Devices and methods for methods for cleaning of excess cement from a production assembly as well as from the annulus surrounding the production assembly. A hydrostatic closed circulation valve (HCCV) assembly is described that is primarily actuatable between open and closed positions by varying hydraulic pressure in the flowbore of the production assembly. The valve assembly is useful for selectively circulating working fluid into the annulus from the flowbore of the production assembly.

BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates generally to valve assemblies useful in well completions wherein it is desired to cement in a portion of a production liner and, thereafter, utilize gas lift technology to assist production of fluids from a well. 
   2. Description of the Related Art 
   After a well is drilled, cased, and perforated, it is necessary to anchor a production liner into the wellbore and, thereafter, to begin production of hydrocarbons. Oftentimes, it is desired to anchor the production liner into place using cement. Unfortunately, cementing a production liner into place within a wellbore has been seen as foreclosing the possibility of using gas lift technology to increase or extend production from the well in a later stage. In addition, cementing is of the production liner may make it difficult to produce hydrocarbons in a standard manner, without artificial lift. Excess cement may clog portions of the flowbore of the production system. Cementing the production liner into place prevents the production liner from being withdrawn from the well. Because a completion becomes permanent when the production liner is cemented, any gas lift mandrels that are to be used will have to be run in with the production string originally. This is problematic, though, since the operation of cementing the production liner into the wellbore tends to leave the gas inlets of a gas lift mandrel clogged with cement and thereafter unusable. Additionally, the annulus above the cemented portion may contain excess cement that would hamper the ability to transmit gas down to the gas lift valves via the annulus. To date, there is no satisfactory method known for cleaning cement from the annulus surrounding the production assembly. 
   The present invention addresses the problems of the prior art. 
   SUMMARY OF THE INVENTION 
   The invention provides devices and methods for cleaning of excess cement from a production assembly as well as from the annulus surrounding the production assembly. A hydrostatic closed circulation valve (HCCV) assembly is described that is primarily actuatable between open and closed positions by varying hydraulic pressure in the flowbore of the production assembly. The valve assembly is useful for selectively circulating working fluid into the annulus from the flowbore of the production assembly. 
   In a preferred embodiment, the HCCV assembly includes a tubular inner mandrel having a lateral fluid flow port. The inner mandrel has threaded axial ends for incorporation into a production assembly. The lateral flow port is initially closed to fluid flow port by a frangible rupture member. The valve assembly is also provided with an outer sleeve that is axially moveable upon the inner mandrel between the original, first position, wherein the flow port is substantially not blocked against fluid flow, and a final, second position, wherein the outer sleeve does substantially block flow of fluid through the flow port. 
   The valve assembly is also provided with an inner sleeve that is axially moveable within the inner mandrel. The inner sleeve serves as a backup means for selectively closing the fluid flow port against fluid flow. The inner sleeve is moveable by mechanical means, such as a wireline-run shifting tool. 
   In operation, the HCCV valve assembly is incorporated into a completion system that is secured within a wellbore by cementing. Following the cementing operation, a well working fluid for cleaning of excess cement is flowed into the flowbore of the completion system. The valve assembly is opened upon application of fluid pressure within the flowbore that is sufficient to rupture the rupture member in the valve assembly. Working fluid is then circulated through the valve assembly. Upon application of a second, increased level of fluid pressure within the flowbore and annulus, the outer sleeve of the valve assembly is shifted to its closed position, thereby closing off fluid communication between the flowbore and the annulus. In the event that the outer sleeve does not close, a wireline shifting tool may be disposed down the flowbore to engage the inner sleeve of the valve assembly and close it. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side, cross-sectional view of an exemplary hydrostatic closed circulation valve assembly constructed in accordance with the present invention. 
       FIG. 2  is a side, cross-sectional view of the valve assembly depicted in  FIG. 1  with the outer sleeve in a closed position. 
       FIG. 3  is a side cross-sectional view of the valve assembly depicted in  FIGS. 1 and 2  with the inner sleeve now in a closed position. 
       FIG. 4  is a side, cross-sectional view of an exemplary completion system that incorporates the hydrostatic closed circulation valve depicted in  FIGS. 1–3 . 
       FIG. 5  is a side, cross-sectional view of the completion system shown in  FIG. 4 , following flowing of cement into the annulus. 
       FIG. 6  is a side, cross-sectional view of the completion system shown in  FIGS. 4 and 5  showing an included packer assembly actuated. 
       FIG. 7  is a side, cross-sectional view of the completion system shown in  FIGS. 4–6  now with the surrounding formation having been perforated. 
       FIG. 8  is a side, cross-sectional view of the completion assembly shown in  FIGS. 4–7  with a wiper plug being pumped down the flowbore. 
       FIG. 9  is a side, cross-sectional view of the completion assembly shown in  FIGS. 4–8  with the HCCV valve assembly in an open position for circulation of working fluid into the annulus following rupture of a frangible rupture member. 
       FIG. 10  is a side, cross-sectional view of the completion assembly shown in  FIGS. 4–9  now with the HCCV valve assembly in a closed position and during subsequent production of hydrocarbon fluids. 
       FIG. 11  depicts an exemplary wiper plug device used with the completion system shown in  FIGS. 4–10 . 
       FIG. 12  is a detail view showing seating of the wiper plug within the landing collar. 
       FIG. 13  is a cross-sectional depiction of an exemplary side-pocket mandrel used in the completion system shown in  FIGS. 4–10 . 
       FIG. 14  is an axial cross-section taken along lines  14 — 14  of  FIG. 13 . 
       FIG. 15  shows an exemplary filler guide section used within the side-pocket mandrel shown in  FIGS. 13 and 14 . 
   


   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1–3  illustrate a hydrostatic closed circulation valve (HCCV)  10  constructed in accordance with the present invention. The HCCV  10  includes an inner mandrel  12  having threaded pin and box-type connections at either axial end  14 ,  16 . The inner mandrel  12  defines an axial flowbore  18  along its length. The inner mandrel  12  may be a unitary piece or, alternatively, made up of a series of components that are in threaded connection with one another, as illustrated in  FIG. 1 . An upper sub  20  is affixed to a central sleeve  22 . In turn, the central sleeve  22  is secured at its lower end to a lower sub  24 . The central sleeve  22  of the inner mandrel  12  contains a lateral fluid flow port  26  through which fluid communication may occur between the flowbore  18  and the radial exterior of the inner mandrel  12 . Initially, a frangible rupture member, such as rupture disk  28 , closes the fluid port  26  against fluid flow. The rupture disk  28  is designed to break away upon the application of a predetermined fluid pressure differential, for example 4,500 psi. A snap ring  29  radially surrounds the inner mandrel  12  and resides within a complimentary groove in the surface of the inner mandrel  12 . 
   An outer sleeve  30  radially surrounds the inner mandrel  12  and is capable of axial movement upon the inner mandrel  12 . A fluid opening  32  is disposed through the outer sleeve  30 . A frangible shear pin  34  secures the outer sleeve  30  to the inner mandrel  12 . Additionally, the upper end  36  of the outer sleeve  30  provides a pressure receiving area. Below the upper end  36 , is a radially interior relief  37  that is shaped and sized to engage the snap ring  29  when the outer sleeve  30  has been moved to a closed position ( FIG. 2 ). 
   The HCCV  10  also includes an inner sleeve  38  that is located within the flowbore  18  of the inner mandrel  12 . The inner sleeve  38  features a fluid aperture  40  that is initially aligned with the fluid opening  26  in the inner mandrel  12 . The upper end of the inner sleeve  38  provides an engagement profile  42  that is shaped to interlock with a complimentary shifting element. The inner sleeve  38  is also axially moveable within the flowbore  18  between the initial, first position, shown in  FIG. 1 , wherein the fluid aperture  40  is aligned with the lateral fluid flow port  26  of the inner mandrel  12 , and a second position (shown in  FIG. 3 ) wherein the fluid aperture  40  is not aligned with the flow port  26 . When the inner sleeve  38  is in the second position, fluid communication between the flowbore  18  and the exterior radial surface of the valve assembly  10  is blocked. 
   The HCCV valve assembly  10  is integrated into a completion assembly that is run into a wellbore and is used to produce hydrocarbon fluids thereafter from the wellbore. The valve assembly  10  is particularly useful for completions wherein a production liner portion of the completion assembly is cemented in place within the wellbore. As part of a cleaning process, the valve assembly  10  can be selectively opened and closed to flow a well working fluid into the annulus surrounding the completion assembly and, thereby, clean excess cement from the annulus as well as the interior of the completion assembly. The valve assembly  10  can then be selectively closed when cleaning is complete in order to produce hydrocarbons through the flowbore of the completion assembly. 
   To aid in explanation of the valve assembly  10  and its operation,  FIGS. 4–10  illustrate the structure and operation of an exemplary completion assembly  100 , which incorporates the valve assembly  10  therein.  FIG. 4  depicts a wellbore  102  that has been drilled into the earth  104 . A hydrocarbon formation  106  is illustrated. The exemplary wellbore  102  is at least partially cased by metal casing  108  that has been previously cemented into place, as is well known. An exemplary completion system or assembly, illustrated generally at  100 , is shown suspended from production tubing  110  and disposed within the wellbore  102 . An annulus  112  is defined between the completion system  100  and the wellbore  102 . In addition, it is noted that the production tubing  110  and the completion system  100  define therewithin an axial flowbore  114  along their length. 
   The upper portions of the exemplary completion system  100  include a number of components that are interconnected with one another via intermediate subs. These components include a subsurface safety valve  116 , a side-pocket mandrel  118 , and the hydrostatic closed circulation valve (HCCV) assembly  10 . A packer assembly  120  is located below the HCCV assembly  10 . A production liner  122  extends below the packer assembly  120  and is secured, at its lower end, to a landing collar  124 . A shoe track  126  is secured at the lower end of the completion system  100 . The shoe track  126  has a plurality of lateral openings  128  that permit cement to be flowed out of the lower end of the flowbore  114  and into the annulus  112 . 
   The subsurface safety valve  116  is a valve of a type known in the art for shutting off the well in case of emergency. As the structure and operation of such valves are well understood by those of skill in the art, they will not be described in any detail herein. 
   The side pocket mandrel  118  is of the type described in our co-pending application Ser. No. 60/415,393, filed Oct. 2, 2002. The side pocket mandrel  118  is depicted in greater detail and apart from other components of the completion system in  FIGS. 13 ,  14  and  15 . The side pocket mandrel  118  includes a pair of tubular assembly joints  130  and  132 , respectively, at the upper and lower ends. The distal ends of the assembly joints  130 ,  132  are of the nominal tubing diameter as extended to the surface and are threaded for serial assembly. Distinctively, however, the assembly joints  130 ,  132  are asymmetrically swaged from the nominal tube diameter at the threaded ends to an enlarged tubular diameter. In welded assembly, for example, between the enlarged diameter ends of the upper and lower assembly joints  130 ,  132  is a larger diameter pocket tube  134 . Axis  136  respective to the assembly joints  130  and  132  is off-set from and parallel with the pocket tube axis  138  ( FIG. 14 ). 
   A valve housing cylinder  140  is located within the sectional area of the pocket tube  134  that is off-set from the primary flow channel area  142  of the tubing string  110 . External apertures  144  in the external wall of the pocket tube  134  laterally penetrate the valve housing cylinder  140 . Not illustrated is a valve or plug element that is placed in the cylinder  140  by a wireline-manipulated device called a “kickover” tool. For wellbore completion, side pocket mandrel  118  is normally set with side pocket plugs in the cylinder  140 . Such a plug interrupts flow through the apertures  144  between the mandrel interior flow channel and the exterior annulus and masks entry of the completion cement. After all completion procedures are accomplished, the plug may be easily withdrawn by wireline tool and replaced by a wireline with a fluid control element. 
   At the upper end of the mandrel  118  is a guide sleeve  148  having a cylindrical cam profile for orienting the kickover tool with the valve housing cylinder  140  in a manner well known to those of skill in the art. 
   Set within the pocket tube area between the side pocket mandrel valve housing cylinder  140  and the assembly joints  130  and  132  are two rows of filler guide sections  150 . In a generalized sense, the filler guide sections  150  are formed to fill much of the unnecessary interior volume of the valve housing cylinder  140  and thereby eliminate opportunities for cement to occupy that volume. Of equal but less obvious importance is the filler guide section function of generating turbulent circulations within the mandrel voids by the working fluid flow behind a wiper plug. 
   Similar to quarter-round trim molding, the filler guide sections  150  have a cylindrical arcuate surface  152  and intersecting planar surfaces  154  and  156 . The opposing face separation between the surfaces  154  is determined by clearance space required by the valve element inserts  150  and the kick-over tool. 
   Surface planes  156  serve the important function of providing a lateral supporting guide surface for a wiper plug as it traverses the side pocket valve housing cylinder  146  and keep the leading wiper elements within the primary flow channel  142 . 
   At conveniently spaced locations along the length of each filler section  150 , cross flow jet channels  158  are drilled to intersect from the faces  154  and  156 . Also at conveniently spaced locations along the surface planes  154  and  156  are indentations or upsets  160 . Preferably, adjacent filler guide sections  150  are separated by spaces  162  to accommodate different expansion rates during subsequent heat-treating procedures imposed on the assembly during manufacture. If deemed necessary, such spaces  162  may be designed to further stimulate flow turbulence. 
     FIG. 11  schematically illustrates an exemplary wiper plug  170  that is utilized with the completion system  100 . A significant distinction this wiper plug  170  makes over similar prior art devices is the length. The length of the plug  170  is correlated to the distance between the upper and lower assembly joints  130  and  132 . Wiper plug  170  has a central shaft  172  with leading and trailing groups of nitrile wiper discs  174 . As is apparent from  FIG. 11 , the leading group of wiper discs  174  is located proximate the nose portion  176  of the shaft  172 , while the trailing group of discs  174  is located proximate the opposite, or rear, end of the shaft  172 . Each of the discs  174  surround the shaft  172  and have radially extending portions designed to contact the flowbore  114  and wipe excess cement therefrom. It is also noted that the discs  174  are concavely shaped so that they may capture pressurized fluid from the rear of the shaft  172 . Between the leading and trailing groups is a spring centralizer  178 . 
   As will be explained in further detail shortly, the design of the side pocket mandrel  118  is particularly useful in conjunction with the wiper plug  170  as the wiper plug  170  is pumped down the flowbore  114  to clean excess cement from the completion assembly  100 . As the leading wiper group of discs  174  enters the side pocket mandrel  118 , fluid pressure seal behind the wiper discs  174  is lost but the filler guide planes  156  keep the leading group of discs  174  in line with the primary tubing flow bore axis  136 . The trailing group of discs  174  is, at the same time, still in a continuous section of tubing flow bore  142  above the side pocket mandrel  118 . Consequently, pressure against the trailing group of discs  174  continues to load the plug shaft  172 . As the wiper plug  170  progresses through the side pocket mandrel  118 , the spring centralizer  178  maintains the axial alignment of the shaft  172  midsection. By the time the trailing group of discs  174  enters the side pocket mandrel  118  to lose drive seal, the leading group of discs  174  has reentered the flowbore  114  below the mandrel  118  and regained a drive seal. Consequently, before the trailing seal group of discs  174  loses drive seal, the leading seal group of discs  174  have secured traction seal. 
   Exemplary operation of the overall completion system  100  containing the valve assembly  10  is illustrated by  FIGS. 4-10 . In  FIG. 4 , the assembly  100  is shown after having been disposed into the wellbore  102  so that the production liner  122  is located proximate the formation  106 . Once this is done, cement  180  is flowed downwardly through the central flowbore  114  and radially outwardly through the lateral openings  128  in the shoe track  126 . Cement  180  fills the annulus  112  until a desired level  182  of cement  180  is reached for anchoring the system  100  in the wellbore  102 . Typically, the desired level  182  of cement  180  will be such that portions of the packer assembly  124  are covered (see  FIG. 5 ). The packer assembly  124  is then set within the wellbore  102 , as illustrated by  FIG. 6  to complete the anchorage. Next, a perforation device  184 , of a type known in the art, is run into the flowbore  114 , as illustrated in  FIG. 7 . The perforation device  184  is actuated to create perforations  186  in the casing  108  and surrounding formation  106 . The perforation device  184  is then withdrawn from the flowbore  114 . If desired, the packer assembly  120  may be set after the perforation device  184  has been actuated and the cement cleaned from the system  100  in a manner which will be described shortly. Typically, the perforation device  184  is actuated to perforate the formation  106  after the cement  180  has been flowed into the wellbore  102  and the wiper plug  170  has been run into the flowbore  114 , as will be described. Also, the cement  180  is typically provided time to set and cure somewhat before perforation. 
   Cement is cleaned from the system  100  by the running of the wiper plug  170  into the flowbore  114  to wipe excess cement from the flowbore  114  and the components making up the assembly  100 . Thereafter, a well working fluid is circulated through the assembly  100  to further clean the components. As  FIG. 8  illustrates, the wiper plug  170  is inserted into the flowbore  114  and urged downwardly under fluid pressure. A working fluid is used to pump the wiper plug  170  down the flowbore  114 . Fluid pressure behind the discs  174  will drive the wiper plug  170  downwardly along the flowbore  114 . Along the way, the discs  174  will efficiently wipe cement from the flowbore  114 . When the wiper plug  170  reaches the lower end of the flowbore  114 , it will become seated in the landing collar  124 , as illustrated in  FIG. 9 . 
     FIG. 12  illustrates in greater detail,the seating arrangement of the wiper plug  170  in the landing collar  124 . As shown there, the landing collar  124  includes an outer housing  190  that encloses an interior annular member  192 . The annular member  192  provides an interior landing shoulder  194  and a set of wickers  196 . The nose portion  176  of the wiper plug  170  lands upon the landing shoulder  194 , which prevents the wiper plug  170  from further downward motion. The wickers  196  frictionally engage the nose portion  176  to resist its removal from the landing collar  124 . Landing of the wiper plug  170  in the landing collar  124  will close off the lower end of the flowbore  114  to prevent further fluid flow outwardly via the shoe track  126 . 
   Prior to running the completion system  100  into the wellbore  102 , the HCCV assembly  10  is in the configuration shown in  FIG. 1  with the outer sleeve  30  secured by shear pin  34  in an upper, open position upon the inner mandrel  12  so that the fluid flow port  32  in the outer sleeve  30  is aligned with the fluid port  26  of the inner mandrel  12 . Once the wiper plug  170  has been landed in the landing collar  124 , as described, the flowbore  114  will be closed at its lower end and, thereafter may be pressurized from the surface. Upon application of a first, suitable fluid pressure load within the flowbore  114 , and, thus, the flowbore  18  of the HCCV assembly  10 , the rupture disk  28  will be broken, thereby permitting fluid to be communicated between the flowbore  18  and the radial exterior of the HCCV assembly  10 . 
   Once the rupture disc  28  has been destroyed, well working fluid can be circulated down the flowbore  114  and outwardly into the annulus  112  of the wellbore  102 , as indicated by arrows  123  in  FIG. 9 . The working fluid may then return to the surface of the wellbore  102  via the annulus  112 . As the working fluid is circulated into the flowbore  114  to the HCCV assembly  10 , it is flowed through the side pocket mandrel  118 . During this process, cement is cleaned from the completion system  100  by the flowing working fluid and, most particularly, from the side-pocket mandrel  118  so that it may be used for gas lift operations at a later point. 
   When sufficient cleaning has been performed, it is necessary to substantially close the fluid port  26  of the HCCV assembly  10  against fluid flow therethrough. The wellbore annulus  112  should be closed off at the surface of the wellbore  102 . Thereafter, fluid pressure is increased within the flowbore  114  and the annulus  112  above the level  182  of the cement  180  via continued pumping of working fluid down the flowbore  114 . Pumping of pressurized fluid should continue until a second, predetermined level of pressure is achieved. This predetermined level of pressure will act upon the upper end  36  of the outer sleeve  30  to shear the shear pin  34  and move the outer sleeve  30  to the closed position illustrated in  FIG. 2 . In this position, the outer sleeve  30  covers the fluid flow port  26  of the inner mandrel  12 . Fluid communication between the flowbore  18  and the annulus  112  will be blocked. In this manner, circulation of a working fluid through the valve assembly  10 , other portions of the completion system  100 , and the annulus  112  may be selectively stopped. The flowbore  114  can then be pressure tested for integrity. 
   In the event of failure of the outer sleeve  30  to close, as desired, a wireline tool, shown as tool  200  in  FIG. 3 , having a shifter  202 , which is shaped and sized to engage the profile  42  of the inner sleeve  38  in a complimentary manner, is lowered into the flowbore  114  and flowbore  18  of the valve assembly  10 . When the shifter  202  engages the profile  42 , the shifter  200  is pulled upwardly to move the inner sleeve  38  to its second, substantially closed position (shown in  FIG. 3 ) so that the opening  40  on the inner sleeve  38  is not aligned with the flow port  26  of the inner mandrel  12 . In this position, fluid flow through the flow port  26  is substantially blocked. 
   Following closure of the HCCV assembly  10 , by either shifting of the outer sleeve  30  or inner sleeve  38 , and pressure testing of the flowbore  114 , hydrocarbon fluids may be produced through the flowbore  114  from the formation  106  under impetus of surface pumps (not shown) through the flowbore  114 . At some point during the life of the wellbore  10 , artificial lift may be needed or desired to assist production of fluids. The completion assembly  100  will accommodate such artificial lift measures due to the presence of the side pocket mandrel  118  and the techniques used to remove excess cement from the components of the completion assembly  100 . 
     FIG. 10  illustrates the addition of exemplary gas lift valves  210  into the side pocket mandrel  118  in completion system  100  in order to assist production of hydrocarbons from the formation  106 . A kickover tool (not shown), of a type known in the art, is used to dispose one or more gas lift valves  210  into the cylinder  140  of the side pocket mandrel  118 . The use of kickover tools is well known by those having skill in the art. Similarly, gas lift valves are well known to those of skill in the art and a variety of such devices are available commercially. Therefore, a discussion of their structure and operation is not being provided. 
   The gas lift valves  210  may be placed into the side pocket mandrel  118  and operable thereafter. The apertures  144  in the side pocket mandrel  118  should be substantially devoid of cement due to the measures taken previously to clean the completion system  100  of excess cement or prohibit clogging by cement. These measures include the presence of removable side pocket plugs in the cylinder  140  of the side pocket mandrel  118  and filler guide sections  150  with features to stimulate flow turbulence, including cross-flowjet channels  158  and spaces  162  between the guide sections  150 . In addition, circulation of the working fluid throughout the system  100 , in the manner described above, will help to clean excess cement from the side pocket mandrel  118 , and other system components, prior to insertion of the gas lift valves  210 . 
   After the gas lift valves  210  are placed into the side pocket mandrel  118 , hydrocarbon fluids may be produced from the formation  106  by the system  100 . Fluids exit the perforations  186  and enter the perforated production liner  122 . They then flow up the flowbore  114  and into the production tubing  110 . The gas lift valves  210  inject lighter weight gases into the liquid hydrocarbons, in a manner known in the art, to assist their rise to the surface of the wellbore  102 . 
   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.