DEVICE FOR MOVING AN ELONGATED OBJECT, IN PARTICULAR A RISER PART OR A DRILL PIPE CASSETTE The present invention relates to a device for moving an elongated object, in particular a riser part or a drill pipe cassette, between a storage space and a drilling tower or drilling mast of a drilling vessel or drilling platform, said device comprising: a main frame which is mounted so that it is movable at right angles to the longitudinal direction thereof on the deck of said drilling vessel or said drilling platform, a top carriage which is fixed on the main frame and is movable in the longitudinal direction thereof, and a guide frame which is fixed on the top carriage and can pivot about a horizontal axis relative to the top carriage.

Such a device is known from British Patent Application GB 2264736.

A borehole can be made in the earth's surface by means of a drilling platform or a drilling vessel, using a drilling string. The first part of a borehole can be drilled from a drilling platform or drilling vessel using a"bare"drilling string. Said drilling string is constructed of drilling string elements which lie stored on the drilling platform or drilling vessel. However, after some time a pipe encasing the drilling string must be mounted between the earth's surface and the drilling vessel or the drilling platform. This encasement is also known as the riser. By means of said riser, drilling fluid can be taken from the borehole on the outside of the drilling string and on the inside of the riser up to the drilling platform or the drilling vessel. The riser is constructed from riser parts extending from the drilling vessel or the drilling platform.

Said parts are stored on the drilling platform or on the drilling vessel, and are supplied to a mast or tower placed on the vessel or the platform and constructed at the bottom of said mast or tower and supplied in the direction of the earth's surface.

During the construction of a drilling string the drilling string elements are supplied to the drilling tower or drilling mast. From the drilling string elements drilling string parts consisting of three elements are constructed first of all, and said drilling string parts are added to the already constructed drilling string at the tower. That means that during the construction of the drilling string individual drilling string elements are supplied to the mast or tower, are combined on the spot, and only then are supplied to the drilling string. The same applies in the reverse order for dismantling the drilling string.

The ahovemcntioned British Patent Application GB 2264736 discloses a

device of the type mentioned in the preamble for supplying pipes to a drilling tower, said pipes being supplied substantially vertically to the drilling mast from a horizontal storage position. The known device makes use of a telescopic arm which can pick up the pipes in the horizontal position and can manoeuvre them in the direction of the drilling tower. First, with the known device it is not possible to pick up vertically placed pipes and supply them to the drilling tower. Secondly, the presence of a telescopic swivelling arm will mean that relatively great forces are exerted upon the support of said telescopic arm.

It is a first object of the present invention to provide a device by means of which it is possible to supply drilling string elements which are combined to drilling string parts consisting of three drilling string elements in the form of one unit from a storage position to the drilling tower or drilling mast. The time-consuming and expensive assembly of the drilling string parts at the tower or the dismantling of the drilling string elements is thus avoided.

It is very advantageous here if the drilling string parts, consisting of three drilling string elements, can be supplied to or removed from the tower in groups. Such supplying and removal would then have to be effected, for example, by means of cassettes in which various drilling string parts are accommodated. If such a cassette can be supplied in its entirety to the drilling tower, enormous time savings can be achieved.

It is known in the prior art to store riser parts on a drilling platform or vessel. Said riser parts are long (approx. 20 metres) and heavy, and are generally stored in a horizontal position on the deck of the drilling vessel. The horizontal storage of the riser parts has a number of disadvantages. First, the large and heavy riser parts lie on the top deck of the drilling vessel, and are thus lying relatively high up with respect to sea level. That means that the riser parts make the centre of gravity of the entire vessel lie at a relatively high level. Secondly, the horizontally stored riser parts require a relatively large amount of storage space.

In the prior art solutions are also known for placing riser parts in a vertical position on the drilling vessel. In that case the riser parts are generally stored vertically on deck in the vicinity of the drilling tower. It is true that vertical storage of the riser parts in this way produces a space saving, but the problem of a high centre of gravity is not solved by this method.

It is therefore a second object of the present invention to provide a device

for the storage and manoeuvring of riser parts which are stored either vertically or horizontally on a drilling platform or drilling vessel.

The above objects are achieved in the present invention by the fact that the present invention makes provision as follows: that the guide frame is pivotable from a first position substantially parallel to the main frame to a second position substantially at right angles relative to the main frame, and that the device comprises a hoisting carriage, which is provided with means for clamping or gripping one end of a riser part or a drill pipe cassette, the hoisting carriage being fixed so that it is movable on the guide frame.

The advantage of such a device is in the first place that during the construction or dismantling of a drilling string the drilling elements do not have to be manoeuvred individually, but that by means of the device according to the present invention the pre-assembled drilling string parts can be manoeuvred in groups, for example accommodated in drilling string cassettes, on the drilling vessel or the drilling platform. That means that pre-assembled drilling string parts can be supplied to the drilling tower or removed from the drilling tower in a relatively limited number of hoisting actions.

Since riser parts and drilling string elements can be supplied from a vertical storage position to a drilling tower or drilling mast by means of the device according to the present invention, another major advantage of such a device is that it is possible to store riser parts in the feet, which are generally hollow in any case. A great space saving is therefore achieved in this way. Furthermore, the centre of gravity of the drilling vessel is lowered by placing the riser parts in the feet, and the drilling vessel consequently becomes more stable.

With the device according to the present invention the riser parts are hoisted vertically and subsequently tilted and then moved horizontally-and thus safely-over the deck. When the riser parts are being moved from the foot of the drilling vessel to the drilling tower, the riser parts can be hoisted out of the moving device according to the present invention by conventional means at the tower or mast.

The device according to the present invention is further improved by the fact that the guide frame is composed of several parts, in such a way that the guide frame can be made longer by extending it, or can be made shorter by retracting it. The advantage of this measure is that during manoeuvring of a drill pipe cassette said cassette

can be moved out of a horizontal position into a vertical position by means of a telescopic guide frame.

The device according to the present invention is further improved by the fact that the main frame is provided with a hoist guide, said hoist guide being fixed on the main frame so that it is movable in a substantially vertical direction relative to said main frame, which is positioned in a substantially horizontal direction.

By this measure, a cassette in which drilling string parts are accommodated can be manoeuvred, on the one hand, by means of the hoisting carriage movably fixed on the guide frame and, on the other hand, by means of the hoist guide in a horizontal position in the vertical direction.

It is true that US Patent 4,552,498 discloses a hoisting device in the case of which riser parts can be moved in the vertical direction by means of two substantially vertically placed elements. The device from this US patent comprises substantially a main frame which has fitted on either side thereof a vertically movable manoeuvring arm. As already said, it is possible to move horizontally placed riser parts and drill pipes upwards in the vertical direction by means of this known device, but this known device is totally unsuitable for picking up and supplying vertically placed riser parts or drill pipes. By means of the device according to the present invention, it is thus possible to pick up and manoeuvre both vertically placed riser parts and pipes and horizontally placed pipes and cassettes. This combination is not possible with the device which is known from US Patent 4,552,498.

The present invention also relates to a drilling vessel on which the device according to the present invention is mounted.

The present invention will be explained further with reference to the following drawings, in which: Figure 1 is a general view of a drilling vessel, having thereon the device according to the present invention; Figure 2 shows the device according to the present invention at a moment when a riser part or pipe is being removed from the horizontal storage position; Figure 3 shows the device according to the present invention at the moment when the riser part or pipe is being moved from the horizontal orientation into a vertical position; Figure 4 shows the device according to the present invention at the moment

when the riser part or the pipe is being placed from the vertical position in a horizontal position on the main frame; Figure 5 shows the case where the riser part or the pipe has been moved from the main frame by means of tackle means on the drilling mast into a vertical position below the drilling mast; Figure 6 shows the device according to the present invention at the moment when a riser part or a pipe is being removed from a vertical storage position; Figure 7 shows a case where the riser part or the pipe has been placed in the horizontal position on the main frame; Figure 8 shows the case where a horizontally placed drill pipe cassette is being lifted by means of the device according to the present invention; Figure 9 shows the case where a drill pipe cassette is being moved from a horizontal position into a vertical position by means of a telescopic guide frame; Figure 10 shows the case where a drill pipe cassette has been placed in a vertical position in the set-back.

Figure 1 shows a drilling vessel 1 on which the device 2 according to the present invention has been placed. The drilling vessel 1 comprises two floating bodies 3 on which four feet 4 have been placed. Said feet are generally of a hollow design. The feet are connected to each other at the top end by the top deck 5. A drilling tower or drilling mast 6 and also a crane 7 have been placed on the top deck. When the drilling vessel 1 is employed for drilling a borehole, a drilling string is constructed from the drilling tower or drilling mast 6 and moved in the direction of the earth's surface. In order to be able to continue the drilling, there comes a certain point when a riser has to be constructed from the seabed to the drilling vessel 1. The riser 10 forms an encasement for the drilling string, so that an annular space is created between the riser and the drilling string. Drilling fluid, inter alia, can be guided upwards from the borehole in the direction of the drilling vessel through said annular space. Such a riser is constructed of riser parts 10. These riser parts 10 are generally stored on the deck 5 of the drilling vessel 1. The disadvantage of this in the first place is that a large part of the deck is occupied by riser parts 10, and also that the centre of gravity of the entire drilling vessel 1 ultimately lies at a relatively high level, owing to the storage of the relatively heavy riser parts 10.

By means of the drilling vessel I and the device 2 according to the present

invention, it is possible to store the riser parts 10 vertically in one or more of the feet 4 of the drilling vessel 1.

Figure 2 shows the case where riser parts 10 are removed from horizontal storage by means of the device 2. The top end of the riser part 10 is clamped or gripped by means of a hoisting carriage 21. The hoisting carriage 21 is mounted movably on a guide frame 22, which is placed in a vertical position above the horizontally stored riser parts 10. By means of the hoisting carriage 21, the riser part 10 can be moved upwards along the guide frame 22, this being shown in Figure 3.

When the riser part 10 has been moved into the vertical position along the guide frame 22, the riser part 10 can be moved together with the guide frame 22 by means of cylinders 24 into a horizontal position. This is shown in Figure 4. When the riser part 10 has been moved into the horizontal position, the riser part can be moved by means of the main frame 25 over the vessel or platform 1 in the direction of the drilling tower or mast.

When the riser part 10 has been positioned by means of the guide frame 25 in the direction at right angles to the longitudinal direction of the riser part 10 in the correct position for the drilling mast 6, one end of the riser part is moved by means of the guide frame within the reach of lifting means 50 on the drilling mast. Figure 5 shows further that the riser part 10 is moved into the vertical position by these lifting means 50.

From this position the riser part is then added to the piece of riser (not shown) constructed in the meantime.

Figures 6 and 7 then show the case where a vertically stored riser part is being moved in the direction of the drilling mast 6 by means of the device 2 according to the present invention. After the position shown in Figure 7, the riser part is moved vertically upwards, as already shown in Figure 5.

Figures 8,9 and 10 show the case where a drill pipe cassette 80 is being moved upwards from a horizontal storage position (Figure 8) by means of the device 2 according to the present invention. The drill pipe cassette 80 is being moved upwards at one side (left side in the figure) by means of the hoisting carriage 21 and at the other side (right side in the drawing) by means of the hoisting guide 85. Said hoisting guide 85 is connected to the main frame 25 in such a way that it is movable in a substantially vertical direction relative to the main frame 25.

It can be seen in Figure 9 that the cassette 80 is positioned in front of the

drilling mast 6 by means of the device 2 according to the present invention, and is moved into a vertical position by means of the telescopic guide frame 22. Finally, the cassette is placed vertically next to the drilling mast 6 (Figure 10) by means of the device 2.

It can be seen in Figures 8,9 and 10 that for the construction of a drilling string means 81 are placed near the drilling mast 6 for manoeuvring vertically oriented drilling string elements. During the construction of a drilling string 88 the drilling string elements are taken below the hoisting means 50 by said means 81, and during the dismantling of a drilling string 88 the drilling string elements are removed by means of said means 81.

It must be understood that the embodiments shown are intended only as examples. Modifications on the various parts of the device according to the present invention are possible without leaving the scope of the appended claims.

It must also be pointed out that the sequence of movement of the riser parts 10 or drilling string parts shown in Figures 2 to 10 can also be effected in the reverse order.