Apparatus and Method for Containment of Well Fluids from a Subsea Well Fluid Leak

Abstract

Apparatus and method for containment of well fluids flowing from a subsea well fluid leak feature a containment structure positioned over the well blowout, and an elongated collection conduit supported with an upper end exposed to atmospheric pressure above sea level and a lower end in fluid communication with surrounding sea water over an upper opening of the containment structure. Collected well fluid rises in the elongated conduit due to a lower specific gravity of the well fluid relative to the sea water, and is discharged from the elongated conduit at a location above sea level to a receiving vessel. The open piping system allows for easier installation of the separate containment system and collection conduit, and allows sea water to be displaced from the open lower end of the conduit above the containment structure under filling of the conduit with rising well fluid.

Description

FIELD OF THE INVENTION

The present invention relates to containment or recovery of fluids escaping a subsea well blowout or leak.

BACKGROUND OF THE INVENTION

The recent occurrence of a major oil spill on Apr. 20, 2010 following an explosion on the “Deep Water Horizon” well has demonstrated a significant need for an effective containment means for dealing with such potentially disastrous subsea well blowouts.

Regarding this particular event, the defective Blowout Preventer (BOP) is at the sea floor at approximately 5000 feet deep. Within a week or two of the explosion, BP built a 100-ton containment house dome and lowered it over top of the largest of three pipe ruptures to try and capture the oil as it exited from a leaking 21-inch diameter pipe. At the top of this dome, they had installed a 12-inch pipe so that they could suck the oil up unto a waiting tanker at the top. It will be appreciated that any information presented herein on this particular event, including dimensions and equipment/operation details, are based on Applicant's best understanding based on information presented in various media reports, and therefore cannot be guaranteed to be 100% accurate.

This plan failed, perhaps at least in part due to the following issues pondered by the Applicant.

Firstly, apparently methane clathrate crystals formed, plugging the 12-inch hole and making the 100-ton dome buoyant. Even if those crystals hadn't formed, it is difficult to imagine how the oil could be sucked out fast enough from a 12-inch pipe at a rate equal to or exceeding the oil entering the containment dome through the 21-inch pipe under high pressure. The negative pressure to suck the oil up could only be one atmosphere maximum or approximately 14.7 psi reduced pressure at the suction end.

Secondly, if these methane crystals did form, it would have been due to the cold water and pressure at the sea bed. This temperature would be approximately 2° C. to 10° C. and difficult to heat under a closed piping system.

Applicant has designed a unique solution to address the ongoing spill and which may accordingly be similarly applied to future subsea blowouts or leaks.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided an apparatus for containment of well fluids flowing from a subsea well blowout, the apparatus comprising:

• • a containment structure comprising a hollow interior space having upper and lower openings at top and bottom ends of the hollow interior space, the lower opening being larger than the upper opening and being positioned over the well blowout to receive well fluid therefrom;
  • an elongated collection conduit supported with an upper end thereof at an elevation above sea level and a lower end thereof submerged at a position over the upper opening of the containment structure to receive well fluid passing upward through the containment structure, the upper end of the collection conduit being exposed to atmospheric pressure and the lower end of the collection conduit being in fluid communication with sea water surrounding the containment structure and the collection conduit;
  • a discharge conduit having an inlet end thereof connected to the elongated conduit at a position between the sea level and the upper end of the elongate conduit to fluidly communicate with a buildup of well fluids above sea level; and
  • a receiving vessel at an outlet end of the discharge conduit opposite the inlet end thereof.

Preferably the lower end of the collection conduit is open to the sea water surrounding the containment structure and the collection conduit at a location above the lower opening of the containment structure.

Preferably the containment structure comprises a hollow neck extending upward from the upper opening of the interior space of the containment structure, the hollow neck being of smaller diameter than the collection conduit and extending upward thereinto through the lower end thereof, leaving an annular space at least partially open between the hollow neck and the lower end of the collection conduit to fluidly communicate the collection conduit with the sea water through said annular space.

Preferably there are provided supports projecting externally from the hollow neck at circumferentially spaced positions thereabout to define a seat upon which the lower end of the collection conduit rests.

Preferably there is provided a control valve installed on the discharge conduit and operable control a rate at which well fluids are drawn off from the buildup thereof above sea level.

The outlet end of the discharge conduit may be positioned at an elevation below the inlet end thereof for gravity fed flow of well fluids through the discharge conduit to the collection vessel.

Alternatively, a discharge pump may be installed on the discharge conduit and operable to pump well fluids through the discharge conduit to the collection chamber.

There may be provided a fluid circulation line extending downwardly inside the collection conduit to proximate the upper opening of the containment structure and a circulation pump operable to convey warming fluid down toward the upper opening of the containment structure through the fluid circulation line.

The fluid circulation line may be open at a bottom portion thereof within the containment structure.

In such instance, preferably there is provided a circulation outlet pump on an outlet line connected to the collection conduit below the sea level, the outlet line being selectively openable to the collection conduit for operation of the circulation output pump to extract the warming fluid therefrom.

Preferably an inlet of the fluid circulation line draws from warm sea water proximate sea level under operation of the fluid circulation pump. Preferably the outlet line discharges the warming fluid to sea.

According to a second aspect of the invention there is provided a method for containment of well fluids flowing from a subsea well blowout, the method comprising:

• • (a) positioning an elongated collection conduit with an upper end thereof open to atmospheric pressure at an elevation above sea level and a lower end of the collection conduit at a submerged position receiving well fluid from the blowout;
  • (b) allowing well fluid to pass upward through sea water in the elongated conduit to a surface of the sea water under a rising effect provided by a lower specific gravity of the well fluid relative to the sea water;
  • (c) discharging collected well fluid from the elongated conduit at a location above sea level; and
  • (d) receiving the well fluid discharged from the elongated conduit at a receiving vessel.

Preferably step (a) comprises positioning a bottom opening of a hollow containment structure over the blowout and positioning the lower end of the collection conduit over a top opening of an interior space of the hollow containment structure, the top opening of the interior space being smaller than the bottom opening of the containment structure.

Preferably step (a) comprises leaving the lower end of the collection conduit open to sea water outside the hollow containment structure.

Preferably step (a) comprises positioning the lower end of the collection conduit around a hollow neck of the containment structure that projects upward from the upper opening of the interior space thereof into the collection conduit, and leaving an annular space between the hollow neck and the collection conduit at least partly open.

Preferably step (a) comprises first positioning the hollow containment structure and then lowering the collection conduit into place.

Preferably step (a) comprises seating the lower end of the collection conduit on the containment structure.

Steps (c) and (d) may comprise gravity draining well fluid from the collection conduit to the vessel.

Alternatively, steps (c) and (d) may comprise pumping well fluid from the collection conduit to the vessel.

Preferably step (b) comprises allowing a buildup of well fluid to form atop the surface of the sea water before discharging the collected well fluid in step (c).

The method may include pumping warm fluid downward through a circulation line in the collection conduit to provide heating proximate the lower end of the collection conduit.

The warm fluid preferably comprises sea surface water pumped from proximate the surface of the sea water.

Alternatively, in employment of the invention in colder climates a different method of heating the containment structure and collection conduit may be employed, since warm surface water is not available in such applications.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which illustrate exemplary embodiments of the present invention:

FIG. 1 is a schematic illustration of an apparatus for containment of a subsea blowout at a deepwater well, in which an open system conduit extends from a dome placed over the blowout to the surface to allow the less dense oil to rise to the surface through the column of water in the conduit, where the buildup of oil can be drained away to a suitable vessel for transport from the spill site.

FIG. 2 is a schematic illustration of the apparatus of FIG. 1 featuring the addition of a circulation line through which warm surface water is pumped down through the open system conduit toward the open top of the dome to prevent crystal formation from blocking the conduit.

DETAILED DESCRIPTION

The present invention is designed to contain oil from a subsea blowout as it exits from the leaking pipe or equipment at the sea bed. The solution includes two primary parts in order to deal with this containment problem.

The first part is illustrated in FIG. 1 and essentially deals with how to capture and contain the oil using a containment dome and upright collection conduit or vertical riser extending therefrom.

The second part is illustrated in FIG. 2 and deals with warming the containment dome and vertical riser if required to deal with or prevent methane clathrate crystals, should the conditions for their occurrence be present. This may be unlikely during use of a preferably sufficiently large pipe for the collection conduit, but a strategy is nonetheless considered by the Applicant in case this still poses a problem.

Referring to FIG. 1, a containment dome 12 is a hollow structure featuring peripheral wall sections 14 closing around a central axis of the structure, and an upward tapering domed or inverted funnel-like cover 16 fixed atop the peripheral wall to narrow the hollow interior space of the dome 12 from a larger diameter at the peripheral wall to a smaller diameter at the top of the cover, where a central opening is disposed at what would otherwise be the peak of the cover. The open bottom of the containment dome 12, bound by the peripheral wall sections 14 thereof, is seated on the sea bed around the rupture from which the oil is leaking so that the oil spills into the hollow interior of the containment dome through the open bottom thereof. The dome is to be positioned above the leak in a manner suitable to capture as much oil as possible, which may or may not be accomplished by seating on the sea floor depending on the type and location of leaking equipment. For example, in other situations, it may be more appropriate to suspend the dome at a height above the sea bed to capture leakage from a ruptured point upward therefrom.

A pipe fixed atop the cover 16 of the containment dome 12 around the central opening in the cover projects upward therefrom to form a neck-like hollow extension 18 communicating with the containment dome's hollow interior space beneath the cover 16. The extension extends vertically upward from the cover 16 on the central axis of the containment structure and is open at its top end.

After placement of the containment dome 12 above the leak, a length of piping of inner diameter greater than the outer diameter of the neck-like extension 18 of the containment dome 12 is lowered into the sea from the surface to form a collection conduit 20 from the containment dome 12 to the surface. The open bottom end of the collection conduit 20 is lowered over the top end of the neck-like extension 18 to sit atop a series of external projections 22 provided on the neck 18 at positions spaced around the circumference thereof to project radially outward therefrom. These projections 22 are positioned nearer the cover 16 of the containment dome 12 than the upper end of the neck 18 so that the neck's length lies substantially within the collection conduit 20. Except at the spaced apart projections 22, an annulus between the neck 18 and the conduit 20 is left open at the bottom end of the collection conduit 20 to communicate with the sea water externally surrounding the containment dome 12 and the collection conduit 20.

The top end of the collection conduit 20 is disposed well above the sea level surface and is left open to the atmosphere to cooperate with the open bottom of the conduit to define an open system conduit extending from the containment dome 12 to above the surface. During lowering of the collection conduit 20 onto the containment dome 12, sea water occupies the conduit from the open lower end thereof up to the sea level surface. Once the collection conduit is in place, the oil from the leak flows upward through the containment dome 12 and into the collection conduit 20 via the neck 18 of the dome. The lower density of the oil relative to the sea water causes the oil to automatically rise through the vertical column of water in the collection conduit up to the surface

At an elevation above the water's surface, an oil discharge line or conduit 24 connects to the collection conduit 20 to fluidly communicate therewith. A control valve 26 installed on the discharge line 24 is operable to control a degree of opening and closing of the discharge line 24. When oil rising through the collection conduit 20 has built up above the sea level surface in an amount sufficient to at least reach the discharge line 24, the control valve 26 is in an open state and thus allows the oil to pass through the discharge line 24 and into a vessel 28 positioned at the outlet of the discharge conduit 24 to receive the collected oil therefrom. The annular space between the two pipes forming the containment structure neck 18 and the collection conduit 20 is dimensioned to be large enough in area to handle all the water being downwardly displaced from the collection conduit by rising oil introduced to the system from the leak during this initial stage of building up oil at a top portion of the subsea column to build up to the draw-off level of the discharge conduit.

The vessel is preferably provided in the form of a ship or other transportable vessel that can be used to transport the received oil away from the offshore site. In the illustrated embodiment, the discharge conduit 24 is gravity operated, with its outlet end disposed at a lower elevation that its connection to the collection conduit 20 so that oil built up in the collection conduit to the discharge conduit will automatically drain therethrough to the vessel. Other embodiments may employ a discharge pump on the discharge conduit to pump collected oil to the receiving vessel.

Should temperatures and pressures at the containment dome 12 or lower portions of the collection conduit 20 be such that methane clathrate crystals form to an extent plugging the flow to the surface, even where large piping is used with the intention of avoiding such problems, then extra measures can be taken to prevent or alleviate such plugging, as now will be described with reference to FIG. 2.

Turning to FIG. 2, a fluid circulation line 30 has an inlet 30a disposed within the sea water a shod distance below the surface thereof, and has a pump 32 installed on the line to draw warm surface water into the line through the inlet and pump it onward through the line into the collection conduit 20, for example through the open top end thereof disposed above sea level. The circulation line 30 passes downward through the collection conduit 20 to proximate the lower end thereof, and in the illustrated embodiment, slightly past the bottom end of the collection conduit 20 so as to depend into the interior space of the containment dome 12. A lower end portion of the circulation line 30 is open at one or more locations therealong.

Should a heating function be required to remove or prevent crystal plugging of the upper opening of the dome's interior space or the dome's extension neck, the circulation line is run into the collection conduit (if not having been previously deployed or installed therein), a circulation shut-off valve 34 on the circulation line is opened, and the circulation pump 32 is activated to pump the warm surface water through the circulation line down to the bottom of the collection conduit 20, where this warmer water exits the circulation and provides heat to remove or prevent crystal formation at these narrowest points in the flow passage from the blowout to the surface through the containment dome and collection conduit.

While this warm water is being pumped in to remove a plug, simultaneously a circulation outlet pump 36 on an outlet line 38 connected to the collection conduit a short distance below the seal level surface may be operated with a shut-off valve 40 on this line opened in order to pump sea water out of the collection conduit (the collection conduit containing only sea water at this point in time due to the plugging of further oil flow through the system due to the plugging at the containment dome) and back to the sea at a significant distance from the circulation line inlet 30a. The circulation pumps thus keep circulating a fresh supply of warm surface water through the open system to warm the interior of the collection conduit 20 to remove any clogging thereof. When the circulation is not required, the circulation pumps 32, 36 are shut down and shut off valves 34, 40 on the circulation lines are closed.

The use of an open piping system above the dome between the two sizes of pipes presents advantages over known subsea containment systems employing a dome or inverted funnel coupled to an above surface receiving or processing vessel by a closed piping system.

At the start of the operation, as leaking oil gets added in the vertical riser pipe, sea water in the riser pipe has to be displaced. If the riser or collector pipe was to be solidly connected to the dome in a closed fashion, this displaced water would have to be released below the dome, forcing oil in the dome downwards in the dome and causing the oil to escape to the sea. With the system having the riser pipe open to the sea above the dome, water is allowed to leave the riser pipe column via the space between the two pipes and oil should not escape at all. This opening always allows the vertical column pressure to equalize with the sea irrespective of how much oil is entering the column and irrespective of how much oil is removed at the top of the column.

Another advantage to this system is that the dome can be lowered and put in place completely separate from the vertical column pipe, potentially making the installation much easier from the top. This way, it may be that no work has to take place at the bottom of the sea.

Furthermore, if for some reason, a miscalculation of the amount of oil and gas flow coming out was made, causing the neck of the dome to be undersized, or if methane clathrate crystals formed due to temperature or pressure, this problem would be obvious as soon as the dome is put in place, and remedial steps could be taken prior to manufacturing and installing the long vertical pipe column.

As an example of how the present invention may be implemented, the installation and use of the apparatus is now described as follows in terms of the spill at the Deepwater Horizon location in the Gulf of Mexico. The dimensions used in the following description are exemplary only, and are not intended to limit the scope of the present invention, nor even limit dimensions that will result in a functional embodiment in this particular exemplary context. All pipe sizes shown may be increased in size or even reduced to deal with larger spills depending on anticipated flows.

Part A (FIG. 1)

• • 1—Raise the existing 100-ton containment dome to the top surface and equip it with a much larger pipe at the top to replace the 12-inch pipe that is there and define the neck-like extension of the above described containment dome. This steel pipe may be approximately 36 inches diameter, which presents approximately 9 times the flow area of the 12-inch pipe and 3 times the area of the 21-inch ruptured pipe. This new 36-inch pipe could protrude approximately 30 feet above the top of the dome. At a short height above the top of the dome, for example approximately 5 feet, pieces of steel would be welded to the four exterior sides of the 36-inch pipe to project outward therefrom. A larger pipe to be slipped over the 36-inch pipe to define the collection conduit could therefore rest on these four welded pieces of steel. This allows the vertical piping to be an open piping system rather than a closed piping system, while still preventing the oil from escaping downwards through the cavity between the two pipes. In this way, the pressures on the exterior and interior of all piping remain in balance facilitating greatly the implementation of strategies without concerns of high pressures.
  • 2—The dome can now be lowered over top the leak to observe if the oil exits through the top of the 36-inch pipe. If it does, than the rest of the plan should work successfully without having to implement the additional fluid-circulation part of FIG. 2, meaning that crystals have not formed and the oil can simply rise through the pipe due to a lighter specific gravity than the sea water's specific gravity, which is approximately 1.025.
  • 3—A larger piece of pipe with an inner diameter larger than the outer diameter of the 36-inch pipe, for example approximately 4 inches larger or another possibly greater size large enough to handle the expected rate of water displaced downward by rising oil leakage flow when collected oil is not being drawn off above the surface, is manufactured and slipped over top of the 36-inch pipe to rest on the welded steel pieces mentioned in item 1 above. This larger pipe would extend from the top of the containment dome to the sea surface to define the collection conduit. As examples, this pipe could be a steel pipe, or even PVC pipe to make it easier to fabricate. A PVC pipe can easily be welded at 20 ft. intervals with PVC cement glue. For example, 200 ft. of steel pipe could be used for the lower portion of the conduit, and the rest could be PVC pipe. Due to the ocean currents which may pull the pipe sideways though, such PVC pipe may need to be encircled with steel cables which are used to lower the steel pipe to the bottom and hold it from falling. This way, there is sufficient weight from the steel pipe to keep the lowering cables tight to keep the vertical PVC pipe straight and upright. If no crystals were formed as mentioned in item 2 above, the oil should simply rise to the surface.
  • 4—With oil rising to the surface naturally because of its lower specific gravity, the larger pipe would need to extend a considerable distance above the sea surface, for example to approximately 50 feet. A pipe with a control valve would be connected to this larger vertical pipe above the sea surface, for example by some 30 ft., to act as the discharge conduit capturing the rising oil and allowing it to simply flow to a waiting tanker vessel via gravity or pump suction. Due to the upward force of the weight of the water at the bottom of the sea entering the open piping system at the bottom and pushing up the oil, a column of oil and water results in this larger pipe. The oil will rise to the upper portion of the column and extend at a fairly great distance above the sea surface. For example, from initial calculation based on an assumed oil specific gravity of 0.90, maintaining a top oil-filled portion of the below-sea-surface column as 6% of the overall column height after allowing sufficient initial oil flow to reach this buildup of oil before opening the discharge conduit will result in the oil rising approximately 42 ft. above the surface of the sea due to the heavier sea water pushing it up in the column. By controlling the rate of oil that exits this vertical collection pipe via the control valve on the discharge pipe, the amount of oil in the column is controlled as a percentage of the sea water in the column. This balance can be achieved by simply using a level controller and sensor to control the oil outlet valve to maintain a constant oil level in the vertical riser.

Part B (FIG. 2)

• • 5—If the oil doesn't come through due to crystals forming, even though this may be very unlikely due to the relatively large size used in this example, then warming of the water inside the containment dome to a higher temperature can be employed to address this issue. Apparently, crystals have never been observed to form above approximately 10° C. at the seabed pressure. Fortunately, there is a virtually infinite supply of warm water at the sea surface. The water temperature at this time of year in the region concerned is approximately 30° C. By pumping this warm sea water to the bottom through a smaller pipe, for example 6 or 8-inch diameter lowered inside the larger 42-inch pipe, and at the same time pumping out sea water from this larger vertical pipe at the top portion thereof at a level near the sea surface, for example about 10 ft. below, and just simply pumping this water back to the sea; the water inside the containment dome and the vertical riser pipe can be warmed up significantly. It is estimated that pumping at a rate of approximately 1,000 usgpm, it would take about 6 hours to completely change the water in this larger vertical pipe, meaning that now the temperature inside the containment dome and the vertical riser pipe may approach somewhere between 20° C. (due to heat losses in the pipe) and 30° C. PVC pipe would lessen this temperature loss as compared to steel pipe. As schematically shown in FIG. 2, this warm supply pipe may be capped at the bottom with drilled holes in the pipe sides in the bottom 30 feet of piping. Water would escape at this drilled bottom portion of this warm supply pipe to heat the dome and vertical riser pipe. This allows a free exchange of warm sea water throughout the vertical column without having cold water come in from the bottom of the pipe. This would enable the oil to rise to the surface and all water pumping would cease once the oil comes up the vertical riser column and arrives at the top.
  • 6—This containment process can be maintained indefinitely until the well can be plugged permanently via the extra intercepting well that BP is presently working on, which will take about three months from the start of drilling operations. Other leaks can be contained in the same manner. As well, for future drilling, this approach can be repeated as many times as needed and provide the oil industry and the government a new and a rather foul proof way of containing spills without having to try and work at ocean depths to contain spills. This approach also uses basic physics and mechanics that doesn't depend on sophisticated technology and is therefore very reliable. The approach makes it easy for the public and various politicians to understand and approve the ultimate back-up plan. Equipment could be built early and stored for use in case of emergencies arising from similar spills in the future.

While the illustrated embodiment is left entirely open to the atmosphere at the top end of the collection conduit piping above sea level, it will be appreciated that methane and other gases may be given off at this open top end of the system, and alternate embodiments may additionally feature equipment for capturing, flaring or burning such released gases while maintaining an open conduit system that is exposed to atmospheric pressure above sea level. Also, while having the system open at the transition between the collection conduit and the containment structure has advantages, other embodiments may alternatively have the bottom “opening” of instead formed by open space left between the sea bed and parts of the containment dome wall sections supported thereon.

Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.

Claims

1. An apparatus for containment of well fluids flowing from a subsea well fluid leak, the apparatus comprising: a containment structure comprising a hollow interior space having upper and lower openings at top and bottom ends of the hollow interior space, the lower opening being larger than the upper opening and being positioned over the well blowout to receive well fluid therefrom;an elongated collection conduit supported with an upper end thereof at an elevation above sea level and a lower end thereof submerged at a position over the upper opening of the containment structure to receive well fluid passing upward through the containment structure, the upper end of the collection conduit being exposed to atmospheric pressure and the lower end of the collection conduit being in fluid communication with sea water surrounding the containment structure and the collection conduit;a discharge conduit having an inlet end thereof connected to the elongated conduit at a position between the sea level and the upper end of the elongate conduit to fluidly communicate with a buildup of well fluids above sea level; anda receiving vessel at an outlet end of the discharge conduit opposite the inlet end thereof.

2. The apparatus of claim 1 wherein the lower end of the collection conduit is open to the sea water surrounding the containment structure and the collection conduit at a location above the lower opening of the containment structure.

3. The apparatus of claim 1 wherein the containment structure comprises a hollow neck extending upward from the upper opening of the interior space of the containment structure, the hollow neck being of smaller diameter than the collection conduit and extending upward thereinto through the lower end thereof, leaving an annular space at least partially open between the hollow neck and the lower end of the collection conduit to fluidly communicate the collection conduit with the sea water through said annular space.

4. The apparatus of claim 3 comprising supports projecting externally from the hollow neck at circumferentially spaced positions thereabout to define a seat upon which the lower end of the collection conduit rests.

5. The apparatus of claim 1 comprising a control valve installed on the discharge conduit and operable control a rate at which well fluids are drawn off from the buildup thereof above sea level.

6. The apparatus of claim 1 further comprising a fluid circulation line extending downwardly inside the collection conduit to proximate the upper opening of the containment structure and a circulation pump operable to convey warming fluid down toward the upper opening of the containment structure through the fluid circulation line.

7. The apparatus of claim 6 wherein the fluid circulation line is open at a bottom portion thereof within the containment structure.

8. The apparatus of claim 7 comprising a circulation outlet pump on an outlet line connected to the collection conduit below the sea level, the outlet line being selectively openable to the collection conduit for operation of the circulation output pump to extract the warming fluid therefrom.

9. The apparatus of claim 8 wherein the outlet line discharges the warming fluid to sea.

10. The apparatus of claim 6 wherein an inlet of the fluid circulation line draws from warm sea water proximate sea level under operation of the fluid circulation pump.

11. A method for containment of well fluids flowing from a subsea well fluid leak, the method comprising: (a) positioning an elongated collection conduit with an upper end thereof open to atmospheric pressure at an elevation above sea level and a lower end of the collection conduit at a submerged position receiving well fluid from the blowout;(b) allowing well fluid to pass upward through sea water in the elongated conduit to a surface of the sea water under a rising effect provided by a lower specific gravity of the well fluid relative to the sea water;(c) discharging collected well fluid from the elongated conduit at a location above sea level; and(d) receiving the well fluid discharged from the elongated conduit at a receiving vessel.

12. The method of claim 11 wherein step (a) comprises positioning a bottom opening of a hollow containment structure over the blowout and positioning the lower end of the collection conduit over a top opening of an interior space of the hollow containment structure, the top opening of the interior space being smaller than the bottom opening of the containment structure.

13. The method of claim 1 wherein step (a) comprises leaving the lower end of the collection conduit open to sea water outside the hollow containment structure.

14. The method of claim 11 wherein step (a) comprises positioning the lower end of the collection conduit around a hollow neck of the containment structure that projects upward from the upper opening of the interior space thereof into the collection conduit, and leaving an annular space between the hollow neck and the collection conduit at least party open.

15. The method of claim 11 wherein step (a) comprises first positioning the hollow containment structure and then lowering the collection conduit into place.

16. The method of claim 15 wherein step (a) comprises seating the lower end of the collection conduit on the containment structure.

17. The method of claim 11 wherein step (b) comprises allowing a buildup of well fluid to form atop the surface of the sea water before discharging the collected well fluid in step (c).

18. The method of claim 11 comprising pumping warm fluid downward through a circulation line in the collection conduit to provide heating proximate the lower end of the collection conduit.

19. The method of claim 18 wherein the warm fluid comprises sea surface water pumped from proximate the surface of the sea water.