Multi-activity offshore exploration and/or development drilling method

ES 2 300 409 T3

DESCRIPTION

Drilling vessel or semi-submersible and multi-activity drilling set.

Background of the invention

This invention relates to a drilling vessel or semi-submersible and a multi-activity drilling rig.

In the past, substantial gas and oil reserves have been located under the Gulf of Mexico, the North Sea, the Beaufort Sea, the Far East regions, the Middle East, West Africa, etc. In the initial stages of offshore exploration and / or development drilling, operations were conducted in relatively shallow waters, from a few meters to 30 meters or so, along the nearshore regions and parts of the Gulf of Mexico. Over the years, the Gulf and other regions of the world have been extensively explored and known shallow-water oil and gas reserves have been identified and drilled. As the need for profitable energy continues to increase around the world, additional oil and gas reserves have been sought in waters with depths of 900 to 1,500 m or more on the continental shelf. As an example, there is a field currently in production off the Louisiana coast in 853m of water, and drilling operations off New Orleans are anticipated in the near future at approximately 914-2,286m of water. Furthermore, blocks have been tendered in fields of 3,048 m and by the year 2000 it is anticipated that there will be a desire to drill in 3,658 m of water or more.

Deep-sea exploration not only comes from a growing need to locate new reserves, as a general proposition, but also with the evolution of the knowledge of interpreting three-dimensional seismic images, and the better knowledge of the attributes of turbidites and sands of deep water, Substantial large reserves for oil and gas production are now believed to exist in the Gulf of Mexico and elsewhere in waters with depths of 3,048 m or more.

Along the regions near the coast and the continental slope, oil reserves have been drilled and exploited using fixed towers and mobile units such as forklift platforms. Fixed towers or platforms are typically manufactured inland and transported to the drilling site on a barge or are self-floating using buoyancy chambers within the tower legs. At the point of work, the towers are erected and fixed to the seabed. A jack-up rig typically includes a barge or self-propelled rig that is used to float the rig to the point of drilling. At the drill site, the legs at the corners of the barge or self-propelled platform are extended downward, into the seabed, until the platform is raised a suitable working distance above the statistical wave height of a storm. . An example of a self-elevating platform is described in US Patent No. 3,412,981 to Richardson. A forklift barge is described in US Patent No. 3,628,336 to Moore et al.

Once in position, fixed towers, barges, and jack-up rigs are used to drill in small tidal ranges in a non-dramatic manner unlike operations carried out on land. It will be readily seen that although fixed platforms and self-lifting drilling rigs are suitable for waters with depths of 30 to 100 m or so, they are not at all useful for deep water applications.

In deeper waters, a forklift tower is planned in which a platform is used to float and then one more legs are lowered to the seabed. The anchors of these forklift platforms are characterized in two categories: (1) supported pile designs and (2) gravity-based structures. An example of a gravity-based jack-lift tower is shown in US Patent No. 4,265,568 to Herrmann et al. Again, although a simple forklift leg has advantages in water depths of a few thousand meters it is no longer a suitable design for deep water.

For drilling in deep water, semi-submersible rigs have been designed, as described in US Patent No. 3,919,957 to Ray et al. In addition, tension leg platforms have been used as described in US Patent No. 3,982,492 to Steddum. A platform with legs in tension includes a platform and a plurality of relatively large legs that extend downward into the sea. Anchors are attached to the seabed below each leg, and a plurality of permanent mooring lines extend between the anchors and each leg. These mooring lines are tensioned to partially exert traction on the legs, opposing their buoyancy, out to sea to provide stability to the platform. An example of a tension leg platform is described in US Patent No. 4,281,613 to Ray et al.

Even in deeper waters, turret moored derrick ships and dynamically positioned derrick ships have been used. Moored derrick ships are described in US Patent Nos. 3,191,201 and 3,279,404 to Richardson et al.

A drillship with dynamic positioning is similar to a ship moored to a drilling tower in which drilling operations are carried out through a large central opening or central well.

ES 2 300 409 T3 vertically across the central area of ​​the ship. Bow and stern thruster assemblies are used in collaboration with multiple sensors and computer controls to dynamically hold the vessel at desired latitude and longitude coordinates. A drillship with dynamic positioning and elevation angle positioning system is described in US Patent No. 4,317,174 to Dean.

Each of the patented inventions referred to above has been transferred with the present application.

Despite widespread success in shallow water drilling to medium depth, there is a reaffirmed belief that significant energy reserves exist below deep water of 2,134 to 3,658 m or more. However, the challenges of drilling exploratory wells to tap those reservoirs, and pursuing development drilling in a plurality of those wells, are formidable. With respect to this, it is believed that the procedures and apparatus existing in the past will not be adequate to economically treat the new frontier that deep waters represent.

As drilling depths double and triple, drilling efficiency must be improved and / or new techniques must be devised to offset the large daily costs that would be required to operate equipment capable of coping with deep-water applications. This difficulty is increased in field development drilling where twenty or more wells are often required to be drilled and retrofitted. Also, workover work such as removing drill trains, or operating pipeline, acidification of the well, cementing, workover of the well, replacement of pumps, etc. in deep water it can occupy a rig for a long period of time.

Accordingly, it would be desirable to provide a novel method and apparatus that is suitable for all offshore applications, but particularly suitable for deep water exploration and / or development drilling applications that would utilize drill ships, semi-submersible rigs, drilling rigs, legs in tension and the like, with improved performance to counteract inherent increases in costs, corresponding to deep water applications.

Reference is made to GB-A-2 041 836 which presents a drilling vessel having a single drilling rig with which drilling operations can be carried out using two drilling rigs recurrently, drilling each drilling rig. a single respective well on the seabed.

One aspect of the invention is to provide a boat according to claim 1.

Another aspect of the invention is to provide a multi-activity drilling, according to claim 7.

A procedure and apparatus for carrying out offshore exploration drilling with a single drilling rig in which primary and auxiliary exploration drilling operations can be carried out simultaneously to shorten the primary activity path is described below. drilling. The single tower can be used to carry out multiple drilling, development and workover operations simultaneously.

The method and apparatus to be described are suitable for exploration and / or development drilling of an offshore oil and gas reserve field, particularly in deep water areas.

The method and apparatus uses a multi-activity drilling rig for offshore drilling operations relating to the exploration and / or development of a field, which can be used in deep water with improved efficiency.

Also described below is a novel method and apparatus for offshore drilling relating to the exploration and / or development of a field where a single drilling rig can be used simultaneously for primary, secondary and tertiary tubing activities.

With the method and apparatus for exploration offshore drilling, multi-drilling activities can be performed simultaneously from a single rig and thus certain tubular operations can be removed from a critical pathway of primary drilling activity. .

Furthermore, with the method and apparatus, multi-tubular activities can be performed from a single drilling rig, and primary drilling or auxiliary tubular activity can be performed simultaneously by means of a plurality of tubular handling locations within a single drilling rig. .

The derrick system for offshore exploration and / or field development drilling operations can be used effectively and efficiently by a drillship, semi-submersible rig, tension leg rig, jack-up rig, fixed tower or similarly, to improve the drilling efficiency of previously known systems.

The novel method and apparatus can be used for deep water exploration and / or production drilling applications with improved reliability as well as efficiency.

ES 2 300 409 T3

Also described below is a novel method and apparatus for deep water field development drilling or workover activity, where multiple wells can be worked simultaneously from a single derrick.

A preferred embodiment of the invention, which is intended to meet at least some of the above objectives, comprises a multi-activity drilling assembly which is operative to be mounted on a deck of a drillship, semi-submersible platform, tension leg platform , off-shore drilling tower or similar, to support exploration and / or development drilling operations through a deck and into the bed of a body of water.

The multi-activity drilling set includes a drilling tower to simultaneously support exploration and / or production drilling operations and tubular activity or other auxiliary activity to drilling operations by means of a drilling platform. A first tubular station is located within the periphery of the drilling tower to perform drilling operations by means of the drilling platform. A second tubular station is located adjacent to the first, but separate from it, and within the periphery of the drilling tower to perform auxiliary operations to the primary drilling function.

With the above multi-activity drilling tower, the primary drilling activity can be carried out by the first tubular station and, simultaneously, the auxiliary drilling and / or related activity can be carried out within the same drilling tower by means of the second station. tubular to effectively suppress some critical primary perforation pathway activity.

Other objects and advantages of the present invention will become apparent from the following detailed description of a preferred manner of carrying it, given by way of example with reference to the accompanying drawings, in which:

Figure 1 is an axonometric perspective view of a drillship of the type that is suitable for advantageously using the multi-activity field exploration and / or development drilling apparatus and method in accordance with the present invention;

Figure 2 is a side elevational view of the multi-activity drillship depicted in Figure 1 with the central well area cut away to represent the double tubular strings extending from a single drilling tower;

Figure 3 is a plan view of the drillship depicted in Figures 1 and 2, which comprises a preferred embodiment of the invention;

Figure 4 is a plan view of a mechanical deck of the drillship illustrated in Figure 3, depicting various operational features;

Figure 5 is a starboard elevation view of the multi-activity drilling tower, according to a preferred embodiment of the present invention, mounted on a substructure or hold platform;

Figure 6 is a stern elevational view of the multi-activity drilling tower shown in Figure 5;

Figure 7 is a plan view of a drilling deck for the multi-activity drilling tower according to a preferred embodiment of the invention;

Figure 8 is an illustrative elevational view of a top drive device whose function is to rotate and drive tubular according to a preferred embodiment of the invention;

Figures 9 to 22 depict a schematic sequence of views illustrating primary and auxiliary activity of tubulars, being performed in accordance with a scan drilling sequence using the present method and apparatus; and Figures 23a and 23b show a timing chart for an illustrative exploratory drilling operation, in which Figure 23a shows a critical path of activity for a conventional drilling operation; and Figure 23b shows a time profile of a similar critical path for the same drilling activity, according to a present method and apparatus. Figure 23b shows a dramatic increase in exploration drilling efficiency that can be achieved with the use of the apparatus and procedure presented herein.

Referring now to the drawings, in which like reference numerals indicate like parts, and initially to Figure 1, an axonometric view of an offshore drillship in accordance with a preferred embodiment of the present invention will be seen. This dynamically positioned drillship discloses the best way to carry out the invention currently envisioned by the patent applicants. More specifically, the present multi-activity drillship 30 of the invention comprises an oil tanker type hull 32, which is constructed with a large central shaft 34 between the bow 36 and the stern 38. A multi-activity drilling tower 40 is mounted on the drillship substructure above a central well 34 and operable from

ES 2 300 409 T3 perform the primary pipe operations and, simultaneously, the auxiliary operations to the primary pipe operations from a single drilling rig through the central well. In this application, the term tubular is used as a generic term for conduits used in the drilling industry and includes relatively large riser conduits, casing pipes, and drill strings of various diameters.

Drillship 30 may be held in position by tie-downs or by turret tie-downs, as described, for example, in the aforementioned US Patent Nos. 3,191,201 and 3,279,404 to Richardson. In a preferred embodiment the drillship 30 is precisely held in position by dynamic positioning. Dynamic positioning is performed using a plurality of bow thrusters 42 and stern thrusters 44 that are precisely controlled by computers that use input data to control the multiple degrees of freedom of the vessel afloat in changing environmental conditions, such as the wind, the current, waves, stretched sea, etc. Dynamic positioning is relatively sophisticated and by using satellite references it is able to very precisely hold a drillship at a desired latitude and longitude, in position, over the wellhead.

Multi-activity drillship

Referring now to Figures 1 to 4, a plurality of views will be seen here revealing, in some detail, a multi-activity drillship according to a preferred embodiment of the invention. In these, Figure 2 depicts a starboard elevation of the multi-activity drillship including an aft heliport 46, over a vessel space 50 and a main engine room 52. The riser storage racks 54 are located above an auxiliary machine room 56. The first 58 and second 60 tube racks are located in front of the riser storage area 54 and above a storage room. auxiliary machines 62, baghouse 64 and mud rooms 66. A shaker house 68 extends above mud room 66 and is contiguous with a stern portion of multi-activity drilling tower 40. A first 70 and a second 72 68 metric ton cranes, with 45.7 m jibs are mounted aft of the multi-activity derrick 40 and are used, for example, in connection with the handling requirements of the riser and the operating pipes of the drillship.

A well 74 machinery room and test area is built adjacent to a forward edge of the multi-activity derrick 40 and an additional riser storage area 76 and crew quarters 78 are located forward of the drilling area. well tests as shown in figure 2. Another 68 metric ton crane 82, with a 45.7 m boom, is located forward of the multi-activity Derrick 40 and services a portion of the drillship forward.

Referring to Figures 3 and 4, here will be seen plan views of a tube deck and machinery deck of a preferred embodiment of the drillship 30. Looking first at Figure 3, a plan view of the ship is shown. drilling 30, a helipad aft 46 over a vessel space 50 and aft of a riser storage area 54. A second riser storage area 55 is adjacent to storage 54 and on similar ribs, tube racks 63 and 65 are adjacent to tube racks 62 and 64, respectively, previously noted. The agitator house 68 is located forward of the tube racks and adjacent to the multi-activity derrick 40, and a mud recorder 67 is shown above the mud room 66. A walkway 69 extends between the riser and pipe rack to facilitate transportation of riser, casing, and drill pipe lengths from the warehouse areas to the multipurpose drilling tower 40.

A test area for well 74 and 75 is shown adjacent to drilling tower 40 and aft, approximately an additional 3,000 m, of pipe storage racks 76 and 77. A forward helipad 80 is shown located above the crew quarters 78, as noted above, and the bow tube area is serviced by a 68 metric ton crane 72 as specified above.

A plan view of the machinery deck is shown in Figure 4, and includes an engine room 56 having fuel tanks on the starboard side and a compressed air and water generation system 84 on the port side. . Auxiliary machinery 62 such as a machine shop, welding shop and air conditioning shop are located adjacent to the gear change mechanism, control modules and SCR room 86. In front of the SCR room, on the machinery deck, there is the air conditioning warehouse 88 and storage rooms 64 as previously mentioned. The mud pump rooms 66 include a plurality of essentially identical drilling mud and cement pumps 90 and mixing and storage tanks 92.

Derrick seats 94, 96, 98 and 100 are shown on the hold deck and are located symmetrically around the area of ​​a central shaft 34. A parallel raceway 101 extends over the central shaft and is arranged between an area aft of subsea drill train systems and an area aft of the room below sea level. A riser compressor room 102 is shown in a position adjacent to the bow machinery zone 74 which includes a control zone for the anti-burst shutters 104.

The drillship's hull can be 260 m in length and similar in design to that of the North Sea shuttle tankers. The various component packages arranged in modules are easily contained within

ES 2 300 409 T3 of a vessel of this capacity and dynamically positioned drillship provides a large stable platform for deep water drilling operations. The above multi-activity drillship and operational components are described in an illustrative arrangement and it is envisaged that other equipment may be used and placed elsewhere, and other vessel or platform design. However, the foregoing is typical of the primary operating facilities that are intended to be included in the scope of the multi-activity drillship invention.

Multi-activity drilling tower

Referring now to Figures 5 through 7, a multi-activity drilling rig 40 is shown in accordance with a preferred embodiment of the invention. Derrick 40 includes a base 110 that is symmetrically attached to drillship substructure 112 above central shaft 34. Base 110 is preferably square and extends up to a level of rig floor 114. Above the level of the drill floor there is a platform for extraction tasks 116 and a roof 118 for the platform for extraction tasks. Derrick legs 120, 122, 124, and 126 are formed of graduated, projecting upward tubular conduits and slope inward from the rig floor 114. The derrick ends in a structure, or deck, 128 at the top, generically, rectangular. The legs are spatially fixed by means of a network of struts 130 to form a rigid drilling tower that allows the handling of tubes in continuous service and multi-activity functions according to the object of the invention.

As can be seen particularly in figure 5, the upper part 128 of the drilling tower serves to support a first 132 and a second 134 mini drilling tower, which serve as guides to a pulley and a hydraulic system for compensating the movement.

As shown in Figures 5 to 7, the multi-activity derrick 40 preferably includes a first 140 and a second 142 extraction workshop of a conventional design. A cable 144 extends upward from stripping shops 140 over sheaves 146 and 148 and offset sheaves 150 at the top of derrick 40. The stripping shop wiring extends down into the derrick to the first 152 and second 154 displacement blocks, see again Figure 5. Each of the stripping shops 140 and 142 is independently controlled by different driller consoles 156 and 158, respectively.

The drilling rig floor 114 includes first 160 and second 162 tube advance stations, which in one embodiment comprise essentially identical first rotary table and second rotary table. The rotary tables are symmetrically positioned at a relative spacing within the derrick 40, and in one embodiment, along the centreline of the drillship 30.

Other envisaged embodiments include rotary tables positioned from side to side of the ship and even following an inclined line. The extraction workshops 140 are adjacent to the first tubular 160 and the extraction workshops 142 are located adjacent to the second station 162 for advancing the tubular and have the mission of carrying out drilling operations and / or auxiliary operations to drilling operations. through the central shaft 34 of the drillship. Each tube advance station includes, in one embodiment, a rotary machine, rotary driver, main bushings, bushings, and pull rod drive slides. In addition, each tube advance station 160 and 162 operatively includes an iron drilling key, pliers for carrying tubes, and a rotating chain, pull rod, and rotating head for assembling and disassembling tubes in a conventional manner.

A first tube handling apparatus 164 and a second tube handling apparatus 166 are positioned, in one embodiment, on a rail 168 extending from a position adjacent the first tube advancement means 160 to the second tube advancement means 162. advance of tubes. A first tubular stacked string wrap 170 abuts the first tube handling apparatus 164 and a second tubular stacked string wrap 172 abuts the second tubular handling apparatus 166. A third tubular stacked string wrapper 174 may be located between the first stacked tubular string wrapper 170 and the second tubular stacked string wrapper 172 and is operative to receive tubulars either from said first tubular handling apparatus 164 or from the aforementioned second tubular handling apparatus 166 as they move on rail 168. Located adjacent to the first tube advance station 160 is a first iron piercing key 180 and a second iron piercing key 181 is adjacent to the second tube advance station 162. The iron piercing key is located adjacent to the first tube advance station 160. used operatively in collaboration with rotary stations 160 and 162, respectively, to replace and disassemble tubes.

It will be seen by looking in particular at FIG. 7, that rail 168 allows first tubular handling assembly 164 to withdraw and receive conduit from any of the tubular stacked string wraps 170, 172, and 174. Primary use for the assembly tube handling 164, however, will be relative to stacked string wraps 170 and 174. Similarly, rail 168 allows second tubular handling assembly 166 to transfer conduits such as riser, casing, or drill pipes between second rotary station 162 and tubular stacked string wraps 172, 174, and 170 However, tube handling assembly 166 will be used more frequently with conduit stacked string wraps 172 and 174. Although a particular rail-supported tube handling system is shown in Figure 7, it is

ES 2 300 409 T3 contemplate other tubular handling arrangements within the scope of the appended claims. However, an element common to all systems will be the ability to compose and disassemble tubes in both the first and second tubular stations for advancing the tubes through the central well. In addition, a feature of tube handling systems will be the ability to transfer tube segments back between the first tube advance station through the center well and the second tube advance station and the stacked string wraps, as shown. discussed above.

In a currently preferred embodiment, the rotary function is applied to tubes made by first 182 and second 183 drivers, again look at FIG. 5. Each upper driver is similar, and unit 182 is shown more specifically in FIG. 8. The upper driver is attached to a shift block 152 and is balanced by hydraulic balance cylinders 184. A guide nose 185 supports a power train 186 that drives a tube handling assembly 188 on the rig floor 114.

Although both a tube advance rotary table system and a top drive device have been described and discussed above, the top drive system is currently preferred. In certain circumstances, both systems can even be installed on a drillship. Furthermore, other systems may eventually be envisioned, however an operational feature of all tube systems will be the ability to independently handle, compose or disassemble, withdraw and advance tubes through multiple stations over a central well and into from the sea bed.

It will be seen by consulting and comparing Figures 5, 6, and 8 that the multi-activity drilling tower 40 comprises two identical top drives and / or separate rotary tables, stripping workshops, motion compensators, and displacement block located within a single multipurpose drilling rig. Consequently, the multi-activity drilling tower allows a primary drilling activity and an auxiliary activity to be carried out simultaneously and, in this way, the critical stages of a drilling operation to be carried out through the central well 34 can be optimized. Alternatively, units are envisioned that will not be identical in size or even function, but will certainly be capable of handling tubes and transferring tubes between tube advance stations within a single drilling rig. Furthermore, in a preferred embodiment, the multi-activity support structure is in the form of a four-sided drilling tower. The object of the invention, however, is intended to include other superstructure arrangements, such as tripod assemblies or even two contiguous but interconnected vertical racks and superstructures that are operative to perform a support function for more than one pipe drilling or activity. to perform simultaneous operations through the deck of a drillship, semi-submersible platform with tension legs or similar.

Operating procedure

Referring now specifically to Figures 9 to 22, a sequence of operation of the present multi-activity drilling rig and drillship will be seen wherein a first means, or main means for advancing tubulars is operative to perform the primary drilling activity. and a second means, or auxiliary means of advance of tubular is used for the functions critical to the drilling process, but it can be advantageously removed from the critical drilling path to dramatically shorten the total drilling time.

Turning specifically to FIG. 9, there is shown a schematic drawing of a multi-activity drilling rig 40 positioned on a drilling rig 190 of a drillship, tension-leg semi-submersible rig, or the like, of the type described above.

A central well opening in drilling rig 192 allows tubulars, such as risers, casing, or drill pipes to be compounded within derrick 40 and extend through a body of water 194 to perform drilling. Drilling activity and / or activity associated with drilling in and on the seabed 196.

The main drilling station 160 is used to collect and compose a 76.2 cm high pressure waterjet drill assembly for waterjet drilling into the seabed and 66 cm drill assemblies and place them within the Derrick stacked string wraps for auxiliary station 162 to run within 30-inch casing. The main rig then composes the 18 "wellhead and returns it to the derrick to lay 20" casing tubes.

At the same time, the auxiliary station 162 is used to collect the 30-inch casing and receives the high pressure water jet drilling assembly from the main rig and moves the entire assembly to the seabed, where a high pressure water jet drilling operation begins in the 76.2 cm casing.

Referring to Figure 10, the main rig slides an anti-burst plug pile 200 under the rig floor and performs a test run of the pile and its control system. At the same time, the auxiliary rig and rotary station 162 are used to drill with water and lay the 30-inch casing. The auxiliary rig then disconnects the wellhead manipulation tool and continues drilling the 66 cm section of the borehole.

ES 2 300 409 T3

In FIG. 11, the main drill rig is used to initiate the travel of the anti-burst plug stack 200 and drill the riser to the seabed. Simultaneously, the auxiliary rig, including the second rotary station 162, is used to finish drilling the 26-inch hole section and then pulls the 26-inch drill assembly to the surface. The auxiliary station then mounts and moves the 20 '' casing 202 and after placing the 20 '' casing in the wellhead, the auxiliary rig hooks the cement line and cements the 20 '' casing pipe in position. The auxiliary drill rig then removes the 50.8 cm casing string.

In Figure 12, the main rig and rotary station 160 deposits the anti-burst plug 200 on the wellhead and verifies the wellhead attachment. At the same time, the auxiliary rotary station 162 is used to lay out the 76.2 cm high pressure water jet assembly and the 66 cm piercing assembly. Once this operation is complete, the auxiliary rotary station 162 is used to compose a 17-inch downhole assembly, and places the assembly in the derrick for the primary or main rotary assembly to pick up. .

In Figure 13, the main rotary assembly picks up the 44.45 cm bottomhole assembly 204, which was previously made up of the auxiliary rig, and places it and the drill pipe in the hole to begin drilling. section 44.45 cm. At the same time, the auxiliary rotary station takes individual 34 cm casing sections from the drillship's tube racks, composes them into 38 m lengths, and then places the lengths back into the casings of the rig. drilling tower in preparation for the 34 cm casing.

In Figure 14 the main rotary station 160 completes the drilling of the 44.45 cm well section. The drilling assembly is then brought back to the surface through the central well and the main rotary station then proceeds to assemble and place the 34 cm casing segments that were previously replaced and placed inside the drilling tower. . After depositing the casing on the wellhead, the rig cements the casing in place. At the same time, the auxiliary rotary station 162 collects 9-inch casing joints from the drill ship's tube racks, replenishes them into triple racks, and then returns them into the tubular handling casings. the drilling tower to prepare the run of a 24.46 cm casing.

In Figure 15, the main rotary station tests the anti-burst plug stack after adjusting the 34 cm seal assembly and the auxiliary rotary station changes the 44.45 cm bottom well assembly to a 31 cm assembly. The 31 cm assembly is then removed in the rig's chute handling casings to a position where it can be picked up by the main rotary station.

In Figure 16, the main rotary station 160 is used to drive the 31 cm bottomhole assembly into the well. and start drilling the 31 cm drill section. At the same time, the auxiliary rotary station is used to complete the 24.46 cm casing handling tool and cementing head, and then retracting both complete assemblies into the conduit handling shell of the tube. drilling tower to prepare the 24.46 cm casing run.

In Figure 17, the main rotary station 160 is used to finish drilling the 31 cm hole section and remove the 31 cm assembly to the surface. The main rotary station then mounts and places the 24.46 cm casing into the wellbore and cements the casing in place. At the same time, the auxiliary rotary station changes the bottomhole assembly from 31 cm to 21.6 cm and places the 21.6 cm assemblies back into the derrick to be picked up by the main rotary station.

In Figure 18, the main rotary station is shown moving 21.6 cm drill sets down the hole and begins drilling the 21.6 cm well with the first upper rotary driver. During this operation, the auxiliary rotary station is used to complete the casing cutter.

In Figure 19, the main rotary station 160 completes the drilling of the 21.6 cm shaft section and removes the drill assembly to the surface. The main rotary station then proceeds to probe down the risers and begins to retrieve the stack from the anti-burst plug 200.

As shown in Figure 20, once the anti-burst plug 200 is cleared from the wellhead, the auxiliary rotary station enters the well with a casing cutter 210 and cuts the casing.

In FIG. 21, the main rotary station is used to further retrieve the stack from the anti-burst plug 200 and the auxiliary rotary station is used to retrieve the wellhead 212.

In Fig. 22, the main rotary station is preparing to move the drillship and the auxiliary rotary station assists in this operation.

ES 2 300 409 T3

Comparative analysis

Referring now specifically to Fig. 23a, a timing chart will be seen for a typical subsea well drilling operation in accordance with a conventional drilling operation. The filled horizontal bars represent time segments along an abscissa, and tube activity is displayed along an ordinate. As an initial operation, eight hours are used to take pipes and twenty-seven hours are required to drill the 30-inch casing with a high pressure water jet in position. It then takes three hours to complete and place downhole assemblies and handling tools. Then forty four and a half hours, look at bar 226, it takes to drill and cement the 20 '' casing. Sixty-nine hours 228 are required to operate and test an anti-burst shutter. It takes three hours to compose and position the downhole assemblies and handling tools. The sequence continues with thirty-nine hours, watch bar 234, and twenty-one hours, watch bar 236, required to place and cement a 34 cm casing. Four and three-quarters hours are required to compose and position the downhole assemblies and handling tools, look at bar 238, and ten and a half hours are used to check the blowout plug, look at bar 240. Then eighty and one and a half hours, look at bar 242, is used to pierce the 31 cm borehole, and twenty-two hours is used to place and cement a 24.46 cm casing, look at bar 244. Two and three-quarters hours are then required to compose and position the downhole assemblies and handling tools, look at bar 246, and fourteen hours, look at bar 248, are used to drill the 21.6 hole. cm. Next, thirty-one and a half hours are spent retrieving the burst plug, note bar 250, seventeen hours are spent raising and retrieving the wellhead, as represented by time bar 252, and finally position the drill pipe in eight hours, see time bar 254.

Compared to a conventional drilling sequence, an identical drilling operation is described by a timing diagram in figure 23b according to the object of the invention, where a main and auxiliary tube stations are used simultaneously in a preferred embodiment of the present invention, to drastically reduce the total drilling time and thus increase the efficiency of the drilling operation. More specifically, it will be seen that the main drilling operation can be carried out through a first tube advance station and the critical path of the drilling sequence is represented by the solid time bars while the auxiliary activity through a second Tube advance station is shown by hatched time bars.

Initially the main rotary station takes eight and a half hours to mount a downhole assembly and collect tubes, observe time bar 260. The anti-burst plug is then slid into position and tested, which takes twelve hours, as shown by the time bar 262. Forty-two hours are then required to lower the blowout plug to the seabed, as shown by time bar 264 and fifteen hours, as shown by time bar 266, are used to position and test the blowout plug. The 17 "hole is then drilled by the primary rotary station and rotary table 160 as described by time bar 268. Subsequently, the 34 cm casing is made and cemented in place using fourteen hours as shown by time bar 270.

The following operation requires ten and a half hours to test the anti-burst plug, as shown by time bar 272. Eighty-one and a half hours uses the main rotary station and rotary table 160 to drill the 31 cm well as shown by the time bar 274. Time bar 276 represents sixteen hours to place and cement the 24.46 cm casing. A 21.6 cm well drilled, then consumes fourteen hours, as represented by time bar 278, and finally, the main rig uses thirty-one and a half hours, which is represented by time bar 280, to retrieve the anti-burst shutter.

During this same sequence of times the secondary, or auxiliary, tube advance station, 162 is used to jet-drill the 30-inch casing in twenty-one and a half hours, as represented by the time bar. Striped 282. Next, the 20-inch casing is drilled and run over a period of forty-four and a half hours as time bar 284 shows. The auxiliary drill is then used for five hours to compose and position the downhole assemblies and handling tools for five hours, as shown by time bar 286. Eight and a half hours is used to remove 34 cm doubles , as shown by time bar 288. Time bar 290 illustrates the use of four and a quarter hours to compose and position downhole assemblies and handling tools, and ten hours is required, as time bar 292 shows, to remove 24.46 cm doubles. Four hours is then required, as time bar 300 shows, to compose and place downhole assemblies and handling tools, and then nine and a half hours are used to compose and run a casing cutter, such as represents time bar 302. The wellhead is then recovered in six and a half hours as shown in time bar 304 and finally eight hours as shown in time band 206 are used to lay the drill harrow.

When comparing the identical sequence of events between a conventional drilling operation and the present method and the multi-activity drilling apparatus, it will be seen that the critical path has been reduced essentially. In this particular example of exploratory drilling activity, the time savings comprise a twenty-nine percent reduction in time spent on a drilling operation. In other cases, and depending on the depth of the water, this sequence of times may be longer or shorter, but it will be appreciated by those skilled in the art that I

The water depth increases, which enhance the advantages of a disclosed multi-activity drilling apparatus and method.

The example above is illustrated in relation to an exploration drilling program. Development drilling activity may be necessary, which would entail twenty or more wells. In this case, the drillship can advantageously perform multi-well development drilling activity, or work on the activity, simultaneously in multiple wells, and again drastically reduce the time the drillship needs to stay in the field. place.

Summary of the main advantages

Upon reading and understanding the foregoing description of the preferred embodiments of the invention in conjunction with the illustrative drawings, it will be seen that several distinct advantages are obtained from the present process and multi-activity drilling apparatus.

Without attempting to state all the desirable features and advantages of the present method and apparatus, at least some of the great advantages of the drill ship, process and multi-activity drilling apparatus are described by comparing Figures 23a and 23b which visually illustrate the improvements. drastic in efficiency. As noted above, even higher efficiencies over time will be achieved in development drilling or well work overhauls.

Improved drilling time, and hence cost savings, is provided by the multi-activity derrick having essentially identical tube advance stations, where the primary drilling activity can be performed within the derrick and the drilling rig. Concomitant ancillary activity can be through the same drilling tower and through the same central well.

The derrick includes dual rotary stations, and in a preferred embodiment, top drives and a dual tube handling system. A plurality of tubular stacked string casings are adjacent to the dual rotary station, and the first and second conduit handling assemblies operatively transfer riser segments, casing, and drill tubular assemblies between the first and second stations. tube advancement and any of the stacked string wraps. The dual derrick extraction workshops are independently controlled by essentially identical drilling consoles mounted on the drilling rig floor, such that independent operations can be carried out simultaneously by a main rotary drilling station through a central well while auxiliary operations can be carried out simultaneously through a second rotary station and the central well.

The multi-station derrick allows a driller to move many rotary operations out of the critical path, such as the anti-burst plug and operating the riser while drilling an upper hole; replenishing upper well assemblies or operating tools with an auxiliary rotary station while drilling with a primary rotary station; repositioning and reversing the casing with the auxiliary rotation station while drilling with the primary rotation assembly; the execution of tests; taking measurements while continuing to drill while continuing with primary drilling activity; and the deployment of a second high pressure stack / riser outside of the primary sounding time. Furthermore, an operator is allowed to probe branches with the auxiliary rotary station while performing normal operations with a first rotary station; the execution of an offshore branch at the bottom with the auxiliary rotary station while completing the riser operations and simultaneously perform two offshore branches, bases, etc.

In the foregoing description, reference has been made to preferred embodiments and illustrative advantages. In particular, a large drillship 30 with the dimensions of a tanker has been specifically illustrated and studied, which is the currently envisioned preferred embodiment. However, those skilled in the art will appreciate that the single target derrick with multirotation structure can be advantageously utilized by other offshore oil rig systems such as jack-up rigs, semi-submersibles, tension leg rigs, fixed towers and the like. within the scope of the appended claims. Those skilled in the art and those familiar with the present invention may also recognize other additions, deletions, modifications, substitutions, and / or other changes that may fall within the scope of the claims.