GB2053318A

GB2053318A - Installing well conductors

Info

Publication number: GB2053318A
Application number: GB7924778A
Authority: GB
Original assignee: TECHN ADV BUREAU PRAKSIS BV; VOS BOORMAATSCHAPPIJ FOXDRILL
Current assignee: TECHN ADV BUREAU PRAKSIS BV; VOS BOORMAATSCHAPPIJ FOXDRILL
Priority date: 1979-06-28
Filing date: 1979-07-17
Publication date: 1981-02-04
Also published as: GB2053318B; DE2926141A1; FR2461803A1

Abstract

A device for introducing a conductor into the ground when drilling an oil- or gas well, more particularly for off-shore use, comprises a derrick 21 adapted for holding and lowering of conductors and drilling strings, and a rotary table 7 for introducing drilling strings, there being means 12, 16 for temporarily holding the lowered conductor(s), while the rotary table 7 is mounted in a frame 6 for displacement between an active position in alignment with the axis of the well to be drilled and a lateral, inactive position. Means 19 are mounted in said frame for movement from an inactive position beyond the path of the conductor(s) towards an active position and adapted for holding drilling strings at a level below the rotary table 7 and when the latter is taking its inactive position. <IMAGE>

Description

SPECIFICATION A device for introducing a conductor into the bottom The invention relates to a device for introducing a conductor into the bottom when drilling an oilor gas-well, more particularly for off-shore use, comprising a derrick adapted for holding and lowering of conductors and drilling strings, and provided with a rotary table for introducing drilling strings, there being means for temporarily holding the lowered conductor(s), while the rotary table is mounted in a frame for displacement between an active position in alignment with the axis of the well to be drilled and a lateral, inactive position.

Devices of this type are known in which the displacement of the rotary table to the lateral, inactive position, serves for passing in the completed well large pieces, for example blow-out preventers.

The invention aims at improving a device of this type such that it is particularly suitable for carrying out a method whereby for introducing the conductor (pre)drilling and hammering have to be alternately carried out.

This problem is solved by the invention in that in the rotary table frame means are provided which are movable between an inactive position beyond the path of the conductor and an active position, these means being adapted to be situated in the active position just below the plane of the rotary table and, when this table is in its inactive position, are suitable for retaining a drilling string.

Thereby the device according to the invention permits catching, after predrilling has been carried out with the intermediary of the rotary table situated in its active position, the relative drilling string, which is suspended in the conductor, through the laterally movable means below the rotary table, such that the drilling string may be released from the rotary table and the rotary table may be moved to its inactive position, in which position sufficient space has been cleared for passing the hammering block. The drilling string may then be connected to the lower end of an intermediary piece which is to be provided on the conductor, which has to be introduced further into the bottom by hammering, whereafter the conductor with the drilling string suspended therewithin may be further introduced into the bottom by hammering.

In a preferred embodiment the derrick is constituted by a column which is eccentrically positioned relative to the axis of the active rotary table position, said column carrying at least one hoisting arm and being provided with vertical guide means for a hammering device, said guide means and said hammering device being pivotable between an inactive position and an active position, while in the active position the axis of the hammering device coincides with the axis of the active rotary table position.

The invention is further explained herebelow with reference to the drawing of an embodiment.

Figure 1 shows a perspective view of the device according to the invention, and Figures 2A and 2H show the device according to the invention in a plurality of successive positions when introducing a conductor series into the bottom under water.

The device as shown in the drawing comprises a portal shaped carrier 1 movably provided in the direction of the arrow I on a bridge 2 which extends in transverse direction of a well-series to be drilled. The bridge 2 comprises two drilling mud tanks and has two rails 4 on which the carrier 1 is traversably supported. The bridge 2 in its turn is supported by two rails 5 extending in the longitudinal direction of the well series to be drilled (the so-called "skid beams") which form part of the fixed structure of a drilling platform or production platform respectively and along which the bridge 2 with the carrier 1 is traversable in the longitudinal direction of the well series to be drilled, in the direction of arrow 11.

A supporting frame 6 (see Fig. 1) is supported by the carrier 1, on which frame on the one hand the rotary table 7 is supported and from which on the other hand is detachably suspended a cagelike structure 8 which extends downwardly between both side parts 1 a and 1 b of the carrier 1 and up to a level situated below that of the bridge 2. The cage 8 comprises a floor 9 having a central aperture 10 through which may pass drilling strings and conductors as well as, if necessary, a transition or adapter piece to be used when hammering the conductors.

A fixed pipe tong 12 is suspended from the floor 9 through two releasable tie rods 11. Said pipe tong is of a pneumatically or hydraulically contractable and expandable type, which is known per se and therefore only schematically shown in the drawing.

Spaced above and parallel to the floor 9 is a supporting platform 1 3 which is up and down movably guided along guide rods 14 in the cage 8 and provided with a central aperture 9a, aligned with the aperture 10, for passing conductors, drilling strings and adapter pieces if any. A second pipe tong 16 is suspended from the platform 13 through tie rods 1 5, which pipe tong may be of the same type as the pipe tong 12 and is provided between the floor 9 and the pipe tong 12. The tie rods 14 are releasably connected to the supporting platform 13 and extend downwardly through apertures in the floor 9.

For moving the supporting platform 13 with the movable pipe tong 16 upwardly and downwardly two hydraulic piston-cylinder assemblies 1 7 serve in the contemplated embodiment, the cylinders of which are fixedly mounted on the floor 9 while the piston rods are connected to the supporting platform 13.

In order to permit movement of the device in the direction of the arrow II along the rails 5 it may be necessary to release the pipe tongs 12 and 1 6 with the tie rods 11 and 1 5 respectively from the cage 8.

The rotary table 7 which may be otherwise of a type known per se, is movable in the direction of the arrow Ill between the active position shown in Fig. 1 and a laterally situated inactive position.

For this purpose two piston-cylinder assemblies 18 are used in the contemplated embodiment. In the inactive position the rotary table 7 clears a wide passing aperture provided in the supporting frame 6 (which is not shown in detail in the drawing), through which aperture conductors, drilling strings, adapter pieces and even a hammering block may well pass. Further the rotary table 7 is drivable in known manner by a power source which is not further shown.

A member 19 is also mounted in the supporting frame 6 which is movable through two pistoncylinder assemblies 20 according to arrow IV from an inactive position as shown in the drawing to an active position. This member 1 9 serves for temporary receiving and retaining drilling strings, particularly during the period in which the rotary table is in the inactive position.

The derrick of the device according to the invention, serving for the necessary hoisting, is constituted by a column 21 positioned on the carrier 1 eccentrically with respect to the well to be drilled. This column comprises a supporting part 22, fixedly mounted on the carrier 1 and on which the column 23 proper is rotatably journalled. The rotatable column 23 carries a load arm 24 at its upper end, from which a hoist 25 adapted for raising and lowering conductors is suspended, movable in radial direction. The rotatable column 23 further comprises a vertical guideway 26 along which a hammering machine is mounted upwardly and downwardly movable, while adjacent to the upper end of the column a hoisting position 28 is provided which is aligned with respect to the axis of the rotary table (in any case in the active position thereof).This hoisting position, constituted by a hoist, is adapted for lowering and raising drilling strings and cooperates with a winch 29 provided at the basis of the rotatable column 21.

Now below the introduction into the bottom of a conductor series by means of the above described device is further discussed in detail.

Figure 2A shows the device according to the invention in a position in which the load arm 24 is in a position in which the first conductor 30 has been taken from a storing space for conductors.

The rotary table 7 is in the laterally retracted inactive position while the hammering machine 27 and the hoisting position 28 are likewise in the inactive position. In the position according to Fig. 2B the load arm 24 with the hoist 25 and the conductor 30 suspended therefrom have been moved to a position over the axis of the well to be drilled. In this position the conductor 30 is lowered until it may be grasped at its lower end by the pipe tongs 12 and 1 6. The conductor 30 is further released from the load arm 24 in order to be further lowered by the pipe tongs 12 and 1 6.

The movable pipe tong 1 6 is manoeuvred such that the upper end of the conductor 30 just extends above the pipe tong 16 when the supporting platform 13 with the pipe tong 1 6 are in their lower positions. The pipe tong is then energized while the pipe tong 1 6 is actuated to its inactive condition in the upper position, ready for clamping the lower end of a next conductor 30a which in the meantime has been raised in that the cleared load arm has been pivoted to the position according to Fig. 1 A and thereafter has been pivoted back in alignment over the well axis. This phase is illustrated by Fig. 2C and Fig. 2D. In the position according to Fig. 2D both conductors 30 and 30a may be mutually welded at x.Thereafter by alternately energizing the pipe tongs 12 and 1 6 and moving the pipe tong 1 6 upwardly and downwardly the conductor set 30, 30a may be lowered stepwise (see Fig. 2E) i.e. until the upper end of the conductor set just extends above the lower fixed pipe tong and therefore is in a position in which it may be welded to the lower end of a next conductor. The supply and lowering of further conductors is continued until the lower conductor of the series not further penetrates under the influence of the own weight into the solid bottom under water.Then the moment has arrived in which the rotatable column 23 with the hoist position 28 is rotated to the active position in order to pick up a drilling string series from a stock, e.g. provided around the column, to connect the series and to lower it within the conductor series which has already been introduced.

Therefore the rotary table 7 is moved to its active position in order to serve thereafter first as pipe tong and thereby to stepwise lower the "growing" drilling string series. After, if necessary, hammering has taken place with the drilling string series suspended in the conductor series, for which purpose the rotary table 7 has been temporary laterally moved out of the way, drilling takes place with the intermediary of the rotary table 7 and the conventional kelly 31 belonging thereto (see Fig. 2F). By driving the rotary table then a hole is predrilled to a depth beyond the lower point of the conductor series, in which hole the conductor series may be further lowered and may be further driven into the bottom by hammering (see the phase according to Fig. 2G).

Before the phase according to Fig. 2G can take place of course first the kelly 31 must be released and the rotary table has to be repositioned in its inactive position. By the member 1 9 moved to its active position the drilling string series is then temporary retained, i.e. until the moment in which the upper drilling string has been coupled to the lower end of the conventional transition or adapter piece 32 to be placed on the upper end of the upper conductor. Thereafter the device is ready for carrying out the hammering phase according to Fig. 2G.

After in this way a predetermined resistance against further penetration into the bottom has been obtained the device is again moved to a position in which by connecting further drilling strings, the drilling is continued whereafter again a hammering phase follows and so on. Fig. 2F shows that during the hammering the load arm 24 may be actuated for picking up a next conductor 30c. The introduction of this conductor may take place after the hammering machine has been moved to its inactive position (see Fig. 2H).

Claims

CLAIMS 1. A device for introducing a conductor into the bottom when drilling an oil- or gas-well, more particularly for off-shore use, comprising a derrick adapted for holding and lowering of conductors and drilling strings, and provided with a rotary table for introducing drilling strings, there being means for temporarily holding the lowered conductor(s), while the rotary table is mounted in a frame for displacement between an active position in alignment with the axis of the well to be drilled and a lateral, inactive position, characterized by means mounted in said frame for movement from an inactive position beyond the path of the conductor(s) towards an active position and adapted for holding drilling strings at a level below the rotary table and when the latter is taking its inactive position. 2. A device according to claim 1, in which the derrick is formed by a column eccentrically positioned relative to the active rotary table position, said column carrying at least one hoisting arm and being provided with vertical guide means for a hammering device, said guide means and said hammering device being rotatably adjustable between an active position in alignment with said active rotary table position and an inactive position. New claims or amendments to claims filed on 24 December 1979. Superseded claims 1,2. New or amended claims

1. A device for introducing a pipe into a bottom to be drilled when drilling an oil- or gaswell, particularly an off-shore well, comprising a derrick for holding and lowering lengths of pipe and drilling strings, a rotary table for driving a drilling string, means for temporarily holding a lowered pipe, the rotary table being mounted in a frame for displacement between an active position in alignment with the axis of the well to be drilled and a lateral inactive position, and laterally movable means mounted in the frame for movement from an inactive position beyond the path of the pipe towards an active position for holding a drilling string at a level below the rotary table when the rotary table is in its inactive position.

2. A device according to claim 1, in which the derrick is formed by a column eccentrically positioned relative to the active position of the rotary table, the column carrying at least one hoisting arm and having vertical guide means for a hammering device, the guide means and the hammering device being movable, by rotation of the column, between an active position in alignment with said active position of the rotary table and an inactive position.

3. A device for introducing a pipe into a bottom to be drilled when drilling an oil- or gas-well, particularly an off-shore well, substantially as hereinbefore described and illustrated with reference to the accompanying drawings.