Abstract:
A multiple-positioning mechanical shifting system including for used in hydrocarbon wells. The system includes a shifting tool capable of selectively positioning a mechanical sliding sleeve valve in multiple operational positions that varying the flow rate and/or volume of tubing string fluid flowing to the well annulus. The system also includes a multiple position mechanical choke valve. A method of operating the mechanical choke valve using the shifting tool is described.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a multiple-positioning mechanical shifting system and method for use in hydrocarbon wells and more particularly to a shifting tool for manipulation of a mechanical sliding sleeve valve capable of multiple operational positions. 
     BACKGROUND OF THE INVENTION 
     Sliding sleeve valves have been used in tubing string for oil and gas wells to control fluid flow between the tubing string and the well annulus during circulation or production. The valves contain an inner sliding sleeve having a port that can be shifted to an opened position in alignment with a port in the outer valve body to permit fluid to flow from the tubing string to the well annulus. Shifting the sliding sleeve to a closed position blocks the port in the valve body to prevent the fluid from flowing into the well annulus. Mechanical sliding sleeve valves are manipulated by shifting tools customarily deployed on wireline or slickline. Shifting tools move the sliding sleeve to either the fully shifted up or fully shifted down position. Accordingly, sliding sleeve valves customarily have only two positions opened or closed. 
     Sliding sleeve valves have been developed that have a third position known as the equalizing position. The equalizing position is located intermediate of the opened and closed positions. In these valves, a smaller diameter equalizing port is provided in the inner sliding sleeve. The equalizing port serves to balance the tubing pressure and the annulus pressure before fully opening the valve in order to reduce the likelihood of a pressure surge as the valve is fully opened. The process of equalizing the pressures is carried out by shifting the sliding sleeve to a position where the equalizing port in the sliding sleeve is in fluid communication with the port of the valve body. Shifting tools have been produced to manipulate such sliding sleeve valves. U.S. Pat. No. 5,305,833, which is incorporated herein by reference, describes a shifting tool capable of positioning a sliding sleeve valve in a fully closed position, equalizing position, and fully opened position. 
     Multi-positioned sliding sleeve valves have also been developed. U.S. Pat. No. 6,722,439, which is incorporated herein by reference, describes a downhole choke valve in the form of a hydraulically controlled sliding sleeve valve operable in a plurality of positions including fully opened, fully closed and intermediate positions. 
     Despite the development of shifting tools that can position a sliding sleeve valve in three distinct positions, fully closed, equalizing, and fully opened, the need still exists for a shifting tool that can position a mechanical sliding sleeve valve in multiple positions and which can be used in conjunction with a multiple position mechanical choke valve. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide mechanical shifting system that functions as a multiple position mechanical choke valve. 
     It is a further object of the present invention to provide a shifting tool for use with a multiple position mechanical sliding sleeve valve. 
     It is a further object of the present invention to provide a multiple position mechanical choke valve. 
     These objects and other objects and advantages of the present invention are achieved by a novel multiple-position shifting system which includes a shifting tool for use with a mechanical sliding sleeve valve deployed in a tubing string of a hydrocarbon well. The sliding sleeve valve may include an internal sliding sleeve and an outer valve body. The shifting tool may include a top sub. A shifting tool key may be positioned on the top sub. The shifting tool key may be radially expandable to engage the internal sliding sleeve to enable shifting of the internal sliding sleeve relative to the outer valve body by displacement of the shifting tool within the sliding sleeve valve during valve shifting operations. The shifting tool key may also be radially retractable to disengage from the internal sliding sleeve to enable release of the sliding sleeve valve from the shifting tool during valve release operations. The shifting tool may also include a bottom sub. 
     The shifting tool may include a reciprocating assembly interconnecting the top sub and the bottom sub. The reciprocating assembly may include an inner mandrel and an outer housing disposed about the inner mandrel. The outer housing may have a biasing means to reciprocate the outer housing in a first direction during the valve shifting operations. The outer housing may also have an actuating means to cause reciprocation of the outer housing in a second direction during said valve release operations. The actuating means may operatively cooperate with the shifting tool key during valve release operations to disengage the shifting tool key from the internal sliding sleeve to place the internal sliding sleeve at a spatial position relative to said valve body. The spatial position may be selected from a plurality of possible spatial positions. 
     The shifting tool key may be retained on the top sub by a pair of retainers detachably affixed to the top sub. The top sub and the bottom sub may each be threadedly connected to the inner mandrel of the reciprocating assembly. The outer housing of the reciprocating assembly may be moveably connected to the inner mandrel of the reciprocating assembly. 
     The shifting tool key may have an outer profile that includes an engagement shoulder. The engagement shoulder may cooperate with a mating shoulder on the internal sliding sleeve. The cooperation between the engagement shoulder and the mating shoulder may enable the engagement of the shifting tool key with the internal sliding sleeve during valve shifting operations. 
     The outer profile of the shifting tool key may also include a releasing shoulder. The releasing shoulder may be actuated to radially retract the shifting tool key to disengage the engagement shoulder from the mating shoulder during valve release operations. The releasing shoulder may be actuated by reciprocation of the outer housing in the second direction. 
     The shifting tool key may also include biasing means. The biasing means may cause the radial expansion of the shifting tool key. The shifting tool key may have a recess. The recess may house or contain the biasing means. The biasing means may be a spring. 
     The reciprocating assembly may likewise include a recess. The recess may house or contain the biasing means of the reciprocating assembly. The biasing means may be a spring. 
     The sliding sleeve valve may contain an end sub. When the actuating means on the outer housing of the reciprocating assembly engages the end sub (during valve release operations), the outer housing is reciprocated in the second direction to disengage the shifting tool key from the internal sliding sleeve. Reciprocation in the second direction occurs by compression of the biasing means housed in the reciprocating assembly. 
     The actuating means may be any device that is capable of engaging or cooperating against the end sub to move or reciprocate the outer housing in the second direction. For example, the actuating means may be one or more collets. 
     The feature of the present invention wherein the internal sliding sleeve may be released at multiple positions relative to the outer valve body may be achieved based on a specified distance or length between the releasing shoulder of the shifting tool key and the actuating means on the outer housing of the reciprocating assembly. Such distance or length may be determinative of the spatial positioning of the internal sliding sleeve relative to the outer valve body. Accordingly, the shifting tool of the present invention may include a means to adjust the distance or length between the releasing shoulder and the actuating means to achieve multiple positioning of the internal sliding sleeve. 
     In one embodiment of the present invention, the mechanical sliding sleeve valve is a mechanical choke valve in which the internal sliding sleeve includes a plurality of a series of ports capable of providing fluid communication of the tubing string fluid there-through. Each of the plurality of the series of ports may provide a different flow rate and/or volume of the tubing string fluid flowing there-through. The spatial position selected for the internal sliding sleeve as described above may comprise one of the plurality of the series of ports, which are aligned with one or more ports in the outer valve body. 
     In another embodiment of the present invention, a shifting tool is provided for use with a mechanical sliding sleeve valve deployed in a tubing string of a hydrocarbon well. The mechanical sliding sleeve valve may include an internal sliding sleeve, an outer valve body, and an end sub. The shifting tool may include a top sub. The shifting tool may also include a shifting tool key positioned on the top sub. The shifting tool key may include an outer profile having an engagement shoulder and a release shoulder. The shifting tool key may also include a biasing means to radially expand the shifting tool key for engagement of the engagement shoulder with a mating shoulder of the internal sliding sleeve to enable shifting of the internal sliding sleeve relative to the outer valve body by displacement of the shifting tool within the sliding sleeve valve during valve shifting operations. The bias means also permit the radial retraction of the shifting tool key to disengage the engagement shoulder from the mating shoulder to enable release of the sliding sleeve valve from the shifting tool during valve release operations. 
     The shifting tool may also have a bottom sub. A reciprocating assembly may interconnect the top and bottom subs. The reciprocating assembly may include an inner mandrel and an outer housing disposed about the inner mandrel. The outer housing may have an upper end and a lower end. The outer housing may also have a biasing means to reciprocate the outer housing in a first direction during the valve shifting operations. The outer housing may include an actuating means to cause reciprocation of the outer housing in a second direction during the valve release operations by compressing the biasing means of the reciprocating assembly when the actuating means engages the end sub. The actuating means may operatively cooperate with the shifting tool key during valve release operations to cause the upper end of the outer housing to collapse the release shoulder to disengage the engagement shoulder from the mating shoulder and thereby place the internal sliding sleeve at a spatial position relative to said valve body. The spatial position may be selected from three or more possible spatial positions based on a pre-selected distance between the actuating means and the release shoulder. In this embodiment, the actuating means may be one or more collets. 
     The shifting tool may be deployed on wireline and preferably slickline. However, the shifting tool could also be deployed on coiled tubing or pipe string. 
     The present invention also is directed to a novel method of operating a mechanical sliding sleeve valve having an internal sliding sleeve, an outer valve body and an end sub for selective placement of the internal sliding sleeve at a spatial position relative to the valve body. The spatial position may be selected from any number of possible spatial positions or a plurality of possible spatial positions. 
     The method includes providing a shifting tool as set forth and described above. The method also includes pre-selecting the distance between the actuating means on the outer housing of the reciprocating assembly and the release shoulder on the shifting tool key. The shifting tool is deployed down a tubing string. The tubing string may include or contain the mechanical sliding sleeve valve. The method includes the step of causing the engagement shoulder on the shifting tool key to engage the mating shoulder on the internal sliding sleeve to operatively connect the shifting tool and the internal sliding sleeve. The method involves shifting the internal sliding sleeve relative to the valve body by displacing the shifting tool within the mechanical sliding sleeve valve. The outer housing is reciprocated in the second direction by causing the actuating means to engage the end sub so as to affect compression of the biasing means in the reciprocating assembly. The method includes the step of causing the upper end of the outer housing to collapse the release shoulder to disengage the engagement shoulder from the mating shoulder thereby releasing the internal sliding sleeve from the shifting tool at a selected spatial position relative to the valve body. The spatial position where the internal sliding sleeve is released may be pre-determined by selecting a specified distance between the actuating means and the release shoulder. The selected spatial position of the internal sliding sleeve achieved may be a fully closed position, a plurality of intermediate positions, an equalizing position, or a fully opened position. 
     The step of pre-selecting the distance between the actuating means and the release shoulder may be undertaken by: (i) adjusting the length of the outer housing where the actuating means is at a fixed position on the outer housing; (ii) adjusting the position of the actuating means on the outer housing where the actuating means is detachably fixed to the outer housing; or (iii) affixing a selected outer housing having a specified length and a fixed actuating means thereon (the selected outer housing may be chosen from among a plurality of outer housings each having a different length and a fixed actuating means thereon). 
     The shifting tool of the present invention may be used with a mechanical choke valve deployed in a tubing string of a hydrocarbon well. The mechanical choke valve may include an internal sliding sleeve. The internal sliding sleeve may have a mating shoulder for operable engagement with the shifting tool as described above. The internal sliding sleeve may have a plurality of a series of ports capable of providing fluid communication of a tubing string fluid there-through. Each of the plurality of series of ports may provide a different flow rate and/or volume of the tubing string fluid flowing there-through. The mechanical choke valve may also include an outer valve body disposed about the internal sliding sleeve. The outer valve body may have one or more ports capable of providing fluid communication of the tubing string fluid there-through. Preferably, each of the plurality of series of ports in the internal sliding sleeve may be capable of being selectively aligned with one or more ports of the outer valve body to provide fluid communication of the tubing string fluid to the well annulus by displacement of the shifting tool as described hereinabove. 
     Each embodiment of the shifting tool described above may be used in connection with the operation of the mechanical choke valve. 
     The mechanical choke valve of the present invention may also include an outer valve body that has one or more detent grooves. The internal sliding sleeve may be provided with one or more locking collets. The locking collect may be snapped into positioned within a corresponding detent groove to lock the internal sliding sleeve in place when the internal sliding sleeve is released from the shifting tool. The locking of the collect with the detent grooves helps prevent any unintentional shifting of the internal sliding sleeve due to fluid pressures in the tubing string. 
     In an embodiment of the mechanical choke valve, the plurality of series of ports of the internal sliding sleeve include: (1) a first series of ports that when aligned with one or more ports of the outer valve body place the mechanical choke valve in a fully opened position; (2) a second series of ports that when aligned with one or more ports of the outer valve body place the mechanical choke valve in a first intermediate position; (3) a third series of ports that when aligned with one or more ports of the outer valve body place the mechanical choke valve in a second intermediate position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are a sequential partial, cross-sectional side view of an embodiment of the shifting tool of the mechanical shifting system of the present invention. 
         FIGS. 2A and 2B  are a sequential cross-sectional side view of the mechanical shifting system of the present invention with the shifting tool situated within the sliding sleeve valve in a closed position. 
         FIGS. 3A and 3B  are a sequential cross-sectional side view of the mechanical shifting system of the present invention with the shifting tool situated within the sliding sleeve valve in an opened position. 
         FIG. 4  is a cross-sectional side view of the mechanical shifting system of the present invention with the shifting tool situated within the sliding sleeve valve after release of the sliding sleeve. 
         FIG. 5  is a schematic illustration of the mechanical shifting system of the present invention suspended within a well from a platform. 
         FIG. 6  is a partial cross-sectional side view of the mechanical choke valve of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the figures where like elements have been given like numerical designation to facilitate an understanding of the present invention, and in particular with reference to the embodiment of the present invention illustrated in  FIG. 1 , shifting tool  10  may include top sub  12 , shifting tool key  14 , reciprocating assembly  16  and bottom sub  18 . Top sub  12  and bottom sub  18  are positioned in spaced apart relation and interconnected by reciprocating assembly  16 . Shifting tool key  14  is positioned on the outer surface of top sub  12  between upper key retainer  24  and lower key retainer  26 . Upper and lower key retainers  24 ,  26  maintain shifting key  14  in position relative to top sub  12 . Upper and lower key retainers  24 ,  26  are preferably slidably positioned on top sub  12  and held in place by mandrel  32 . 
     Shifting tool key  14  may include recess  20  that accommodates biasing means  22 . Biasing means  22  are capable of causing the radial, outward expansion of shifting key  14 . Biasing means  22  may be a spring such as a grasshopper spring or butterfly spring. Shifting tool key  14  may include an outer profile containing engagement shoulder  28  and releasing shoulder  30 . When radially expanded, the outer profile of shifting tool key  14  cooperates with a mating profile on the inner surface of internal sliding sleeve  44  of mechanical sliding sleeve valve  42 . For example, engagement shoulder  28  may cooperate with mating shoulder  52  of internal sliding sleeve  44  as shown in  FIG. 2 . 
     Again with reference to  FIG. 1 , reciprocating assembly  16  includes mandrel  32  and outer housing  34 . The upper end of mandrel  32  is detachably connected to the lower end of top sub  12  preferably by threaded connection. The lower end of mandrel  32  is detachably connected to the upper end of bottom sub  18  preferably by threaded connection. Outer housing  16  is positioned external to and around mandrel  32 . The outer surface of outer housing  16  contains one or more collets  36 . Reciprocating assembly  16  also includes recess  38  that accommodates biasing means  40 . Biasing means  40  bias or expand outer housing  16  downwardly when shifting tool  10  is prepared to conduct or is conducting valve shifting operations. Biasing means  40  may be a spring such as a compression spring. 
     In  FIG. 2 , shifting tool  10  has been run down hole by conventional means such as wireline or slickline. It is to be understood that shifting tool  10  could also be operated on coiled tubing or pipe. Shifting tool  10  is situated within mechanical sliding sleeve valve  42 . Sliding sleeve valve  42  may be connected to a work string such as production tubing. Shifting tool  10  is operationally engaged with sliding sleeve valve  42  and in particular with sliding sleeve  44  by conventional procedures well known to those skilled in the art. 
     With reference to  FIG. 3 , shifting tool  10  has been lowered within sliding sleeve valve  42  such that sliding sleeve  44  as been repositioned so that ports  46  on sliding sleeve  44  are aligned with ports  48  on outer valve body  50  to permit the flow of fluid between the tubing string and the well annulus. Repositioning of sliding sleeve  44  is accomplished by physical force, namely causing shifting tool  10  to push internal sliding sleeve  44  downward within outer valve body  50 . It is to be understood that reposition of internal sliding sleeve  44  may also be accomplished by causing shifting tool  10  to pull internal sliding sleeve  44  upward within outer valve body  50 . The force of shifting tool  10  is transferred to internal sliding sleeve  44  by engagement of engaging shoulder  28  of shifting tool key  14  with mating shoulder  52  of internal sliding sleeve  44 . 
     Again with reference to  FIG. 3 , as shifting tool  10  travels downward through sliding sleeve valve  42 , collet  36  on outer housing  34  encounters and engages shoulder  54  on end sub  56 , which is connected to and a part of sliding sleeve valve  42 . The engagement of collect  36  with shoulder  54  causes compression of biasing means  40  and the upward movement, relative to shifting tool  10 , of outer housing  34 . The upper end of outer housing  34  contacts or engages releasing shoulder  30  of shifting tool key  14 . The engagement of outer housing  34  with releasing shoulder  30  causes compression of biasing means  22  and the radial inward retraction of shifting tool key  14 . The radial inward retraction of shifting tool key  14  releases sliding sleeve  44  from connection with shifting tool  10 . Shifting tool  10  may then be relocated without interfering with or causing sliding sleeve  44  to be repositioned. 
     As seen in  FIGS. 2-4 , the outer surface of internal sliding sleeve  44  may have one or more locking collets  58  which cooperate with one or more detent grooves  60  in the inner surface of valve body  50  to lock sliding sleeve  44  in position on valve body  50  and keep it from being unintentionally shifted. Locking collets  58  may be positioned at varying locations on the outer surface of internal sliding sleeve  44 . For example, locking collets  58  may be positioned at locations on the outer surface of internal sliding sleeve  44  that correspond to the closed position, fully opened position, equalizing position, or any intermediate position of sliding sleeve valve  42 . 
     The releasing mechanism of shifting tool  10  may be employed to selectively place sliding sleeve  44  at a spatial position relative to outer valve body  50 . Such selective placement of sliding sleeve  44  is accomplished by varying the distance or length between collet  36  of outer housing  34  and releasing shoulder  30  of shifting tool key  14 . For example, a greater distance between collet  36  and releasing shoulder  30  would mean that sliding sleeve  44  will be released, and therefore placed, at a higher location within sliding sleeve valve  42 . A lesser distance between collet  36  and releasing shoulder  30  would mean that sliding sleeve  44  will be released, and therefore placed, at a lower location within sliding sleeve valve  42 . Any number of placement positions is achievable with shifting tool  10  such as fully opened, fully closed, or one or more intermediate positions between fully opened and fully closed. 
     Varying the distance between collet  36  on outer housing  34  and releasing shoulder  30  of shifting tool key  14  may be accomplished in a number of ways. For instance, outer housing  34  could be made so that its length could be adjusted to account for variable distances between collet  36  and releasing shoulder  30 . One or more segments of outer housing  34  could be added to increase the overall length of outer housing  34  or removed to decrease the overall length of outer housing  34 . Alternatively, outer housing could be made so that the positioning of collet  36  on outer housing  34  could be adjusted to account for variable distances between collet  36  and releasing shoulder  30 . Collet  36  could be detachably connected to outer housing  34  and movable in a downward direction on outer housing  34  to increase the distance between collet  36  and releasing shoulder  30  or moveable in an upward direction on outer housing  34  to decrease the distance between collet  36  and releasable shoulder  30 . As another alternative, outer housing  34  could be made in multiple lengths. If an operator desired to increase the distance between collet  36  and releasable shoulder  30 , the operator could configure shifting tool  10  with one of the outer housings  34  having a greater length. Conversely, if an operator desired to decrease the distance between collet  36  and releasable shoulder  30 , the operator could configure shifting tool  10  with one of the outer housings  34  having a shorter length. 
     As shown in  FIG. 4 , sliding sleeve valve  44  has been released from shifting tool  10 . Shifting tool  10  is free to move upward or downward within sliding sleeve valve  42  without causing the movement of internal sliding sleeve  44 . As described earlier herein, after release, sliding sleeve  44  may be locked into position on outer valve body  50  by engagement of locking collet  58  in detent groove  60 . 
       FIG. 5  is a schematic illustration of shifting tool  10  suspended within well  62  from drilling rig  64 . Shifting tool  10  is operatively positioned within sliding sleeve valve  42  which is connected to work string  66 . Shifting tool  10  is preferably deployed in work string  66  on wireline or slickline (not shown). The outer surface of work string  66  and well  62  form well annulus  68 . Packer means  70  is set in well  62 . Packer mean  70  is operatively attached to work string  64  and generally sealing engages the inner portion of well  62 . Well  62  may have perforations  72  communicating an inner portion of well  62  with hydrocarbon reservoir  74 . In accordance with the teachings of the present invention, shifting tool  10  is manipulated to shift and release sliding sleeve  44  in multiple positions relative to outer valve body  50  of sliding sleeve valve  42 . 
     Shifting tool  10  may be used with a mechanical choke valve that includes a sliding sleeve with one or more series of different numbered and/or sized ports that could be selectively positioned in fluid communication with the ports of the outer valve body for controlled fluid flow into the well annulus.  FIG. 6  reveals a mechanical choke valve that could be used in conjunction with shifting tool  10 . 
     With reference to  FIG. 6 , mechanical choke valve  100  includes outer valve body  102  and internal sliding sleeve  104 . Seals  106 ,  108  provide a sealing engagement between outer valve body  102  and internal sliding sleeve  104 . Internal sliding sleeve  104  may contain a plurality of a series of ports (e.g., three or more series of ports). For example, internal sliding sleeve  104  may have a first series of ports  110 ,  112 , a second series of ports  114 ,  116 ,  118 , and a third series of ports  120 . As described herein, internal sliding sleeve  104  may be shifted by displacement of shifting tool  10  to place internal sliding sleeve  104  in various positions relative to outer valve body  102  and in particular relative to and aligned with ports  122 ,  124 ,  126  of outer valve body  102 . Engagement shoulder  28  of shifting tool key  14  cooperates with mating shoulder  128  of internal sliding sleeve  104  during shifting operations to move sliding sleeve  104 . As also described herein, internal sliding sleeve  104  may be released at selective spatial positions relative to outer valve body  102  and in particular relative to and aligned with ports  122 ,  124 ,  126  of outer valve body  102  during releasing operations. 
     Depending on the desired flow rate and/or volume of tubing string fluid to be flowed into the well annulus, an operator may choose to place mechanical choke valve  100  in a fully opened position in which case the second series of ports  114 ,  116 ,  118  would be positioned in fluid communication with ports  122 ,  124 ,  126  of outer valve body  102 . The operator may decide to place mechanical choke valve  100  in a first intermediate position (e.g., partially opened) in which case the first series of ports  110 ,  112  would be positioned in fluid communication with ports  112 ,  124 ,  126  of outer valve body  102  (i.e., between seals  106 ,  108 ) The operator may decide to place mechanical choke valve  100  in a second intermediate position (partially closed) in which case the third series of port  120  would be positioned in fluid communication with ports  112 ,  124 ,  126  of outer valve body  102 . The operator may decide to place mechanical choke valve  100  in a fully closed positioned in which case a portion of internal sliding sleeve with no ports would be positioned to prevent fluid communication with ports  122 ,  124 ,  126  of outer valve body  102  (i.e., positioned between seals  106 ,  108  to block fluid communication to ports  122 ,  124 ,  126 ). 
     To achieve differing flow rates and/or volumes, each series of ports may have different numbers of ports, different sized ports or both. Within a series having two or more ports, each port mat be differently sized. The number and size of ports will depend in the desired flow rate and/or volume to be achieved. 
     While preferred embodiments of the present invention have been described, it is to he understood that the embodiments described are illustrative only and that the scope of the invention is to be defined solely by the appended claims when accorded a full range of equivalents, many variations and modifications naturally occurring to those skilled in the art from a perusal hereof.