METHOD FOR FIGHTING AN OILSPILL IN THE AFTERMATH OF AN UNDERWATER OIL WELL BLOWOUT AND INSTALLATION FOR CARRYING OUT THE METHOD

Abstract

A method for pumping away the oil in the aftermath of a blowout in an offshore oil well includes the steps of putting a support structure with a surrounding foil over the leaking oil well or pipe in order to create a hollow space overhead the leaking spot on the sea bottom. Thereafter, pumping water and oil through the top of the support structure for creating an underpressure below the foil, so the foil will be pressed onto the sea bottom due to hydrostatic pressure of the outside water. Then, continuously pumping away the liquid below the foil from within the support structure until it is pure crude oil and collecting the same. A related apparatus includes a support structure with an enclosure for providing a hollow room overhead a leaking spot or oil pipe and a reinforced foil having such size that it extends at least ten meters into the surrounding of the support structure. The reinforced foil is tightly attached to the lower edge of the enclosure of the support structure. A pumping pipe connects to the top of the support structure to pump liquid from within the support structure and lower side of the foil.

Description

This invention concerns a method for fighting oil spills in the aftermath of a blowout, and also an installation for carrying out the method. A blowout is the uncontrolled release of crude oil or natural gas or a mixture of the two from a well, typically for petroleum production, after pressure control systems have failed. When such an incident occurs, formation fluids begin to flow into the wellbore and up the annulus and/or inside the drill pipe, and this is commonly called a kick. If the well is not shut in (common term for the closing of the blow-out preventer valves), a kick can quickly escalate into a blowout when the formation fluids reach the surface, especially when the fluid is a gas which rapidly expands as it flows up the wellbore, further decreasing the effective weight of the fluid, and accelerates to near the speed of sound. The gas and other hydrocarbons commonly ignite during a blow-out, creating explosions and vigorous fires which are difficult to extinguish. Blowouts can cause significant damage to drilling rigs, injuries or fatalities to rig personnel, and significant damage to the environment if hydrocarbons are spilled. Prior to the development of blow-out preventers, blowouts were common during drilling operations, and were referred to as gushers. Sometimes, blowouts can be so forceful that they cannot be directly brought under control from the surface, particularly if there is so much energy in the flowing zone that it does not deplete significantly over the course of a blowout. In such cases, other wells (called relief wells) may be drilled to intersect the well or pocket, in order to allow kill-weight fluids to be introduced at depth. Contrary to what might be inferred from the term, such wells generally are not used to help relieve pressure using multiple outlets from the blowout zone.

An “underground blowout” is a special situation where fluids from high pressure zones flow uncontrolled to lower pressure zones within the open-hole portion of the wellbore. Usually they come up the wellbore to shallower formations (typically near the last casing shoe) that have been fractured from the overall effect of hydrostatic mud head plus casing pressure imposed at the time of the initial kick. Underground blowouts can be very difficult to bring under control although there is no outward flow at the drill site itself. However, if left unchecked, in time the fluids may find their way to the surface elsewhere in the vicinity (possibly “cratering” the rig), or may pressurize other zones, leading to problems when drilling subsequent wells.

A very major blowout occurred on Apr. 20, 2010 approx. 135 sea miles (250 km) south east of New Orleans in the Mexican Gulf. And it was a very special case since the blowout occurred very deep in the sea, and oil leaked out of the hole in a depth of 5000 ft or approx. 1500 meters. It is estimated that up to 10 million litres or 10,000 m³ of oil per day were being spilled into the ocean from underground or from broken drill pipes near the hole, which caused a dramatic disaster for the environment of an entire large region.

There are no experienced and demonstrated techniques available in order to stop such an enormous spill of oil and the obstacles to stop such uncontrolled flow of oil are tremendous since the leaks are located 1500 m below sea level on the hole. The oil formations from where the oil was taken out are located approx. 18,000 ft or approx. 5,500 m below sea level, that is some 13,000 ft or approx. 4,000 m below hole in the underground. Relief borings from the side have been brought down in order to reach the leaking oil well pipe, open it there and pump great amounts of mud at high pressure into it in order to block it by the weight of this pumped in material. However, to bring down such relief borings is time consuming. And even if the mud would arrive at the leaking oil pipe, the mud could not prevent a leaking that occurs through slits and cracks around the pipe and up the annulus or through natural cracks in the formation which may have occurred due to detonations in the underground.

Another proposal was to put a domelike shell made of steel or reinforced concrete on top of the leaking points and evacuate their content and thereby creating a big pressure onto the outer side of the shell and keep it in place, and then continuously pump the inflowing oil to the surface. However, underground streams and waves created heavy problems for this undertaking, and due to the low temperatures, freezing of valves created severe problems.

The purpose of this invention is to present a method by which such a leaking of oil from the hole and from well pipes can be fought successfully so that the oil spill into the water can be stopped and prevent devastating consequences for the environment. A further purpose is to teach an installation which allows it to carry out this method even at great depths, that is deep in the sea on the hole.

The method according to claim 1 and the installation according to claim 5 are being presented in the following, by the example of the recent heavy blowout in the Mexican gulf. The method comprises several steps and is promising for successfully deal with that enormous problem and get the oil leaking into the water eventually stopped completely.

10,000 m³ of oil per day equals to roughly 375 tons per hour, or 104 kg per second. This is the proximate mass flow that has to be dealt with. But this method has the potential to keep up with an even substantially greater flux of oil. In the accident in the Mexican gulf, the oil has an initial temperature of approx. 80° C. and originates from sea bottom at depths of approx. 18,000 ft or 5500 m below sea level. At such depths there is an enormous hydrostatic pressure of approx. 550 bar or even more acting. Apparently, there were several leaks—such ones in the collapsed oil well pipes—and further leaks of oil in the hole where the oil escapes through several cracks.

This present method is in essence a low tech method, and therefore quickly to apply, at low cost, and it does prevent the further spilling of oil into the sea water. With the exception of some rare special cases, this method will allow to pump pure crude oil after an initial phase of executing the method. Although the method is not thought to be a permanent solution, it can be in operation several months in order to bridge the time it takes to bring down release borings and put them in operation.

The installation for execution of the method is suitable to serve as an emergency equipment and may be built in advance for future incidents should they ever occur. There are hundreds of deep sea borings in operation and therefore, a situation as the one which occurred in the Gulf of Mexico might occur on other sites in the future.

The method can be carried out no matter whether the leaking of the oil is from a broken pipe over the hole or comes out of the sea bottom through open cracks. The method will now be described and its operation explained by reference to the accompanying drawings. These figures show:

FIG. 1: The overall situation of a underwater oil spill with the installation for executing the method;

FIG. 2: The three-leg pyramid-like steel support;

FIG. 3: A section view of the three-leg support structure and the adjacent covering foil on the sea bottom, with the detail of its attachment to the support;

FIG. 4: The stabilization of the three-leg support and foil on the sea bottom, seen from above;

FIG. 5: The connection of the pumping pipe with the top of the support structure;

FIG. 6: A side view of several steps to lowering down the foil and the support structure to the sea bottom;

FIG. 7: A side view of an alternative method for lowering down the support structure and foil to the sea bottom.

This method is suitable for leaking pipes over the level of the sea bottom as well as for situations where the oil is leaking out of the sea bottom through cracks since a pipe did break below sea bottom or there was a bursting out of oil through natural channels. The method does make use of the hydrostatic pressure difference between the static pressure at the sea bottom and the reduced pressure in a hollow room created at the sea bottom of which liquid is pumped out. If oil and water is being pumped out of such an artificially created hollow room over the sea bottom, at a pressure drop of merely 50 kPa (0.5 bar), the pressure from outside will amount to 50 kN/m².

For realizing this method, a support structure or bearing support together with a reinforced foil are the key elements of the installation. The entire installation is shown in FIG. 1. The support structure 4 is a steel construction in the form of a three-leg pyramid-like steel structure which is covered and completely enclosed by strong steel plates 17 and this support structure 4 or support structure has three legs 2 so it always stands safely and in a definite position on any ground 10. The legs 2 are equipped each with a foot 3 that can swivel in any direction around the leg 2 end so the feet 3 will adapt to any underground surface and provide stability for the entire structure. The three legs 2 keep the entire support structure in a stable position so it can carry much load. The size of this support structure 4 may vary according the situation on site, e.g. the legs 2 stand on a circle of several meters in diameter, at least large enough in order to completely enclose the leaking spot, that is e.g. a crack 19 in the sea bottom, or a pipe 26 that was broken. The height of this support structure 4 measures anything between approx. 3 and 15 meters, in special cases the height may be even higher, and the side length at the bottom will be approx. 10 meters. In any case, the most important point is that this support structure 4 will cover the entire spot where oil is leaking out into the sea water.

On this support structure 4, a strong reinforced, water tight, oil and sea-water resistant foil 1 is being connected along the lower edge 33 of the pyramid-like structure 4. The foil 1 can be composed of a number of strips that are being welded or glued together along their edges. The foil 1 is reincored by a steel fabric or by a carbon-fabric in its interior. This foil 1 is finally lying on the sea bottom around the support structure 4. The foil 1 has in its center a hole of triangular shape which is being put over the neck of the support structure 4 so the inner edge of said hole will fit to the lower edge 33 of steel plates 17 on the structure. The foil 1 is securely attached on the lower edge 33 of the steel plates 17 that cover the structure and hence the foil 1 covers the entire surroundings of the structure. At its periphery or outer edge, a surrounding frame 5 made of strong steel tubes or profiles is being placed in order to keep the position of the foil 1 on the sea bottom 10 and to keep it stretched. This frame 5 can form a circle, a square, a triangle or have a rectangular shape when seen from above. Alternatively, blocks 34 of concrete can be placed, one after the other, in a row along the outer edge of the foil 1, as shown in FIG. 4.

A pipe 6,7 coming from a tanker ship 9 on the surface of the sea can be connected with a pipe neck that is extending out of the top of the support structure 4 and once the connection is established, liquid can be pumped from below the structure 4 and foil 1 to the sea surface into tanks of a tanker ship 9. Since the depth at which the installation is being placed may be several hundred or even thousand meters deep, several underwater pumps 8 will be used since sucking is only possible over somewhat less than 10 meters height. The power of these pumps 8 are regulated by their revolution per minute, according to the difference between the pressure inside and outside the support structure 4 and to keep that difference constant in a certain range. By using underwater pumps 8, the liquid can be pressed with high pressures onto the surface of the sea. Several pumps 8 can be installed over the entire distance which even act parallel in order to establish a redundancy. As soon as the pressure within that pipe 6,7 and hence in the room within the support structure 4 is dropped to a pressure lower than the pressure acting outside of the foil and structure, the foil 1 is being pressed with enormous forces to the sea bottom and also the support structure 4 is being pressed onto the sea bottom since the hydrostatic pressure of the sea water will cause that pressing force. If the pressure within the support structure 4 and underneath the foil 1 is merely lowered at around 0.5 bar, the pressure which then acts from outside is about 50 kN/m² and this pressure causes the foil 1 to be pressed to the sea bottom and the pressure also acts on the plates 17 which enclose the entire support structure 4. This will keep the structure 4 and adjacent foil 1 in place no matter what happens. The foil 1 and support structure 4 will even resist substantial underground streams. The foil 1 is likewise pressed onto the sea bottom 10 and hence follows the form and shape of its surface. Even if some water is leaking from the outer edge underneath the foil 1 toward its center, the force which does press the foil 1 onto the sea bottom is substantial, although it does slightly decrease toward the outer edge of the foil 1. At all times the pressure within the support structure 4 and underneath the foil 1 will be kept lower than the outside acting water pressure. This will cause the entire installation to rest absolutely stable on the sea bottom.

In FIG. 2, the support structure 4 on the sea bottom 10 is shown in a perspective view. Reinforcement struts 20 or bars are welded into the lower side of the bearing support 4 in order to strengthen its load capacity and in order to provide a support structure for the steel plates 17 to be fixed around the support structure 4 so they will completely enclose it and ultimately form the outer side of the structure. The lower edge of the steel plates 17 will be positioned approx. 0.5 m to 1.5 m above sea ground 10 so it will not touch it even if the sea bottom is uneven. The foil 1 will be connected tightly to the lower edge of the steel plates 17 and from there extend on to the surrounding sea bottom 10. On the top of the structure, the neck 21 is shown which does communicate with the inner side of the support structure 4.

In FIG. 3, further details of the support structure 4 and foil 1 are being shown. The structure 4 may be equipped with an electrical heating installation 30 in order to keep the seawater which is mixing with the spilled oil warm enough for pumping. On the lower edge 33 of the steel plates 17, the foil 1 is tightly attached. This is shown here on the left side of the structure by way of example. As shonw in the respective enlarged view, a clamping device 35 holds a steel plate 32 which is slightly bent upwards. Along the lower surface of this steel plate 32, the foil 1 will smoothly adapt when the entire structure and attached foil will be lowered down onto the sea bottom as will be explained later. Underneath this bent steel plate 32, there is a flexible deflecting steel plate 31 which is bent toward the sea bottom. Between these two steel plates 31,32, the reinforced foil 1 is clamped by the clamping device 35 and thereby securely attached to the structure 4. When the structure 4 is lowered from a ship down to the sea bottom, the surrounding flexible steel plates 31 adapt to the uneven sea bottom and there outer edge will lay on the sea bottom. The outer edge of the foil 1 is attached to a frame 5 made of strong steel pipes or profiles. This frame 5 forms a circle with a radius of approx. 10 meters, or a square, triangle or rectangle with a side length of approx. 20 meters around the entire support structure 4 and the attached foil 1 and keeps the foil 1 stretched at all times.

In FIG. 4, the support structure 4, foil 1 and the surrounding frame 5 are shown from above, laying on the sea bottom. The corners of the frame 5 are stabilized by cables 36 which are attached to concrete blocks 34 positioned on the sea bottom. Further blocks 18 can be put onto the edge of the foil 1. In FIG. 5, the connection of the pumping pipe 6 with the top of the foil 1 on the support structure 4 or support structure is shown. The neck 21 comes through the steel plate 17 on top of the structure 4. A conical connecting piece 16 is put over the neck 21 and will be sucked onto the steel plate 17 once the pressure within the support structure 4 is lower than the outside pressure of the seawater. The connecting piece is followed by a pipe with a flange 14 at its end. To this flange 14, another one is fixed which is connected to a strong rubber bellow 15 which provides a certain flexibility. This rubber bellow pipe 15 may have a steel spring in its interior in order to withstand the pressure difference between outside and inside. The pumping pipe 6 is connected to the upper flange 13 of the rubber bellow 15. The pumping pipe 6 can therefore move a certain distance in any direction and also its direction may vary from the straight upward direction. This pumping pipe 6 may be equipped with electrical heating means, e.g. a heating coil surrounding the pipe 6 over the initial section in order to prevent a freezing of the pumped liquids due to the lowered pressure and the low temperature of the surrounding sea water.

FIG. 6 does show in a schematic view how the reinforced foil 1 with the support structure 4 being attached to it is brought down onto the sea bottom. Typically, three or even four or more ships are being used which do cooperate with each other. They are equipped with winches with long steel cables 22. The ends of these steel cables 22 are fixed to the frame 5 with the reinforced foil 1 attached to it and the entire installation will be lowered down within the sea in a generally horizontal position. Therefore the ships must pull their cables radially away from a definite center and contemporarily lowering their cables from their winches. A strong steel cable 24 may be used as a guiding cable so the structure 4 hanging on the foil 1 will be directed to the spilling spot on the sea bottom. The cable 24 hangs on a swimmer 23 and the edge of the hole 25 in the structure 4 is made of a strong steel ring in order to prevent the structure 4 to be damaged. At the lower end, the cable 24 is fixed on a concrete block that has been positioned in advance. Therefore, the structure 4 and foil 1 will be perfectly guided with the central hole 25 of the structure. Once, the structure 4 and foil 1 are positioned on the sea bottom, the pumping pipe will be directed with its conical connecting piece 16 over the neck 21. Then, the pumping can start which will help cause the foil 1 to be sucked tightly around the support structure 4 and onto the sea bottom. The pumping pipe 6 and its connecting piece may likewise be put over the neck 21 by using guiding cables which are fixed on top of the support structure 4.

FIG. 7 shows an alternate way to bring down the support structure 4 and the foil 1. Four or even more ships are being used which do cooperate with each other. They first lower down heavy weights 27 hanging on a loose roll 28. This weights may be concrete blocks 27 of several tons of weight. These weights 27 are being positioned exactly around the spot where the support structure 4 needs to be positioned on the sea bottom 10. They then have a definite distance from that selected spot. Once the weights 27 are in position, the cables 29 going around the loose rolls 28 on the weights 27 will serve as guiding cables for lowering down the support structure 4 and the foil 1. E.g. for such weights and guiding strings can be used, or even more which are positioned overhead the edge of the foil 1 when it is finally down on the bottom of the sea. The support structure 4 can fixed to the foil 1 so it will furtheron hang on the center of the foil 1. The connection to the pumping pipe 6 is then already established. The foil 1 can then be lowered down, contemporarily with the support structure 4 hanging on it. One pipe piece of the pumping pipe after the other will be installed as the lowering down proceeds. The frame 5 around the foil 1 is attached via holding elements which are fixed on the cables 29 of each guiding string. By this, the foil 1 can be held almost horizontal and stretched and can be lowered down in completely controlled manner. This also facilitates the task to bring the support structure 4 exactly over the leaking pipe on the sea bottom since the foil and the support structure 4 are precisely guided along the stretched vertical cables 29 going down do definite points. Once the support structure 4 is close to the leaking spot, e.g. several meters, the pumps are activated and start to pump liquid from the interior of the support structure. Once the support structure 4 is layed onto the sea bottom and finds a definite stand, the foil 1 is completely lowered down on the sea bottom as well and the pumping out of liquid through the top neck of the support structure 4, the foil 1 will be tightly sucked to the outer surface of the support structure and also to the surrounding sea bottom.

Once the pumps are active, the pressure in the interior of the support structure 4 and underneath the foil 1 will at all times be kept lower than the outside water pressure. This will keep the structure and foil 1 in place and the oil is being sucked out of the created hollow room and pumped to the surface. A further spilling of oil into the sea water is prevented and time is gained for bringing release borings down and eventually shut down the well in a conventionally and approved manner.

Claims

1-13. (canceled)

14. A method for pumping away the oil in the aftermath of a blow out in an offshore oil well, comprising the steps of:

putting an installation made of a support structure with an enclosure and an attached reinforced foil extending horizontally into its surrounding, over a leaking oil well or pipe;

pumping water and oil out of an interior of the support structure for creating an underpressure underneath support structure and the covering foil, so that the support structure and the foil will be pressed onto the sea bottom due to hydrostatic pressure of outside water;

continuously pumping away liquid from the interior of the support structure, and therefore from below the foil, until it is pure crude oil; and,

collecting the pure crude oil in a tank ship.

15. A method for pumping away the oil in the aftermath of a blow out in an offshore oil well according to claim 14, further comprising the steps of

putting a weight block on a guiding string on the leaking oil well or pipe for serving as a guide for lowering an installation down onto the sea bottom;

lowering the installation made of a support structure with enclosure and an attached reinforced foil extending horizontally to a frame over the leaking oil well or pipe along the guiding string by at least three ships with the frame, foil and support structure hanging on steel cables attached to the frame, while the cables come from winches installed on the ships, while the ships pull in a radial direction from a center overhead the support structure on the sea bottom, and the support structure being guided by at least one guiding cable fixed on a weight block on the sea bottom and hanging on a swimmer;

putting the pumping pipe with its conical connecting piece over the neck on the support structure and then pumping water and oil through the top of support structure and from underneath the reinforced foil for creating an underpressure underneath the foil, so the foil will be pressed onto the sea bottom due to hydrostatic pressure of the outside water; and,

continuously pumping away the liquid from the interior of the support structure, and therefore from below the foil, until the oil well pipe is blocked.

16. The method for pumping away the oil in the aftermath of a blow out in an offshore oil well according to claim 14, wherein the lowering of the frame, the foil with the support structure and the connecting of the pumping pipe is enabled by guiding cables stretched between the weight block and a swimmer on top of the sea along by which the entire installation and the pumping pipe are being guided when lowered down and until put in operation.

17. A method for pumping away the oil in the aftermath of a blow out in an offshore oil well, comprising the steps of:

putting a support structure with an enclosure and a reinforced foil attached to its lower edge and with the foil being surrounded by a frame to which it is fixed, over the leaking oil well or pipe, so that the support structure and the foil with its frame are lowered downwardly contemporarily along at least one guiding string leading to a weight positioned on a sea bottom;

pumping water and oil through the reinforced foil for creating an underpressure underneath the foil, so the foil will be pressed onto the support structure and the sea bottom due to hydrostatic pressure of the outside water; and,

continuously pumping away liquid from an interior of the support structure, and therefore from below the foil, until it is pure crude oil; and,

collecting the pure crude oil in a tank ship.

18. The method for pumping away the oil in the aftermath of a blow out in an offshore oil well according to claim 17, wherein the lowering of the frame, the foil with the support structure and the connecting of the pumping pipe is enabled by guiding cables stretched between the weight block and a swimmer on top of the sea along by which the entire installation and the pumping pipe are being guided when lowered down and until put in operation.

19. An apparatus for pumping away oil in the aftermath of a blow out in an offshore oil well, comprising:

a support structure with an enclosure for providing a hollow room overhead a leaking spot or oil pipe;

a reinforced foil extending at least ten meters into a surrounding of the support structure and attached to a lower edge of the enclosure of the support structure; and,

a pumping pipe connectable to a top of the support structure for pumping liquid from within the support structure and a lower side of the foil.

20. The apparatus for pumping away the oil in the aftermath of a blow out in an offshore oil well according to claim 19, wherein the support structure is enclosed with an enclosure made of steel plates, the steel plates being fixed on the support structure and on a plurality of struts for reinforcing the support structure and providing a structure for fixing said steel plates.

21. The apparatus for pumping away the oil in the aftermath of a blow out in an offshore oil well according to claim 19, wherein the support structure has at least three legs with each leg of the at least three legs being equipped with a swivel-able foot.

22. The apparatus for pumping away the oil in the aftermath of a blow out in an offshore oil well according to claim 19, wherein the support structure is equipped with a neck extending upwards from its top for establishing a connection to a pumping pipe.

23. The apparatus for pumping away the oil in the aftermath of a blow out in an offshore oil well according to claim 19, wherein the reinforced foil has a circular shape and is made of a steel- or carbon-fiber reinforced plastic foil.

24. The apparatus for pumping away the oil in the aftermath of a blow out in an offshore oil well according to claim 19, wherein the reinforced foil has a square shape and is made of a steel- or carbon-fiber reinforced plastic foil.

25. The apparatus for pumping away the oil in the aftermath of a blow out in an offshore oil well according to claim 19, wherein the reinforced foil is a steel- or carbon-fiber reinforced plastic foil with a further reinforced edge and a frame surrounding the foil and on which said frame, an outer edge of the foil is securely attached to said frame.

26. The apparatus for pumping away the oil in the aftermath of a blow out in an offshore oil well according to claim 19, wherein a lower edge the enclosure of the support structure is equipped with clamping devices for clamping a steel plate extending horizontally from the support structure and being bent upwards, and for further clamping flexible steel plates bent downwards for adapting to a sea bottom, and between said flexible steel plates, for clamping the reinforced foil.

27. The apparatus for pumping away the oil in the aftermath of a blow out in an offshore oil well according to claim 19, wherein the pumping pipe is equipped on its lower end with a flexible reinforced rubber bellow pipe for a flexible connection to a neck on the support structure, and is further equipped with a heater for preventing a freezing of pumped liquid.

28. The apparatus for pumping away the oil in the aftermath of a blow out in an offshore oil well according to claim 19, wherein the interior of the support structure is equipped with an electrical heating installation.