Abstract:
Apparatus and methods for providing fluid and projectiles to downhole tubulars includes a manifold. The manifold may include a housing, a cartridge disposed within the housing, and an actuator. The cartridge includes multiple throughbores for selectively allowing a fluid flow to pass through, and storing a projectile. The actuator is adapted to move the multiple throughbores of the cartridge out of and into the fluid flow to release the stored projectile into the fluid flow. The manifold may include multiple projectiles that are stored laterally relative to each other for radial translation and release into the fluid flow.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     BACKGROUND 
     1. Field of Art 
     The present invention relates generally to apparatus and methods for cementing downhole tubulars into a well bore. More particularly, the present invention relates to a cementing manifold and method of use. 
     2. Description of Related Art 
     A well-known method of drilling hydrocarbon wells involves disposing a drill bit at the end of a drill string and rotating the drill string from the surface utilizing either a top drive unit or a rotary table set in the drilling rig floor. As the well is formed, it is desirable to line the well bore. Thus, as drilling continues, progressively smaller diameter tubulars comprising casing and/or liner strings may be installed end-to-end to line the drilled borehole. As the well is drilled deeper, each string is run through and secured to the lower end of the previous string to line the borehole wall. The string is then cemented into place by flowing cement down the flowbore of the string and up the annulus formed by the string and the borehole wall. 
     To conduct the cementing operation, typically a cementing manifold is disposed between the top drive unit or rotary table and the drill string. Due to its position in the drilling assembly, the cementing manifold must suspend the weight of the drill pipe, contain pressure, transmit torque, and allow unimpeded rotation of the drill string. When utilizing a top drive unit, a separate inlet is typically provided to connect the cement lines to the cementing manifold. This allows cement to be discharged through the cementing manifold into the drill string without flowing through the top drive unit. 
     In operation, the cementing manifold allows fluids, such as drilling mud or cement, to flow therethrough while simultaneously enclosing and protecting from that flow, a series of projectiles, e.g., darts and spheres, that are released on demand and in sequence to perform various operations downhole. Thus, as fluid flows through the cementing manifold, the darts and/or spheres are isolated from the fluid flow until they are ready for release. 
     Conventional cementing manifolds are available in a variety of configurations, with the most common configuration including a single sphere/single dart manifold. Using such a device, the sphere is dropped at a predetermined time during drilling to perform a particular function. For example, a sphere may be dropped to form a temporary seal or closure of the flowbore of the drill string or to actuate a downhole tool, such as a liner hanger, in advance of the cementing operation. Once the cement has been pumped downhole, the dart is dropped to perform another operation, such as wiping cement from the inner wall of a string of downhole tubular members. 
     Another common cementing manifold employs a single sphere/double dart configuration. The sphere may be released to actuate a downhole tool, for example, followed by the first dart being launched immediately ahead of the cement, and the second dart being launched immediately following the cement. Thus, the dual darts cap the “ends” of the cement and prevent the cement from mixing with drilling fluid as the cement is pumped downhole through the drill string. Each dart typically also performs another operation upon reaching the bottom of the drill string, such as latching into a larger dart to wipe cement from the string of downhole tubular members. 
     Whether the cementing manifold includes a single sphere/single dart or single sphere/double dart configuration, there are operational characteristics common to both. Loading and certification of the cementing manifold is not performed at the drill site. Instead, the sphere and dart(s) are typically loaded into the cementing manifold, with the customer present to verify the loading procedure, prior to transporting the cementing manifold to the drill site. Also, the majority of cementing jobs require a single sphere and at most two darts. Thus, a cementing manifold with a single sphere/single dart or single sphere/double dart configuration is sufficient for most cementing jobs. 
     Usually, two loaded cementing manifolds, including one for backup purposes, are then transported to the drilling rig. Prior to conducting a cementing job, rotation of the drill string is interrupted so that a loaded cementing manifold may be installed between the cementing swivel and drill string. In some configurations, the cementing manifold weighs several thousand pounds and may be 13 feet in length. Thus, given the weight and size of the cementing manifold, lifting it into position, which may be 20-30 feet above the rig floor, raises concerns for the safety of rig personnel. Therefore, it is desirable to reduce the size and weight of the cementing manifold so that installation of the cementing manifold may be both safer and easier. 
     Once the cementing manifold is installed, rotation of the drill string may resume, at least until the cementing operation begins. As previously stated, a sphere and dart(s) are released to perform various tasks at different stages of a cementing operation. During most cementing operations, actuation of valves to release the sphere and darts is performed manually by rig personnel. Rotation of the drilling string is again interrupted to allow rig personnel to traverse the thirty or so feet above the rig floor to the cementing manifold and manually actuate valves on the cementing manifold to release the sphere and darts. This too raises safety concerns. For this reason, some cementing manifolds may now be actuated to release the sphere and darts via remote control from the rig floor. Remote control actuation also allows rotation of the drill string to continue uninterrupted because rig personnel remain on the rig floor, a safe distance from the rotating equipment. 
     Verification that the sphere or dart has been released from the cementing manifold is performed by visual inspection. In the case of manual actuation, as the sphere or dart exits the cementing manifold, a flag on the cementing manifold is triggered. While this flag is designed to be visible from the rig floor, resetting the flag requires rig personnel to ascend the rig to manually reset the flag, there again raising safety concerns. In the case of remote control actuation, instead of a triggered flag, rig personnel view an indicating device that changes orientation on the cementing manifold when a sphere or dart has been released. However, the indicator is often shrouded within a plate assembly, requiring the rotating speed of the drill string be reduced so that rig personnel can clearly see the indicator orientation from the rig floor. 
     Thus, at the minimum, releasing a sphere or dart and verifying that release requires slowing the rotation of the drill string. Further, such release and verification frequently requires rig personnel to ascend the rig to the cementing manifold, raising concerns for the safety of rig personnel. Therefore, it is desirable to remotely actuate and remotely verify the release of spheres and darts from the cementing manifold, including resetting any involved devices prior to subsequent releases, without either the need to reduce the rotation speed of the drill string or for rig personnel to position themselves in proximity of the cementing manifold. 
     Once the cementing operation is complete, the cementing manifold may be empty. Typically, the cementing manifold is not reloaded and recertified on the drilling rig. Rather the empty manifold is removed from the drill string and stored on the drilling rig until it can be transported back to the laboratory for reloading and recertification. Given its size, storing the cementing manifold on the drilling rig may be less than convenient. At a length of 13 feet, the cementing manifold may not fit in standard racks, requiring it to be stored elsewhere on the drilling rig and thereby consuming valuable rig space. Therefore, it is also desirable to reduce the size of the cementing manifold such that it may be easily stored in standard sized racks. 
     SUMMARY OF DISCLOSED EMBODIMENTS 
     Apparatus and methods for cementing tubulars in a borehole are disclosed. In some embodiments, the downhole apparatus includes a housing, a cartridge disposed within the housing, and an actuator. The housing includes a fluid entry port and a fluid exit port. The cartridge includes a first chamber and is moveable between a first and a second position. In the first position, the first chamber is out of fluid communication with the entry port and the exit port. In the second position, the first chamber is in fluid communication with the entry port and the exit port. The actuator is adapted to move the cartridge between the first and second positions. 
     Some method embodiments for cementing tubulars in a borehole include providing a cement manifold having a through-passage in fluid communication with a tubing string which includes the tubulars, providing a cartridge disposed in the cement manifold, storing a projectile in the cartridge and isolated from the through-passage, conveying cement through the passageway, moving the cartridge in the cement manifold to bring the projectile into the through-passage, and expelling the projectile from the through-passage into the tubing string. 
     Some method embodiments for field-loading of a cement manifold include providing the cement manifold, a cartridge, and a projectile at a well site, inserting the projectile into the cartridge at the well site, and loading the cartridge into the cement manifold at the well site. 
     In some embodiments, the apparatus for installing tubulars in a borehole includes a fluid supply, a tubular member, and a manifold coupled to the fluid supply and the tubular member. The manifold includes a fluid passageway therethrough and a projectile stored therein. The apparatus further includes an actuator configured to move the projectile into the fluid passageway. 
     Thus, the embodiments described herein include a combination of features and characteristics that are intended to advance the state of the art involving cementing methods and apparatus. The various characteristics described above, as well as other features, will be readily apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments and by referring to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more detailed description of the preferred embodiments, reference will now be made to the accompanying drawings, wherein: 
         FIG. 1  schematically depicts an exemplary drilling system in which the various embodiments of a cementing manifold in accordance with the present invention may be used; 
         FIG. 2  schematically depicts a representative cementing manifold connected above to a cementing swivel and below to a drill string; 
         FIG. 3  is a cross-sectional view of the cementing manifold shown in  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of the cementing manifold of  FIG. 3  after the ball container is actuated; 
         FIG. 5  is a cross-sectional view of the cementing manifold of  FIG. 3  after the sphere is released; 
         FIG. 6  is a cross-sectional view of the cementing manifold of  FIG. 3  after the dart cartridge is actuated to release a first dart; 
         FIG. 7  is a cross-sectional view of the cementing manifold of  FIG. 3  after the first dart is released; 
         FIG. 8  is a cross-sectional view of the cementing manifold of  FIG. 3  after the dart cartridge is actuated to release a second dart; 
         FIG. 9  is a cross-sectional view of the cementing manifold of  FIG. 3  after the second dart is released; 
         FIG. 10  schematically depicts another embodiment of a representative cementing manifold; and 
         FIG. 11  schematically depicts the cementing manifold of  FIG. 10  after actuation. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Certain terms are used throughout the following description and claims to refer to particular features or, components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. Further, the drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in interest of clarity and conciseness. 
     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 . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections. 
       FIG. 1  schematically depicts an exemplary drilling system, one of many in which cementing manifolds and methods disclosed herein may be employed. The drilling system  100  includes a derrick  102  with a rig floor  104  at its lower end having an opening  106  through which drill string  108  extends downwardly into a well bore  110 . The drill string  108  is driven rotatably by a top drive drilling unit  120  that is suspended from the derrick  102  by a traveling block  122 . The traveling block  122  is supported and moveable upwardly and downwardly by a cabling  124  connected at its upper end to a crown block  126  and actuated by conventional powered draw works  128 . Corrected below the top drive unit  120  is a kelly valve  130 , a pup joint  132 , a cementing swivel  160 , and a cementing manifold, such as the canister fed cementing manifold  200 , described more fully below. A flag sub  150 , which provides a visual indication when a dart or sphere passes therethrough, is connected below the cementing manifold  200  and above the drill string  108 . A drilling fluid line  134  routes drilling fluid to the top drive unit  120 , and a cement line  136  routes cement through a valve  138  to the swivel  160 . Tie-off connections  162 ,  164  secure the cementing swivel  160  to the derrick  102 . 
       FIG. 1  depicts one example of a drilling environment in which the cementing manifolds and methods disclosed herein may be utilized. One of ordinary skill in the art will readily appreciate, however, that the embodiments disclosed herein are not limited to use with a particular type of drilling system. Rather, these embodiments may be utilized in other drilling environments such as, for example, to cement casing into an offshore well bore. 
       FIG. 2  schematically depicts a representative cementing manifold connected above to a cementing swivel and below to a drill string. As described in reference to and shown in  FIG. 1 , the cementing swivel  160  and the cementing manifold  200  are coupled to a drill string  108 . Cement is provided to the cementing swivel  160  through cement line  136 . The cement passes through the cementing swivel  160  and into the cementing manifold  200  through a fluid entry port  202 . The cement continues through the cementing manifold  200  via a through-passage, such as a flowbore, and finally exits the cementing manifold through a fluid exit port  204 . As the cement flows through the cementing manifold  200 , projectiles, such as a dart and/or a sphere, may be released into the cement flow at desired times. 
     To release such projectiles, the cementing manifold  200  further includes a dart cartridge (not shown), a ball container (not shown), and an actuation system  210 . The cartridge may store one or more darts for use in a cementing operation. Similarly, the container may store a sphere also for use in the cementing operation. 
     The actuation system  210  is configured to actuate the cartridge and the container to release the one or more darts and sphere, respectively, at desired times during the cementing operation. The actuation system  210  may use electrical, hydraulic, pneumatic, or other suitable means known in the industry to actuate the cartridge and the compartment. In the embodiments exemplified by  FIG. 2 , the actuation system  210  uses pressurized air to actuate the cartridge aid the container to release the dart(s) and sphere, respectively. In some embodiments, the operating range for the pressurized air may be 90 psi to 150 psi. To deliver pressurized air to the dart cartridge and the ball container, the actuation system  210  further includes air swivel  215  and air flow line  220 . 
       FIGS. 3 through 9  are cross-sectional views of the cementing manifold  200 , depicted in  FIG. 2 , before and after the dart cartridge and/or ball container have been actuated. In all of these figures, the cementing manifold  200  is shown coupled to the cementing swivel  160 . Cement is provided to the cementing swivel  160  through cement line  136 . Similarly, pressurized air is provided through the air flow line  220  to the air swivel  215  for actuating the dart cartridge and/or ball container. 
     Referring to  FIG. 3 , the cementing manifold  200  further includes an enclosure  230 . The enclosure  230  further includes an upper end  250 , a lower end  255 , a body  260 , a chamber  235 , a compartment  240 , and a flowbore  245  therethrough. The body  260  further includes two sides  265 ,  270 , a base  275 , and a top  280 , all of which enclosure the chamber  235 . Compartment  240  is disposed within the enclosure  230  near the lower end  255  of the enclosure  230 . Compartment  240  bounded by enclosure walls  285 ,  290 ,  295 ,  297 . The upper end  250  of the enclosure  230  may be connected to another tool, such as the cementing swivel  160 , via a threaded connection or other suitable type of connection. Similarly, the lower end  255  of the enclosure  230  may be connected to another tool, such as the flag sub  150 , or directly to the drill string  108  via a threaded connection or other suitable type of connection. 
     A cartridge  205  is disposed within the chamber  235  of the enclosure  230  and is free to translate along the base  275  of the enclosure body  260 . The cartridge  205  further includes a body  300  having three longitudinal throughbores  305 ,  310 ,  315 , each of which permits cement flow therethrough when aligned with the flowbore  245  of the enclosure  230  in  FIG. 3 , the center throughbore  310  of the cartridge  205  is aligned with the flowbore  245  of the enclosure  230 . Moreover, the outer throughbores  305 ,  315  of the cartridge  205  are each designed to store a single dart. Thus, a loaded cartridge  205  stores a single dart in either or both of the outer throughbores  305 ,  315 . In this figure, a first dart  320  is stored in the throughbore  305 , and a second dart  325  is stored in the throughbore  315 . The center throughbore  310  is not designed to store a dart. Rather, the throughbore  310  permits cement flow through the cementing manifold  200 , including the cartridge  205 , without exposing dart(s) stored in the outer throughbores  305 ,  315  to cement flow. 
     A container  225  is disposed within the compartment  240  and is flee to translate along enclosure wall  295 . The container  225  is designed to hold a single ball or sphere. In this figure, a ball  335  is stored in container  225 . The container  225  further includes a throughbore  330  which permits cement flow therethrough when aligned with the flowbore  245  of the enclosure  230 . However, when throughbore  330  and flowbore  245  are not aligned, the container  225  isolates the ball  335  from cement flowing through the flowbore  245 . Such is the configuration depicted in  FIG. 3 . 
     As described in reference to  FIG. 2 , the actuation system  210  includes the air swivel  215  and the air flow line  220 , which provide pressurized air to the cementing manifold  200  for actuating the dart cartridge  205  and/or ball container  225 . To distribute the pressurized air to the chamber  235  and the compartment  240 , the actuation system  210  further includes the air distribution lines  340 ,  345 ,  350 , as depicted in  FIG. 3 . The distribution lines  340 ,  345  are routed from the air swivel  215  through the enclosure body  260  along the sides  265 ,  270 , respectively. The distribution line  340  provides a pathway for pressurized air to enter chamber  235  through side  265 , while distribution line  345  provides a pathway for pressurized air to enter chamber  235  through side  270 . The distribution line  350  is routed from the air swivel  215  through the enclosure body  260  along side  270 , and through enclosure wall  285 , which bounds compartment  240 . The distribution line  350  provides a pathway for pressurized air to enter compartment  240  through enclosure wall  285 . 
       FIG. 4  depicts the container  225  after actuation. As seen in this figure, the throughbore  330  is aligned with the flowbore  245 , and the ball  335  sits ready for delivery into the drill string  108 . When cement flows through the cementing manifold  200  via the flowbore  245 , the ball  335  is carried from the cementing manifold  200  by the cement flow.  FIG. 5  depicts the ball  335  after the cement flow has carried the ball  335  from the container  225  but prior to the ball  335  exiting the cementing manifold  200 . 
       FIG. 6  depicts the cartridge  205  after actuation to release dart  320 . As seen in this figure, the throughbore  305  is aligned with the flowbore  245 , and the dart  320  sits ready for delivery into the drill string  108 . When cement flows through the cementing manifold  200  via the flowbore  245 , the dart  320  is carried from the cementing manifold  200  by the cement flow.  FIG. 7  depicts the daft  320  after the cement flow has carried the dart  320  from the cartridge  205  but prior to the dart  320  exiting the cementing manifold  200 . 
       FIG. 8  depicts the cartridge  205  after actuation to release dart  325 . As seen in this figure, the throughbore  315  is aligned with the flowbore  245 , and the dart  325  sits ready for delivery into the drill string  108 . When cement flows through the cementing manifold  200  via flowbore  245 , the dart  325  is carried from the cementing manifold  200  by the cement flow.  FIG. 9  depicts the dart  325  after the cement flow has carried dart  325  from cartridge  205  but prior to the dart  325  exiting the cementing manifold  200 . 
     Prior to a cementing operation, one or two darts  320 ,  325  may be loaded into the cartridge  205 , as shown in  FIG. 3 . Similarly, a ball or sphere  335  may be loaded into the container  225 . The loaded cartridge  205  and/or loaded container  225  may then be inserted into the cementing manifold  200 . The cementing manifold  200  may be located on the rig floor  104  awaiting installation below the cementing swivel  160  or already suspended below the cementing swivel  160 . In either scenario, the cartridge  205  and/or container  225  is field-loaded, meaning a dart  320 ,  325  and/or sphere  335  is loaded into the cartridge  205  and/or container  225  at the well site and the cartridge  205  and/or container  225  is inserted into the cementing manifold  200  also at the well site. This loading procedure may be verified at the well site. By contrast, conventional manifolds are typically loaded in a location remote from the well site, e.g., in a laboratory or assembly shop, and verified there as well. Moreover, the loading procedure may be verified at the well site. 
     Once the cementing operation begins, referring again to  FIG. 17  drilling fluid flows through line  134  down into the drill string  108  while the top drive unit  120  rotates the drill string  108 . The housing  166  of cementing swivel  160  is tied-off to the derrick  102  via lines or bars  140 ,  142  such that the swivel housing  166  cannot rotate aid remains stationary while the mandrel of the swivel  160  rotates within housing  166  to enable the top drive unit  120  to rotate the drill string  108 . To perform an operation such as, for example, actuating a downhole tool to suspend a tubular  144  from existing and previously cemented casing  146 , a projectile, such as a sphere or ball, may be dropped from the cementing manifold  200 . 
     Release of a ball  335  from cementing manifold  200  is remotely actuated via a signal transmitted from a location remote to the cementing manifold  200 , including the rig floor  104 . When the actuation system  210  receives a signal directing the system  210  to actuate the container  225  to release the ball  335 , the actuation system  210  in response permits a burst of pressurized air to flow from the air flow line  220 , through the air swivel  215  and the distribution line  350 , and into compartment  240 . Upon injection into compartment  240 , the pressurized air actuates the container  225  by applying a pressure load to the container  225 . The pressure load causes the container  225  to translate along the enclosure wall  295  until the container  225  contacts the enclosure wall  290 . When the container  225  contacts the wall  290 , the container  225  ceases to translate along the wall  295 , leaving the throughbore  330 , which contains the ball  335 , aligned with the enclosure flowbore  245 , as shown in  FIG. 4 . Thus, the actuation system  210 , in response to a remote signal, actuates the container  225  to release the ball  335  without the need to position rig personnel in close vicinity of the cementing manifold  200  and without the need to slow or interrupt rotation of the drill string  108 . 
     In the exemplary embodiments described herein, actuation system  210  actuates cartridge  205  and container  225  to move radially within enclosure  230  to position dart  320 ,  325  and sphere  335  in flowbore  245 , where the radial direction is normal to the centerline of enclosure  230 . In other embodiments, the actuation system  210  may actuate cartridge  205  and/or container  225  to move axially, or to move radially and axially, to position darts  320 ,  325  and sphere  335  in flowbore  245 , where the axial direction is parallel to the centerline of enclosure  230 . 
     Moreover, cartridge  205  and container  225  are axially displaced from one another within enclosure  230 . For example, cartridge  205  is positioned above container  225 , closer to the upper end  250  of enclosure  230 . In other embodiments, container  225  may be positioned above cartridge  205 , and in still other embodiments, cartridge  205  and container  225  may be axially aligned. 
     When ball container  225  is actuated, the actuation system  210  transmits a signal to a remote location indicating that the ball container  225  was actuated. Moreover, as the ball  335  exits the cementing manifold  200 , the actuation system  210  transmits another signal to a remote location indicating that the sphere  335  has been delivered from the cementing manifold  200  into the drill string  108 . Thus, actuation of the ball container  225  as well as the release of a sphere  335  from the cementing manifold  200  into the drill string  108  are remotely verified without the need to position rig personnel in the vicinity of the cementing manifold  200  and without the need to slow or interrupt rotation of the drill string  108 . 
     After the ball  335  is released and the tubular  144  is suspended from the casing  146  via a rotatable liner hanger  151 ,  154 , cement will be pumped down through the drill string  108  and through the tubular  144  to fill the annular area  148  in the uncased well bore  110  around the tubular  144 . To initiate the cementing operation, the kelly valve  130  is closed, and the valve  138  to the cement line  136  is opened, thereby allowing cement to flow through the swivel  160  and down into the drill string  108 . Thus, the swivel  160  enables cement flow to the drill string  108  while bypassing the top drive unit  120 . 
     It is preferable to rotate the drill string  108  during cementing to ensure that cement is distributed evenly around the tubular  144  downhole. More specifically, because the cement is a thick slurry, it tends to follow the path of least resistance. Therefore, if the tubular,  144  is not centered in the well bore  110 , the annular area  148  will not be symmetrical, and cement may not completely surround the tubular  144 . Thus, it is preferable for the top drive unit  120  to continue rotating the drill string  108  through the swivel  160  while cement is introduced from the cement line  136 . 
     As the cementing operation progresses, cement flows through the cementing swivel  160  and into the cementing manifold  200 . When passing through the cementing manifold  200 , the cement flows through only one of the throughbores  305 ,  310 ,  315  of the cartridge  205  at any given time, depending on which of the throughbores  305 ,  310 ,  315  is aligned with the flowbore  245  of the enclosure  230 . In  FIG. 3 , the center throughbore  310  is aligned with the flowbore  245 . Thus, in this configuration, cement flow through the cementing manifold  200  passes through the center throughbore  310  of the cartridge  205 . Moreover, since the darts  320 ,  325  are stored in the throughbores  305 ,  315  and throughbores  305 ,  315  are out of communication with the cement flow, the cement passes through the cementing manifold  200  without the darts  320 ,  325  being exposed to the cement flow. 
     When the throughbore  305  is aligned with the flowbore  245 , cement flow through the cementing manifold  200  passes through the aligned throughbore  305  and carries the dart  320  from the cementing manifold  200 . Similarly, when the throughbore  315  is aligned with the flowbore  245 , cement flow through the cementing manifold  200  passes through the aligned throughbore  315  and carries the dart  325  from the cementing manifold  200 . To align either the throughbore  305  or the throughbore  315  with the flowbore  245  requires actuation of the cartridge  205  by the actuation system  210 . 
     When the appropriate volume of cement has been pumped into the drill string  108 , another projectile, for instance a dart, is typically dropped from the cementing manifold  200  to latch into a larger dart  152 , shown in  FIG. 1 , to wipe cement from the tubular  144  and land in the landing collar  153  adjacent the bottom end of the tubular  144 . Release of a dart  320 ,  325  from cementing manifold  200  is also remotely actuated via a signal transmitted from a location remote to the cementing manifold  200 , including the rig floor  104 . 
     When the actuation system  210  receives a signal directing the system  210  to actuate the cartridge  205  to release the dart  320 , the actuation system  210  in response permits a burst of pressurized air to flow from the air flow line  220 , through the air swivel  215  and the distribution line  345 , and into chamber  235 . Upon entering the chamber  235 , the pressurized air actuates the cartridge  205  by applying a pressure load to the body  300  of the cartridge  205 , causing the cartridge  205  to translate along the base  275  until the cartridge  205  contacts side  265  of the enclosure body  260 . When the cartridge  205  contacts the side  265 , the cartridge  205  ceases to translate along the base  275  and the throughbore  305 , which contains the dart  320 , is aligned with the enclosure flowbore  245 , as seen in  FIG. 6 . Thus, the actuation system  210 , in response to a remote signal, actuates the cartridge  205  to release the dart  320  without the need to position rig personnel in close vicinity of the cementing manifold  200  and without the need to slow or interrupt rotation of the drill string  108 . 
     After dart cartridge  205  is actuated, the actuation system  210  transmits a signal to a remote location indicating that the dart cartridge  205  was actuated. Moreover, as the dart  320  exits the cementing manifold  200 , the actuation system  210  transmits another signal to a remote location indicating that the dart  320  has been delivered from the cementing manifold  200  into the drill string  108 . Thus, actuation of the dart cartridge  205  as well as the release of a dart  320  from the cementing manifold  200  into the drill string  108  are remotely verified without the need to position rig personnel in the vicinity of the cementing manifold  200  and without the need to slow or interrupt rotation of the drill string  108 . 
     During some cementing operations, it may be necessary to release a second dart. Referring again to  FIG. 7 , when the actuation system  210  receives a signal directing the system  210  to actuate the cartridge  205  to release the second dart, specifically dart  325 , the actuation system  210  in response permits a burst of pressurized air to flow from the air flow line  220 , through the air swivel  215  and the distribution line  340 , and into chamber  235 . Upon entering the chamber  235 , the pressurized air actuates the cartridge  205  by applying a pressure load to the cartridge  205 , causing the cartridge  205  to translate along the base  275  until the cartridge  205  contacts the side  270  of the enclosure body  260 . When the cartridge  205  contacts side  270 , the cartridge  205  ceases to translate along base  275  and the throughbore  315 , which contains the dart  325 , is aligned with the enclosure flowbore  245 , as shown in  FIG. 8 . Thus, the actuation system  210 , in response to a remote signal, actuates the cartridge  205  to release the dart  325 , again without the need to position rig personnel in close vicinity of the cementing manifold  200  and without the need to slow or interrupt rotation of the drill string  108 . 
     After dart cartridge  205  is actuated, the actuation system  210  transmits a signal to a remote location indicating that the dart cartridge  205  was actuated. Moreover, as the dart  325  exits the cementing manifold  200 , the actuation system  210  transmits another signal to a remote location indicating that the dart  325  has been delivered from the cementing manifold  200  into the drill string  108 . Thus, actuation of the dart cartridge  205  as well as the release of a dart  325  from the cementing manifold  200  into the drill string  108  are remotely verified without the need to position rig personnel in the vicinity of the cementing manifold  200  and without the need to slow or interrupt rotation of the drill string  108 . 
     When the dart cartridge  205  and/or the ball container  225  are empty, the cementing manifold  200  may be preferably reloaded in place, meaning as the cementing manifold  200  remains suspended below the cementing swivel  160 . Alternatively, the cementing manifold  200  may be disengaged from below the cementing swivel  160  and returned to the rig floor  104  for reloading. In either scenario, the empty cartridge  205  and/or empty ball container  225  may be removed from the cementing manifold  200  and replaced with a loaded cartridge and/or ball container at the well site. If the cementing operation is complete and the cementing manifold  200  no longer needed, the cementing manifold  200  may be disengaged from below the cementing swivel  160  and stored in a standard rack located somewhere on the rig floor  104 . 
     Referring next to  FIG. 10 , another embodiment of a cementing manifold is shown. A cementing manifold  400 , exemplified by  FIG. 10 , is similar to cementing manifold  200 , described with reference to  FIGS. 2 through 9 , both in structure and operation. While cementing manifold  400  depicted in  FIG. 10  is not shown to include a ball container, in some embodiments the cementing manifold  400  may include a ball container similar to container  225  employed in cementing manifold  200  previously described. The primary difference between the cementing manifold  200  exemplified by  FIGS. 2 through 9  and cementing manifold  400  exemplified by  FIG. 10  relates to the dart cartridge. 
     In cementing manifold  200 , depicted in  FIGS. 2 through 9 , the cartridge  205  includes a single body  300  having three longitudinal throughbores  305 ,  310 ,  315 . By contrast, the cementing manifold  400  depicted in  FIG. 10  includes two separate tubes  405 ,  410 , in place of the single cartridge  205 , within the chamber  235  of the enclosure  230 . A dart may be stored within each tube  405 ,  410  for subsequent release during a cementing operation. The tube  405  further includes a throughbore  415  that permits cement flow therethrough when aligned with the flowbore  245  of the enclosure  230 . Similarly, the tube  410  further includes a throughbore  420  that permits cement flow therethrough when aligned with the flowbore  245 . 
     Referring still to  FIG. 10 , cementing manifold  400  employs an actuation system  210  as previously described. When the actuation system  210  receives a signal directing the system  210  to actuate the tube  405  to release a dart stored therein during a cementing operation, the actuation system  210  in response permits a burst of pressurized air to flow from the air flow line  220 , through the air swivel  215  and the distribution line  345 , and into chamber  235 . Upon entering the chamber  235 , the pressurized air actuates the tube  405  by applying a pressure load to the outer surface of the tube  405 , causing the tube  405  to translate along the base  275  until the tube  405  contacts the tube  410 . When the tube  405  contacts the tube  410 , the tube  405  ceases to translate along the base  275  and the throughbore  415 , which contains a dart, is aligned with the enclosure flowbore  245 . Thus, the actuation system  210 , in response to a remote signal, actuates the tube  405  to release a dart. 
     Alternatively, the actuation system  210  may receive a signal directing the system  210  to actuate the tube  410  to release a dart stored therein. In response, the actuation system  210  permits a burst of pressurized air to flow from the air flow line  220 , through the air swivel  215  and the distribution line  340 , and into chamber  235 . Upon entering the chamber  235 , the pressurized air actuates the tube  410  by applying a pressure load to the outer surface of the tube  410 , causing the tube  410  to translate along the base  275  until the tube  410  contacts the tube  405 . When the tube  410  contacts the tube  405 , the tube  410  ceases to translate along the base  275  and the throughbore  420 , which contains a dart, is aligned with the enclosure flowbore  245 . Thus, the actuation system  210 , in response to a remote signal, actuates the tube  410  to release a dart. 
       FIG. 11  depicts the tube  405  after actuation. As seen in this figure, the throughbore  415  of the tube  405  is aligned with the flowbore  245  of the enclosure  230 . A dart, which was previously stored in tube  405 , has been released from the tube  405  and carried from the cementing manifold  400  by cement flow through the flowbore  245 . 
     After a dart has been released from the tube  405  in the manner described above, the actuation system  210  may receive another signal directing the system  210  to actuate the tube  410  to release a dart stored therein. In response, the actuation system  210  permits a burst of pressurized air to flow from the air flow line  220 , through the air swivel  215  and the distribution line  340 , and into chamber  235 . Upon entering the chamber  235 , the pressurized air actuates the tube  410  by applying a pressure load to the outer surface of the tube  410 , causing both tubes  405 ,  410  to translate along the base  275  until the tube  405  contacts the enclosure side  270 . When the tube  405  contacts the side  270 , the tubes  405 ,  410  cease to translate along the base  275  and the throughbore  420  of the tube  410 , which contains a dart, is aligned with the enclosure flowbore  245 . Thus, the actuation system  210 , in response to two remote signals, actuates the tubes  405 ,  410  to release two darts into a cementing operation. 
     Thus, the cementing manifolds  200 ,  400  share common features believed advantageous. In particular, the manifolds  200 ,  400  are preferably loaded and reloaded as needed at the well site. Additionally, actuation of the cementing manifolds  200 ,  400  is accomplished by remote activation without the need to position rig personnel in vicinity of the manifolds  200 ,  400  and without the need to slow or interrupt rotation of the drill string. Moreover, actuation of the cementing manifolds  200 ,  400  as well as the release of a dart(s) or sphere from the manifolds  200 ,  400  into the drill string are remotely verified without the need to position rig personnel in the vicinity of the cementing manifold and without the need to slow or interrupt rotation of the drill string. 
     While preferred embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the system and apparatus are possible and are within the scope of the invention. For instance, the actuation system may use another type of gas, in place of air, to actuate the dart cartridge and/or ball container. Furthermore, the actuation system may actuate the dart cartridge and/or ball container using an electrical, hydraulic, or other means. Additionally, the dart cartridge and ball container may be configured to store and release more than two darts and one sphere, respectively. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims.