Patent Publication Number: US-7909108-B2

Title: System and method for servicing a wellbore

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not applicable. 
     BACKGROUND 
     Subterranean formations that contain hydrocarbons are sometimes non-homogeneous in their composition along the length of wellbores that extend into such formations. It is sometimes desirable to treat and/or otherwise manage the formation and/or the wellbore differently in response to the differing formation composition. Some wellbore servicing systems and method allow such treatment and may refer to such treatments as zonal isolation treatments. However, some wellbore servicing systems and methods are limited in the number of different zones that may be treated within a wellbore. Accordingly, there exists a need for improved systems and method of treating multiple zones of a wellbore. 
     SUMMARY 
     Disclosed herein is a wellbore servicing system, comprising a first sleeve system disposed in a wellbore, the first sleeve system comprising a first seat landing surface, a second sleeve system disposed in the wellbore and uphole of the first sleeve system, the second sleeve system comprising a second seat landing surface, wherein the first seat landing surface and the second seat landing surface are each at least partially frusto-conical in shape, and wherein a first seat landing surface angle of the first seat landing surface is less than a second seat landing surface angle of the second seat landing surface. In an alternative embodiment, a first seat landing surface angle of the first seat landing surface may be about equal to a second seat landing surface angle of the second seat landing surface. In further embodiments, the landing seat angles may be about constant and/or may vary across a plurality of sleeve systems disposed in the wellbore. At least one of the first seat and the second seat may be configured to sealingly engage a dart. The dart may comprise a dart outer diameter smaller than a second seat passage diameter of the second seat, and the dart outer diameter may be larger than a first seat passage diameter of the first seat. The dart may comprise a dart landing seat angle smaller than the second seat landing surface angle, and the dart landing seat angle may be substantially the same as the first seat landing surface angle. The dart may be substantially symmetrical along a dart central axis. The dart may comprise one or more alignment features. The alignment feature may be a rounded nose tip. The rounded nose tip may comprise a radius of curvature of at least about 0.5 inches. The rounded nose tip may comprise a substantially cylindrical extension joined to a substantially spherical section. The alignment feature may be a dart centralizer. The dart centralizer may comprise foam. The dart centralizer may be received on a nose of the dart. The alignment feature may be a substantially cylindrical shelf of the dart that is smaller in diameter than the dart outer diameter. The alignment feature may be a plurality of substantially cylindrical shelves having different diameters, the plurality of substantially cylindrical shelves being disposed on the dart with an increasing order of diameter from a distal end of the dart toward a center of the dart. The alignment feature may be a substantially cylindrical shelf of the dart that is smaller in diameter than the dart outer diameter and wherein the cylindrical shelf comprises a chamfered edge near a distal end of the shelf. At least a portion of at least one of the first seat, the second seat, and the dart may comprise a degradable material. At least one of the first seat and the second seat may comprise cast iron, and at least a portion of the dart that contacts the first seat landing surface may comprise cast iron. The dart comprises cast iron and a material relatively more easily degradable than cast iron. A dart body that seals against the first seat landing surface may comprise cast iron, and a dart nose of the dart may comprise a material relatively more easily degradable than cast iron. The dart, the seat, or both may be comprised of a composite material. The dart, the seat, or both may be formed as a single unitary structure. At least one of the first seat and the second seat may be frangible. The at least one frangible seat may be configured to comprise a radial array of seat pieces (e.g., sliced pie-shaped pieces). The seat pieces may be selectively held together by an epoxy resin. At least a portion of at least one of the seat pieces may be constructed of cast iron. At least a portion of at least one seat piece may be constructed of a material more easily degraded than cast iron. Such darts and seats may be removed in whole or in part by subjecting the darts and seats to degradable conditions, by reverse/back flowing the wellbore, and/or applying a mechanical force to the darts (e.g., drilling or fishing them out of the wellbore). A minimum gap may be provided between a second seat passage diameter and a dart outer diameter. The minimum gap may be within a range of about 0.030 inches and about 0.090 inches. The minimum gap may be about 0.060 inches. A minimum seal radial distance may be provided that is measured as a radial distance relative to a dart central axis over which a sealing contact interface between the first seat landing surface and a dart landing surface extends. The minimum seal radial distance may be within a range of about 0.030 inches and about 0.090 inches. The minimum seal radial distance may be about 0.060 inches. 
     Further disclosed herein is a method of servicing a wellbore, comprising disposing a first seat within a wellbore and disposing a second seat within the wellbore and uphole of the first seat, the first seat and the second seat comprising a first seat landing surface and a second seat landing surface, respectively, passing a first dart through a second passage of the second seat, and contacting the first dart with the first seat landing surface, wherein the first seat landing surface and second seat landing surface are at least partially frusto-conical in shape and wherein the first dart complements the first seat landing surface but does not complement the second seat landing surface. A second seat landing surface angle of the second seat landing surface may be greater than a first seat landing surface angle of the first seat landing surface. The first seat, the second seat, or both may be coupled to a sliding sleeve. A first sliding sleeve coupled to the first seat may be shifted to an open position via contact of the first seat and the first dart, thereby revealing a plurality of ports in fluid communication with a surrounding formation. The method may further comprise flowing a wellbore servicing fluid down the wellbore, through the plurality of ports, and into the surrounding formation. The wellbore servicing fluid may be a fracturing fluids and the surrounding formation may be fractured thereby. The method may further comprise degrading at least a portion of the first dart. The method may further comprise degrading at least a portion of at least one of the first seat and the second seat. The method may further comprise contacting a second dart with the second seat landing surface. The second dart may complement the second seat landing surface, and in the second dart cannot completely pass through the second passage. The method may further comprise degrading at least a portion of the second dart. The method may further comprise backflowing at least a portion of the wellbore so that any remaining portions of the first dart and any remaining portions of the second dart may be removed from contact with the first seat and the second seat, respectively. 
     Further disclosed herein is a wellbore servicing system, comprising a plurality of seats disposed within a work string, each successively downhole located seat comprising a smaller seat passage than the respective immediately uphole seat, the seat located furthest uphole comprising the largest seat passage amongst the plurality of seats, and a plurality of darts, each of the plurality of darts configured to sealingly engage one seat, respectively, of the plurality of seats, each dart being configured to pass through each of the plurality of seat passages located uphole of the one seat with which each dart, respectively, is configured to sealingly engage, and wherein at least one of the darts comprises an alignment feature. At least 10 seats may be disposed in a work string comprising about a 4.5 inch casing. The difference in seat passage sizes may be about 0.120 inches. A second upper seat landing surface angle of a second seat may be greater than a first upper landing surface angle of a first seat, and the first seat may be located downhole relative to the second seat. A first dart that is configured for sealing engagement with the first seat may comprise a first dart landing surface that complements the first seat but does not complement the second seat. A second dart that is configured for sealing engagement with the second seat may comprise a second dart landing surface that complements the second seat, and the second dart cannot pass through a second seat passage of the second seat. In an embodiment, at least about 20 seats may be disposed in a work string comprising about a 4.5 inch casing. 
     Further disclosed herein is a wellbore servicing system, comprising a plurality of sleeve systems disposed in a wellbore, each sleeve system comprising a seat and a dart configured to selectively seal against the seat to the exclusion of other seats, the seats each comprising an upper seat landing surface and the darts each comprising a dart landing surface, wherein each of the seat landing surfaces and each of the dart landing surfaces are at least partially substantially frusto-conical in shape. A first seat may comprise a smaller seat landing surface angle as compared to a seat landing surface angle of a second seat that is located uphole relative to the first seat. A relatively greater number of seats may be disposed in the wellbore by configuring the seats and the darts according to a relatively smaller minimum gap required between a dart and the seats through which the dart must pass fully through. A relatively greater number of seats may be disposed in the wellbore by configuring the seats and the darts according to a relatively smaller minimum seal radial distance. At least 8 seats may be disposed in a work string comprising about a 4.5 inch casing. Alternatively, at least 10 seats may be disposed in a work string comprising about a 4.5 inch casing. Alternatively, at least 15 seats may be disposed in a work string comprising about a 4.5 inch casing. Alternatively, at least 18 seats may be disposed in a work string comprising about a 4.5 inch casing. Alternatively, about 20 seats may be disposed in a work string comprising about a 4.5 inch casing. Alternatively, about 20 or more seats may be disposed in a work string comprising about a 4.5 inch casing. At least one of the darts may comprise an alignment feature. At least one of the darts and/or seats may comprise a degradable material. At least one of the seats may be frangible. At least one of the darts may be substantially symmetrical. Darts and seats that are configured to seal against each other are configured to comprise complementary dart landing surface angles and upper seal landing surface angles, respectively. Darts and seats may be configured to comprise substantially the same dart landing surface angles and upper seal landing surface angles, respectively. The dart landing surface angles and the upper seal landing surface angles for each sleeve assembly disposed in wellbore (e.g., each mating seat/dart pair) may be the same or different. For example the angles may increase, decrease, and/or stay about constant when traversing uphole and/or downhole in the wellbore. The dart landing surface angles and the upper seal landing surface angles may be equal to about 45 degrees. Alternatively, the dart landing surface angles and the upper seal landing surface angles may be less than or equal to about 45 degrees. 
     Further disclosed herein is a wellbore servicing system, comprising a plurality of sleeve systems disposed in a wellbore, each sleeve system comprising a seat and a dart configured to selectively seal against the seat to the exclusion of other seats, the seats each comprising an upper seat landing surface and the darts each comprising a dart landing surface, wherein the darts each comprise a dart landing surface that is configured to complement an upper seat landing surface of the seat to which the dart is configured to selectively seal against. The dart landing surface that is configured to complement an upper seat landing surface of the seat to which the dart is configured to selectively seal against may comprise a dart landing surface angle that complements an upper seat landing surface angle of the upper seat landing surface. The dart landing surface that is configured to complement an upper seat landing surface of the seat to which the dart may be at least partially configured to have a substantially frusto-conical shape. A first seat of the plurality of seats may be disposed within the wellbore downhole relative to a second seat of the plurality of seats, and a first upper seat landing surface of the first seat may comprise a first upper seat landing surface angle that is smaller than a second upper seat landing surface angle of a second upper seat landing surface of the second seat. A first seat of the plurality of seats may be disposed within the wellbore downhole relative to a second seat of the plurality of seats, and a first upper seat landing surface of the first seat may comprise a first upper seat landing surface angle that is substantially equal to a second upper seat landing surface angle of a second upper seat landing surface of the second seat. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description: 
         FIG. 1  is a cut-away view of an embodiment of a wellbore servicing system according to the disclosure; 
         FIG. 2  is a cross-sectional view of a sleeve system of the wellbore servicing system of  FIG. 1 ; 
         FIG. 3  is an oblique view of the sleeve system of  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of a seat of the sleeve system of  FIG. 2 ; 
         FIG. 5  is an orthogonal end view of the seat of  FIG. 4 ; 
         FIG. 6  is an oblique view of the seat of  FIG. 4 ; 
         FIG. 7  is an orthogonal side view of a dart body of a dart of the sleeve system of  FIG. 2 ; 
         FIG. 8  is an oblique view of the dart body of  FIG. 7 ; 
         FIG. 9  is a cross-sectional view of a dart nose of a dart of the sleeve system of  FIG. 2 ; 
         FIG. 10  is an oblique view of the dart nose of  FIG. 9 ; 
         FIG. 11  is a cross-sectional view of a dart centralizer of a dart of the sleeve system of  FIG. 2 ; 
         FIG. 12  is an oblique view of the dart centralizer of  FIG. 11 ; 
         FIG. 13  is a cross-sectional view of a seat of another embodiment of a sleeve system of the wellbore servicing system of  FIG. 1 ; 
         FIG. 14  is an orthogonal end view of the seat of  FIG. 13 ; 
         FIG. 15  is an oblique view of the seat of  FIG. 13 ; 
         FIG. 16  is a cross-sectional view of a dart of another embodiment of a sleeve system of the wellbore servicing system of  FIG. 1 ; 
         FIG. 17  is an oblique view of the dart of  FIG. 16 ; 
         FIG. 18  is a cross-sectional view of a dart body of the dart of  FIG. 16 ; 
         FIG. 19  is an oblique view of the dart body of  FIG. 18 ; 
         FIG. 20  is a cross-sectional view of a dart nose of the dart of  FIG. 16 ; 
         FIG. 21  is an oblique view of the dart nose of  FIG. 20 ; 
         FIG. 22  is a cross-sectional view of a dart centralizer of the dart of  FIG. 16 ; 
         FIG. 23  is an oblique view of the dart centralizer of  FIG. 22 ; 
         FIG. 24  is a cross-sectional view of a seat of still another embodiment of a sleeve system of the wellbore servicing system of  FIG. 1 ; 
         FIG. 25  is an orthogonal end view of the seat of  FIG. 24 ; 
         FIG. 26  is an oblique view of the seat of  FIG. 24 ; 
         FIG. 27  is a cross-sectional view of a dart of still another embodiment of a sleeve system of the wellbore servicing system of  FIG. 1 ; 
         FIG. 28  is an oblique view of the dart of  FIG. 27 ; 
         FIG. 29  is an orthogonal side view of a dart body of the dart of  FIG. 27 ; 
         FIG. 30  is an oblique view of the dart body of  FIG. 29 ; 
         FIG. 31  is a cross-sectional view of a dart nose of the dart of  FIG. 27 ; 
         FIG. 32  is an oblique view of the dart nose of  FIG. 31 ; 
         FIG. 33  is a cross-sectional view of a dart centralizer of the dart of  FIG. 27 ; 
         FIG. 34  is an oblique view of the dart centralizer of  FIG. 33 ; 
         FIG. 35  is a cross-sectional view of an alternative embodiment of a sleeve system in a closed or installation configuration; 
         FIG. 36  is a cross-sectional view of the sleeve system of  FIG. 35  in an open configuration; 
         FIG. 37  is a cross-sectional view of the sleeve system of  FIG. 35  in a configuration with a seat at least partially removed from a baffle; 
         FIG. 38  is an orthogonal end view of a seat of the sleeve system of  FIG. 35 ; 
         FIG. 39  is a cross-sectional view of the seat of  FIG. 38 ; 
         FIG. 40  is an oblique view of the seat of  FIG. 38 ; 
         FIG. 41  is an oblique cut-away view of yet another alternative embodiment of a sleeve system; 
         FIG. 42  is an oblique view of another alternative embodiment of a seat; 
         FIG. 43  is an oblique bottom view of another alternative embodiment of a seat; 
         FIG. 44  is an oblique top view of the seat of  FIG. 43 ; 
         FIG. 45  is a cut-away view of the seat of  FIG. 43  and another alternative embodiment of a dart; 
         FIG. 46  is an oblique view of another alternative embodiment of a dart; 
         FIG. 47  is an oblique view of a dart body of the dart of  FIG. 46 ; 
         FIG. 48  is an oblique view of still another alternative embodiment of a dart; 
         FIG. 49  is a cut-away view of another alternative embodiment of a sleeve system; 
         FIG. 50  is a cut-away view of a seat and other components of the sleeve system of  FIG. 49 ; 
         FIG. 51  is an orthogonal side view of a dart of the sleeve system of  FIG. 49 ; 
         FIG. 52  is a cut-away view of yet another alternative embodiment of a sleeve system; 
         FIG. 53  is a cut-away view of a seat and other components of the sleeve system of  FIG. 52 ; 
         FIG. 54  is an orthogonal side view of a dart of the sleeve system of  FIG. 52 ; 
         FIG. 55  is a cut-away view of still another alternative embodiment of a sleeve system; 
         FIG. 56  is a cut-away view of a seat and other components of the sleeve system of  FIG. 55 ; and 
         FIG. 57  is an orthogonal side view of a dart of the sleeve system of  FIG. 55 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     In the drawings and description that follow, like parts are typically marked throughout the specification and drawings with the same reference numerals, respectively. The drawing figures are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. 
     Unless otherwise specified, any use of any form of the terms “connect,” “engage,” “couple,” “attach,” or any other term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements and may also include indirect interaction between the elements described. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ”. Reference to up or down will be made for purposes of description with “up,” “upper,” “upward,” or “upstream” meaning toward the surface of the wellbore and with “down,” “lower,” “downward,” or “downstream” meaning toward the terminal end of the well, regardless of the wellbore orientation. The term “zone” or “pay zone” as used herein refers to separate parts of the wellbore designated for treatment or production and may refer to an entire hydrocarbon formation or separate portions of a single formation such as horizontally and/or vertically spaced portions of the same formation. The various characteristics mentioned above, as well as other features and characteristics described in more detail below, will be readily apparent to those skilled in the art with the aid of this disclosure upon reading the following detailed description of the embodiments, and by referring to the accompanying drawings. 
     Referring to  FIG. 1 , an embodiment of a wellbore servicing system  100  is shown in an example of an operating environment. As depicted, the operating environment comprises a drilling rig  106  that is positioned on the earth&#39;s surface  104  and extends over and around a wellbore  114  that penetrates a subterranean formation  102  for the purpose of recovering hydrocarbons. The wellbore  114  may be drilled into the subterranean formation  102  using any suitable drilling technique. The wellbore  114  extends substantially vertically away from the earth&#39;s surface  104  over a vertical wellbore portion  116 , deviates from vertical relative to the earth&#39;s surface  104  over a deviated wellbore portion  136 , and transitions to a horizontal wellbore portion  118 . In alternative operating environments, all or portions of a wellbore may be vertical, deviated at any suitable angle, horizontal, and/or curved. 
     At least a portion of the vertical wellbore portion  116  is lined with a casing  120  that is secured into position against the subterranean formation  102  in a conventional manner using cement  122 . In alternative operating environments, a horizontal wellbore portion may be cased and cemented and/or portions of the wellbore may be uncased. The drilling rig  106  comprises a derrick  108  with a rig floor  110  through which a tubing or work string  112  (e.g., cable, wireline, E-line, Z-line, jointed pipe, coiled tubing, casing, or liner string, etc.) extends downward from the drilling rig  106  into the wellbore  114 . The work string  112  delivers the wellbore servicing system  100  to a selected depth within the wellbore  114  to perform an operation such as perforating the casing  120  and/or subterranean formation  102 , creating perforation tunnels and fractures (e.g., dominant fractures, micro-fractures, etc.) within the subterranean formation  102 , producing hydrocarbons from the subterranean formation  102 , and/or other completion operations. The drilling rig  106  comprises a motor driven winch and other associated equipment for extending the work string  112  into the wellbore  114  to position the wellbore servicing system  100  at the selected depth. 
     While the operating environment depicted in  FIG. 1  refers to a stationary drilling rig  106  for lowering and setting the wellbore servicing system  100  within a land-based wellbore  114 , in alternative embodiments, mobile workover rigs, wellbore servicing units (such as coiled tubing units), and the like may be used to lower a wellbore servicing system into a wellbore. It should be understood that a wellbore servicing system may alternatively be used in other operational environments, such as within an offshore wellbore operational environment. 
     The wellbore servicing system  100  comprises a liner hanger  124  (such as a Halliburton VersaFlex® liner hanger) and a tubing section  126  extending between the liner hanger  124  and a wellbore lower end. The tubing section  126  comprises a float shoe and a float collar housed therein and near the wellbore lower end. Further, a tubing conveyed device is housed within the tubing section  126  and adjacent the float collar. 
     The horizontal wellbore portion  118  and the tubing section  126  define an annulus  128  therebetween. The tubing section  126  comprises an interior wall that defines a flow passage  132  therethrough. An inner string  134  is disposed in the flow passage  132  and the inner string  134  extends therethrough so that an inner string lower end extends into and is received by a polished bore receptacle near the wellbore lower end. 
     The subterranean formation  102  comprises a deviated zone  150  associated with deviated wellbore portion  136 . The subterranean formation  102  further comprises first, second, third, fourth, an fifth horizontal zones,  150   a ,  150   b ,  150   c ,  150   d ,  150   e , respectively, associated with the horizontal wellbore portion  118 . In this embodiment, the zones  150 ,  150   a ,  150   b ,  150   c ,  150   d ,  150   e  are offset from each other along the length of the wellbore  114  in the following order of increasingly downhole location:  150 ,  150   e ,  150   d ,  150   c ,  150   b , and  150   a . In this embodiment, stimulation and production sleeve systems  200 ,  200   a ,  200   b ,  200   c ,  200   d , and  200   e  are located within wellbore  114  in the work string  112  and are associated with zones  150 ,  150   a ,  150   b ,  150   c ,  150   d , and  150   e , respectively. It will be appreciated that zone isolation devices such as annular isolation devices (e.g., annular packers and/or swellpackers) may be selectively disposed within wellbore  114  in a manner that restricts fluid communication between spaces immediately uphole and downhole of each annular isolation device. 
     Referring now to  FIGS. 2-3 , a cross-sectional view and an oblique view of an embodiment of a stimulation and production sleeve system  200  (hereinafter referred to as “sleeve system”  200 ) is shown, respectively. Many of the components of sleeve system  200  lie substantially coaxial with a central axis  202  of sleeve system  200 . Sleeve system  200  comprises an upper adapter  204 , a lower adapter  206 , and a ported case  208 . The ported case  208  is joined between the upper adapter  204  and the lower adapter  206 . Together, inner surfaces  210 ,  212 ,  214  of the upper adapter  204 , the lower adapter  206 , and the ported case  208 , respectively, substantially define a sleeve flow bore  216 . The upper adapter  204  comprises a collar  218 , a makeup portion  220 , and a case interface  222 . The collar  218  is internally threaded and otherwise configured for attachment to an element of work string  112  that is adjacent and uphole of sleeve system  200  while the case interface  222  comprises external threads for engaging the ported case  208 . The lower adapter  206  comprises a nipple  224 , a makeup portion  226 , and a case interface  228 . The nipple  224  is externally threaded and otherwise configured for attachment to an element of work string  112  that is adjacent and downhole of sleeve system  200  while the case interface  228  also comprises external threads for engaging the ported case  208 . 
     The ported case  208  is substantially tubular in shape and comprises an upper adapter interface  230 , a central ported body  232 , and a lower adapter interface  234 , each having substantially the same exterior diameters. However, the inner surface  214  of ported case  208  comprises an upper shoulder  236  that extend between a threaded interior of the upper adapter interface  230  to an inner slide surface  238  of the ported body  232 . The interior of the upper adapter interface  230  is smaller in diameter relative to a diameter  240  of the inner slide surface  238 . Similarly, the inner surface  214  of ported case  208  comprises a lower shoulder  242  between a threaded interior of the lower adapter interface  234  to the inner slide surface  238  of the ported body  232 . The interior of the lower adapter interface  234  is smaller in diameter relative to the diameter  240  of the inner slide surface  238 . The ported case  208  further comprises ports  244  and shear apertures  246 . As will be explained in further detail below, ports  244  are through holes extending radially through the ported case  208  and are selectively used to provide fluid communication between sleeve flow bore  216  and a space immediately exterior to the ported case  208 . Further, the shear apertures  246  accept shear screws  248  therethrough to selectively restrict movement of a baffle  250  of the sleeve system  200  with respect to the ported case  208 . Each of upper adapter  204 , lower adapter  206 , and ported case  208  comprise flat tool landings  252  which allow rotary tools, vices, and/or other suitable equipment to grip and/or rotate the upper adapter  204 , lower adapter  206 , and ported case  208  relative to each other during assembly and/or disassembly of the sleeve system  200 . 
     Baffle  250  is formed substantially as a cylindrical tube having an exterior surface  254  sized slightly smaller than the diameter  240  of inner slide surface  238 . The baffle  250  further comprises an upper groove  256  located near an upper end  258  of the baffle  250  and formed in the exterior surface  254 . Similarly, the baffle  250  comprises a lower groove  260  located near a lower end  262  of the baffle  250  and formed in the exterior surface  254 . The upper and lower grooves  256 ,  260  accept sealing members that form seals between the exterior surface  254  of baffle  250  and the inner slide surface  238  of the central ported body  232 . In this embodiment, the baffle  250  comprises an inner surface  264  having a diameter  266  that is substantially similar to an inner diameter of the case interface  222  of the upper adapter  204 . The baffle  250  further comprises a shear groove  268  and an expansion ring groove  270 . 
     The shear groove  268  provides a circumferential recess configured to receive shear screws  248 . Accordingly, while shear screws  248  extend into both shear apertures  246  and shear groove  268 , relative movement between the baffle  250  and the ported case  208  along the central axis  202  is restricted. More specifically, with the baffle  250  and the ported case  208  relatively positioned as shown in  FIG. 2 , the baffle  250  is restrained so that ports  244  do not provide fluid communication between sleeve flow bore  216  and a space immediately exterior to the ported case  208  via ports  244 . Instead, the portions of the inner slide surface  238  adjacent the ports  244  are substantially covered by the exterior surface  254  of the baffle  250 . Further, when a sealing member is disposed within the upper groove  256  of the baffle  250 , any annular space between the baffle  250  and the inner slide service  238  downhole upper groove  256  is sealed from fluid communication with portions of sleeve flow bore  216  that are uphole of upper groove  256 . 
     However, it will be appreciated that without sufficient restriction from shear screws  248 , the baffle  250  may be caused to slide relative to the ported case  208  downhole along the central axis  202  toward the lower adapter  206 . With sufficient downhole movement of the baffle  250  relative to the central ported body  232  of the ported case  208 , fluid communication between sleeve flow bore  216  and a space immediately exterior to the ported case  208  via ports  244  may be achieved. Such fluid communication may occur when the baffle  250  is located so that a seal member carried within upper groove  256  of baffle  250  is located downhole of at least a portion of a port  244 . Further, substantially unrestricted fluid communication may occur when the baffle  250  is located so that the upper end  258  of baffle  250  is located downhole of at least a portion of a port  244 . Still further, substantially fully unrestricted fluid communication may occur between the sleeve flow bore  216  and a space immediately exterior to the ported case  208  via ports  244  when the upper end  258  of baffle  250  is located downhole of all ports  244 . With baffle  250  moved sufficiently downhole relative to position of the baffle  250  shown in  FIG. 2 , the expansion ring groove  270  extends beyond the lower shoulder  242  of the ported case  208  and into the lower adapter interface  234 . Such location allows radially outward expansion of an expansion ring  272  carried within expansion ring groove  270 . Such expansion of the expansion ring  272  prevents subsequent uphole movement along central axis  202  of baffle  250  due to interference between the expansion ring  272  and the lower shoulder  242  of the ported case  208 . 
     Still referring to  FIG. 2-3 , the sleeve system  200  further comprises a seat  300  carried by baffle  250 . The seat  300  is discussed below in greater detail with reference to  FIGS. 4-6 . Most generally, the seat  300  is substantially tubular in shape. The seat  300  comprises an exterior surface  302 , an interior surface  304 , a lower seat end  306 , and a seat upper landing surface  308 . A portion of the exterior surface  302  of the seat  300  is threaded for engagement with a similarly threaded portion of the inner surface  264  of the baffle  250 . Further, the seat  300  is sized and shaped so that seat upper landing surface  308  restricts passage of a dart  400  through a seat passage  310 . The dart  400  is discussed below in greater detail with reference to  FIGS. 7-12 . The dart  400  comprises a dart body  402  and two noses  404  attached to dart body  402  so that dart  400  is substantially symmetrical along the central axis  202 . As will be explained below in greater detail, dart body  402  of dart  400  can be caused to seal against at least the seat upper landing surface  308  of seat  300 , thereby contributing to the above mentioned downhole movement of baffle  250 . In other words, the dart  400  can be caused to act against the seat  300 , thereby moving the baffle  250  from the position shown in  FIG. 2  to allow fluid communication between the sleeve flow bore  216  and a space immediately exterior to the ported case  208  via ports  244 . 
     Referring now to  FIGS. 4-6 , seat  300  is shown in greater detail. Seat  300  further comprises a seat central axis  312  that, when installed with baffle  250  is substantially coaxial with the central axis  202  of sleeve system  200 . The exterior surface  302  comprises a baffle interface surface  314  that is threaded for engagement with inner surface  264  of baffle  250 . The exterior surface  302  further comprises a tool interface surface  316  having a tool interface surface length  348  that extends between the baffle interface surface  314  and the lower seat end  306 . The seat  300  further comprises tool notches  318  that extend from the lower seat end  306  toward the seat upper landing surface  308 . The tool notches  318  comprise a tool notch depth  320 , a tool notch width  350 , and a tool notch bisection length  352 . The tool notch bisection length  352  represents the distance between a first notch side  354  and a bisection plane  356  that substantially bisects seat  300  in  FIG. 5 . The tool notches  318  accept portions of tools used to rotate the seat  300  about the central axis  312  and/or to restrict rotation of seat  300  about central axis  312  relative to the baffle  250  to allow assembly/disassembly of the seat  300  to the baffle  250 . Further, the interior surface  304  comprises an interior surface length  322  and an interior surface diameter  324 . The exterior surface  302  comprises an exterior surface length  326  and exterior surface diameter  328 . The exterior surface  302  is joined to each of the lower seat end  306  and the seat upper landing surface  308  by chamfers  330  each having a chamfer angle  332 . The lower seat end  306  is substantially formed as a frusto-conical surface having a lower seat end base  334 , lower seat end truncated tip  336 , and a lower seat end angle  338 . The lower seat end angle  338  is measured relative to the central axis  312 . Similarly, the seat upper landing surface  308  is substantially formed as a frusto-conical surface having a seat upper landing surface base  340 , a seat upper landing surface truncated tip  342 , and a seat upper landing surface angle  344 . The seat upper landing surface angle  344  is also measured relative to the central axis  312 . The seat upper landing surface base has a base diameter  346 . In this embodiment, seat  300  is sized and otherwise configured to complement dart  400 . 
     Referring now to  FIGS. 7-8 , the dart body  402  is shown in greater detail. The dart body  402  is generally symmetrical along a dart central axis  406 . When dart  400  is seated against seat  300  as shown in  FIG. 2 , dart central axis  406  is substantially coaxial with central axis  312  of seat  300  and is substantially coaxial with central axis  202  of sleeve system  200 . Dart  400  symmetry is generally made with reference to dart bisection plane  408  which is substantially normal to dart central axis  406 . Accordingly, dart body  402  is likewise substantially symmetrical in the above-described manner. Dart body  402  generally comprises a central disc  410  joined between two body arms  412  along the dart central axis  406  by body necks  414 . Central disc  410  comprises a central disc length  416  along the dart central axis  406 . The central disc  410  further comprises a central ring  418  joined along the dart central axis  400  between two central shelves  420 . The central ring  418  comprises a central ring diameter  422  while each of the central shelves  420  comprise smaller central shelf diameters  424 . The central shelves  420  each comprise a central shelf length  426  along the dart central axis  406  while the central ring comprises a central ring length  436  along the dart central axis  406 . Still further, the central ring  418  comprises two dart landing seats  428  that provide a transition between central ring  418  and central shelves  420 . More specifically, each dart landing seat  428  is formed substantially as a frusto-conical surface having a dart landing seat base  430 , a dart landing seat truncated tip  432 , and a dart landing seat angle  434 . The dart landing seat angle  434  is measured relative to the dart central axis  406 . Further, the dart landing seat bases  430  are adjacent to the central ring  418  while the dart landing seat truncated tips  432  are adjacent the central shelves  420 . Still further, central shelves  420  comprise chamfers  438 , each having a central shelf a chamfer angle  440 . 
     Body necks  414  are substantially disc shaped, lie substantially coaxial with dart central axis  406 , and abut against opposing lengthwise sides of central disc  410 . Each body neck  414  comprises a body neck length  442  and a body neck diameter  444 . Body necks  414  are joined to central disc  410  with rounded transitions  446 , each having substantially the same radius of curvature. Further, body necks  414  are abutted between the central ring  418  and body arms  412 . Body arms  412  are also substantially disc shaped and lie substantially coaxial with dart central axis  406 . Each body arm  412  comprises a body arm length  448  along the dart central axis  406 , a body arm minor diameter  450 , and a body arm major diameter  462 . Each body arm  412  also comprises an inner chamfer  452  and an outer chamfer  454 . The inner chamfers  452  comprise inner chamfer angles  456  while the outer chamfers  454  comprise outer chamfer angles  458 . Body arm threaded portions  464  extend between the inner chamfers  452  and outer chamfers  454 . It will be appreciated that the entire dart body  402  comprises a dart body length  460  along the dart central axis  406 . In this embodiment, the central ring diameter  422  represents the largest radial extension of dart body  402  from dart central axis  406  while the central shelf diameter  424  is slightly smaller than the central ring diameter  422 . Further, in this embodiment, the body neck diameter  444  is substantially the same as body arm minor diameter  450  while body arm major diameter  462  is slightly larger than body arm minor diameter  450 . 
     Referring now to  FIGS. 9-10 , a dart nose  404  is shown in greater detail. Dart nose  404  comprises a dart nose base end  466  and the dart nose tip end  468 . Dart nose  404  further comprises a dart nose base  470 , a dart nose transition  472 , a dart nose shelf  474 , a dart nose centralizer support  476 , and a dart nose tip  478  disposed successively along the dart central axis  406 . The dart nose base  470  is substantially disc shaped and has a dart nose base diameter  480  and a dart nose base length  488  along the dart central axis  406 . The dart nose transition  472  is substantially frusto-conical in shape and comprises a nose transition base  482  adjacent the dart nose transition  472 , a nose transition truncated tip  484 , and a nose transition angle  486 . The nose transition angle  486  is measured relative to the dart central axis  406 . Further, the dart nose transition  472  has a transition length  490  along the dart central axis  406 . The dart nose shelf  474  is substantially disc shaped and lies adjacent dart nose transition  472  at nose transition truncated tip  484 . The dart nose shelf  474  comprises a dart nose shelf diameter  490  and a dart nose shelf length  492 . The dart nose centralizer support  476  is also substantially disc shaped and lies adjacent dart nose shelf  474 . The dart nose centralizer support  476  comprises a centralizer support diameter  494  and a centralizer support length  496 . Further, the dart nose tip  478  lies adjacent the dart nose centralizer support  476  and is substantially formed as a spherical section. The dart nose tip  478  comprises a substantially flat section base  498  and a rounded surface  500 . The dart nose tip  478  further comprises a spherical section radius of curvature and a dart nose tip length  502 . Still further, dart nose  404  comprises rounded transitions  504  each having a rounded transition radius of curvature. Dart nose  404  further comprises a dart nose length  506  that extends between dart nose base end  466  and dart nose tip end  468 . While geometry of the dart nose base  470 , the dart nose transition  472 , the dart nose shelf  474 , the dart nose centralizer support  476 , and the dart nose tip  478  are individually explained above, it will be appreciated that, in this embodiment, each of the components of the dart nose  404  are integrally formed. Dart nose  404  further comprises a countersunk hole  508  that lies substantially coaxial with the dart central axis  406  and extends into the dart nose  404  from the dart nose base end  466 . The countersunk hole  508  comprises a countersink major diameter  510  and countersink angle  512 . A countersunk hole inner wall  514  is threaded over a substantial portion of a threaded length  516 . The countersunk hole  508  further comprises a countersunk hole length  518 . 
     Referring now to  FIGS. 11-12 , a dart centralizer  405  is shown in greater detail. Dart centralizer  405  is substantially shaped as a cylindrical annular ring. Dart centralizer  405  comprises an inner centralizer surface  520 , an outer centralizer surface  522 , and substantially parallel centralizer ends  524 . The dart centralizer  405  further comprises a centralizer inner diameter  526 , a centralizer outer diameter  528 , and a centralizer length  530 . 
     Referring now to FIGS.  2  and  7 - 11 , dart  400  may be assembled in the manner described below. Assembly of dart  400  may begin first by aligning both the dart body  402  and one dart nose  404  along the dart central axis  406  so that a dart body  402  and the dart nose  404  are offset from each other with dart nose tip end  468  located furthest from the dart body  402 . Next, the dart body  402  and the dart nose  404  may be moved toward each other along the dart central axis  406  until a body arm  412  of dart body  402  contacts the dart nose  404  in the countersunk hole  508 . Next, dart body  402  and the dart nose  404  may be rotated relative to each other about the dart central axis  406  so that threads of the body arm threaded portion  464  increasingly engage the threads of the countersunk hole  508  along a threaded length  516 . Such relative rotation is continued until dart nose base end  466  contacts central disc  410 . Another dart nose  404  may be assembled to the remaining body arm  412  of the same dart body  402  in substantially the same manner described above. Finally, dart centralizers  405  may be assembled to dart noses  404 , one each respectively, by passing dart nose tip  478  within the centralizer inner diameter  526  along the centralizer length  530 . Dart centralizer  405  is moved toward dart nose base end  466  until the opposing centralizer ends  524  are substantially carried between dart nose tip  478  and dart nose shelf  474 . In this embodiment, the centralizer inner diameter  526  is substantially similar to the centralizer support diameter  494 . Further, in this embodiment, the centralizer length  530  is substantially similar to the centralizer support length  496 . In a manner described above, dart  400  is assembled so that dart  400  is substantially symmetrical along the dart central axis  406 . 
     It will be appreciated that sleeve system  200   b  is substantially similar in form and function to sleeve system  200 . However, seat  300   b  and dart  400   b  each comprise differences from seat  300  and dart  400 . Accordingly, this detailed discussion will not address every dimensional difference and/or similarity between shared features, but rather, will focus on some of the notable differences amongst the components. For ease of reference, features that are substantially similar between seat  300  and seat  300   b  and dart  400  and dart  400   b  are denoted with like numerical references but different alphabetical references. Most generally, seat  300   b  comprises a smaller passage  310   b  as compared to passage  310  and dart  400   b  comprises a smaller central ring diameter  422   b  as compared to central ring diameter  422 . With reference to  FIG. 1 , it will be appreciated that dart  400   b  is generally sufficiently smaller than dart  400  so that dart  400   b  may be flowed entirely through seat  300  of sleeve system  200 . However, dart  400   b  is sized relative to seat  300   b  so that dart  400   b  cannot pass through seat  300   b . Instead, dart  400   b  is sized to form a seal between dart landing seat  428   b  and seat upper landing surface  308   b  in a substantially similar manner as dart  400  seals against seat  300 . The components of sleeve system  200   b  are shown in greater detail  FIGS. 13-23 . 
     Seat  300   b  is shown in  FIGS. 13-15 . A first difference between seat  300   b  and seat  300  is that lower seat end  306   b  is not a frusto-conical surface, but rather, is substantially flat an orthogonal to central axis  312   b . Further, lower seat end  306   b  does not comprise tool notches, but rather, comprises tool holes  358   b  that extend from the lower seat end  306   b  substantially parallel to central axis  312   b . The tool holes  358   b  each have a tool hole diameter  360   b  and are disposed in a radial array about the central axis  312   b  along a tool hole pattern diameter  362   b . Also, the exterior surface length  326   b  is substantially longer than the exterior surface length  326 . However, the interior surface length  322   b  associated with the passage  310   b  is substantially smaller in proportion to the exterior surface length  326   b  as compared to the proportion between interior surface length  322  and exterior surface length  326 . Further, the interior surface diameter  324   b  is substantially less than the interior surface diameter  324 . Also, the seat upper landing surface  308   b  extends substantially longer along central axis  312   b  as compared to the distance seat upper landing surface  308  extend along central axis  312 . Still further, the seat upper landing surface angle  344   b  is substantially less than the seat upper landing surface angle  344 . Nonetheless, the exterior surface diameter  328   b  is substantially similar to the exterior surface diameter  328 , thereby encouraging interchangeability of seats within baffles  250  and, in some cases, eliminating the need for differently configured baffles  250  for use among the various seats, such as seats  300 ,  300   b.    
     Dart  400   b  is shown in  FIGS. 16 and 17 . Like dart  400 , dart  400   b  is substantially symmetrical along the length of dart central axis  406   b  and about dart bisection plane  408   b . Also like dart  400 , dart  400   b  comprises a dart body  402   b , two dart noses  404   b , and two dart centralizers  405   b . Dart  400   b  is configured to interact with seat  300   b  in a substantially similar manner as dart  400  interacts with seat  300 . Dart length  532   b  is less than the overall length of dart  400  and also comprises substantially smaller radial dimensions as compared to dart  400 . It will be appreciated that dart  400   b  is assembled in substantially the same manner as dart  400 . 
     Dart body  402   b  is shown in  FIGS. 18 and 19 . Dart body  402   b  is substantially similar to dart body  402  in form and function. However, dart body  402   b  is appropriately sized for interaction with seat  300   b  rather than seat  300 . More specifically, dart landing seat angle  434   b  comprises a relatively more acute angle as compared to dart landing seat angle  434 . Further, central ring diameter  422   b  is substantially smaller than central ring diameter  422  so that dart body  402   b  may pass through seat  300 . However, central ring diameter  422   b  is not so small as to be able to pass through seat  300   b.    
     Dart nose  404   b  is shown in  FIGS. 20 and 21 . Dart nose  404   b  comprises many substantial similarities with dart nose  404 . However, dart nose  404   b  does not comprise a dart nose transition such as dart nose transition  472 , but rather, dart nose shelf  474   b  directly abuts dart nose base  470   b . Further, dart nose tip  478   b  comprises a substantially cylindrical portion extending from the rounded surface  500   b  rather than being shaped substantially as a spherical section like dart nose tip  478 . Still further, the radius of curvature of the rounded surface  500   b  is substantially smaller than the radius of curvature of the rounded surface  500 . 
     Dart centralizer  405   b  is shown in  FIGS. 22 and 23 . Dart centralizer  405   b  is substantially similar in form and function to dart centralizer  405 . However, dart centralizer  405   b  is appropriately sized, generally smaller, than dart centralizer  405 . 
     It will be appreciated that sleeve system  200   a  is substantially similar in form and function to sleeve system  200   b . However, seat  300   a  and dart  400   a  each comprise differences from seat  300   b  and dart  400   b . Accordingly, this detailed discussion will not address every dimensional difference and/or similarity between shared features, but rather, will focus on some of the notable differences amongst the components. For ease of reference, features that are substantially similar between seat  300   b  and seat  300   a  and dart  400   b  and dart  400   a  are denoted with like numerical references but different alphabetical references. Most generally, seat  300   a  comprises a smaller passage  310   a  as compared to passage  310   b  and dart  400   a  comprises a smaller central ring diameter  422   a  as compared to central ring diameter  422   b . With reference to  FIG. 1 , it will be appreciated that dart  400   a  is generally sufficiently smaller than dart  400   b  so that dart  400   a  may be flowed entirely through seat  300   b  of sleeve system  200   b . However, dart  400   a  is sized relative to seat  300   a  so that dart  400   a  cannot pass through seat  300   a . Instead, dart  400   a  is sized to form a seal between dart landing seat  428   a  and seat upper landing surface  308   a  in a substantially similar manner as dart  400   b  seals against seat  300   b . The components of sleeve system  200   a  are shown in greater detail  FIGS. 24-34 . 
     Seat  300   a  is shown in  FIGS. 24-26 . A first difference between seat  300   a  and seat  300   b  is that the exterior surface length  326   a  is longer than the exterior surface length  326   b . Further, the interior surface length  322   a  associated with the passage  310   a  is larger in proportion to the exterior surface length  326   a  as compared to the proportion between interior surface length  322   b  and exterior surface length  326   b . Still further, the interior surface diameter  324   a  is less than the interior surface diameter  324   b . Also, the seat upper landing surface  308   b  extends longer along central axis  312   a  as compared to the distance seat upper landing surface  308   b  extends along central axis  312   b . In addition, the seat upper landing surface angle  344   a  is less than the seat upper landing surface angle  344   b . Nonetheless, the exterior surface diameter  328   a  is substantially similar to the exterior surface diameter  328   b , thereby encouraging interchangeability of seats within baffles  250  and, in some cases, eliminating the need for differently configured baffles  250  for use among the various seats, such as seats  300   a ,  300   b.    
     Dart  400   a  is shown in  FIGS. 27 and 28 . Like dart  400   b , dart  400   a  is substantially symmetrical along the length of dart central axis  406   a  and about dart bisection plane  408   a . Also like dart  400   b , dart  400   a  comprises a dart body  402   a , two dart noses  404   a , and two dart centralizers  405   a . Dart  400   a  is configured to interact with seat  300   a  in a substantially similar manner as dart  400   b  interacts with seat  300   b . Dart length  532   a  is less than the dart length  532   b  and also generally comprises smaller radial dimensions as compared to dart  400   b . It will be appreciated that dart  400   a  is assembled in substantially the same manner as dart  400   b.    
     Dart body  402   a  is shown in  FIGS. 29 and 30 . Dart body  402   a  is substantially similar to dart body  402   b  in form and function. However, dart body  402   a  is appropriately sized for interaction with seat  300   a  rather than seat  300   b . More specifically, dart landing seat angle  434   a  comprises a relatively more acute angle as compared to dart landing seat angle  434   b . Further, central ring diameter  422   a  is smaller than central ring diameter  422   b  so that dart body  402   a  may pass through seat  300   b . However, central ring diameter  422   a  is not so small as to be able to pass through seat  300   a . Further, unlike dart body  402   b , dart body  402   a  does not comprise central shelves such as central shelves  420   b . Instead, dart landing seats  428   a  directly abut central ring  418   a.    
     Dart nose  404   a  is shown in  FIGS. 31 and 32 . Dart nose  404   a  is substantially similar to dart nose  404   b . However, dart nose base diameter  480   a  is smaller than dart nose base diameter  480   b . Further, the radius of curvature of the rounded surface  500   a  is smaller than the radius of curvature of the rounded surface  500   b . Also, the countersink hole major diameter  510   a  is smaller than the countersink hole major diameter  510   b.    
     Dart centralizer  405   a  is shown in  FIGS. 33 and 34 . In this embodiment, dart centralizer  405   a  identical to dart centralizer  405   b.    
     It will be appreciated that each of the above sleeve systems  200 ,  200   b , and  200   a  are individually operated in substantially the same manner. Accordingly, the below is a description of operation of sleeve system  200  and substantially represents the individual operation of sleeve systems  200   a - 200   e  as well. Sleeve system  200  is initially disposed in the wellbore  114  in the above-described closed position where baffle  250  is retained relative to the ported case  208  by shear screws  248 . As such, fluid communication between the sleeve flow bore  216  and a space immediately exterior to the ported case  208  via ports  244  is prevented. When such fluid communication is desired, the dart  400  of sleeve system  200  is sent downhole from a position located uphole of the ported case  208 . The dart  400  eventually approaches the ported case  208 . It will be appreciated that the longitudinal nature of the dart  400  shape aids in preventing flipping of the dart  400  within the work string  112 , thereby ensuring that whichever dart nose  404  was placed in a downhole position relative to the other dart nose  404  of dart  400  predictably remains in the initial downhole position. 
     Further, it will be appreciated that the dart centralizers  405 , while not necessarily contacting and inside diameter of the work string  112 , maintains a degree of alignment between the dart central axis  406  and a central axis associated with the components of the work string  112  through which the dart  400  travels. The dart centralizer  405  also serves to reduce dart damage by reducing contact between the other components of the dart  404  with the interior of the work string  112 . If the dart  400  is not substantially aligned with the seat central axis  312 , the rounded surface  500  of the dart nose  404  may contact seat upper landing surface  308 . Such contact in addition to downhole force applied to the dart  400  results in further alignment between the dart central axis  406  and the seat central axis  312  as the rounded surface  500  slides along the seat upper landing surface  308  in a downhole direction. Further, during such movement, the downhole dart centralizer  405  may wipe against the seat upper landing surface  308 , thereby cleaning the seat upper landing surface  308  and preparing it for sealing engagement with dart landing seat  428 . Next, with sufficient further downhole movement of the dart  400 , dart nose tip  478  and centralizer  405  pass through at least a portion of seat passage  310 . 
     Further, with sufficient downhole movement of dart  400 , dart nose shelf  474  may contact seat upper landing surface  308  and subsequently enter seat passage  310 , both of which actions guarantee further alignment between dart central axis  406  and seat central axis  312 . With further sufficient movement downhole of dart  400 , dart nose transition  472  may contact seat upper landing surface  308  and subsequently enter seat passage  310 , both of which actions guarantee further alignment between dart central axis  406  and seat central axis  312 . With still further sufficient movement downhole of dart  400 , dart nose base  470  may contact seat upper landing surface  308  and subsequently enter seat passage  310 , both of which actions guarantee further alignment between dart central axis  406  and seat central axis  312 . With still further sufficient movement downhole of dart  400 , central shelf  420  of dart body  402  may contact seat upper landing surface  308  and subsequently enter seat passage  310 , both of which actions guarantee further alignment between dart central axis  406  and seat central axis  312 . Finally, with still further sufficient movement downhole of dart  400 , dart landing seat  428  may contact seat upper landing surface  308 , thereby establishing a substantially fluid tight seal between the dart landing seat  428  and seat upper landing surface  308 . The act of forming such a seal may itself further align dart central axis  406  and seat central axis  312 . It will be appreciated that any of the above-described dart features associated with aligning dart central axis  406  and seat central axis  312  may be referred to as “alignment features.” 
     Once such a seal is established, pressure may be applied to the portion of the work string  112  uphole of the seal until such pressure causes the dart  400  to adequately contribute to the transferring downhole force of a magnitude sufficient to shear the shear screws  248 . Once the shear screws  248  have been sheared, downhole movement of the baffle  252  to which the seat  300  is attached is substantially unrestricted. Accordingly, the baffle  250 , along with the attached seat  300  and abutted dart  400  slide downhole relative to the ported case  208 . As described above, with sufficient downhole movement of the ported case  208 , fluid communication between the sleeve flow bore  216  and a space immediately exterior to the ported case  208  via ports  244  is allowed. With sufficient such downhole movement of the baffle  250 , the expansion ring  272  may expand and thereby restrict uphole movement of the baffle  250  due to interference between the expansion ring  272  and the lower shoulder  242  of the ported case  208 . In this embodiment, dart  400  may be removed from seat  300  by the application of pressure provision of fluid to the portion of the work string downhole of the seal between the dart landing seat  428  and seat upper landing surface  308 . Such application pressure and provision of fluid is sometimes referred to as “backflowing.” Such backflowing may cause uphole movement of the dart  400  away from the seat  300  so that the dart  400  may be caught within and/or removed from the work string  112 . Still further, one or more components of the dart  400  and/or the seat  300  may be selectively degraded, thereby allowing easier backflowing and/or eliminating the need to backflow. Even further, the dart  400  and/or the seat  300  may be drilled out or otherwise manually degraded, manipulated, and/or removed, thereby allowing fluid flow through the ported case  208  in an uphole direction. 
     Referring now to  FIG. 1 , a method of servicing wellbore  114  using wellbore servicing system  100  is described. In some cases, wellbore servicing system  100  may be used to selectively treat selected ones of deviated zone  150 , first, second, third, four, and fifth horizontal zones  150   a - 150   e . More specifically, using the above-described method of operating the sleeve systems, any one of the zones  150 ,  150   a - 150   e  may be treated using the respective associated sleeve systems. For example, treatment of zones  150 ,  150   a , and  150   b  without the need for any backflowing or other dart-seat removal processes. To accomplish such treatment, first, dart  400   a  is sent downhole within the work string  112  until dart  400   a  lands on seat  300   a , thereby enabling fluid communication via ports of sleeve system  200   a  as described above. Once such fluid communication is established, fluids (e.g., a fracturing fluid comprising proppant) may be flowed through the work string  112  through sleeve system  200   a  and into contact with zone  150   a  in a desired manner, thereby treating zone  150   a  (e.g., fracturing the zone and propping the fractures open). After treating zone  150   a , dart  400   b  is sent downhole within the work string  112  until dart  400   b  lands on seat  300   b , thereby enabling fluid communication via ports of sleeve system  200   b  as described above. Once such fluid communication is established, fluids may be flowed through the work string  112  through sleeve system  200   b  and into contact with zone  150   b  in a desired manner, thereby treating zone  150   b . Next, if zones  150   c - 150   e  are not to be treated using sleeve systems  200   c - 200   e , zone  150  may be treated by sending dart  400  downhole within the work string  112  until dart  400  lands on seat  300 , thereby enabling fluid communication via ports  244  of sleeve system  200  as described above. Once such fluid communication is established, fluids may be flowed through the work string  112  through sleeve system  200  and into contact with zone  150  in a desired manner, thereby treating zone  150 . After such treatment of zones  150 ,  150   a , and  150   b , each of the darts  400 ,  400   a , and  400   b  may be removed from the corresponding seats  300 ,  300   a , and  300   b  using a backflowing process or any other means of removal as described above. Once the seals between the darts  400 ,  400   a , and  400   b  and the seats  300 ,  300   a , and  300   b  have been overcome, in some embodiments, production fluids may pass uphole from zones  150 ,  150   a , and  150   b  through the respective associated sleeve systems  200 ,  200   a , and  200   b . It will be appreciated that, in some cases, darts  400 ,  400   a , and  400   b  may not be fully removed from the work string  112 , but rather, remain captured below adjacent uphole sleeve systems. It will further be appreciated that using the teachings disclosed herein, other selected zones and/or all of the zones  150 ,  150   a - 150   e  may be treated before a need to remove a dart arises. More specifically, each zone  150 ,  150   a - 150   e  may be treated using above-described method by operating sleeve systems  200   a ,  200   b ,  200   c ,  200   d ,  200   e , and  200 , beginning with the downhole-most located zone,  150   a , and subsequently treating zones  200   b ,  200   c ,  200   d , and  200   e  in this listed order. 
     Referring now to  FIGS. 35-37 , another embodiment of a sleeve system  600  is shown. Sleeve system  600  is substantially similar to sleeve system  200 . Sleeve system  600  comprises a central axis  602 , an upper adapter  604 , a lower adapter  606 , and a ported case  608 . The ported case  608  comprises an inner surface  614  and the sleeve system  600  comprises a sleeve flow bore  616 . Upper adapter  604  comprises an upper shoulder  636  substantially similar to upper shoulder  236  and ported case  608  comprises a lower shoulder  642  substantially similar to lower shoulder  242 . Further, sleeve system  600  comprises a baffle  650  substantially similar to baffle  250 . Baffle  650  comprises an upper end  658  and a lower end  662 . However, while an exterior surface  654  of the baffle  650  is substantially similar to exterior surface  254 , an inner surface  664  of baffle  650  is different from inner surface  264  of baffle  250 . More specifically, inner surface  664  of baffle  650  is not threaded near a lower end  662  of baffle  650  to receive a seat  700 . Instead, seat  700  is received within a baffle groove  674  formed in the inner surface  664 . The baffle groove  674  extends from a baffle shoulder  676  to the upper end  658  of baffle  650 . The baffle groove  674  comprises a baffle groove diameter  678  is larger than the inner surface diameter  666  of baffle  650 . Accordingly, when sleeve system  600  is configured in an installation configuration and/or closed position where baffle  650  prevents fluid communication as described above (see  FIG. 35 ) with regard to baffle  250 , seat  700  is captured within baffle groove  674  between baffle shoulder  676  and the upper shoulder  636  of the upper adapter  604 . 
     Further, seat  700  is frangible as described in greater detail below. The frangible nature of seat  700  causes the overall operation of sleeve system  600  to differ from operation of sleeve system  200 . Specifically, as a dart  680  contacts seat  700  and substantially similar manner as dart  400  contacts seat  300 , dart  680 , baffle  650 , and the seat  700  captured between dart  680  and the baffle  650  may be moved in a downhole direction to allow the above-described fluid communication through ports  644 .  FIG. 36  shows dart  680 , baffle  650 , and the seat  700  after being moved to a fully open position where uphole movement of baffle  650  is restricted by expansion ring  672  potentially interfering with lower shoulder  642  of ported case  608 . After passing fluids through ports  644  to treat an associated wellbore zone, fluid pressure may be applied to downhole side of the dart  680  and seat  700 , for example, during a backflowing process. Such pressure and fluid flow may then cause uphole movement of the dart  660  and/or the seat  700  relative to the baffle  650  as shown in  FIG. 37 . Such uphole movement allows the seat  700  to exit the baffle  650 . As shown in  FIG. 37 , the seat  700  is no longer restrained within baffle groove  674 , but rather, is free to move uphole within sleeve flow bore  616 . During such a backflowing process, the seat  700  may break into multiple pieces. Accordingly, the dart  680  and pieces of the seat  700  may flow in an uphole direction through upper adapter  604  and other portions of the associated work string. 
     Referring now to  FIGS. 38-40 , the frangible seat  700  is shown in greater detail. Seat  700  is substantially formed as an annular ring having a substantially cylindrical passage  710  and a substantially frusto-conical seat upper landing surface  708 . Seat upper landing surface  708  and passage  710  perform in substantially the same manner as seat upper landing surface  308  and passage  310 , respectively. However, seat upper landing surface  708  and passage  710  are not substantially formed by a single piece of material, but rather, the seat  700  and the features of seat  700  are formed of a plurality of seat pieces  770 . Seat pieces  770  are each substantially similar in shape and size and are each radially disposed about seat axis  712  in a substantially equidistant manner. Seat pieces  770  each have sidewalls  772  that are configured to receive adhesive, epoxy, or any other suitable material or device for positionally retaining the plurality of seat pieces  770  relative to each other in the manner shown in  FIGS. 38-40 . Seat  700  further comprises raised shoulders  774  along the exterior surface  702 . An o-ring, band, seal, retaining ring, or any other suitable material or device may be received between raised shoulders  774  to selectively retaining seat pieces  770  relative to each other and/or to provide a seal between seat  700  and baffle groove  674  of baffle  650 . 
     Referring now to  FIG. 41 , an alternative embodiment of a sleeve system  800  is shown. Sleeve system  800  is substantially similar to sleeve system  200 , however, a seat  802  is substantially symmetrical along a seat axis  804 . In some embodiments, provision such a symmetrical seat  802  may better enable passage of darts through seat  802  in an uphole direction and/or may better enable dislodging a dart  806  from the seat  802 . 
     Referring now to  FIG. 42 , an alternative embodiment of a frangible seat  900  is shown. The frangible seat  900  is substantially similar to frangible seat  700 , however, seat  900  is formed so that seat pieces  902  have increasing angular dimension about a seat central axis  904  so that uphole ends  906  of seat pieces  902  have greater angular dimensions than downhole ends  908  of the seat pieces  902 . In some embodiments, provision such a seat pieces  902  may provide improved sealing between darts and the seat  900  and/or may better enable dislodging a dart from the seat  900 . 
     Referring now to  FIGS. 43-45 , an alternative embodiment of a frangible seat  1000  is shown. The frangible seat  1000  is substantially similar to frangible seat  700 , however, frangible seat  1000  comprises have generally frusto-conical shaped downhole profile  1002 . Further, frangible seat  1000  comprises a substantially enlarged uphole profile  1004  that is substantially orthogonal to seat axis  1006 . 
     Referring now to  FIGS. 46-47 , an alternative embodiment of a dart  1100  is shown. Dart  1100  is not symmetrical about dart axis  1102 . Instead, dart  1100  comprises a downhole dart nose  1104 , an uphole dart nose  1106 , and a dart body  1108  having a single dart landing surface  1110 . Dart body  1108  is shown in  FIG. 47  as comprising a dart body downhole end  1112  and a dart body uphole end  1114 . 
     Referring now to  FIG. 48 , an alternative embodiment of a dart  1200  is shown. Dart  1200  is not symmetrical about dart axis  1202 . Instead, dart  1200  comprises a substantially annular ring shaped first dart centralizer  1204  that is smaller in outside diameter than a substantially annular ring shaped second dart centralizer  1206 . 
     In some embodiments, one or more components of the sleeve systems disclosed herein comprise a degradable material. Herein, the term “degradable materials” refer to materials that readily and irreversibly undergo a significant change in chemical structure under specific environmental conditions that result in the loss of some properties. For example, the degradable material may undergo hydrolytic degradation that ranges from the relatively extreme cases of heterogeneous (or bulk erosion) to homogeneous (or surface erosion), and any stage of degradation in between. In some embodiments, the components are degraded under defined conditions (e.g., as a function time, exposure to chemical agents, etc.) to such an extent that the components are structurally compromised and will no longer function for their intended purpose. In an alternative embodiment, the components can be degraded under defined conditions to such an extent that the component no longer maintains its original form and is transformed from a component having defined structural features consistent with its intended function to a plurality of masses lacking features consistent with its intended function. 
     In some embodiments, the degradable material is any material capable of being degraded as described previously herein and that may be formed into the components. The degradable material may be further characterized by possessing physical and/or mechanical properties that are compatible with its use in a wellbore servicing operation. In choosing the appropriate degradable material, one should consider the degradation products that will result. Also, these degradation products should not adversely affect other operations or components. One of ordinary skill in the art, with the benefit of this disclosure, will be able to recognize which degradable materials would produce degradation products that would adversely affect other operations or components. 
     In some embodiments, the components are comprised of a degradable polymer. The degradability of a polymer depends at least in part on its backbone structure. For instance, the presence of hydrolyzable and/or oxidizable linkages in the backbone often yields a material that will degrade as described herein. The rates at which such polymers degrade are dependent on the type of repetitive unit, composition, sequence, length, molecular geometry, molecular weight, morphology (e.g., crystallinity, size of spherulites, and orientation), hydrophilicity, hydrophobicity, surface area, and additives. The degradable polymer may be chemically modified (e.g., chemical functionalization) in order to adjust the rate at which these materials degrade. Such adjustments may be made by one of ordinary skill in the art with the benefits of this disclosure. Further, the environment to which the polymer is subjected may affect how it degrades, e.g., temperature, presence of moisture, oxygen, microorganisms, enzymes, pH, and the like. 
     Examples of degradable polymers suitable for use in this disclosure include, but are not limited to, homopolymers, random, block, graft, and star- and hyper-branched aliphatic polyesters. Specific examples of suitable polymers include, but are not limited to, polysaccharides such as dextran or cellulose; chitin; chitosan; proteins; orthoesters; aliphatic polyesters; poly(lactide); poly(glycolide); poly(.epsilon.-caprolactone); poly(hydroxybutyrate); poly(anhydrides); aliphatic polycarbonates; poly(orthoesters); poly(amino acids); poly(ethylene oxide); and polyphosphazenes. Such degradable polymers may be prepared by polycondensation reactions, ring-opening polymerizations, free radical polymerizations, anionic polymerizations, carbocationic polymerizations, and coordinative ring-opening polymerization for, e.g., lactones, and any other suitable process. 
     In some embodiments, one or more components are comprised of a biodegradable material. Herein biodegradable materials refer to materials comprised of organic components that degrade over a relatively short period of time. Typically such materials are obtained from renewable raw materials. In some embodiments, the components are comprised of a biodegradable polymer comprising aliphatic polyesters, polyanhydrides or combinations thereof. 
     In some embodiments, the components are comprised of a biodegradable polymer comprising an aliphatic polyester. Aliphatic polyesters degrade chemically, inter alia, by hydrolytic cleavage. Hydrolysis can be catalyzed by either acids or bases. Generally, during the hydrolysis, carboxylic end groups are formed during chain scission, and this may enhance the rate of further hydrolysis. This mechanism is known in the art as “autocatalysis,” and is thought to make polyester matrices more bulk eroding. 
     Suitable aliphatic polyesters have the general formula of repeating units shown below: 
                         
where n is an integer between 75 and 10,000 and R is selected from the group consisting of hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatoms, and mixtures thereof. In some embodiments, the aliphatic polyester is poly(lactide). Poly(lactide) is synthesized either from lactic acid by a condensation reaction or more commonly by ring-opening polymerization of cyclic lactide monomer. Since both lactic acid and lactide can achieve the same repeating unit, the general term poly(lactic acid) as used herein refers to Formula I without any limitation as to how the polymer was made such as from lactides, lactic acid, or oligomers, and without reference to the degree of polymerization or level of plasticization.
 
     The lactide monomer exists generally in three different forms: two stereoisomers L- and D-lactide and racemic D,L-lactide (meso-lactide). The oligomers of lactic acid, and oligomers of lactide are defined by the formula: 
                         
where m is an integer: 2≦m≦75. Alternatively m is an integer: 2≦m≦10. These limits correspond to number average molecular weights below about 5,400 and below about 720, respectively.
 
     In some embodiments, the aliphatic polyester is poly(lactic acid). D-lactide is a dilactone, or cyclic dimer, of D-lactic acid. Similarly, L-lactide is a cyclic dimer of L-lactic acid. Meso D,L-lactide is a cyclic dimer of D-, and L-lactic acid. Racemic D,L-lactide comprises a 50/50 mixture of D-, and L-lactide. When used alone herein, the term “D,L-lactide” is intended to include meso D,L-lactide or racemic D,L-lactide. Poly(lactic acid) may be prepared from one or more of the above. The chirality of the lactide units provides a means to adjust degradation rates as well as physical and mechanical properties. Poly(L-lactide), for instance, is a semicrystalline polymer with a relatively slow hydrolysis rate. This may be advantageous for downhole operations where slow degradation may be appropriate. Poly(D,L-lactide) is an amorphous polymer with a faster hydrolysis rate. This may be advantageous for downhole operations where a more rapid degradation may be appropriate. 
     The stereoisomers of lactic acid may be used individually or combined in accordance with the present disclosure. Additionally, they may be copolymerized with, for example, glycolide or other monomers like ε-caprolactone, 1,5-dioxepan-2-one, trimethylene carbonate, or other suitable monomers to obtain polymers with different properties or degradation times. Additionally, the lactic acid stereoisomers can be modified by blending, copolymerizing or otherwise mixing high and low molecular weight polylactides; or by blending, copolymerizing or otherwise mixing a polylactide with another polyester or polyesters. 
     The aliphatic polyesters may be prepared by substantially any of the conventionally known manufacturing methods such as those described in U.S. Pat. Nos. 6,323,307; 5,216,050; 4,387,769; 3,912,692; and 2,703,316, the relevant disclosure of which are incorporated herein by reference. 
     In some embodiments, the biodegradable polymer comprises a plasticizer. Suitable plasticizers include but are not limited to derivatives of oligomeric lactic acid, selected from the group defined by the formula: 
                         
where R is a hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatom, or a mixture thereof and R is saturated, where R′ is a hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatom, or a mixture thereof and R′ is saturated, where R and R′ cannot both be hydrogen, where q is an integer: 2≦q≦75; and mixtures thereof. Alternatively q is an integer: 2≦q≦10. As used herein the term “derivatives of oligomeric lactic acid” includes derivatives of oligomeric lactide.
 
     The plasticizers may be present in any amount that provides the desired characteristics. For example, the various types of plasticizers discussed herein provide for (a) more effective compatibilization of the melt blend components; (b) improved processing characteristics during the blending and processing steps; and (c) control and regulate the sensitivity and degradation of the polymer by moisture. For pliability, plasticizer is present in higher amounts while other characteristics are enhanced by lower amounts. The compositions allow many of the desirable characteristics of pure nondegradable polymers. In addition, the presence of plasticizer facilitates melt processing, and enhances the degradation rate of the compositions in contact with the wellbore environment. The intimately plasticized composition may be processed into a final product in a manner adapted to retain the plasticizer as an intimate dispersion in the polymer for certain properties. These can include: (1) quenching the composition at a rate adapted to retain the plasticizer as an intimate dispersion; (2) melt processing and quenching the composition at a rate adapted to retain the plasticizer as an intimate dispersion; and (3) processing the composition into a final product in a manner adapted to maintain the plasticizer as an intimate dispersion. In certain embodiments, the plasticizers are at least intimately dispersed within the aliphatic polyester. 
     In some embodiments, the biodegradable material is a poly(anhydride). Poly(anhydride) hydrolysis proceeds, inter alia, via free carboxylic acid chain-ends to yield carboxylic acids as final degradation products. The erosion time can be varied by variation of the polymer backbone. Examples of suitable poly(anhydrides) include without limitation poly(adipic anhydride), poly(suberic anhydride), poly(sebacic anhydride), and poly(dodecanedioic anhydride). Other suitable examples include but are not limited to poly(maleic anhydride) and poly(benzoic anhydride). 
     In various embodiments, the components are self-degradable. Namely, the components, are formed from biodegradable materials comprising a mixture of a degradable polymer, such as the aliphatic polyesters or poly(anhydrides) previously described, and a hydrated organic or inorganic solid compound. The degradable polymer will at least partially degrade in the releasable water provided by the hydrated organic or inorganic compound, which dehydrates over time when heated due to exposure to the wellbore environment. 
     Examples of the hydrated organic or inorganic solid compounds that can be utilized in the self-degradable components include, but are not limited to, hydrates of organic acids or their salts such as sodium acetate trihydrate, L-tartaric acid disodium salt dihydrate, sodium citrate dihydrate, hydrates of inorganic acids or their salts such as sodium tetraborate decahydrate, sodium hydrogen phosphate heptahydrate, sodium phosphate dodecahydrate, amylose, starch-based hydrophilic polymers, and cellulose-based hydrophilic polymers. 
     In some embodiments, the components comprised of degradable materials of the type described herein are degraded subsequent to the performance of their intended function. Degradable materials and method of utilizing same are described in more detail in U.S. Pat. No. 7,093,664 which is incorporated by reference herein in its entirety. 
     In some embodiments, the darts and/or seats of the present disclosure may comprise Garolite. More specifically, some embodiments of the darts and/or seats of the present disclosure may comprise High-Temperature Garolite (G-11 Epoxy Grade). 
     In some embodiments, the darts and/or seats of the present disclosure may comprise resins or epoxies that are at least partially degradable by exposure to water. 
     In some embodiments, components may be held, adhered, and/or otherwise maintained in a relative spatial relationship using an epoxy, resin, and/or epoxy resin. More specifically, components of some embodiments may be held, adhered, and/or otherwise maintained in a relative spatial relationship using Weld-Aid epoxy resin. 
     It will be appreciated that a wellbore servicing system comprising a plurality of sleeve systems disposed along a wellbore may be configured so that a seat passage inside diameter of an intermediate sleeve system is smaller than all of the seat passage inside diameters of the sleeve systems located uphole of the intermediate sleeve system. 
     It will be appreciated that a wellbore servicing system comprising a plurality of sleeve systems disposed along a wellbore may be configured so that a seat upper landing surface angle of an intermediate sleeve system is smaller than all of the seat upper landing surface angles of the sleeve systems located uphole of the intermediate sleeve system. 
     It will be appreciated that a wellbore servicing system comprising a plurality of sleeve systems disposed along a wellbore may be configured so that dart landing seat angles of each sleeve system is substantially the same angle of each associated seat upper landing surface angle. 
     It will be appreciated that a wellbore servicing system comprising a plurality of sleeve systems disposed along a wellbore may be configured so that dart landing seat angles of each sleeve system is substantially complementary to each associated seat upper landing surface angle. 
     It will be appreciated that any seat, dart, and/or components thereof may comprise any of the materials described herein. Further, it will be appreciated that components of the sleeve systems disclosed herein may be formed of degradable and/or selectively degradable materials that improve the ease of and/or eliminate the need for backflowing, drilling, and/or other component removal procedures. 
     It will be appreciated that a wellbore servicing system comprising a plurality of sleeve systems disposed along a wellbore may be configured so that darts with relatively larger central ring diameters and/or dart outside diameters are constructed of materials having relatively higher compressive strength than darts with relatively smaller central ring diameters and/or dart outside diameters. 
     It will be appreciated that a wellbore servicing system comprising a plurality of sleeve systems disposed along a wellbore may be configured so that darts with relatively larger central ring diameters and/or dart outside diameters are constructed of materials having relatively higher hardness than darts with relatively smaller central ring diameters and/or dart outside diameters. 
     It will be appreciated that darts may be constructed of the plurality of materials and so that dart noses are constructed of relatively softer materials as compared to relatively harder materials used to construct dart bodies. 
     It will be appreciated that darts may be constructed integrally as a single unit and/or of a single material and so that dart landing seats are relatively harder and/or have higher compressive strength than dart noses. In other words, any of the darts disclosed herein described as being constructed of multiple components (such as dart bodies, dart noses, and/or dart centralizers) may alternatively be constructed integrally as a single unit and/or in a manner comprising more or fewer discrete components. 
     It will be appreciated that a radius of curvature of a rounded surface of a dart nose tip may have a value of at least about 0.5 inches, thereby improving dart compatibility with being launched from existing ball drop system ball launchers. 
     It will be appreciated that any dart may comprise one or more of the alignment features disclosed herein. 
     It will be appreciated that a sealing surface area between a dart landing seat and a seat upper landing seat may be increased by reducing the seat upper landing surface angle and reducing the associated dart landing seat angle. 
     It will be appreciated that a wellbore servicing system comprising a plurality of sleeve systems disposed along a wellbore may be configured so that seats with relatively larger seat passages and/or interior surface diameters may be constructed of materials having relatively higher compressive strength than seats with relatively smaller seat passages and/or interior surface diameters. 
     It will be appreciated that one or more components of sleeve system may be selectively configured to have a desired specific gravity. More specifically, such components may be selectively configured to comprise a specific gravity of about 1.7. For example, when a dart substantially similar to dart  400  comprises a dart body constructed of cast iron, dart noses constructed of materials less dense than cast iron, and dart centralizers constructed of foam, material may be removed from the interior of the dart body to achieve a lower dart specific gravity. 
     It will be appreciated that a wellbore servicing system substantially similar to wellbore servicing system  100  may be configured so that portions of substantially all seats and darts comprise cast iron. More specifically, cast iron may be used to construct any of the components that serve to form a seal between a dart and an associated seat. 
     It will be appreciated that in a wellbore servicing system substantially similar to wellbore servicing system  100 , darts comprising dart central shelves substantially similar to dart central shelves  420  may be increasingly advantageous as a seat upper landing surface angle is relatively larger. For example, dart central shelves may be substantially less advantageous and/or unnecessary when a seat upper landing surface angle is about 20° or less. 
     It will be appreciated that in some embodiments of a dart that is not symmetrical along a dart central axis, an entire portion of the dart on a single side of what would be a bisection plane in dart  400 , may be replaced by a substantially cylindrical tail having a tail outside diameter substantially similar in size to a central ring diameter of the dart. 
     It will be appreciated that in a wellbore servicing system substantially similar to wellbore servicing system  100 , a “minimum gap” may be described as the minimum acceptable difference in size between a dart outside diameter and a seat passage diameter through which the dart must fully pass. In some embodiments, the minimum gap may be within a range of about 0.010 inches to about 0.11 inches, alternatively about 0.20 inches to about 0.10 inches, alternatively about 0.030 inches to about 0.090 inches, alternatively about 0.040 inches to about 0.080 inches, alternatively about 0.050 inches to about 0.070 inches, alternatively about 0.055 inches to about 0.065 inches, alternatively about 0.059 inches to about 0.061 inches. In another embodiment, the minimum gap may be about 0.060 inches. Using a minimum gap of about 0.060 inches allow for using more than 8 sleeve systems within a 4.5 inch casing, alternatively more than 10 sleeve systems within a 4.5 inch casing, alternatively more than 12 sleeve systems within a 4.5 inch casing, alternatively more than 14 sleeve systems within a 4.5 inch casing, alternatively more than 16 sleeve systems within a 4.5 inch casing, alternatively more than 18 sleeve systems within a 4.5 inch casing, alternatively more than 20 sleeve systems within a 4.5 inch casing, or even more sleeve systems. Of course, the number of sleeve systems able to be used within such a wellbore servicing system is generally increased when using such a wellbore servicing system that has a casing size greater than 4.5 inches. It will be appreciated that relatively more sleeve systems may be used in a casing of a particular size as the minimum gap chosen is reduced. 
     It will be appreciated that in a wellbore servicing system substantially similar to wellbore servicing system  100 , a “minimum seal radial distance” may be described as the minimum acceptable radial distance (relative to the seat central axis) over which a sealing contact interface between a seat upper landing surface and a dart landing seat must extend. In some embodiments, the minimum seal radial distance may be within a range of about 0.010 inches to about 0.11 inches, alternatively about 0.020 inches to about 0.10 inches, alternatively about 0.030 inches to about 0.090 inches, alternatively about 0.040 inches to about 0.080 inches, alternatively about 0.050 inches to about 0.070 inches, alternatively about 0.055 inches to about 0.065 inches, alternatively about 0.059 inches to about 0.061 inches. In another embodiment, the minimum seal radial distance may be about 0.060 inches. It will be appreciated that a relatively smaller minimum seal radial distance may be acceptable where components are constructed of materials having relatively higher compressive material strengths. It will be appreciated that relatively more sleeve systems may be used in a casing of a particular size as the minimum seal radial distance chosen is reduced. 
     EXAMPLES 
     Example 1 
     In some embodiments substantially similar to wellbore servicing system  100 , some components may comprise the following dimensions (in inches): 
     
       
         
           
               
               
               
               
               
             
               
                   
               
               
                 Example 
                   
                 Sleeve 
                 Sleeve 
                 Sleeve 
               
               
                 reference 
                   
                 System 
                 System 
                 System 
               
               
                 number 
                 Dimension Description 
                 200 
                 200b 
                 200a 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 240 
                 diameter of inner slide surface 
                 4.625 
                 4.625 
                 4.625 
               
               
                 266 
                 diameter of inner surface of 
                 3.83 
                 3.83 
                 3.83 
               
               
                   
                 baffle 
               
               
                 320 
                 tool notch depth 
                 0.2 
                 N/A 
                 N/A 
               
               
                 322 
                 interior surface length 
                 1.47 
                 1.04 
                 1.16 
               
               
                 324 
                 interior surface diameter 
                 3.34 
                 1.18 
                 1.06 
               
               
                 326 
                 exterior surface length 
                 1.96 
                 5.56 
                 5.71 
               
               
                 328 
                 exterior surface diameter 
                 3.8 
                 3.78 
                 3.78 
               
               
                 332 
                 chamfer angle 
                 45° 
                 45° 
                 45° 
               
               
                 338 
                 lower seat end angle 
                 45° 
                 N/A 
                 N/A 
               
               
                 344 
                 seat upper landing surface angle 
                 45° 
                 20° 
                 15° 
               
               
                 346 
                 seat upper landing surface base 
                 3.74 
                 3.6 
                 3.5 
               
               
                   
                 diameter 
               
               
                 348 
                 tool interface surface length 
                 0.5 
                 1.5 
                 1.5 
               
               
                 350 
                 tool notch width 
                 0.38 
                 N/A 
                 N/A 
               
               
                 352 
                 tool notch bisection length 
                 0.19 
                 N/A 
                 N/A 
               
               
                 360 
                 tool hole diameter 
                 N/A 
                 0.375 
                 0.375 
               
               
                 362 
                 tool hole pattern diameter 
                 N/A 
                 3 
                 3 
               
               
                 416 
                 central disc length 
                 1.01 
                 0.75 
                 0.74 
               
               
                 422 
                 central ring diameter 
                 3.4 
                 1.24 
                 1.12 
               
               
                 424 
                 central shelf diameter 
                 3.325 
                 1.165 
                 N/A 
               
               
                 426 
                 central shelf length 
                 0.18 
                 0.12 
                 N/A 
               
               
                 434 
                 dart landing seat angle 
                 45° 
                 20° 
                 15° 
               
               
                 436 
                 central ring length 
                 0.58 
                 0.31 
                 0.3 
               
               
                 440 
                 central shelf chamfer angle 
                 45° 
                 45° 
                 N/A 
               
               
                 442 
                 body neck length 
                 0.12 
                 0.12 
                 0.12 
               
               
                 444 
                 body neck diameter 
                 1.31 
                 0.48 
                 0.38 
               
               
                 448 
                 body arm length 
                 0.75 
                 0.58 
                 0.58 
               
               
                 450 
                 body arm minor diameter 
                 1.31 
                 0.48 
                 0.38 
               
               
                 456 
                 body arm inner chamfer angle 
                 45° 
                 45° 
                 45° 
               
               
                 458 
                 body arm outer chamfer angle 
                 45° 
                 45° 
                 45° 
               
               
                 460 
                 dart body length 
                 2.75 
                 2.16 
                 2.14 
               
               
                 462 
                 body arm major diameter 
                 1.49 
                 0.617 
                 0.493 
               
               
                 480 
                 dart nose base diameter 
                 3.28 
                 1.12 
                 1 
               
               
                 486 
                 nose transition angle 
                 12° 
                 N/A 
                 N/A 
               
               
                 488 
                 dart nose base length 
                 0.5 
                 1.35 
                 1.35 
               
               
                 490 
                 dart nose shelf diameter 
                 2.62 
                 0.75 
                 0.75 
               
               
                 492 
                 dart nose shelf length 
                 0.63 
                 0.75 
                 0.75 
               
               
                 494 
                 centralizer support diameter 
                 2 
                 0.625 
                 0.625 
               
               
                 496 
                 centralizer support length 
                 0.75 
                 0.5 
                 0.5 
               
               
                 502 
                 dart nose tip length 
                 1.12 
                 1 
                 1 
               
               
                 506 
                 dart nose length 
                 3.5 
                 3.6 
                 3.6 
               
               
                 510 
                 countersink major diameter 
                 1.56 
                 0.67 
                 0.55 
               
               
                 512 
                 countersink angle 
                 45° 
                 45° 
                 45° 
               
               
                 516 
                 threaded length 
                 0.87 
                 0.8 
                 0.8 
               
               
                 518 
                 countersunk hole length 
                 1 
                 0.9 
                 0.9 
               
               
                 526 
                 centralizer inner diameter 
                 1.5 
                 0.5 
                 0.5 
               
               
                 528 
                 centralizer outer diameter 
                 3.75 
                 1.5 
                 1.5 
               
               
                 530 
                 centralizer length 
                 1 
                 0.5 
                 0.5 
               
               
                 532 
                 dart length 
                 8.01 
                 7.96 
                 7.94 
               
               
                   
               
            
           
         
       
     
     Example 2 
     In some embodiments substantially similar to wellbore servicing system  100 , component materials may be selected as follows. Seats  300 ,  300   b , and  300   a  may be constructed of cast iron. Dart body  402  may be constructed of cast iron while dart bodies  402   b ,  402   a  may be constructed of High-Temperature Garolite (G-11 Epoxy Grade). Dart noses  404 ,  404   b , and  404   a  may be constructed of High-Temperature Garolite (G-11 Epoxy Grade). Dart centralizers  405 ,  405   b , and  405   a  may be constructed of foam. 
     Example 3 
     In some embodiments substantially similar to wellbore servicing system  100 , a plurality of sleeve systems may comprise seat and darts comprising the following dimensions: 
     
       
         
           
               
               
               
             
               
                   
               
               
                   
                 Seat Passage Inside 
                   
               
               
                   
                 Diameter (also 
                 Dart Outside Diameter 
               
               
                 Order of increasing 
                 referred to as seat 
                 (also referred to as 
               
               
                 uphole location within 
                 inside surface 
                 central ring diameter 
               
               
                 wellbore 
                 diameter (in) 
                 (in) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 1 
                 1.06 
                 1.12 
               
               
                 2 
                 1.18 
                 1.24 
               
               
                 3 
                 1.3 
                 1.36 
               
               
                 4 
                 1.42 
                 1.48 
               
               
                 5 
                 1.54 
                 1.6 
               
               
                 6 
                 1.66 
                 1.72 
               
               
                 7 
                 1.78 
                 1.84 
               
               
                 8 
                 1.9 
                 1.96 
               
               
                 9 
                 2.02 
                 2.08 
               
               
                 10 
                 2.14 
                 2.2 
               
               
                 11 
                 2.26 
                 2.32 
               
               
                 12 
                 2.38 
                 2.44 
               
               
                 13 
                 2.5 
                 2.56 
               
               
                 14 
                 2.62 
                 2.68 
               
               
                 15 
                 2.74 
                 2.8 
               
               
                 16 
                 2.86 
                 2.92 
               
               
                 17 
                 2.98 
                 3.04 
               
               
                 18 
                 3.1 
                 3.16 
               
               
                 19 
                 3.22 
                 3.28 
               
               
                 20 
                 3.34 
                 3.4 
               
               
                   
               
            
           
         
       
     
     It will be appreciated that the above-described system may be referred to as comprising a maximum adjacent seat resolution of 0.120 inches since successive uphole seats comprise a seat passage inside diameter that is 0.120 inches larger than the next adjacent downhole seat. Specifically, for example, according to the chart above the seat located most downhole comprises a seat passage inside diameter of 1.06 inches while the next adjacent uphole seat comprises a seat passage inside diameter of 1.120 inches. It will be appreciated that in the sleeve systems described above, such as sleeve system  200 , a maximum adjacent seat resolution of 0.120 inches corresponds to the provision of a 0.060 inch minimum gap between the seat passage inner diameter and the dart outside diameter while also providing for a minimum seal radial distance of 0.060 inches. 
     Example 4 
     It will be appreciated in some embodiments of a wellbore servicing system such as wellbore servicing system  100 , material selection for various components of the sleeve systems may be made in relation to anticipated pressures and related anticipated forces to be exerted on the components of the sleeve systems. The table below indicates that as the seat passage diameter of a sleeve system is increased, an accompanying anticipated force exerted on the components of the sleeve system also increases. 
     
       
         
           
               
               
               
               
               
             
               
                   
               
               
                   
                   
                 Down 
                   
                   
               
               
                   
                 Dart 
                 force 
                 Stress 
                 % increase of stress 
               
               
                   
                 landing 
                 (lbf) @ 
                 on dart 
                 on dart landing seat 
               
               
                 Seat 
                 seat 
                 7,500 psi 
                 landing seat 
                 surface (relative to the 
               
               
                 passage 
                 surface 
                 (applied 
                 surface @ 
                 down force associated 
               
               
                 diameter 
                 area 
                 uphole of 
                 7500 psi 
                 with seat passage 
               
               
                 (in) 
                 (in{circumflex over ( )}2) 
                 the dart) 
                 (lbf/in{circumflex over ( )}2) 
                 diameter of 1.06 inches) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 1.06 
                 0.108 
                 8146 
                 75674 
                 0 
               
               
                 1.18 
                 0.119 
                 9887 
                 83169 
                 10 
               
               
                 1.3 
                 0.130 
                 11796 
                 90665 
                 20 
               
               
                 1.42 
                 0.141 
                 13874 
                 98162 
                 30 
               
               
                 1.54 
                 0.153 
                 16120 
                 105660 
                 40 
               
               
                 1.66 
                 0.164 
                 18535 
                 113157 
                 50 
               
               
                 1.78 
                 0.175 
                 21119 
                 120655 
                 59 
               
               
                 1.9 
                 0.186 
                 23870 
                 128153 
                 69 
               
               
                 2.02 
                 0.197 
                 26791 
                 135652 
                 79 
               
               
                 2.14 
                 0.209 
                 29879 
                 143150 
                 89 
               
               
                 2.26 
                 0.220 
                 33137 
                 150649 
                 99 
               
               
                 2.38 
                 0.231 
                 36563 
                 158148 
                 109 
               
               
                 2.5 
                 0.242 
                 40157 
                 165647 
                 119 
               
               
                 2.62 
                 0.254 
                 43919 
                 173146 
                 129 
               
               
                 2.74 
                 0.265 
                 47851 
                 180645 
                 139 
               
               
                 2.86 
                 0.276 
                 51950 
                 188144 
                 149 
               
               
                 2.98 
                 0.287 
                 56219 
                 195643 
                 159 
               
               
                 3.1 
                 0.299 
                 60655 
                 203143 
                 168 
               
               
                 3.22 
                 0.310 
                 65260 
                 210642 
                 178 
               
               
                 3.34 
                 0.321 
                 70034 
                 218141 
                 188 
               
               
                   
               
            
           
         
       
     
     While the above table is calculated assuming 90 degree dart seat landing angles, the table nonetheless illustrates that anticipated stresses increase as seat/dart sizes increase. Accordingly, materials having relatively higher compressive strengths, in some embodiments, may be used for constructing seats and/or darts having relatively larger sizes. For example, a smaller dart body of a dart may comprise a composite material that forms a dart landing surface of the smaller dart while cast iron may be used to form a dart landing surface of a relative larger dart. Similarly, a smaller upper seat landing surface of a smaller seat may comprise a composite material while cast iron may be used to form an upper seat landing surface of a relative larger seat. 
     At least one embodiment is disclosed and variations, combinations, and/or modifications of the embodiment(s) and/or features of the embodiment(s) made by a person having ordinary skill in the art are within the scope of the disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of the disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, R 1 , and an upper limit, R u , is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=R 1 +k*(R u −R 1 ), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50 percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. Use of the term “optionally” with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. Use of broader terms such as comprises, includes, and having should be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of. Accordingly, the scope of protection is not limited by the description set out above but is defined by the claims that follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present invention.