Patent Publication Number: US-9428990-B2

Title: Rotational wellbore test valve

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 13/007,168, filed on Jan. 14, 2011, entitled “Rotational Wellbore Test Valve” which is hereby incorporated by reference in its entirety for all purposes. 
    
    
     BACKGROUND 
     Technical Field 
     The invention relates generally to an apparatus for use in testing a hydrocarbon well and, more particularly, to an apparatus for conducting testing of hydrocarbon bearing subterranean formations, such as injection fall off and drawdown testing. 
     SUMMARY OF THE INVENTION 
     One method of testing subterranean hydrocarbon wells involves isolating a segment of the wellbore and subjecting that segment to pressure testing. In one example, pressure buildup in the segment is measured over time. In another example, pressure in the segment is raised and its fall off over time is measured. Typically, the well segment to be tested is isolated by a pair of spaced packers positioned in the well on a test tubing string. A valve is assembled in the tubing string between the packers, and during testing, the valve is opened and closed to provide flow between the interior of the test tubing string and the wellbore section being tested. Transducers are also present in the assembly to measure pressure and other conditions in the segment during the test. The testing procedure involves positioning the test tubing string at the wellbore segment to be tested and then setting the packers to isolate a segment of the wellbore for testing or treatment. In operation, the packers are set and the valve is operated to perform pressure tests on the wellbore segment. Thereafter, the packers are unset, the testing string is moved to isolate a different wellbore segment, and the test process is repeated. Accordingly, there is a need for a valve that can be operated (opened and closed) repeatedly and reliably. 
     The present invention provides a valve for connection to a test tubing string and a method for using the valve to selectively connect the interior of the tubing string to the annulus. The valve can be repeatedly actuated (either opened or closed) by rotating the tubing string in one direction (right-hand rotation). 
     As used herein, the words “comprise,” “have,” “include,” and all grammatical variations thereof are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps. The terms “up” and “down” are used herein to refer to the directions along the wellbore toward and away from the wellhead and not to gravitational directions. The term “tubing string” is used herein to refer to coil tubing, tubing, drill pipe or other tool deployment strings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings together with the written description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating at least one preferred example of at least one embodiment of the invention and are not to be construed as limiting the invention to only the illustrated and described example or examples. The various inherent advantages and features of the various embodiments of the present invention are apparent from a consideration of the drawings in which: 
         FIG. 1  is a partial, longitudinal section view of a tubing string positioned to isolate a segment of a wellbore for testing or treatment; 
         FIG. 2A-C  represents a longitudinal section view taken on line  2 - 2  of  FIG. 1 , taken in the direction of the arrows, illustrating an embodiment of the valve of the present invention with the packers removed for simplicity of description; 
         FIG. 3  is a longitudinal section view, similar to  FIG. 2 , illustrating another embodiment of the valve of the present invention; and 
         FIG. 4A-D  are schematic diagrams of the embodiment illustrated in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in  FIG. 1  the valve assembly  10  of the present invention. The valve assembly  10  is illustrated positioned downhole in the wellbore  12  on tubing string  14  extending from the wellhead. The valve assembly  10  is utilized downhole in a wellbore to isolate a segment of annulus  18  surrounding valve assembly  10  and sealed off by the packers. A pair of wellbore packers  16  is mounted on tubing string  14 . As is well known in the industry, these packers can be set and unset to isolate a segment of annulus  18 . For example, packers  16  can be of the Type II weight down or compression packer-type described in E. E. Smart&#39;s July, 1978 article entitled “How To Select The Right Packer For the Job” in  Petroleum Engineering International . The packers  16  can be rotatably mounted on tubing string  14 . 
     The valve assembly  10  contains a valve  20  that can be opened and closed by rotation of tubing string  14  in a single direction. For purposes of describing these inventions, clockwise rotation of the tubing string will be used as an example because it is typical in well equipment. Clockwise rotation will open a port in valve  20  and place tubing string  14  in fluid communication with annulus  18 . Pressure apparatus (not shown) can measure fluid pressure changes in the isolated segment of annulus  18 . 
     An example of a method of using valve assembly  10  of the present invention comprises: connecting valve assembly  10  in a tubing string  14 , lowering the valve into a wellbore to a subterranean location; activating packers  16  to isolate a portion or segment of the wellbore, rotating tubing string  14  clockwise to open valve  20 ; tubing string rotation is discontinued, pressure in the segment is raised; the tubing string is again rotated clockwise to close the valve, tubing string rotation is discontinued and pressure of the fluid in annulus  18  be measured over time. Upon completion of the measuring step, the packers  16  are unset; and thereafter, tubing string  14  is moved (raised and/or lowered) to a different location and the process is repeated without removing tubing string  14  from the wellbore. 
     One embodiment of valve  20  included in valve assembly  10  is illustrated in  FIGS. 2A-C  as having a central passageway  22  extending there through and in communication with the tubing string  14 . The valve  20  is illustrated in the closed position and comprises four major subparts. These major subparts comprise: member  30 , upper housing  50 , valve element  70 , and lower housing assembly  90 . 
     Tubular-shaped member  30  is located on the wellhead side of valve  20  and is coupled to tubing string  14  by a threaded connection  32 . The member  30  has a reduced diameter portion  34  that telescopes into open upper end  52  of upper housing  50 . A seal  54  in the upper housing  50  seals around reduced diameter portion  34  leaving it free to rotate and longitudinally translate with respect to upper housing  50 . Tubular valve actuator  36  is connected to the lower end of member  30 . The lower end of valve actuator  36  forms a piston B to reciprocate in annular hydraulic chamber X. Tubular valve actuator  36  has four circumferentially-spaced ports  38  formed adjacent to its connection to member  30 . Axially extending collet fingers  40  are formed on valve actuator  36  and are separated by a plurality of longitudinally extending slots  42 . Teeth  44  are formed on the exterior of collet fingers  40 . Each of the collet fingers  40  has cam surface  46  formed on the interior thereof. 
     Upper housing  50  is tubular shaped and forms a chamber  60  therein. Ports  53  are formed in the wall of upper housing  50  and are aligned to be longitudinally adjacent to ports  38  in valve actuator  36  when the tool is in the position illustrated in  FIG. 2 . A union  58  is threaded into end  56  of upper housing  50 . A tubular member  62  is mounted in union  58  and extends upward into the lower end of valve actuator  36  and, when in the position illustrated in  FIG. 2 , engages the cam surfaces  46  to spread collet fingers  40  radially outward. 
     Valve element  70  is tubular shaped and is mounted in chamber  60  to slide axially within chamber  60 . Valve element  70  includes a plurality of annular seals  72  which provide sliding sealing engagement with the interior wall of upper housing  50 . An annular chamber is formed below valve element  70  for hydraulic fluid. The lower end valve element  70  acts as a piston A in chamber Y. In this embodiment, two sets of axially spaced ports,  74  and  76 , extend through the wall of the valve element  70 . It should be appreciated that the valve element  70  could have one or even more than two ports as desired. Threads  78  are formed on the interior of the lower end of valve element  70 . Annular slot  80  is formed in the interior wall of valve element  70 . Slot  80  is bound on its upper end by downward-facing shoulder  82 . 
     Lower housing assembly  90  is tubular shaped with one end threaded into union  58 . Lower housing assembly  90  is threaded at  92  for connection to tubing extending below valve  20 . A sleeve  94  is mounted in lower housing assembly  90  to provide a flow path through valve  20  and forms internal annulus  96 . Annulus  96  is closed at both ends and functions as a hydraulic fluid reservoir. Union  58  has internal ports (not shown) that the hydraulic fluid travels through to reset the valve. 
     To open and close valve  20 ; tubing string  14  is rotated in a clockwise direction which, in turn, rotates member  30 . In  FIGS. 2A-C , the valve element  20  is in the closed position with both ports  74  and  76  axially spaced from the ports  53  and  38 . With the valve  20  in this closed position shown in  FIGS. 2A-C , collet fingers  40  are forced outward by tubular member  62  whereby teeth  44  are forced into engagement with threads  78  on valve element  70 . As member  30  rotates, teeth  44  will engage threads  78  and cause valve element  70  to move in a downward direction, away from upper end  52 . As will be appreciated, a set number of rotations will open valve  20  by causing ports  76  to move downward into alignment with ports  38  and  53 . This connects the annulus  18  to the interior of the tubing string. the Additional rotations will close valve  20  by moving parts  76  out of alignment with ports  38  and  53 . A further set number of rotations will open valve element  20  by aligning ports  74  with ports  38  and  53 . With either port  74  or  76  aligned with ports  38  and  53 , the valve interior  22  is open to the annulus  18 . Upon continued rotation, the valve element  70  will move downward until teeth  44  engage slot  80  as ports  74  are closed. Downward movement of valve element  70  will cause piston A to pump hydraulic fluid from chamber Y. Ports  74  will remain closed until the valve is reset without regard to additional rotations. Once the teeth  44  are in the slot  80 , further and continued rotation of the drill string and actuator will cause no additional movement of the valve element  70 . 
     To reset the valve  20 , tubing string  14  is raised and then lowered while the packers  16  are in the set position. This restrains upper housing  50 , union  58  and lower housing assembly  90  against movement in the wellbore. Lifting of the string causes the valve actuator  36  to telescope axially upward with respect to upper housing  50  with the lower end of actuator  36  acting as a piston B in annular chamber X. During this movement, teeth  44  are disengaged and allow valve actuator  36  to move upward without contacting valve element  70 . The upward movement pumps hydraulic fluid from the annulus  96  through a port in union  58  and into chamber X. A valve (not shown) controls hydraulic fluid flow through a port (not shown), connecting chambers X and Y and annulus  96 . When the piston B is in the lowest position, shown in  FIG. 2 b   , the valve opens, permitting hydraulic fluid flow between chambers X and Y and annulus  96 . When the piston B on valve actuator  36  moves out of the lowest position, the valve acts as a check valve, permitting fluid flow from annulus  96  into chambers X and Y while blocking flow from chambers X and Y into annulus  96 . As previously explained, upward movement of the tubing string does not affect the position of the valve, leaving the valve in its last position. 
     Subsequently, when the tubing string is lowered, valve actuator  36  will move down, with piston B pumping fluid from the chamber X to chamber Y, which in turn causes valve element  70  to telescope into the upper housing  50  to the position shown in  FIG. 2A-C . It should be appreciated that as the valve element  70  moves upward, teeth  44  are not extended radially into contact with threads  78 . Teeth  44  do not reengage these threads until cam surface  46  on the collet fingers  40  engage tubular member  62  to spread the collets outward. By resetting the valve  20 , the process of opening and closing can be repeated as many times as desired without unsetting the packers. In addition, the packers can be unset, moved and set to isolate a different section of the wellbore; and the valve can be opened and closed to test the wellbore section. 
     The features of an alternative configuration, downhole valve assembly  110 , are illustrated in  FIGS. 3 and 4  A-D. The valve assembly can be used in the configuration illustrated in  FIG. 1  with spaced packers isolating a wellbore segment. In this embodiment, the valve moves between the open and closed positions by rotating the tubing string a minimum number of revolutions without lifting and lowering the string to reset the valve. For example, if the valve is in the closed position, a minimum number of revolutions of the tubing string in the clockwise direction causes the means for moving the valve to move the valve to the open position and a means for maintaining causes the valve to remain in the open position while rotation continues beyond the minimum number of rotations. The valve will be maintained in the open position after rotation ceases. To close the open valve, a minimum number of revolutions of the tubing string in the clockwise direction moves the valve to the closed position and maintains it in the closed position while rotation continues. The valve will remain in the closed position even after rotation ceases. The process of opening and closing the valve can be repeated, as many times as desired, merely by rotating the tubing string in one direction. Due to the presence of slack, drag, flexure and other factors, rotation of the tubing string by the rig at the wellhead is not necessarily transmitted to the valve at a downhole location. Accordingly, valves that function based on a set amount of rotation are not reliable. The present valve solves that problem by maintaining the valve in position after it has changed position while rotation continues. The present valve is designed to move from one position to another upon the application of at least a set minimum number of revolutions of the tubing string. If the valve is designed to open and/or close after the application of ten (10) revolutions, the operator will exceed that minimum number and rotate the tubing string, for example, twenty (20) revolutions or even more. In this method, the rig operator can be assured that the minimum has been exceeded and the valve actuated. Once the minimum has been reached, the means for maintaining holds the valve in its actuated position. 
     In the  FIG. 3  embodiment, valve assembly  110  is configured as a sliding sleeve-type valve. Valve assembly  110  comprises housing  112 , which can be set in the well as illustrated in  FIG. 1 . Ports  114  extend through the wall of the housing  112  and connect the interior of housing  112  with the annulus  118 . Seals or packing  115  isolate the ports  114 . An annular valve element  120  is located within housing  112  to axially move within housing  112  to engage seals  115  and block flow through ports  114 . An annular double acting piston  122  is mounted to move axially in annular chamber  124 . Piston  122  is connected valve element  120 . Fluid passageways  126  and  128  are in fluid communication with chamber  124 . These passageways are used to create a pressure differential across piston  122  which causes valve element  120  to move between the open and closed positions. 
     Actuator sleeve  130  is connected to rotate with the tubing string (not shown) while the housing  112  is held in place in the well by packers (see  FIG. 1 ). A fluid pump assembly  140  is mounted in housing  112  and is connected to actuator sleeve  130 . Pump assembly  140  contains suitable fluid components, such that when the tubing string is rotated, pressurized fluids are provided to chamber  124  to move piston  122  and the valve element. The pump comprises the actuator. 
     The details of pump assembly  140  and its methods of operation will be described by reference to  FIGS. 4A-D . A rotary fluid pump  142  is connected to actuator  130 , and when the actuator sleeve  130  rotates pump  142 , fluid is pumped from reservoir R. The output  144  of rotary pump  142  is connected to a normally closed pressure relief valve  146 . A flow restrictor  148  is connected between the suction side  150  of rotary pump  142  and valve pressure relief valve  146 . Output  144  is also connected to port  152  of a rotary four port, two-position control valve  154 . Port  156  is connected to reservoir R. Shifter  160  operates valve  154 . 
     In  FIG. 4A , valve element  120  is illustrated in the open position. To move the valve element  120  to the closed position, the tubing string and actuator sleeve  130  are rotated in the clockwise direction. As actuator sleeve  130  is rotated, pump  142  pumps fluid to port  152  on valve  154 . As illustrated in  FIG. 4A , port  152  is connected to fluid passageway  126  which allows fluid to be pumped into the chamber  124  to move the piston  122  and valve element  120  in the direction of arrow A to the closed position. As is illustrated, fluid ejected through fluid passageway  128  is returned to the reservoir via port  156  in valve  154 . The pump, valve and piston comprise an actuator assembly for moving the valve element. 
     As the piston  122  bottoms out as illustrated in  FIG. 4B , valve element  120  had been moved to the closed position, and the pressure of fluid in output  144  will increase, causing pressure relief valve  146  to open. Flow restrictor  148  causes pressurized fluid to back up through line  162  and into chamber  164  of shifter  160 . Fluid pressure in chamber  164  will cause piston  166  to move and compress spring  168 . As long as the tubing string continues to rotate the rotary pump  142 , the piston  166  will remain in a position, compressing spring  168 . Once tubing string rotation ceases and the pump  142  ceases to pump fluids, pressure in chamber  164  will decrease by bleeding off through flow restrictor  148 , allowing the spring  168  to move the piston  166  to the position illustrated in  FIG. 4C . As the piston  166  moves from the position illustrated in  FIG. 4B  to the position illustrated in  FIG. 4C , shifter  160  shifts the valve  154  to the position illustrated in  FIG. 4C . The valve element  120  will remain in the closed position illustrated in  FIG. 4C  until rotation of tubing string is started again. 
     To return valve element  120  to the open position, rotation of the drill string and actuator sleeve  130  must again be initiated. As illustrated in  FIG. 4C , pump  142  is connected through valve  154  to provide fluid in the chamber  124 , and rotation of the tubing string and pump  142  will cause piston  122  to move in the reverse direction of arrow A. This movement of piston  122 , in turn, moves the valve element  120  to the open position illustrated in  FIG. 4D . When piston  122  bottoms out in the reverse direction of arrow A, pressure relief valve  146  will open, supplying fluid pressure to move piston  166  and compress spring  168 , as illustrated in  FIG. 4D . The valve element  120  will remain in the open position as long as rotation of the drill string continues and will even remain in the open position after rotation ceases. 
     According, to this embodiment, the actuation means of the present invention moves or shifts the valve element  120  between open and closed by simply starting clockwise rotation of the drill string and then ceasing rotation. The means for maintaining the valve element maintains the valve element in the shifted position until and after rotation ceases, thus eliminating the necessity of precisely counting tubing string rotations. 
     Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed herein are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art, having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is, therefore, evident that the particular illustrative embodiments disclosed above may be altered or modified, and all such variations are considered within the scope and spirit of the present invention. 
     Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent(s) or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted.