Ambit of the invention

The present invention concerns a process and a device for collecting oil spillage and oil pollution at sea. The process comprises, by starting downwind and/or down-current from the oil spillage/oil pollution, by enclosing parts or all of the oil spillage/oil pollution by initially pulling from one or more vessels an oil lens/enclosure across the area of the oil spillage/oil pollution downwind and/or down-current from the oil spillage/oil pollution for thereafter bringing said oil lens/enclosure past and to the side of of parts or all of the oil spillage/oil pollution area, the oil lens/enclosure being passed freely from the ves- sel(s) so that the oil lens/enclosure drifts in the same direction and with the same speed as the oil spillage/oil pollution while the discharge of the oil lens/enclosure continues, whereafter the ends of the oil lens/enclosure are brought together and closed to include all or parts of the oil spillage/oil pollution, whereafter the enclosed oil spillage/oil pollution is passed downwind and/or down- current to straits that are suited for further collection of the oil spillage/oil pollution. The collecting of the oil may also be done at open sea depending on the weather. The invention also concerns an oil lens/enclosure comprising a number of floating elements of a per se known type, wherein the floating elements at each end of the

lens/enclosure comprises mutually cooperating connecting elements for joining the ends to each other. Background for the invention

Oil pollution from oil spillage, they be from ships in distress (oil tankers, cargo vessels, passenger ships, ferry vessels, etc.) or oil drilling rigs and platforms (uncon- trolled blow-outs or spillages happening through accidents) represents a large environmental hazard. Such oil spillages may happen at sea where the natural and environmental conditions are unfavourable for collecting such oil spill- age. E.g. the wave height at sea may be from 2 m and more, and in addition wind and possibly current or tide will represent a strong contribution to the spreading of the oil spillage while simultaneously the current also may contribute to the spreading of the oil spillage. It is at the same time important that the oil spillage does not spread unhindered since oil will pollute beaches and cliffs when such oil spillage reaches land, something being harmful to the animal life and looks of the area. Consequently it is of importance the oil spillage/oil pollution is collected in a controlled manner at locations suitable for this.

Since the conditions often are not favourable for collecting oil spillage/oil pollution at sea on account of the complicating factor mentioned supra (waves, wind, current, tide) the oil protection at sea is a difficult field where conventional methods for limiting the spreading and collecting the oil often is not sufficient or is conducted in a wrong manner.

Prior art

Limitation of the spreading of oil spillage at sea is con- ducted by discharging oil lenses/enclosures downwind and/or down-current from the relevant oil spillage whereafter the oil lens vessels are moving counter-wind and/or counter- current to prevent the spreading of the oil spillage region. In this way the discharged oil lens/enclosure forms a "U" with the source for the oil spillage at the opening of the "U". The disadvantages of such a collection method are that the vessels will work against the wind and current, and will use large resources and energy in holding the lenses/enclosures stationary. In addition such a method would have as a consequence that the oil lenses/enclosures more easily would break on account of the load and/or that the oil spillage/oil pollution was whipped/thrown over the oil lenses/enclosures by the waves which would break over the lens/enclosure edges because the lenses/enclosures were forced to lie stationary or be pulled against the direction of the wind and/or current. Admittedly the oil would inherently dampen the whipping of the water, but this effect is not sufficient for countering a complete throw-over of the oil across the lens/enclosure edges in high seas and/or in strong wind.

There exist many patents disclosing different kinds of oil spillage prevention devices such as US patents 5.071.286, 3.592.006, 3.607.741, GB patent 2.105.603, 2.250.240 and WO 92/14002. However, none of these documents concern how to dispense and collect oil spillage in view of the wind and current directions at the relevant site.

Thus there exists a need for an improved method for limiting oil spillage/oil pollution at sea where the disadvantages of high seas or strong wind are limited as much as possible.

General disclosure of the invention

The present invention will be disclosed infra in greater detail with the reference to the enclosed figures wherein:

Fig. 1 shows a limitation method for oil spillage/oil pol- lution at sea according to the prior art;

Fig. 2 shows the limitation method for oil spillage/oil pollution at sea according to the present invention where there are used two vessels for locating the oil

lenses/enclosures , Fig. shows the limitation method for oil spillage/oil pollution according to the present invention where there is used one vessel discharging an oil lens/enclosure as a ring net around parts or all of the relevant oil spillage (oil pollution.

In the figures there is shown a source 1 for the oil spillage/oil pollution (here represented as a sketched (here represented as a stylistic oil drilling platform) with an oil spillage/oil pollution area 2. In the figures there is indicated a wind direction 3 with a fat arrow. There may in the relevant area of the ocean exist waves, current and tide (not shown) that may act together with, partly together with, partly against or against the wind direction 3

The process for deploying oil lenses/oil enclosures according to the invention is performed with at least one vessel 4,4' or 4, 4'; 5, 5' that may deploy a number of oil

lenses/oil enclosures 6, 6' being passed to a location being downwind and or down-current for the lowest part of the oil spillage/oil pollution 2 (the part of the oil spillage/oil pollution lying distally from the source of the oil spillage/oil pollution) , whereafter the oil lens/oil enclosure (s) 6,6' is conducted past the farthest border (s) of the oil spillage/oil pollution 2 against the wind/current direction 3, for thereafter, at a distance from the distal end of the oil spillage/oil pollution 2, passing the free lens/enclosure ends 7,7' together for securing them to each other for enclosing the oil spillage/oil pollution 2, the enclosure of the oil spillage/oil pollution by the oil lenses/oil enclosures being performed by letting the oil lenses/oil enclosures 6, 6' being passed freely with the wind and current during the enclosing and connecting stages of the oil lens/oil enclosure ends. The oil lens/oil enclosure is preferably deployed as a ring net. To assist this it is used one or more vessels 4,4'; 5, 5'. The contact with the starting end of the ring net is maintained through the deployment through a line secured to this end and being rolled up on a winch on the vessel. The advantage with such a process is that all the actions are performed in concert with the wind direction for thereby using the forces of nature during the enclosing process of the oil spillage/oil pollution. In some instances the above mentioned forces of nature

(wind, current, waves, tide) may work against each other. In such a case the priority of which forces of nature to mind will be primarily to mind the wind.

Wind participates in spreading the oil spillage/oil pollu- tion and passing it along the surface of the ocean while wind also participates in whipping up waves that may whip the oil spillage over the oil lenses/oil enclosures. It is therefore primarily important that the process according to the invention is conducted in the same direction as the wind. Normally this will not represent any spacing/room problems (as might have been the case in straits closer to land) because the process according to the present invention is meant to be conducted at open sea. The wind strength in this connection is a factor to take notice of. In calm or slight wind it is not particularly important to prioritize the wind direction in relation to the other parameters (see infra), whereas wind strengths of e.g. gale or stronger this will have to be taken into account.

In this connection the expression "open sea" means sea dis- tances being located at least 4 nautical miles from land.

Furthermore, with "open sea" is meant areas of the sea in the meaning supra and that substantially do not contain reefs, islands, cliffs or other types of land being located less than 10 m below the surface of the sea at ebb tide. With the expression "mainly" is in this connection indicated supra meant that there may exist underwater rock or sand formations being less than 500 m ² across over the sea at ebb tide and/or being located less than 10 m below the surface of the sea at ebb tide. Such rock or sand formations may represent a hazard for the capsizing sea-faring vessels and may create oil spillage/oil pollution from such vessels . The next priority after the wind concerning the forces of nature mentioned supra to be assessed is the current. In this connection "current" is meant to be both local current conditions and global current conditions, where local current conditions have more weight than global current condi- tions. Local current conditions may e.g. be formed by un- der-water geographic formations affecting the sea currents based on global currents and based on tide effects. If the local current conditions act in concert with the wind direction, the process according to the present invention is performed in the same direction as both the wind and current direction. If the current direction is different from the wind direction, it will normally primarily be the wind direction that determines which direction the process according to the invention is to be conducted. Anyway it will be the drifting direction of the oil that will determine the direction of the oil entrapment according to the invention that will be performed. Still it might, if the local wind strength is small (no wind up to light breeze) whereas the local strength of the current is large (sur- passes the wind strength) , it will be placed more emphasis on the current conditions than the wind conditions. This is particularly relevant if the wind direction is completely or partially opposite the current direction.

The third priority concerning the forces of nature men- tioned supra, and which are to be observed, are waves.

Waves move in themselves very little water masses in the horizontal direction since the water particles move in circles underneath passing waves. Still large wave heights may make the deployment of oil lenses/oil enclosures at sea difficult because the wave height may be very large (from 2 m and more, e.g. 5 m, 7 m, 10 m and more) . The wave height is in this connection measured as the vertical distance between a wave bottom (nadir) and a wave top (apex) . The wave amplitudes may also become added to each other if there are present crossing waves in the relevant area.

There may e.g. be formed locally waves with one direction of movement, while there may exist swells in the same area with a different direction of movement. Such waves may either cancel each other out of become added to each other. The deployment of oil lenses/oil enclosures has previously also taken into account the size of the waves, so that the selection of such equipment may be performed conventionally .

The fourth priority concerning the above mentioned forces of nature that must be taken into account when performing the process according to the present invention is the tide. Normally the tide will constitute changes in the level of the sea and that are so slow that they do not affect the collection of oil spillage/oil pollution at sea. Still the tide may affect local current conditions (see supra) , in- dieting that tide effects should be taken into account when considering the collection direction of the oil spillage/oil pollution. This may enter the picture if all of the three conditions mentioned supra (wind, current, waves) are too small to be of any concern for the efficacy of the oil collection according to the invention.

The performance of the process disclosed supra may have as an effect that only some of the oil spillage/oil pollution 2 is collected (see Fig. 2) . In such a case it may be relevant to perform the disclosed process anew one or sev- eral more times for collecting as much as possible of the relevant oil spillage/oil pollution 2 at a number of positions .

When all or a part of an oil spillage/oil pollution has been enclosed by an oil lens/oil enclosure 6,6', the oil lens/oil enclosure 6,6' is transported, still in the same or mainly the same direction as the forces of nature indicated supra (wind, current, waves, tide) and in the prioritizing as explained supra. The transporting of the enclosed oil spillage 2 will proceed to shore or into a calmer location where the oil spillage may be removed in a conventional manner, e.g. with an oil skimmer or an oil pump. Such a removal is suggested in fig. 2 by using a dotted arrow 8. When the transporting of the enclosed oil spillage 2 may proceed mainly in the same direction as the above mentioned forces of nature (wind, current, waves, tide) it is thereby meant that the transporting of the oil spillage may proceed in the same direction as the

wind/current/waves/tide up to 90° to this direction. It is still preferred that the transportation does not exceed 60°, and more preferred the angle of transportation should not exceed 45°, more preferred not more than 30°, e.g. not more than 20° or not more than 15°.

An alternative to the transport be an enclosed oil spillage is to break down the oil so that it may be removed be e.g. microorganisms. To do this it is common to spray the oil spillage with degrading chemicals. Such a spraying may also be conducted more easily if the relevant enclosed oil spillage is transported in the same direction as the wind (and optionally in the same direction as the current) as a continuance of the enclosing process according to the invention explained supra. In such an embodiment e.g. the oil lenses/oil enclosures may be equipped with praying nozzles for oil-degrading chemicals and/or the spraying may be performed by the aid of a spraying vessel. The invention also concerns a device for enclosing and optionally transporting an oil spillage/oil pollution region, where such a device comprises a number of conventional oil lens/enclosure elements that may be secured together in a chain, and where the first and last link in such a chain comprise devices that may be linked together for forming a closed circle of the oil lens/oil enclosure elements. The lens/enclosure elements may e.g. be coupled in from the end in the same manner as a ring net, for in this manner to make the region smaller and the oil layer thicker for easing the oil skimming. The circle of lens/enclosure elements may be reduced by employing a pulling device such as a power block or a winch. The invention also concerns the use of oil lenses/enclosures for collecting oil spillage/oil pollution at sea through the process having been explained supra.