Patent Publication Number: US-9404358-B2

Title: Wiper plug for determining the orientation of a casing string in a wellbore

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. §119 of the filing date of International Application No. PCT/US2013/061813, filed Sep. 26, 2013. 
     TECHNICAL FIELD OF THE DISCLOSURE 
     This disclosure relates, in general, to equipment utilized in conjunction with operations performed in relation to subterranean wells and, in particular, to a drillable wiper plug assembly having intelligent components operable for determining the orientation of a casing string in a wellbore. 
     BACKGROUND 
     Without limiting the scope of the present disclosure, its background will be described in relation to forming a window in a casing string for a multilateral well, as an example. 
     In multilateral wells, it is common practice to drill a branch or lateral wellbore extending outwardly from an intersection with a main or parent wellbore. Typically, once the parent wellbore casing string is installed and the parent wellbore has been completed, a whipstock is positioned in the parent wellbore casing string at the desired intersection and then a rotating mill is deflected laterally off the whipstock to form a window through the parent wellbore casing sidewall. 
     Once the casing window is created, the lateral wellbore can drilled. In certain lateral wellbores, when the drilling operation has been completed, a lateral wellbore casing string is installed in the lateral branch. Casing the lateral branch may be accomplished with the installation of a liner string that is supported in the parent wellbore and extends a desired distance into the lateral wellbore. Once the lateral wellbore casing string is installed and the lateral wellbore has been completed, it may be desirable to reestablish access to the main wellbore. In such cases, a rotating mill may be use to form an access window through the lateral wellbore casing sidewall. 
     In certain multilateral installations, it may be desirable to drill the lateral wellbore in a predetermined direction from the parent wellbore such as out of the high side of the parent wellbore. In such installations, it is necessary to form the window at a predetermined circumferential orientation relative to the parent wellbore casing. In order to properly position and rotationally orient the whipstock such that the window is milled in the desired direction, a latch assembly associated with the whipstock may be anchored into and rotationally oriented within a latch coupling interconnected in the parent wellbore casing string. The latch assembly typically includes a plurality of spring operated latch keys, each having an anchoring and orienting profile that is received in a latch profile formed internally within the latch coupling. In this manner, when the latch keys of the latch assembly are operatively engaged with the latch profile of the latch coupling, the latch assembly and the equipment associate therewith are axially anchored and circumferentially oriented in the desired direction within the parent wellbore casing string. Importantly, to obtain the proper orientation of the latch assembly, the latch coupling of the parent wellbore casing string must first be positioned in the desired orientation. One way to orient the latch coupling is to rotate the parent wellbore casing string with a drill string using measurement while drilling data. It has been found, however, that rotationally orienting the parent wellbore casing string in this manner can be imprecise and time consuming. Accordingly, a need has arisen for improved systems and methods for orienting a parent wellbore casing string in a wellbore. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the features and advantages of the present disclosure, reference is now made to the detailed description along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which: 
         FIG. 1  is a schematic illustration of an offshore oil and gas platform installing a casing string in a subterranean wellbore according to an embodiment of the present disclosure; 
         FIGS. 2A-2B  are cross sectional views of a system for determining an orientation of a casing string in a wellbore according to an embodiment of the present disclosure during a casing string orientation procedure; 
         FIGS. 3A-3B  are cross sectional views of a system for determining an orientation of a casing string in a wellbore according to an embodiment of the present disclosure during a liner hanging procedure; 
         FIGS. 4A-4B  are cross sectional views of a system for determining an orientation of a casing string in a wellbore according to an embodiment of the present disclosure prior to a cementing procedure; 
         FIGS. 5A-5B  are cross sectional views of a system for determining an orientation of a casing string in a wellbore according to an embodiment of the present disclosure during a cementing procedure; 
         FIGS. 6A-6B  are cross sectional views of a system for determining an orientation of a casing string in a wellbore according to an embodiment of the present disclosure during a releasing procedure; 
         FIGS. 7A-7C  are various views of a wiper plug for use in a system for determining an orientation of a casing string in a wellbore according to an embodiment of the present disclosure; 
         FIGS. 8A-8C  are cross sectional views of a wiper plug for use in a system for determining an orientation of a casing string in a wellbore according to an embodiment of the present disclosure sending pressure pulse communications; 
         FIG. 9A  is a diagram of an electronics and communication subassembly for use in a system for determining an orientation of a casing string in a wellbore according to an embodiment of the present disclosure; and 
         FIG. 9B  is a diagram of a sensor module for use in a system for determining an orientation of a casing string in a wellbore according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     While various system, method and other embodiments are discussed in detail below, it should be appreciated that the present disclosure provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative, and do not delimit the scope of the present disclosure. 
     In a first aspect, the present disclosure is directed to a system for determining the orientation of a casing string in a wellbore. The system includes a downhole tool disposed interiorly of the casing string in a known orientation relative to at least one feature of the casing string. A sensor module is operably associated with the downhole tool and is configured to obtain data relating to the orientation of the casing string. A communication module is operably associated with the sensor module. The communication module is configured to transmit information to a surface location, wherein, the information corresponds to the data obtained by the sensor module relating to the orientation of the casing string. 
     In a first embodiment, the downhole tool may be a wiper plug that is positioned in a known orientation within a latch coupling interconnected in the casing string. In this embodiment, a window joint may be interconnected in the casing string in a known orientation relative to the latch coupling. In a second embodiment, the sensor module may include one or more of an accelerometer, which may be a three-axis accelerometer, a gyroscope, which may be a three-axis gyroscope and a magnetometer, which may be a three-axis magnetometer. In a third embodiment, a microcontroller may be operably associated with the sensor module and the communication module. In a fourth embodiment, a power supply may be operably associated with the sensor module and the communication module. In a fifth embodiment, the communication module may be a pulser configured to transmit pressure pulses to the surface location. 
     In a second aspect, the present disclosure is directed to a system for determining an orientation of a casing string in a wellbore. The system includes a latch coupling interconnected in the casing string. A wiper plug is received within the latch coupling in a known orientation. A sensor module is disposed within the wiper plug. The sensor module includes at least one of an accelerometer, a gyroscope and a magnetometer configured to obtain data relating to the orientation of the casing string. A communication module is operably associated with the sensor module. The communication module is configured to transmit information to a surface location, wherein, the information corresponds to the data obtained by the sensor module relating to the orientation of the casing string. A microcontroller is operably associated with the sensor module and the communication module. A power supply is operably associated with the sensor module, the communication module and the microcontroller. 
     In a sixth embodiment, the wiper plug may sealingly engage the casing string uphole and downhole of the latch coupling. In a seventh embodiment, the wiper plug may releasably engage the latch coupling. In an eighth embodiment, wiper plug may be a drillable wiper plug. 
     In a third aspect, the present disclosure is directed to a method for orientating a casing string in a wellbore. The method includes disposing a downhole tool interiorly of the casing string in a known orientation relative to at least one feature of the casing string; obtaining data relating to the orientation of the casing string with a sensor module operably associated with the downhole tool; transmitting orientation information corresponding to the data obtained by the sensor module to a surface location with a communication module operably associated with the sensor module; and orienting the casing string to a desired orientation within the wellbore based upon the orientation information received at the surface location. 
     The method may also include disposing the downhole tool interiorly of the casing string in the known orientation relative to the at least one feature of the casing string prior to running the casing string into the wellbore; positioning a wiper plug in a known orientation within a latch coupling interconnected in the casing string; sealing engaging the casing string uphole and downhole of the latch coupling with the wiper plug; obtaining orientation data with at least one of an accelerometer, a gyroscope and a magnetometer; transmitting pressure pulses to the surface location to communicate orientation information and/or destructively removing the downhole tool from the casing string after orienting the casing string to the desired orientation within the wellbore based upon the orientation information received at the surface location. 
     Referring initially to  FIG. 1 , a liner string is being installed in a subterranean wellbore from an offshore oil or gas platform that is schematically illustrated and generally designated  10 . A semi-submersible platform  12  is centered over submerged oil and gas formation  14  located below sea floor  16 . A subsea conduit  18  extends from deck  20  of platform  12  to wellhead installation  22 , including blowout preventers  24 . Platform  12  has a hoisting apparatus  26 , a derrick  28 , a travel block  30 , a hook  32  and a swivel  34  for raising and lowering pipe strings, such as a liner string  36 . 
     A main wellbore  38  has been drilled through the various earth strata including formation  14 . The terms “parent” and “main” wellbore are used herein to designate a wellbore from which another wellbore is drilled. It is to be noted, however, that a parent or main wellbore does not necessarily extend directly to the earth&#39;s surface, but could instead be a branch of yet another wellbore. One or more surface and intermediate casing strings  40  have been installed in an upper and generally vertical section of main wellbore  38  and have been secured therein by cement  42 . The term “casing” is used herein to designate a tubular string used in a wellbore or to line a wellbore. The casing may be of the type known to those skilled in the art as a “liner” and may be made of any material, such as steel or a composite material and may be segmented or continuous, such as coiled tubing. 
     In the illustrated embodiment, liner string  36  is being installed in a generally horizontal section of wellbore  38 . Liner string  36  is being deployed on the lower end of a work string  44 . Liner string  36  includes a liner hanger  46 , a window joint  48  and a latch coupling  50 . Liner hanger  46  may be a conventional pressure or hydraulic set liner hanger with slips, annular seals, packers and the like to establish a gripping and sealing relationship with the interior of casing string  40  when set. Window joint  48  may be of conventional design and may include or may not include a pre-milled window. Latch coupling  50  has a latch profile that is operably engagable with latch keys of a latch assembly such that the latch assembly may be axially anchored and rotationally oriented in latch coupling  50 . In conventional practice, when the primary latch key of the latch assembly operably engages the primary latch profile of latch coupling  50 , a deflection assembly such as a whipstock is positioned in a desired circumferential orientation relative to window joint  48  such that a window can be milled, drilled or otherwise formed in window joint  48  in the desired circumferential direction. Once the window is formed, a branch or lateral wellbore may be drilled from window joint  48  of main wellbore  38 . The terms “branch” and “lateral” wellbore are used herein to designate a wellbore that is drilled outwardly from its intersection with another wellbore, such as a parent or main wellbore. A branch or lateral wellbore may have another branch or lateral wellbore drilled outwardly therefrom. 
     In the illustrated embodiment, liner string  36  includes a system for determining the orientation of liner string  36  in wellbore  38 . Shown in phantom lines, a wiper plug  52  is positioned to the interior of liner string  36  and is preferably received within latch coupling  50  in a known orientation such that seal elements of wiper plug  52  sealingly engage liner string  36  uphole and downhole of latch coupling  50  to protect latch coupling  50  during, for example, cementing operations. Wiper plug  52  may be run downhole positioned within liner string  36 . In this case, wiper plug  36  may be mechanically coupled within latch coupling  50  at the surface or prior to delivery of latch coupling  50 . Alternatively, wiper plug  52  may be conveyed downhole once the liner string  36  is landed within the wellbore  38 . In either case, one or more elements of wiper plug  52  may be configured to locate within a corresponding profile or groove within latch coupling  50 . Wiper plug  52  may further have one or more elements that enable release of wiper plug  52  from latch coupling  50 , if desired. 
     As described in detail below, wiper plug  52  includes electronic components and mechanical devices that provide intelligence and communication capabilities to wiper plug  52 . For example, wiper plug  52  may include a sensor module having one or more sensors such as one or more accelerometers, one or more gyroscopes, one or more magnetometers, pressure sensors, temperature sensors or the like. The sensor module is operable to obtain data relating to the orientation of liner string  36  such that liner string  36  may be circumferentially positioned within wellbore  38  with, for example, the primary latch profile of latch coupling  50  located on the high side of wellbore  38 , which is the preferred orientation for exiting the window of window joint  48  for drilling the lateral branch wellbore. The information obtained by the sensor module may be transmitted to a surface installation  54  by any suitable unidirectional or bidirectional wired or wireless telemetry system such as an electrical conductor, a fiber optic cable, acoustic telemetry, electromagnetic telemetry, pressure pulse telemetry, combinations thereof or the like. Once the orientation information is received and processed by surface installation  54 , work string  44  may be rotated, which in turn rotates liner string  36  until the desired orientation is obtained. The gathering of information by the sensor module and transmission of the information to surface installation  54  may occur in real-time or substantially in real-time to enable efficient orientation of liner string  36  within wellbore  38 . Also shown in phantom lines, a lead wiper  56  and a follow wiper  58  are positioned to the interior of liner string  36  proximate to liner hanger  46 . Together, wiper plug  52 , lead wiper  56  and follow wiper  58  may be referred to collectively as a wiper plug assembly. 
     Even though  FIG. 1  depicts a liner string being installed in a horizontal section of the wellbore, it should be understood by those skilled in the art that the present system is equally well suited for use in wellbores having other orientations including vertical wellbores, slanted wellbores, deviated wellbores or the like. Accordingly, it should be understood by those skilled in the art that the use of directional terms such as above, below, upper, lower, upward, downward, uphole, downhole and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure, the uphole direction being toward the surface of the well, the downhole direction being toward the toe of the well. Also, even though  FIG. 1  depicts an offshore operation, it should be understood by those skilled in the art that the present system is equally well suited for use in onshore operations. 
     Referring next to  FIGS. 2A-2B , therein is illustrated a well system that is generally designated  100 . In the illustrated portions, well system  100  includes a wiper plug assembly depicted as wiper plug  52 , lead wiper  56  and follow wiper  58 . Wiper plug  52  has been installed within the interior of liner string  36  and more particularly, wiper plug  52  is received within latch coupling  50  in a known orientation. As best seen in  FIGS. 7A-7C , wiper plug  52  includes an outer housing  102  including upper housing member  104  and lower housing member  106 . Disposed exteriorly of upper housing member  104  is an upper wiper  108  that is operable to establish a sealing relationship with the interior of liner string  36  when wiper plug  52  is installed within latch coupling  50 . Upper housing member  104  includes a slot  110 . An alignment key  112  radially extends through slot  110  and is operable to be received within a slot profile  114  of latch coupling  50 , as best seen in  FIG. 2B . Slot profile  114  is preferably circumferentially oriented in a known and preferably centered relationship with primary latch profile  116  of latch coupling  50 . In this manner, wiper plug  52  has a known orientation relative to at least one feature of liner string  36  and more particularly, a known orientation relative to latch coupling  50 . Alignment key  112  is slidably received within a guide  118  to enable alignment key  112  to be retracted out of slot profile  114  as explained below. 
     Disposed exteriorly of lower housing member  106  is a lower wiper  120  that is operable to establish a sealing relationship with the interior of liner string  36  when wiper plug  52  is installed within latch coupling  50 . Lower housing member  106  is operable to receive an actuator cover  122  and two electronics covers  124 ,  126  that may be coupled to lower housing member  106  by any suitable technique such as bolting, welding, banding or the like. Lower housing member  106  is also operable to receive an end cap  128  that may be threadedly and sealable coupled to lower housing member  106 . 
     Disposed within upper housing member  104  is a sliding sleeve  130  that is initially secured to upper housing member  104  by a plurality of frangible members depicted as shear pins  132 . Sliding sleeve  130  includes guide  118  discussed above. Disposed within one or more chambers of lower housing member  106  are the electronic components and mechanical devices that provide intelligence and communication capabilities to wiper plug  52 . In the illustrated embodiment, lower housing member  106  includes a lower cylindrical chamber operable to receive a plurality of fuel cells depicted as batteries  134 , such as alkaline or lithium batteries, and a battery connector  136 . Even through the present embodiment has been described as including batteries  134 , those skilled in the art will recognized that other power sources could alternatively be used to power wiper plug  52  including, but not limited to, an electrical line extending from the surface, a downhole power generation unit or the like. 
     Beneath cover  122 , lower housing member  106  includes a communication chamber operable to receive a communication module therein. In the illustrated embodiment, the communication module is depicted as a mud pulser  138  including an actuator  140  and a rocker arm  142  operatively coupled to actuator  140  such that movement of actuator  140  correspondingly moves rocker arm  142 . Actuator  140  may be any suitable actuating device including, but not limited to, a mechanical actuator, an electromechanical actuator, a hydraulic actuator, a pneumatic actuator, combinations thereof and the like. As best seen in  FIGS. 8A-8C , rocker arm  142  may be pivotably coupled to actuator  140  such that when actuator  140  is actuated, rocker arm  142  pivots into a flow path  144  centrally defined within wiper plug  52 . As rocker arm  142  pivots into flow path  144 , rocker arm  142  at least partially occludes flow path  144  and is thereby able to transmit pressure pulses to surface installation  54  via the fluid column present within the interior of liner string  36  and work string  44 . At surface installation  54 , the pressure pulses are received by one or more sensors of a computer system and are converted into an amplitude or frequency modulated pattern of the pressure pulses. The pattern of pressure pulses may then be translated by the computer system into specific information or data transmitted from mud pulser  138 . Even through the present embodiment has been described as including mud pulser  138 , those skilled in the art will recognized that other wireless or wired communication systems could alternatively be used to communication information to the surface including, but not limited to, a communication cable including electrical and/or optical conductors, an electromagnetic telemetry system, a mud pulser having an alternate design, an acoustic telemetry system including, for example, an acoustic receiver operably associated with surface installation  54  and any number of acoustic repeaters or nodes positioned at pre-determined locations along liner string  36  and casing string  40 , combinations thereof or the like. 
     Beneath cover  124 , lower housing member  106  includes a sensor module chamber operable to receive a sensor module  146  therein. Sensor module  146  is operable to obtain orientation information relating to the circumferential positioning of wiper plug  52  and thereby liner string  36 . For example, as best seen in  FIG. 9B , sensor module  146  may include one or more accelerometers depicted as a 3-axis accelerometer  148 , one or more gyroscopes depicted as a 3-axis gyroscope  150  and one or more magnetometers depicted as a 3-axis magnetometer  152 . In certain embodiments, sensor module  146  may be micro-electromechanical systems (MEMS), such as MEMS inertial sensors that include the various accelerometers, gyroscopes and magnetometers. In addition, sensor module  146  may comprise additional sensors including, but not limited to, temperature sensors, pressure sensors, strain sensors, pH sensors, density sensors, viscosity sensors, chemical composition sensors, radioactive sensors, resistivity sensors, acoustic sensors, potential sensors, mechanical sensors, nuclear magnetic resonance logging sensors and the like. 
     Beneath cover  126 , lower housing member  106  includes a computer hardware chamber operable to receive a microcontroller  154  as well as other computer hardware components therein. For example, the computer hardware may be configured to implement the various methods described herein and can include microcontroller  154  configured to execute one or more sequences of instructions, programming stances, or code stored on a non-transitory, computer-readable medium. Microcontroller  154  may be, for example, a general purpose microprocessor, a digital signal processor, an application specific integrated circuit, a field programmable gate array, a programmable logic device, a controller, a state machine, a gated logic, discrete hardware components, an artificial neural network, or any like suitable entity that can perform calculations or other manipulations of data. In some embodiments, the computer hardware can further include elements such as a memory, including, but not limited to, random access memory (RAM), flash memory, read only memory (ROM), programmable read only memory (PROM), electrically erasable programmable read only memory (EEPROM), registers, hard disks, removable disks, CD-ROMS, DVDs, or any other like suitable storage device or medium. 
     As best seen in  FIG. 9A , the measurements obtained by sensor module  146  may be conveyed in real-time or substantially in real-time to microcontroller  154 , which may be configured to receive and process these measurements. In some embodiments, microcontroller  154  may be configured to store the pre-processed or processed measurements. In other embodiments, microcontroller  154  may be configured to translate the processed measurements into command signals that are transmitted to mud pulser  138 . The command signals may be received by mud pulser  138  and serve to actuate mud pulser  138  such that rocker arm  142  is engaged to partially occlude flow path  144  and thereby transmit pressure pulses to surface installation  54  via the fluid column present within liner string  36  and work string  44 . At the surface, the pressure pulses may be received by a computer system including one or more sensors and retranslated back into the measurement data such that the well operator may use the information to orient liner string  36 . 
     As best seen in  FIG. 2A , the upper portion of well system  100  includes lead wiper  56  and follow wiper  58 . As illustrated, lead wiper  56  includes a housing element  160 . Disposed exteriorly of housing element  160  is a wiper  162  that is operable to establish a sealing relationship with the interior of liner string  36 . Disposed within a lower portion of lead wiper  56  is a ball seat  164  that is initially secured to housing element  160  by a plurality of frangible members depicted as shear pins  166 . The lower portion of lead wiper  56  defines a fluid bypass network including openings  168 , fluid passageways  170  and openings  172 , the operation of which is described below. Disposed within an upper portion of lead wiper  56  is a ball seat  174  that is initially secured to housing element  160  by a plurality of frangible members depicted as shear pins  176 . The upper portion of lead wiper  56  defines a fluid bypass network including openings  178 , fluid passageways  180  and openings  182 , the operation of which is described below. 
     The operation of the system for determining the orientation of a casing string in a wellbore will now be described with reference to  FIGS. 2A-2B through 6A-6B . As stated above,  FIGS. 2A-2B  show lead wiper  56  and follow wiper  58  positioned in an upper portion of liner string  36 , for example, proximate liner hanger  46  (see  FIG. 1 ). In addition, wiper plug  52  is positioned in a lower portion of liner string  36 , for example, proximate window joint  48  (see  FIG. 1 ). After liner string  36  has been run in wellbore  38  to the positioned shown in  FIG. 1  wherein the top of liner string  36  including liner hanger  46  is positioned near the bottom of casing string  40 , liner string  36  now requires circumferential orientation to enable the lateral well to be drilled from the parent wellbore in the desired direction. This is achieved using the intelligence and communication capabilities of wiper plug  52 . Specifically, sensor module  146  utilizes its accelerometer, gyroscope and/or magnetometer elements to determine proper orientation, for example, with respect to the Earth&#39;s gravity. Once gathered, this data may be communicated to microcontroller  154  via a suitable interface, such as a hardwire connection. Microcontroller  154  may then process the data and send command signals to mud pulser  138 , which transmits the data to surface installation  54  via pressure pulses, as described above. Surface installation  54  may receive and translate the pressure pulses into data that the well operator can use to make any needed orientation adjustments of liner string  36  by rotating working string  44  at the surface. This process may take place in real-time or using an iterative, stepwise approach until the desired orientation is achieved. 
     During running, positioning and orienting of liner string  36  into wellbore  38 , a drilling fluid may be present and may be circulated through wellbore  38  from the surface through the interior of work string  44  and liner string  36  as well as through the interior of lead wiper  56 , follow wiper  58  and wiper plug  52 . During fluid circulation, the drilling fluid exits the bottom of liner string  36  into the annulus surrounding liner string  36  via a float shoe and is then pumped back up toward the surface within the annulus. A check valve may be positioned within the float shoe to prevent reverse flow of the drilling fluid back into liner string  36  from the annulus. 
     Once liner string  36  is oriented in the desired circumferential direction, liner hanger  46  may be set. As best seen in  FIGS. 3A-3B , this may be accomplished by dropping a ball  184  from the surface into work string  44 . By gravity feed or fluid circulation, ball  184  travels downhole to ball seat  164  of lead wiper  56 . In this configuration, fluid pressure may be increase uphole of ball  184  and pressure variations in work string  44  can be used to set liner hanger  46  in a known manner. After liner hanger  46  is set, increasing the fluid pressure in work string  44  above a predetermined threshold causes ball seat  164  to shear down. In this configuration, openings  168 , fluid passageways  170  and openings  172 , enable fluid circulation through well system  100 , as best seen in  FIG. 4A . For example, a spacer fluid may be pumped into work string  44  and circulated through wellbore  38  to separate the drilling fluid from another fluid, such as the cement slurry to be circulated through wellbore  38  following the spacer fluid. 
     Prior to commencing the cementing operation, as best seen in  FIG. 4A , a second ball  186  may be dropped from the surface into work string  44 . By gravity feed or fluid circulation, ball  186  travels downhole to ball seat  174  of lead wiper  56 . In this configuration, increasing the pressure uphole of lead wiper  56  by, for example, pumping the cement slurry, causes lead wiper  56  to separate from follow wiper  58 . During this process, the fluid behind lead wiper  56  pushes lead wiper  56  downhole as lead wiper  56  pushes the fluid downhole thereof through wiper plug  52  and the float shoe into the annulus surrounding liner string  36  and back up toward the surface. The process continues until lead wiper  56  reaches wiper plug  52 , as best seen in  FIG. 5B . Thereafter, increasing the fluid pressure in work string  44  above a predetermined threshold causes ball seat  174  to shear down. In this configuration, openings  178 , fluid passageways  180  and openings  182 , enable fluid circulation through well system  100 , also as best seen in  FIG. 5B . The cement slurry may be circulated through wiper plug  52  and the float shoe into the annulus surrounding liner string  36  and back up toward the liner top. 
     After the desired volume of cement has been pumped into wellbore  38 , another spacer fluid may be pumped down work string  44  behind the cement slurry. A third ball  188  may now be dropped from the surface into work string  44 . By gravity feed or fluid circulation, ball  188  travels downhole to ball seat  190  of follow wiper  58 . In this configuration, increasing the pressure uphole of follow wiper  58  by, for example, pumping the spacer fluid, causes follow wiper  58  to move downhole enabling follow wiper  58  to push the fluid and/or cement downhole thereof through wiper plug  52  and the float shoe into the annulus surrounding liner string  36  and back up toward the liner top. This process continues until follow wiper  58  reaches lead wiper  56 , as best seen in  FIG. 6B . Thereafter, increasing the fluid pressure in work string  44  above a predetermined threshold causes follow wiper  58  to act on lead wiper  56  and thereby causes lead wiper  56  to act on sliding sleeve  130  of wiper plug  52 . This action cause shear pins  132  to break, which enables sliding sleeve  130  to move downhole relative to upper housing member  104 . This causes alignment key  112  to radially retract from slot profile  114 . Thereafter, fluid pressure acting on ball  188  pushes follow wiper  58 , lead wiper  56  and wiper plug  52  downhole into contact with the float shoe. When desired, the end of liner string  36  may be drilled out to allow the installation of, for example, mainbore screens. In this case, follow wiper  58 , lead wiper  56  and wiper plug  52  are preferably formed from materials that are easily millable or drillable such ceramics, aluminum, polymers or the like. 
     It should be understood by those skilled in the art that the illustrative embodiments described herein are not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments will be apparent to persons skilled in the art upon reference to this disclosure. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.