Method and system for cargo fluid transfer at open sea

Abstract

Methods and systems are for transferring fluid cargo between a first vessel and a second vessel at open sea in a Parallel configuration. The first vessel is equipped with a cargo connection point and the second vessel is equipped with cargo manifold. A tubular line is connectable between the cargo connection point and the cargo manifold. The method can include attaching a self-propelled buoy to the second vessel; connecting a cargo connection between the self-propelled buoy and the cargo manifold; connecting a cargo line between the cargo connection point and the self-propelled buoy; transferring cargo between the cargo connection point and the cargo vessel; and relying on the self-propelled buoy to keep the self-propelled buoy within predetermined distance boundaries from the first vessel also when the self-propelled buoy is attached to the second vessel.

Claims

1. A method for transferring fluid cargo between a first vessel and a second vessel at open sea in a Parallel configuration, wherein the first vessel is equipped with a cargo connection point at a stern portion of the first vessel, wherein the second vessel is equipped with cargo manifold, and wherein a tubular line is connectable between the cargo connection point and the cargo manifold, the method comprising: attaching a self-propelled buoy to the second vessel; connecting a cargo connection between the self-propelled buoy and the cargo manifold; connecting a cargo line between the cargo connection point and the self-propelled buoy; transferring the fluid cargo between the cargo connection point and the second vessel; and relying on the self-propelled buoy to keep the self-propelled buoy within predetermined distance boundaries from the first vessel also when the self-propelled buoy is attached to the second vessel, the second vessel being allowed to turn at an angle relative to the first vessel.

2. The method according to claim 1, further comprising attaching the self-propelled buoy to the second vessel prior to connecting the cargo line between the cargo connection point and the self-propelled buoy.

3. The method according to claim 1, further comprising allowing the second vessel to keep the desired heading of the second vessel by use of its propulsion machinery controlled by its auto-pilot.

4. The method according to claim 1, further comprising emergency disconnecting the cargo line between the cargo connection point and the self-propelled buoy and letting the second vessel with the self-propelled buoy attached, drift off from the first vessel.

5. The method according to claim 1, further comprising attaching a DPS self-propelled buoy to the second vessel and then attaching the self-propelled buoy with the cargo line connected, to the second vessel.

6. A system that transfers fluid cargo between a first vessel and a second vessel at open sea in a Parallel configuration, wherein the first vessel is equipped with a cargo connection point at a stern portion of the first vessel and the second vessel is equipped with a cargo manifold, the system comprising: a tubular line connected between the cargo connection point of the first vessel and the cargo manifold of the second vessel; a cargo line extending from the cargo connection point, at least one self-propelled buoy connected to the cargo line; and a cargo connection connected between the self-propelled buoy and the cargo manifold; wherein the self-propelled buoy is connected to the second vessel, and is configured to keep within predetermined distance boundaries from the first vessel also when the self-propelled buoy is attached to the second vessel, the second vessel being allowed to turn at an angle relative to the first vessel.

7. The system according to claim 6, wherein the first vessel is designed to weather vane.

8. The system according to claim 6, wherein the cargo connection point is at a position distant from a flare tower on the first vessel.

9. The system according to claim 6, wherein the first vessel is equipped with a support boom for the cargo line.

10. The system according to claim 6, wherein the cargo line is a hardpipe with swivels.

11. The system according to claim 6, wherein the cargo line is in the form of a submersible or floatable hose.

12. The system according to claim 6, wherein a service vessel is connectable to the second vessel.

13. A system that transfers fluid cargo between a first vessel and a second vessel at open sea in a Parallel configuration, wherein the first vessel is equipped with a cargo connection point at a stern portion of the first vessel and the second vessel is equipped with a cargo manifold, the system comprising: a tubular line connected between the cargo connection point of the first vessel and the cargo manifold of the second vessel; a cargo line extending from the cargo connection point; at least one self-propelled buoy connected to the cargo line and a cargo connection connected between the self-propelled buoy and the cargo manifold; wherein the self-propelled buoy is connected to the second vessel, and is configured to keep within predetermined distance boundaries from the first vessel also when the self-propelled buoy is attached to the second vessel, wherein, in the Parallel configuration, a longitudinal axis of the first vessel is parallel to a longitudinal axis of the second vessel which is spaced apart from and lies alongside the first vessel, and wherein the second vessel is allowed to turn at an angle relative to the longitudinal axis of the first vessel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) There is now described in the following examples, illustrated in the accompanying drawings, wherein:

(2) FIG. 1 shows a plane view of a first vessel and a second vessel connected for cargo fluid transfer according to the present disclosure;

(3) FIG. 2 shows to a larger scale an end view of a self-propelled buoy in the process of attaching itself to the second vessel;

(4) FIG. 3 shows to a larger scale an end view of the situation in FIG. 1;

(5) FIG. 4 shows a plane view of a situation where the second vessel is allowed to drift away from the first vessel;

(6) FIG. 5 shows a plane view of the first and second vessel in an alternative embodiment; and

(7) FIG. 6 shows a plane view of the first and second vessel in yet an alternative embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

(8) In the drawings, the reference number 1 denotes a first vessel that is connected to a moored swivel 2 and that is equipped with a flare tower 4 and a cargo connection point 6. In FIGS. 1 and 4, the cargo connection point 6 is positioned at a stern portion 8 of the first vessel 1, while it is positioned mid-ships in FIG. 6. The first vessel 1 may have more than one cargo connection point 6 to enable simultaneous loading of more than one second vessel 10.

(9) A second vessel 10 has a self-propelled buoy 12 attached close to its cargo manifold 14. A cargo connection 16 connects the self-propelled buoy 12 to the cargo manifold 14.

(10) A cargo line 18 connects the cargo connection point 6 to the self-propelled buoy 12. A tubular line 20 that in this embodiment includes the cargo connection 16 and the cargo line 18, provides a flow path for fluid cargo between the cargo connection point 6 and the cargo manifold 14.

(11) The cargo line 18 is at least partly carried by a boom 22 as shown in FIG. 3. In some cases, the cargo line 18 may include a hardpipe 24 with swivels 26, or a floating or submerged hose 28 as indicated by dashed lines in FIG. 3.

(12) A service vessel 30 is optionally attached to the bow 32 of the second vessel 10 by a hawser 34.

(13) When cargo is to be transferred between the first vessel 1 and the second vessel 10, the self-propelled buoy 12 meets the second vessel 10 at some distance from the first vessel 1. After the self-propelled buoy 12 is attached to the second vessel 10, the self-propelled buoy 12 will bring the second vessel 10 to the first vessel 1, where the self-propelled buoy 12 will stay within predetermined distance boundaries 36, 38 from the first vessel 1. If attached, the service vessel 30 assists in keeping the second vessel 10 in a desired direction relative to the first vessel 1.

(14) The cargo connection 16 and the cargo line 18 are connected and after normal preparations, the fluid cargo transfer is started. When finished, a reverse procedure is undertaken.

(15) When transferring such cargo as LNG (Liquefied Natural Gas), it is normal to utilize at least one cargo line 18 for liquid transfer and a return cargo line 18 for the return of evaporated boil-off gas.

(16) Should the resultant element forces change, the second vessel may be allowed to turn an angle 40 relative the first vessel 1 as shown in FIG. 1.

(17) In case of an emergency, the cargo line 18 may be disconnected from the self-propelled buoy 12, after which the second vessel 10 may drift away or be moved away typically by the self-propelled buoy 12, from the first vessel 1 as shown in FIG. 4.

(18) In an alternative embodiment shown in FIG. 5, the self-propelled buoy 12 is keeping the second vessel 10 in a desired position relative the first vessel 1, while a propulsion machinery 42 controlled by an auto-pilot 44 of the second vessel is, preferably automatically, maintaining the heading of the second vessel 10.

(19) In FIG. 5 the many systems available for avoiding a collision between the first vessel 1 and the second vessel 10 is outlined.

(20) Firstly, the first vessel 1 will weather-vane because of a resultant element force 46. The second vessel 10 may thus be positioned at the aft of the first vessel 1 and the resultant element force 46 will tend to move the second vessel 10 away from the first vessel 1. Further, in most cases, the first vessel 1 has thrusters 48 that may be used for turning the first vessel 1 away from the second vessel 10. Then the self-propelled buoy 12 may push the second vessel 10 away from the first vessel 1, and finally, the propulsion machinery 42 of the second vessel 10 may move the second vessel away.

(21) Even at a full blackout situation in one or two of these systems, the remaining of functioning systems are sufficient to avoid a collision. Also, in the most unlikely event of simultaneous blackout of all active propulsion systems, the resultant element force 46 will push the second vessel 10 safely away from the first vessel 1.

(22) In another alternative embodiment shown in FIG. 6, a DPS self-propelled buoy 50 has first been attached to the second vessel 10. When the DPS self-propelled buoy 50 has brought the second vessel 10 to the first vessel 1, the self-propelled buoy 12 with connected and cooled down cargo line 18, is attached to the second vessel 1. This method significantly reduces the preparation time for cargo fluid transfer.

(23) 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.

(24) The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.