Patent Publication Number: US-10760357-B2

Title: Triple activity system and method for drilling operations

Description:
CROSS-REFERENCE TO RELATED TO APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/782,546, filed Oct. 5, 2015 that is a national stage filing of PCT Application PCT/SG2014/000152 filed Apr. 4, 2014 that claims priority to Singapore Patent Application 201302600-0 filed Apr. 5, 2013, all of which are expressly incorporated herein by reference in their entirety as if set forth herewith. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a drillship or a drilling rig having a drill-floor with three activity centers. The first activity center includes a main well, the second activity center includes an auxiliary well and the third activity center includes an offline casing and drill pipe stand-building facility. The offline casing and drill pipe stand-building facility is a standalone feature and can be located in the forward or aft side of a drillship or a drilling rig depending on the choice of the builder or operator. 
     PRIOR ART 
     The drilling depths at deep water drill sites easily double or triple as these drill sites move further away from land masses. At such sites, drilling efficiency is of paramount concern as the operating costs at such drill sites depend on the amount of time it takes to complete a drilling operation. 
     A typical drilling operation involves the handling and/or assembly of drill pipes, risers and casings received from a travelling shuttle on an elevated platform leading to the drill floor. The drill pipes will be connected together through stand building operations to form vertical drill strings. The individual drill pipes, risers and casings for the well drilling process are retrieved from a storage location and horizontally transported to the derrick via shuttles for subsequent stand-building, racking or hoisting. The rig or ship designs that adopt a dual hoisting generally have two well center s on a drill floor and each well center usually uses their own tubular feeding system for each well center. The making up operations or stand building operations of drill strings and casings are thus limited by having only one feeder platform on each side at the aft and forward catwalk platforms. Further, drilling activities at the auxiliary well will have to be stopped to allow for the making up operations or drilling pipes or casings. This is inefficient as it increases the amount of time required to complete a drilling operation. 
     SUMMARY OF INVENTION 
     The above and other problems in the art are solved and an advance in the art is made in accordance with this invention. In accordance with a first aspect of the invention, in order to optimize stand-building capabilities, a stand-building facility for drill pipes and casings can be introduced in order to carry out offline make up or break out operations while the other two well center s are occupied by various other drilling activities. Such an arrangement will enable three activities to be simultaneously conducted independent of each other at three separate locations. These three locations are at the first activity center, the second activity center and the third activity center. In accordance with a second aspect of the invention, horizontally travelling platforms are provided to each of the activity center s thereby allowing pipes, risers or casings to be continuously and smoothly supplied to each of these activity center s. 
     The above and other problems in the art are solved and an advance in the art is made in accordance with this invention. In accordance with embodiments of the invention, there is provided a triple activity system at a drill floor on a drillship for conducting drilling operations on a seabed beneath the drillship comprising a first activity center having a main well and a first top drive assembly for advancing tubular members through the main well to the seabed, a second activity center having an auxiliary well and a second top drive assembly for advancing tubular members through the auxiliary well to the seabed and a third activity center having a receptacle for receiving an upright tubular member and an iron roughneck for making modifications to tubular member assemblages wherein the modifications to tubular member assemblages may be carried out when main drilling activities are conducted at the first activity center or when auxiliary drilling activities are conducted at the second activity center. The system also has a storage area positioned adjacent the third activity center for receiving and storing modified tubular member assemblages and tubular members from the third activity center. Further, a first delivery assembly is positioned adjacent the storage area, the first activity center, the second activity center and the third activity center for transferring tubular member assemblages or tubular members between the storage area, the first activity center, the second activity center or the third activity center. 
     In accordance with embodiments of the invention, the first delivery assembly of the triple activity system includes a pipe handling unit that is configured to transfer the tubular member assemblages or the tubular members between a fingerboard rack in the storage area and the second top drive assembly in the second activity center or the first top drive assembly in the first activity center. In embodiments of the invention, the pipe handling unit is further configured to transfer tubular members or tubular member assemblages between the third activity center and the storage area. 
     In accordance with embodiments of the invention, the triple activity system further includes a second delivery assembly positioned adjacent the first activity center and the second activity center for transferring tubular members or tubular member assemblages between the first activity center and the second activity center to facilitate concurrent drilling operations. In accordance with other embodiments of the invention, the second delivery assembly of the triple activity system includes a pipe handling unit configured to transfer the tubular member assemblages or the tubular members between the first top drive assembly in the first activity center and the second top drive assembly in the second activity center. 
     In accordance with embodiments of the invention, the triple activity system further includes a first traveling platform provided between the first activity center and a first tubular member storage bay. This first traveling platform is configured to receive tubular members from the first tubular member storage bay and is configured to transfer the received tubular members to the first top drive assembly. 
     In accordance with embodiments of the invention, the triple activity system further comprises a second traveling platform provided between the second activity center and a second tubular member storage bay. The second traveling platform is configured to receive tubular members from the second tubular member storage bay and is configured to transfer the received tubular members to the second top drive assembly. 
     In accordance with embodiments of the invention, the triple activity system further includes a third traveling platform provided between the third activity center and a third tubular member storage bay. The third traveling platform is configured to receive tubular members from the third tubular member storage bay and is configured to transfer the received tubular members to the iron roughneck. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above advantages and features of a system in accordance with this invention are described in the following detailed description and are shown in the drawings: 
         FIG. 1  illustrating a top view of a drillship having a triple activity system whereby the third activity center is provided at the forward side of the drillship in accordance with embodiments of the invention; 
         FIG. 2  illustrating a top view of a drillship having a triple activity system whereby the third activity center is provided at the aft side of the drillship in accordance with embodiments of the invention; 
         FIG. 3  illustrating an elevated front view of a first activity center and a second activity center in accordance with embodiments of the invention; 
         FIG. 4  illustrating an elevated side view of a third activity center in accordance with embodiments of the invention; 
         FIG. 5A  illustrating a timeline of a conventional drilling operation on a drillship that has two activity centers;  FIG. 5B  illustrating a drill ship having two activity centers to perform the drilling operations shown in  FIG. 5A ; 
         FIG. 6A  illustrating a timeline of a conventional drilling operation on a drillship that has a triple activity system in accordance with embodiments of the invention; and  FIG. 6B  illustrating a drillship having three activity centers to perform the drilling operations shown in  FIG. 6A . 
     
    
    
     DETAILED DESCRIPTION 
     This invention relates to a drillship or a drilling rig having three activity centers at the drill floor of the drillship or drilling rig. The first activity center has a main well, the second activity center has an auxiliary well and the third activity center has an offline casing and drill pipe stand-building facility. The offline casing and drill pipe stand-building facility is a standalone feature and can be located in the forward or aft side of a drillship or a drilling rig depending on the choice of the builder or operator. 
     The stand-building facility for drill pipes and casings at the third activity center r is able to carry out offline make up or break out operations while the other two well center are occupied by various other drilling activities. Through the addition of such an activity center, this enables three activities to be simultaneously conducted at the drill floor, independent of each other at three separate locations thereby greatly reducing the amount of time required for drilling operations. Further, horizontally travelling platforms are provided at each of the activity centers to allow pipes, risers or casings to be continuously and smoothly supplied to each of these activity centers from their respective pipe storage bays. 
       FIG. 1  illustrates a top view of drill rig or drillship  100  having drill floor  105  in accordance with embodiments of the invention. One skilled in the art will recognize that drill floor  105  may be provided on a drill rig, a drillship or any other such vessels that have sufficient space and are able to handle the weight of the various activity centers on the drill floor. As illustrated in  FIG. 1 , drill floor  105  comprises three activity centers. These are first activity center  101 , second activity center  102  and third activity center  103 . These three activity centers are all provided within the footprint of drill floor  105 . In embodiments of the invention, individual derricks may be provided at each of the activity centers to facilitate the drilling activities being carried out at these activity centers. In order to reduce cost and the amount of space occupied on the deck of drillship  100 , other embodiments of the invention provide that a single derrick sufficiently large and wide enough to encompass the drilling activities carried out at first activity center  101 , second activity center  102  and third activity center  103  may be utilized in place of individual derricks at each activity center. 
     In embodiments of the invention, first activity center  101  may be provided with a main well that is configured to handle heavier tubular members such as risers while second activity center  102  may be provided with an auxiliary well that is configured to handle lighter tubular members or tubular member assemblies such as drill pipes, drill strings, or casings. 
     From hereafter, it shall be understood that the phrase tubular members refers to pipes, tubular conduits, conductors, casings, drill pipes and risers while tubular member assemblies/assemblages refer to tubular members that are joined together such as drill pipes that are joined together to from a long vertical drill string, casings that are joined together to form casing stands or pipes that are joined together to form pipe stands. 
     Conventional drilling activities conducted at first activity center  101  may include, but are not limited to, the advancement of tubular members or tubular assemblies through the main well, the running of tubular members or tubular assemblies through the main well, the withdrawal of tubular members or tubular assemblies through the main well, the lifting of tubular members or tubular assemblies through the main well, or the rotating of tubular members or tubular assemblies through the main well to the seabed. These activities may be carried out using a variety of devices including, but not limited to, top drive assemblies, sheaves, draw works, traveling blocks, rotary tables, hydraulic rams. 
     In embodiments of the invention, a top drive assembly may be utilized at first activity center  101  to provide rotational force to the tubular members that are being advanced through the main well. In other embodiments of the invention, a rotary table may be used in place of a top drive assembly to provide the required rotational force if so desired. The top drive assembly may be mounted on the derrick at first activity center  101 . Tubular members or tubular member assemblies received by this top drive assembly are then advanced through the main well towards the seabed. Conversely, the top drive assembly may be used to withdraw the tubular members or tubular member assemblies from the seabed and through the main well onto the deck of drill ship  100  upon completion of drilling operations. 
     Similarly, auxiliary drilling activities that may be conducted at second activity center  102  may include, but are not limited to, the advancement of tubular members or tubular assemblies through the auxiliary well, the running of tubular members or tubular assemblies through the auxiliary well, the withdrawal of tubular members or tubular assemblies through the auxiliary well, the lifting of tubular members or tubular assemblies through the auxiliary well, or the rotating of tubular members or tubular assemblies through the auxiliary well to the seabed. These activities may be carried out using a variety of devices including, but not limited to, top drive assemblies, sheaves, draw works, traveling blocks, rotary tables, hydraulic rams. 
     In embodiments of the invention, a top drive assembly may be utilized at second activity center  102  to provide rotational force to the tubular members or tubular member assemblies that are being advanced through the auxiliary well. In other embodiments of the invention, a rotary table may be used in place of a top drive assembly to provide the required rotational force if so desired. The top drive assembly may be mounted on the derrick at second activity center  102 . Tubular members or tubular member assemblies received by this top drive assembly are then advanced through the auxiliary well towards the seabed. Conversely, the top drive assembly may be used to withdraw the tubular members or tubular member assemblies from the seabed and through the auxiliary well onto the deck of drill ship  100  upon completion of drilling operations. 
     With the commencement of drilling operations at the drill site, tubular member assemblages would have to be assembled before the tubular member assemblages are advanced through the main well or auxiliary well at their respective activity centers. As first activity center  101  and second activity center  102  are focused on drilling operations that involve the advancement or withdrawal of tubular members or tubular member assemblies through their respective drilling wells, third activity center  103  is tasked with stand-building activities as concurrent drilling operations are carried out at the other two activity centers. These stand-building activities include the assembling of drill pipes to form longer drill strings or the assembling of casings, or conversely, the disassembling of drill strings or casings upon completion of the drilling operation. An iron roughneck is provided at third activity center  103  to assist in these stand-building activities. 
     Iron roughneck  110  provided at third activity center  103  may be used to make up or break out tubular member assemblies. Torque wrenches are utilized by iron roughneck  110  to make up or break down the tubular member assemblies. Receptacle  109  that is provided at third activity center  103  is also used to assist in the make up or break down operations. Receptacle  109  may be an offline mouse hole that may be used to receive and store an upright tubular member before the tubular member is assembled. In make up or break down operations, after a tubular member has been delivered to third activity center  103 , the lower section of the tubular member will initially be placed in receptacle  109 . When iron roughneck  110  is ready to receive the tubular member, iron roughneck  110  is brought towards the tubular member located within receptacle  109 . Once iron roughneck  110  is adjacent the tubular member, iron roughneck  110  will clamp the lower section of the tubular member while the second tubular member is attached to the upper section of the clamped tubular member. A spinning or rotary wrench will be used by iron roughneck  110  to turn the top of the second tubular member thereby applying sufficient rotary torque to firmly affix the two tubular members together to form a tubular member assembly/assemblage. 
     The completed tubular member assembly may then be delivered to an adjacent storage area, such as storage area  115  for storage. The completed tubular member assembly may be delivered from third activity center  103  to storage area  115  using a delivery assembly provided adjacent third activity center  103 , second activity center  102 , first activity center  101  and storage area  115  such as a pipe handling unit. The pipe handling unit will have a wrench to grip the tubular member assembly. The gripped tubular member assembly will then be transferred from third activity center  103  to storage area  115 . Storage area  115  may be provided with fingerboards, stand racks or pipe racks for receiving and storing the tubular member assemblies. 
     After a tubular member assembly has been broken down by iron roughneck  110  at triple activity center  103  into individual tubular members, the delivery assembly provided adjacent third activity center  103  and storage area  115  may be used to transport the individual tubular members from third activity center  103  to traveling platform  123  to be transported to storage bay  133  as described in greater detail below. 
     This delivery system may also be used to lift a tubular member assembly from the finger board or pipe racks at storage area  115  and subsequently deliver the gripped tubular member assembly to the second activity center  102 . The tubular member assembly may then be fitted to the top drive assembly at the second activity center to be used for subsequent drilling operations. Once the drilling operations at second activity center  102  has been concluded, the delivery system may then transfer the used tubular member assembly back to storage area  115  for storage. 
     In embodiments of the invention, a further delivery system may also be provided adjacent first activity center  101  and second activity center  102  to transfer tubular members or tubular member assemblies between these two activity centers to facilitate concurrent drilling operations at these two centers. 
     Each of the activity centers are connected to a tubular member feeder system that delivers tubular members from their respective pipe storage bays to the respective activity systems. In embodiments of the invention, as illustrated in  FIG. 1 , traveling platform  121  is provided between storage bay  131  and first activity center  101 . Traveling platform  121  comprises a shuttle for receiving tubular members and also includes a catwalk platform that runs between storage bay  131  and first activity center  101 . The shuttle travels along the catwalk platform transferring tubular members between both locations. In operation, crane  141  will transfer the tubular members from storage bay  131  onto the deck for loading onto the shuttle. Once the shuttle is loaded with the tubular members, the shuttle then travels along the catwalk platform towards drill floor  105  and to first activity center  101 . The tubular members are then unloaded and utilized for the making up process at the first activity center before they are attached to the top drive assembly and utilized in drilling operations. The tubular members are loaded and transported in a horizontal position with respect to the deck of drillship  100 . 
     In embodiments of the invention, traveling platform  121  is configured to accommodate and deliver risers. As risers are tubular members that are extremely heavy and unwieldy, the shuttle used to receive and transport these risers have to be reinforced and have to be securely mounted onto the catwalk platform to ensure that the risers do not drop as they are being transported. 
     In embodiments of the invention, as illustrated in  FIG. 1 , traveling platform  122  is provided between storage bay  132  and second activity center  102  while traveling platform  123  is provided between storage bay  133  and third activity center  103 . Traveling platform  122  comprises a shuttle for receiving tubular members and also includes a catwalk platform that runs between storage bay  132  and second activity center  102 . Similarly, traveling platform  123  comprises a shuttle for receiving tubular members and also includes a catwalk platform that runs between storage bay  133  and third activity center  103 . The shuttle travels along these catwalk platforms transferring tubular members between their respective locations. In operation, cranes  142 ,  143  will transfer the tubular members from storage bay  132 , 133  respectively onto the deck for loading onto the respective shuttles. Once these shuttles are loaded with the tubular members, these shuttles then travel along the respective catwalk platforms towards drill floor  105  and to their respective activity centers. Similarly, these tubular members are loaded and transported in a horizontal position with respect to the deck of drillship  100 . 
     In embodiments of the invention, crane  142  operating on the aft end will transfer the drill pipes from pipe storage  132  to the pipe shuttle for subsequent transportation to the auxiliary well at second activity center  102 . In embodiments of the invention, crane  143  operating on the forward end will transfer drill pipes or casings from pipe storage  133  to the shuttle. The shuttle will then transport the drill pipes or casings to third activity center  103 . Upon receiving the drill pipes or casings from the shuttle, the pipe handling unit adjacent third activity center  103  will lift the drill pipes or casing out of the shuttle. During the process of stand building, these drill pipes or casings will then be vertically mounted on receptacle  109 . Alternatively, if stand building processes are not required, the drill pipes and casings are then moved to their respective travelling platforms to be conveyed to their respective storage bays. 
     For stand building process that involve joint connections, iron roughneck  110  will be used to make up and break out the pipe lengths using a spinning torque wrench. The joint pipes will be conveyed to the second and/or first activity centers for drilling operations. These pipes will then subsequently be run through the main well and/or the auxiliary well at the first and second activity centers respectively. If these joint pipes or casing stands are not yet utilized, these joint pipes or casing stands may be transferred to their respective travelling platforms to be conveyed to their respective storage bays. 
     The speed of stand-building is limited by the availability of the tubular members that can be supplied to the drill floor at any one time. As each activity center is supplied by its own dedicated traveling platform, the speed of stand-building activities is greatly increased. Further, by having three independent traveling platforms, this enhances the overall performance of stand-building and improves redundancy if one of the traveling platforms is out of service. 
       FIG. 1  illustrates an embodiment of the invention whereby third activity center  103  and its various components are provided at the forward section of drillship  100  while  FIG. 2  illustrates an embodiment of the invention whereby third activity center  103  and its various components are provided at the aft section of drillship  100 . In these embodiments of the invention, the positioning of first activity center  101  and second activity center  102  remains unchanged. 
       FIG. 3  illustrates an embodiment of the invention whereby derrick  300  is positioned over first activity center  101  and second activity center  102 . First activity center  101  is provided with top drive assembly  301  that is mounted on the upper section of derrick  300  while second activity center  102  is provided with top drive assembly  302  that is mounted on the upper section of derrick  300  as well. Pipe handling unit  321  is illustrated as being provided adjacent first activity center  101  while pipe handling unit  322  is illustrated as being provided adjacent second activity center  102 . Traveling platform  122  is illustrated as being placed adjacent second activity center  102  allowing for the tubular members to be easily and efficiently transferred between the shuttle of the traveling platform and second activity center  102 . Main well  311 , which is used for drilling operations, is positioned directly above moon pool  305 . This allows the tubular members to be easily advanced through main well  311 , through moon pool  305  towards the seabed beneath drillship  100 . Similarly, auxiliary well  312 , which is used for auxiliary drilling operations, is positioned directly above moon pool  305 . This allows the tubular members to be easily advanced through auxiliary well  312 , through moon pool  305  towards the seabed below drillship  100 . 
       FIG. 4  illustrates an embodiment of the invention whereby derrick  400  is positioned over third activity center  103 . It is illustrated that top drive assembly  403  is provided on the upper section of derrick  400  to apply rotational forces to the tubular members as the tubular members are being assembled to form drill strings or vertical drill pipes or being disassembled into individual tubular members. Iron roughneck  110  is provided as well at third activity center  103  to assist in the make up or break out of the tubular member assemblies. 
     Through the introduction of stand-building facilities at third activity center  103 , this allows for the faster make up and storage of tubular assemblages thereby shortening the overall process time during drilling and well completion activities. To illustrate this point, a general sequence of events for drilling operations and blowout preventer installation is shown in Table 1 below. 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 General Sequence of activities for Drilling and BOP Installation 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 1 
                 Standbuilding for 6-⅝″ &amp; 5-⅞″ DP to Fingerboard 
               
               
                 2 
                 Standbuilding BHA/DC to Fingerboard 
               
               
                 3 
                 Make Up 36″ Bit &amp; Trip In &amp; Drill 36″ Hole 
               
               
                 4 
                 Trip Out &amp; Breakout to Fingerboard 
               
               
                 5 
                 Make up 30″ Casing Tools 
               
               
                 6 
                 Standbuild &amp; Trip in 30″ casing &amp; cement 
               
               
                 7 
                 Retrieve 30″ Casing Tool &amp; Landing String 
               
               
                 8 
                 Install Permanent Guide Base 
               
               
                 9 
                 Standbuilding for 6-⅝″ or 5-⅞″ DP to Fingerboard 
               
               
                 10 
                 Make up 26″ Bit &amp; Trip In &amp; Drill 26″ Hole 
               
               
                 11 
                 Trip Out &amp; Breakout to Fingerboard 
               
               
                 12 
                 Make up 20″ Casing Tools 
               
               
                 13 
                 Standbuild &amp; Trip In 20″ Casing &amp; Cement 
               
               
                 14 
                 Retrieve 20″ Casing Tools &amp; Landing String 
               
               
                 15 
                 Make Up Riser Running Tools 
               
               
                 16 
                 Remove Main Rotary Table Master Bushing 
               
               
                 17 
                 Install Gimbal and Spider on Main Well 
               
               
                 18 
                 Tripping In Riser and BOP 
               
               
                 19 
                 Install Telescopic Joint 
               
               
                 20 
                 Install Diverter with Flex Joint 
               
               
                 21 
                 Remove Gimbal and Spider on Main Well 
               
               
                 22 
                 Replace Main Rotary Table 
               
               
                 23 
                 Standbuilding for 6-⅝″ or 5-⅞″ DP to Fingerboard 
               
               
                 24 
                 Make up 16″ Bit &amp; Trip In &amp; Drill 16″ Hole 
               
               
                 25 
                 Trip Out &amp; Breakout to Fingerboard 
               
               
                 26 
                 Make Up 13-⅜″ casing tools 
               
               
                 27 
                 Standbuild &amp; Store in Fingerboard Then Trip In 13-⅜″ Casing &amp; 
               
               
                   
                 Cement 
               
               
                 28 
                 Retrieve 13-⅜″ casing Tool &amp; Landing String 
               
               
                 29 
                 Standbuilding for 6-⅝″ or 5-⅞″ DP to Fingerboard 
               
               
                 30 
                 Make up 12-¼″ Bit &amp; Trip In &amp; Drill 12-¼″ Hole 
               
               
                 31 
                 Trip Out &amp; Breakout to Fingerboard 
               
               
                 32 
                 Make Up 9-⅝″ casing tools 
               
               
                 33 
                 Standbuild &amp; Store in FB Then Trip In 9-⅝″ Casing &amp; Cement 
               
               
                 34 
                 Retrieve 9-⅝″ casing Tool &amp; Landing Strip 
               
               
                   
               
            
           
         
       
     
       FIG. 5A  shows an illustrative graph of timing of activities performed by drillship that utilizes dual activity centers for drilling an offshore well in accordance with conventional drilling operations_as shown in  FIG. 5B . The filled in horizontal bars represent the amount of time required to complete a particular activity and the various types of drilling activities are shown along the vertical bar. Each time block represents an indicative completion status of an activity from the point of execution and its progress relative to another parallel running activity. 
     At steps  501 ,  509 ,  523 ,  527  and  529 , drill pipes or casings are retrieved from the pipe storage areas using cranes  550 , 551 . The retrieved drill pipes are then placed onto the catwalk shuttles  555  and subsequently transferred to the drill floor  560 . Each individual drill pipe is then joined with other drill pipes to form longer drill strings or drill stands using the iron roughneck and mouse hole. After the required number of drill pipes has been attached to each other up to a required length, each drill string or stand will then be taken by a pipe-handling unit and stored in the fingerboard rack. The stand-building activities at steps  501 ,  509 ,  523  and  529  take place at the activity center  561  with the auxiliary well while the activity at step  527  takes place at the activity center  562  with the main well. This means that when stand-building activities are taking place, the auxiliary well may not be used for auxiliary drilling operations. 
     At step  502 , the bottom-hole assembly and drill collars are built up at the activity center  562  with the auxiliary well. The bottom-hole assembly may include components such as drill collars, stabilizers, reamers, shocks and hole-openers. These components are retrieved from the pipe storage areas using cranes. The retrieved components are then placed onto the catwalk shuttles and subsequently transferred to the drill floor. Each component of the bottom-hole assembly is then assembled to form the required assembly using the iron roughneck and mouse hole. After the bottom-hole assembly has been formed and attached, the bottom-hole assembly will then be taken by a pipe-handling unit and stored in the relevant storage area. The assembly of the bottom-hole assembly will usually take place at the activity center  561 _with the auxiliary well. 
     At step  503 , the drill string with the 36 inch drill bit is made up and run through a rotary table of a selected well center. This occurs at the activity center  561  with the auxiliary well. A 36 inch top-hole or bore hole will then be drilled through at the seabed via the rotary force transmitted from a top drive assembly located in the derrick. This will typically be done through the auxiliary well. In other drill ship configurations, water jet in hole may be used. 
     At step  504 , after the bore hole has been created, the drilling string and the bottom-hole assembly attached to the end of the drill string will be hoisted back up to the drill floor via the activity center  561 _with the auxiliary well. The iron roughneck is then utilized to break up the tubular drill string. The broken up drill pipes are then stored at the fingerboard rack in the storage area. 
     At steps  505 ,  512 ,  515 ,  526  and  532  the setup will be fitted with casing handling tools such as a pickup elevator and tongs, in preparation for the running of the casings. Similarly, the setup may also be fitted with riser handling tools such as a pickup elevator and tongs in preparation of the running of the risers. These activities all take place at the activity center_ 562  with the main well. 
     At steps  506 ,  513 ,  527  and  533 , the casing string is made up in a similar manner to the drill pipes and run into the wellbore. After the conductor pipe and intermediate casing are attached together, cement slurry may then be circulated into the annulus of the casing string and left to set. These activities all take place at the activity center  562  with the main well. 
     At steps  507 ,  514 ,  528  and  534 , the casing tools are then retrieved back to the drill floor after the casing has been lowered to the seabed. All these activities take place at the activity center  562  with the main well. 
     At step  508 , the permanent guide base is then lowered and secured to the casing conductor. This takes place in the activity center  561  with the auxiliary well. 
     At steps  510 ,  524  and  530 , the drill string having the drill bit with the required diameter is made up and run through a selected well center&#39;s rotary table. A hole will then be drilled through at the seabed via the rotary force transmitted from a top drive assembly located in the derrick. The activity at step  510  takes place at the activity center  561  with the auxiliary well while the activities at steps  524  and  530  takes places at the activity center  562  with the main well. 
     At steps  511 ,  525  and  531 , the drill string is then retrieved back to the drill floor. The iron roughneck is utilized to break up the tubular string and the pipe-handler stores then stores the broken up drill pipers and/or stands back into the fingerboard rack at the storage area. The activity at step  511  takes place at the activity center  561  with the auxiliary well while the activities at steps  525  and  531  takes places at the activity center  562  with the main well. 
     At step  516 , the master bushing of the rotary table is taken out to accommodate the running of the riser through the well center. At step  517 , a spider and a gimbal is then installed over the rotary table&#39;s receptacle. The spider is an apparatus that is used to support the riser while it is being made up or broken. The gimbal sits in between the spider and rotary table, functioning as a shock absorber and compensating for any offset. These activities all take place at the activity center  562  with the main well. 
     At step  518 , the riser string is connected up, attached to the blowout preventer (BOP) and is lowered to the seabed for mounting onto a permanent guide base. At step  519 , a telescopic joint is transported to the drill floor and attached to an upper end of a riser. A diverter will then be attached to the end of the telescopic joint at step  520  and at step  521 , after the riser string has been connected and held up by the diverter, the spider and gimbal are then removed. The rotary table is then subsequently reinstated at step  522 . These activities all take place at the activity center  562  with the main well. 
       FIG. 6A  shows an illustrative graph of timing of activities performed by drillship that utilizes an embodiment of this invention for drilling an offshore well in accordance with conventional drilling operations and  FIG. 6B  shows the layout of a triple activity system in accordance with an embodiment of the invention. Similarly, the filled in horizontal bars represent the amount of time required to complete a particular activity and the drilling activities are shown along the vertical bar. Each time block represents an indicative completion status of an activity from the point of execution and its progress relative to another parallel running activity. 
     At steps  601 ,  609 ,  623 ,  627  and  629 , drill pipes are retrieved from the pipe storage areas using cranes  650 . 651 . The retrieved drill pipes are then placed onto the catwalk shuttles  655  and subsequently transferred to the drill floor  660 . Each individual drill pipe is then joined with other drill pipes to form longer drill strings or drill stands using the iron roughneck and mouse hole. After the required number of drill pipes has been attached to each other up to a required length, each drill string or stand will then be taken by a pipe-handling unit and stored in the fingerboard rack. The stand-building activities at steps  601 ,  609 ,  623  and  627  take place at the third activity center  663  whereby the third activity center  663  is provided with an iron roughneck, a receptacle for receiving tubular such as an offline mouse hole, and a pipe handling unit for transferring the completed tubular assemblies to an adjacent storage area. This means that when stand-building activities are taking place, the auxiliary well may be utilized for other types of auxiliary drilling operations. The activity at step  629  takes place at the second activity center  661  with the auxiliary well. 
     At step  602 , the bottom-hole assembly and drill collars are built up. The bottom-hole assembly may include components such as drill collars, stabilizers, reamers, shocks and hole-openers. These components are retrieved from the pipe storage areas using cranes. The retrieved components are then placed onto the catwalk shuttles and subsequently transferred to the drill floor. Each component of the bottom-hole assembly is then assembled to form the required assembly using the iron roughneck and mouse hole. After the bottom-hole assembly has been formed and attached, the bottom-hole assembly will then be taken by a pipe-handling unit and stored in the relevant storage area. The assembly of the bottom-hole assembly will take place at the activity center  661  with the auxiliary well. 
     At step  603 , the drill string with the 36 inch drill bit is made up and run through a rotary table of a selected well center. This activity takes place at the second activity center  662  with the auxiliary well. A 36 inch top-hole or bore hole will then be drilled through at the seabed via the rotary force transmitted from a top drive assembly located in the derrick. This will typically be done through the auxiliary well. In other drill ship configurations, water jet in hole may be used. It can be seen from  FIG. 6  that while the activities at step  602  and  603  are being carried out, the stand-building activities at step  601  are still on-going simultaneously at the third activity center  663 . 
     At step  604 , after the bore hole has been created, the drilling string and the bottom-hole assembly attached to the end of the drill string will be hoisted back up to the drill floor. The iron roughneck is then utilized to break up the tubular drill string. The broken up drill pipes are then stored at the fingerboard rack in the storage area. This occurs at the second activity center  661 . 
     At steps  605 ,  612 ,  615 ,  626  and  632 , the setup will be fitted with casing handling tools such as a pickup elevator and tongs, in preparation for the running of the casings. Similarly, the setup may also be fitted with riser handling tools such as a pickup elevator and tongs in preparation of the running of the risers. All these activities takes place at the first activity center  662  with the main well. 
     At steps  606 ,  613 ,  627  and  633 , the casing string is made up in a similar manner to the drill pipes and run into the wellbore. After the conductor pipe and intermediate casing are attached together, cement slurry may then be circulated into the annulus of the casing string and left to set. The making up of the casing string in steps  606  and  613  takes place at the first activity center with the main well while the making up of the casing string in steps  627  and  633  takes place at the third activity center  663 . 
     At steps  607 ,  614 ,  628  and  634 , the casing tools are then retrieved back to the drill floor after the casing has been lowered to the seabed. All these activities take place at the first activity center  662  with the main well. 
     At step  608 , the permanent guide base is then lowered and secured to the casing conductor. This activity takes place at the second activity center  661  with the auxiliary well. 
     At steps  610 ,  624  and  630 , the drill string having the drill bit with the required diameter is made up and run through a selected well center&#39;s rotary table. A hole will then be drilled through at the seabed via the rotary force transmitted from a top drive assembly located in the derrick. The activity at step  610  takes place at the second activity center  661  with the auxiliary well. The activities at steps  624  and  630  take place at the first activity center  662  with the main well. 
     At steps  611 ,  625  and  631 , the drill string is then retrieved back to the drill floor. The iron roughneck is utilized to break up the tubular string and the pipe-handler stores then stores the broken up drill pipers and/or stands back into the fingerboard rack at the storage area. The activity at step  611  takes place at the second activity center  661  and the activities at steps  625  and  631  takes place at the first activity center  662  with the main well. 
     At step  616 , the master bushing of the rotary table is taken out to accommodate the running of the riser through the well center. At step  617 , a spider and a gimbal is then installed over the rotary table&#39;s receptacle. The spider is an apparatus that is used to support the riser while it is being made up or broken. The gimbal sits in between the spider and rotary table, functioning as a shock absorber and compensating for any offset. These activities all take place at the first activity center  662  with the main well. 
     At step  618 , the riser string is connected up, attached to the blowout preventer (BOP) and is lowered to the seabed for mounting onto a permanent guide base. At step  619 , a telescopic joint is transported to the drill floor and attached to an upper end of a riser. A diverter will then be attached to the end of the telescopic joint at step  620  and at step  621 , after the riser string has been connected and held up by the diverter, the spider and gimbal are then removed. The rotary table is then subsequently reinstated at step  622 . These activities all take place at the first activity center  663  with the main well. 
     By comparing the the timing of activities shown_in  FIG. 5A  with the timings shown in  FIG. 6A , it is shown that a drill ship or drill rig employing an embodiment of the invention is about 20% more efficient as compared to a drill ship that utilizes conventional dual activity drill centers. This is because there are less non-productive time periods due to the availability of drill pipe and casings during critical drilling periods such as during the making up of the drill bit and the tripping riser. One skilled in the art will note that the chain of events, sequences and tubular dimensions listed in  FIGS. 5A and 6A  may vary from one drilling operator to the next and is to be interpreted as a general mode of operation. 
     Further, through the introduction of a third catwalk machine with supporting equipment, this improves drilling efficiency and reduces the lead time. This is due to the increase in supply rate and building up of tubular assemblies on the setback area or storage area. The increase in the readiness of the drill pipes and casings to be run into the wells results in cost savings when the reduction of setup time and expenditure on vessel day rates are taken into account. The added feature also ensures that equipment redundancy for casing and drill pipe assembly are minimized. 
     The above is a description of embodiments of a system and process in accordance with the present invention as set forth in the following claims. It is envisioned that others may and will design alternatives that fall within the scope of the following claims.