  is in an unset position, but is aligned with the impermeable layer  20  and between perforations  22  above and perforations  24  below. In  FIG. 3 , the bridge plug  38  has been inflated by increased fluid pressure within the coiled tubing  32 . When set, the bridge plug  38  forms a fluid seal between the production zones  16  and  18 .  
         [0017]      FIGS. 4 and 5  depict details of the autonomous circulating valve  44  that is constructed and operates in accordance with the present invention. The valve  44  includes a valve body  50  having an upper sub  52  with a box-type threaded portion  54  for interconnection to coiled tubing or other components in the coiled tubing running arrangement  30 . The upper sub  52  is threadedly connected to a circulation sub  56 . An outer housing  58  is secured to the lower end of the circulation sub  56 . A lower sub  60  is secured to the lower end of the outer housing  58 . The lower sub  60  has a defined axial flowbore  62  that passes centrally through and a pin-type threaded connection  64 .  
         [0018]     The outer housing  58  encloses a power screw assembly, designated generally as  66 . Beginning from the lower end, the power screw assembly  66  includes a battery housing connection  68  for interconnection of a battery (not shown) or other power source and an electronics housing  70 . A power lead  72  extends from the electronics housing  70  to a rotary motor  74 . In a currently preferred embodiment, the motor  74  is a brushless motor, but may, in fact, be any type of suitable motor. Rotary shaft  76  from motor  74  is interconnected to transmission  78 , and a transmission drive gear  80  is interconnected to power screw drive member  82  for rotation thereof under impetus of the motor  74 . A helical, or screw-type, interface  84  is provided between the drive member  82  and a valve stem  86 . The helical interface  84  causes rotation of the drive member  82  to be converted into axial movement of the valve stem  86  within a valve stem passage  88  defined within the circulation sub  56 .  
         [0019]     A number of fluid flowpaths are defined within the valve  44 . The circulation sub  56  contains lateral fluid passages  48  that allow fluid communication between the valve stem passage  88  and the annulus  90  surrounding the valve  44 . In addition, there is an axial flow pathway  92  that allows fluid to pass axially through the valve  44  when the valve  44  is in the open configuration shown in  FIG. 4 . In the embodiment depicted, the axial pathway  92  includes flow passages  94 , which are drilled axially through the circulation sub  56 , an annular chamber  96 , and an annular flow space  98 . The annular flow space  98  is defined between the outer housing  58  and an inner housing  100  that protects portions of the power screw mechanism described previously. These flowpaths allow fluid to flow during operation as necessary for equalization and circulation. During run-in of the coiled tubing running arrangement  30 , with the valve  44  in the open position shown in  FIG. 4 , fluid tends to circulate through the lateral flow passages  48 , as this presents the path of least resistance.  
         [0020]     Referring now to  FIG. 6 , the electronics housing  70  is schematically shown to enclose a motor driver  102  and an autonomous actuator, or control module,  104  that actuates the motor driver  102  upon a predetermined condition or set of conditions being reached. In this embodiment, the actuator  104  comprises a timer that can be preset to provide a predetermined delay before the motor driver  102  is actuated by the actuator  104 . In operation, the actuator  104  is preset at the surface  28  before the running string  30  is run into the wellbore  10  to provide a predetermined time delay (8 hours, for example). The running string  30  is then run into the wellbore  10  with the circulating valve  44  in the open configuration so that fluid can be circulated through the ports  64 ,  48  of the valve  44  during run-in. The nipple profile locator  40  lands upon landing nipple  42  to position the bridge plug  38  at its desired setting depth. After the predetermined amount of time has elapsed, the timer  104  will actuate the motor driver  102  to energize the motor  74 . When the motor  74  is energized, it will cause the transmission  78  to rotate the drive member  82  of the power screw assembly  66 . As a result of the rotation of the drive member  82 , the valve stem  86  is moved axially upwardly to the closed position shown in  FIG. 5  wherein the valve stem  86  blocks the lateral flow ports  48 . With the lateral flow ports  48  now closed, fluid flowed down through the coiled tubing  32  is forced to pass through the axial flow pathway  92  of the valve  44 . When the valve  44  is closed in this manner fluid pressure within the coiled tubing  32  can be used to set the bridge plug  38 , in a manner known in the art.  
         [0021]     The valve  44  might, alternatively, utilize an electronics module  70 ′ (shown in  FIG. 7 , that is constructed according to alternative embodiments in order to cause the valve  44  to operate autonomously.  FIG. 7  depicts, in schematic fashion, an electronics module  70 ′ which includes a sensor  106  that is of a type known in the art for detecting a particular wellbore condition, such as temperature or pressure. In operation, the electronics module  70 ′ would cause the valve  44  to close upon the detection of a particular wellbore condition (pressure or temperature) that would occur when the sensor has reached a particular depth or location within the wellbore  10  (i.e., the setting depth).  
         [0022]     Alternatively, the sensor  106  might comprises an accelerometer or position sensor. In such an instance, the sensor  106  might cause the valve  44  to close when the accelerometer or position sensor detects that the running string  30  has been landed into the landing nipple  42 , thus indicating that setting depth has been reached. It is noted, that, while the invention has been described with respect to the running in and setting of a bridge plug packer device  58 , the methods and devices described herein may as well be used for the running in and actuation of other hydraulically-actuated tools.  
         [0023]     Those of skill in the art will recognize that numerous modifications and changes may be made to the exemplary designs and embodiments described herein and that the invention is limited only by the claims that follow and any equivalents thereof.

Summary:
Systems and methods for operating a circulation valve such that the valve will automatically close without the need for a ball to be dropped or other intervention from the surface. The circulation valve is autonomous and will preferably be actuated from an open to a closed position by a motive force such as a power screw. The valve includes an actuator that causes the valve to close in response to particular conditions, such as the passing of a predetermined amount of time, or wellbore conditions, such as pressure, temperature or position.