Arc loading system

Abstract

A system and method are for transferring fluid cargo between a cargo vessel and a cargo connection point at open sea where the cargo vessel is required to keep an end portion of the cargo vessel up towards the resultant element force direction, wherein at least one self-propelled buoy, that is designed to be in fluid connection with the cargo connection point, is connectable to a side portion of the cargo vessel, there being a cargo line that is connectable between the self-propelled buoy and the cargo vessel, and where the self-propelled buoy is designed to keep the self-propelled buoy within predetermined radial distance boundaries from the cargo connection point also when it is attached to the cargo vessel.

Claims

1. A system for transferring fluid cargo between a cargo vessel and a cargo connection point at open sea where the cargo vessel is required to keep bow end portion of the cargo vessel up towards the resultant element force direction, the system comprising: the cargo connection point comprising a platform above sea surface; the cargo vessel; and at least one self-propelled buoy which is configured to be in fluid connection with the cargo connection point through at least one tubular which extends laterally between the platform and the buoy, and which is connectable to the vessel at solely one of two sides of the cargo vessel at a time, there being a cargo line that is connectable between the self-propelled buoy and the cargo vessel, and where the self-propelled buoy is operable to keep within predetermined radial distance boundaries from the cargo connection point also when it is attached to the cargo vessel, such that in use the buoy is spaced a lateral distance away from the platform and the vessel is arranged side-on to the platform; and where the self-propelled buoy and the cargo vessel are operable to turn a predetermined angle about the cargo connection point to maintain the bow end portion of the cargo vessel towards the direction of the resultant element force in a first element force direction sector, and where the self-propelled buoy is connectable to the other of the two sides of the cargo vessel in order to maintain the bow end portion of the cargo vessel towards the resultant element force direction in a second element force direction sector.

2. The system according to claim 1, wherein the total angle of the first element force direction sector and the second element force direction sector added together is 360 degrees.

3. The system according to claim 1, wherein the platform is a floating platform.

4. The system according to claim 1, wherein the platform is fixed in position.

5. The system according to claim 1, wherein the tubular for fluid connection between the self-propelled buoy and the cargo connection point comprises a submersible or floatable hose.

6. The system according to claim 1, wherein the tubular is at least partially carried by a boom.

7. The system according to claim 1, further comprising a service vessel which is connectable to the cargo vessel.

8. A method for transferring fluid cargo between a cargo vessel and a cargo connection point at open sea where the cargo vessel is required to keep a bow end portion of the cargo vessel towards a resultant element force direction, the cargo connection point comprising a platform above sea surface, wherein the method comprises: attaching a self-propelled buoy to the cargo vessel at one of two opposite sides of the cargo vessel; connecting a cargo line between the self-propelled buoy and the cargo vessel; connecting a tubular between the cargo connection point and the self-propelled buoy, the tubular extending laterally between the platform and the buoy; transferring cargo via the cargo line and the tubular between the cargo connection point and the cargo vessel; operating the self-propelled buoy to keep within predetermined radial distance boundaries from the cargo connection point also when it is attached to the cargo vessel, the buoy being spaced a lateral distance away from the platform, and the vessel being arranged side-on to the platform; reacting to a change in the resultant element force direction by allowing the self-propelled buoy to turn a predetermined angle about the cargo connection point to maintain a bow end portion of the cargo vessel towards the resultant element force direction in a first element force direction sector; and rearranging said self-propelled buoy or using another self-propelled buoy to attach to the vessel at the opposite one of the two sides of the cargo vessel in order to maintain the bow end portion of the cargo vessel towards the resultant element force direction in a second element force direction sector.

9. The system according to claim 5, wherein the arc of the work sector has an angle of less than 360 degrees.

10. The system according to claim 1, wherein the platform is not swivel or turret moored.

11. The system according to claim 1, wherein the cargo connection point does not require a swivel or turret to provide for turning the bow end portion of the vessel toward the resultant element force direction.

12. The system according to claim 1, the buoy being operable to connect to the vessel and turn so as to allow the bow end portion to be positioned toward any resultant force element direction.

13. The system according to claim 1 wherein the self-propelled buoy is configured to operate within angular limits between which is defined an arc of a work sector about the cargo connection point.

14. The method according to claim 9, wherein the method comprises attaching the self-propelled buoy to the cargo vessel prior to connecting the tubular between the cargo connection point and the self-propelled buoy.

15. The system according to claim 5, wherein the arc of the work sector has an angle in the range of up to 180 degrees.

16. The system according to claim 1, wherein the tubular is flexible so as to allow the buoy also with the vessel attached to turn for positioning the bow end portion toward the resultant element force direction.

17. The system as claimed in claim 1, wherein the self-propelled buoy has an extension which when the buoy is attached to the cargo vessel extends under the vessel, and which is arranged to be forced up against the underside of the cargo vessel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following is described an example of a preferred embodiment and method illustrated in the accompanying drawings, wherein:

(2) FIG. 1 shows in plane view a principal sketch of an installation at sea where a self-propelled buoy, that is designed to be in fluid connection by tubulars with a cargo connection point on a platform, is in a position for connecting itself to a cargo vessel;

(3) FIG. 2 shows in a larger scale a side view from FIG. 1;

(4) FIG. 3 shows the same as in FIG. 2, but after the self-propelled buoy has connected itself to the cargo vessel;

(5) FIG. 4 shows the installation in operation with tubulars connected, and at a first element force direction;

(6) FIG. 5 shows the installation in operation at a second element force direction;

(7) FIG. 6 shows the installation in operation at a third element force direction;

(8) FIG. 7 shows the installation in operation at a fourth element force direction;

(9) FIG. 8 shows the installation in operation at a fifth element force direction;

(10) FIG. 9 shows the installation in operation at a sixth element force direction;

(11) FIG. 10 shows an alternative embodiment where the hoses are supported by a swingable boom:

(12) FIG. 11 shows an alternative embodiment where the fluid connection includes hard pipes and swivels; and

(13) FIG. 12 shows yet an alternative embodiment where the cargo connection point is positioned on the sea bed.

DETAILED DESCRIPTION OF THE DRAWINGS

(14) On the drawings, the reference numeral 1 denotes a cargo connection point from where at least one tubular 2 extends to a self-propelled, free floating buoy 4 as shown in FIG. 4 to 12. The cargo connection point 1 may be part of a floating or fixed platform 6 or be at the seabed 8 as shown in FIG. 12. When the platform 6 is floating, it is equipped with moorings 10.

(15) The self-propelled buoy 4 is designed to operate within a work sector 12 as shown in FIG. 4. Typically, the work sector is 90 degrees relative the direction of the cargo connection point 1. In this way, no swivel is needed at the cargo connection point 1 as the flexibility of the tubular allows the change in direction. Due to the length of the tubular 2, and safety regulations, the self-propelled buoy 4 has to keep itself between an inner radial boundary 14 and an outer radial boundary 16 from the cargo connection point 1 when connected to a cargo vessel 18.

(16) The cargo vessel 18, which may be assisted by a service vessel 20 having a hawser 22, is in FIG. 1 shown close to the self-propelled buoy 4 at a safe distance from the cargo connection point 1.

(17) The cargo vessel 18 has a first side portion 24, a second side portion 26, a first end portion 28 and a second end portion 30. In this embodiment the first side portion 24 corresponds to the port side portion of the cargo vessel 18, the second side portion 26 correspond to the starboard side portion, the first end portion 28 corresponds to the bow portion and the second end portion 30 corresponds to the stem portion of the cargo vessel 18.

(18) The service vessel 20 assists the cargo vessel 18 in keeping the first end portion 28 up towards a resultant elements force. The resultant element force, below termed element force, includes forces acting on the cargo vessel 18 that are mainly generated by wind, waves and current.

(19) The self-propelled buoy 4 is designed to attach itself to the cargo vessel 18 by altering its deep-draught relative the water surface 31. In this embodiment, as shown in FIG. 2, the self-propelled buoy 4 has an extension 32 that in the connected position extend under the cargo vessel 18. The extension 32 is designed to be forced up against the underside 34 of the cargo vessel 18 as shown in FIG. 3. The self-propelled buoy 4 is attached on the first side portion 24 of the cargo vessel 18.

(20) In this attached position, the self-propelled buoy 4 is designed to move itself with the cargo vessel 18 towards the cargo connection point 1. Further, the self-propelled buoy 4 will keep itself within the inner radial boundary 14 and the outer radial boundary 16, also when the self-propelled buoy 4 is connected to the cargo vessel 18.

(21) A cargo line 38 is connected to the cargo vessel 18 and forms together with the tubular 2, that is connected to the self-propelled buoy 4, a fluid connection between the cargo connection point 1 and the cargo vessel 18.

(22) The cargo vessel 18 is subjected to a resultant element force that may have any horizontal direction. In FIG. 4 the first element force direction 40 is here at 0 degrees. The first end portion 28 of the cargo vessel 18 is kept heading towards first element force direction 40.

(23) As weather changes, the resultant element force changes to a second element force direction 42, here at 45 degrees. The self-propelled buoy 4 and the cargo vessel 18 turns about the cargo connection point 1 until the first end portion 28 of the cargo vessel 18 heads towards the second element force direction 42 as shown in FIG. 5.

(24) Similarly, if the resultant element force changes to a third element force direction 44, here at 180 degrees. The self-propelled buoy 4 and the cargo vessel 18 turns about the cargo connection point 1 until the first end portion 28 of the cargo vessel 18 heads towards the third element force direction 44.

(25) The first, second and third element force directions 40, 42, 44 falls within a first element force direction sector 46 where the change in direction of the self-propelled buoy 4 and cargo vessel 18 falls within the work sector 12.

(26) At further change in element force direction to within a second force direction sector 48, the self-propelled buoy 4 is attached to the second side portion 26 of the cargo vessel 18 as showed in FIG. 7. The first end portion 28 of the cargo vessel 18 may be kept towards a fourth element force direction 50, here at 225 degrees, and still within the work sector 12.

(27) At yet further change in element force direction, the first end portion 28 of the cargo vessel 18 may be kept towards a fifth element force direction 52, here at 270 degrees as shown in FIG. 8. At further change, the first end portion 28 of the cargo vessel 18 may be kept towards a sixth element force direction 54, here at 315 degrees as shown in FIG. 9. The fourth, fifth and sixth element force directions 50, 52, 54 falls within a second direction sector 48 where the self-propelled buoy 4 and the cargo vessel 18 still falls within the work sector 12.

(28) The total work sector is here shown to be 180 degrees. The device and method thus cover all horizontal element force directions within 360 degrees. Other sector sizes may apply.

(29) In an alternative embodiment shown in FIG. 10, a swingable boom 56 is positioned close to the cargo connection point 1 on the platform 6. The boom 56 may swing about a swing axis 58 over at least a part of the work sector 12. The boom 56 partly carries the tubular 2. Generally, the tubular 2 may be of a floating or sinkable type.

(30) In an alternative embodiment shown in FIG. 1, the tubulars 2 are hardpipes with swivels 60.

(31) In yet another embodiment, shown in FIG. 12, the tubulars 2 are connected to a cargo connection point 1 on the sea bed 8.

(32) It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb comprise and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article a or an preceding an element does not exclude the presence of a plurality of such elements.