Abstract:
A blowout containment system is permanently positioned on the wellhead. The blowout containment system is relatively inexpensive, is always available and in place, it does not interfere with normal drilling operations, will capture all of the oil and gas emitted by the blowout, does not require special or unique sea surface or underwater apparatus or vessels, does not have any operational requirements that are different than those which drilling crews normally use and are already familiar, and is activated the using actions are similar to those used by drilling crews for well drilling and completion.

Description:
The present application claims the priority of U.S. Provisional Patent Application Ser. No. 61/353,064 filed Jun. 9, 2010 and U.S. Provisional Patent Application Ser. No. 61/380,178 filed Sep. 3, 2010, which applications are incorporated in their entirety herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to deep water oil well leak containment and in particular to a well-head collapsible enclosure for capturing escaping oil from a deep water well-head leak. 
     Known devices to prevent uncontrolled release of oil into the ocean from underwater well blowouts fall into two categories: a) conical or umbrella-like structures that are lowered from a surface vessel over the blowout, and b) conical or dome-like structures that are permanently installed over the wellhead and that have some means of withdrawing collected oil and gas. None of these devices are permanently deployed in advance of a blowout. 
     These known approaches all have many disadvantages as evidenced by the fact that none of them are in use. Among the more serious drawbacks are difficult if not impossible tasks of positioning a conical, or other structure, over the venting oil and gas plume, failure to contain all or most of the oil, awkward deployment means which often requires specialized support equipment or vessels, obstruction of the wellhead, interference with normal drilling operations, a requirement that the containment apparatus be pre-positioned in a convenient location on land near the drill site or on the drilling platform, a long time delay between well blowout and spill containment, and the need for special training of crews for placement and or operation. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention addresses the above and other needs by providing a blowout containment system permanently positioned at the wellhead. The blowout containment system is relatively inexpensive, is always available and in place, it does not interfere with normal drilling operations, will capture all of the oil and gas emitted by the blowout, does not require special or unique sea surface or underwater apparatus or vessels, does not have any operational requirements that are different than those which drilling crews normally use and are already familiar with, and is activated the using actions are similar to those used by drilling crews for well drilling and completion. 
     In accordance with one aspect of the invention, there is provided a blowout containment system positioned at the wellhead of every undersea drilling site before drilling begins. If a blowout or significant leak occurs and the blowout preventer is unable to contain the escaping oil, with the present invention a means to capture the escaping oil will already be in place at the needed location. The only action required will be to connect loose ends of pre-connected cables to take-up reels aboard a vessel or the drill rig or with a remotely operated vehicle, and to connect relief lines to valves already located on a base cylinder through which the escaping oil and gas can be directed to a manifold and from there to a surface vessel or undersea pipeline. All of these operations are commonplace and routine activities for anyone versed in the art of undersea drilling. 
     In accordance with another aspect of the invention, there is provided an underwater oil well blowout containment device which comprises a set of telescoping steel cylinders attached at the bottom to a heavy steel anchor ring. At the top, the innermost cylinder or alternatively the outermost is attached to closing apparatus. During deployment and normal drilling operations the blowout containment device is collapsed leaving the entire center area of the wellhead free of obstructions. 
     In accordance with yet another aspect of the invention, there is provided closure apparatus comprising an iris valve or clamshell closure for closing the top of the blowout containment device. The Iris valve may be attached to the innermost cylinder of a telescoping cylindrical containment device, and the clamshell device to the outermost cylinder. The iris valve comprises a number of overlapping heavy steel blades which operate in unison to open or close the opening at the top of the blowout containment device, similar in concept to a camera iris. During deployment and normal drilling operations, the blades are swung completely open to a rest position over the collapsed blowout containment device in an annular configuration. The inner diameter of the open iris is approximately equal to the inner diameter of the innermost cylinder, leaving the entire center area free of obstructions. 
     In accordance with still another aspect of the invention, the collapsed height of the concentric cylinders is less than the height of the valves and fittings on the BlowOut Preventer (BOP) so that normal drilling operations are not hindered. 
     In accordance with another aspect of the invention, either the outer cylinder or the inner cylinder, which is rigidly attached to a heavy anchor ring base, is stationary. Additional cylinders are nested within the outer cylinder or outside the inner cylinder. All the additional cylinders are able to move upward when spill containment is required, and at full extension reach a height greater than the top of the BOP. In this configuration the cylinders form a steel wall surrounding the wellhead and BOP. 
     In accordance with still another aspect of the invention, lifting eyes are attached to the inner cylinder of the nested cylinders. Lifting cables may be connected to the eyes before or during deployment of the underwater oil well blowout containment device. Either a surface vessel or remotely operated underwater vehicles can deploy the blowout containment device by lifting the cylinders up by means of these eyes and or cables. 
     In accordance with yet another aspect of the invention, the individual blades of the iris valve may be ganged to operate in unison by means of a pair of rings at the periphery, one of which is stationary and contains blade pivot shafts. The other ring is movable, and contains a set of shafts or pins which slide in slots in the iris valve blades. These slots are positioned and configured so that when this ring is turned, the blades of the valve swing inward to the closed position. 
     In accordance with another aspect of the invention, the iris valve blades are canted downward, so that when the iris is closed, the iris forms a concave shape when viewed from the outside. This increases the pressure holding capability of the containment device. 
     In accordance with yet another aspect of the invention, the geometry of the iris blades is such that the top of the cylinder is completely closed when the blades are moved to the fully closed position, and closure around the drill pipe is obtained at the blades inner boundary. If the blowout incident caused the drill pipe to blow away, the blades will continue closing until complete closure is attained. 
     In accordance with another aspect of the invention, the fixed outer cylinder contains several valves with fittings which transit hoses or lines can be attached to by underwater Remotely Operated Vehicles (ROVs) or by other means to extract oil and gas from the inside of the cylinder. The lines can lead to a manifold which in normal drilling operations is already in place, and from there the oil and gas would be directed to surface tankers or to an undersea pipeline. The transit lines and manifold are part of the complement of apparatus normally associated with underwater drilling operations. 
     In accordance with yet another aspect of the invention, a containment device is provided which can withstand significant pressure, but is not a pressure vessel. In some instances, the pressure of the escaping oil and/or gas may exceed the capability of the containment device to contain the resulting pressure. To accommodate high pressure, two safety measures are incorporated, one in the operational procedure and one in the design. The procedure is to delay closing the iris valve until the oil/gas transit lines are in place and the valves open. In this way, and by adjusting the opening of the valves, adequate pressure is maintained within the device to force the oil through the pipe lines, but the pressure will never be able to increase to unacceptable levels. The design feature, which is a backup to the operational procedure, is pressure relief valves. In addition to the valves described above which direct the oil and gas to a manifold, several pressure relief valves are also included in the same cylinder. If the pressure inside the containment device is excessive due to blowout pressure fluctuations or operator error, the oil and gas will be vented to the ocean until the adverse situation is corrected and it is possible to divert the oil and/or gas to the manifold. 
     In accordance with another aspect of the invention, the blowout containment device is placed around the wellhead in advance the commencement of drilling. As a result, blowout containment device is available for immediate deployment to capture escaping oil and/or gas if a blowout or significant leak beneath the BOP occurs. 
     In accordance with yet another aspect of the invention, the blowout containment device is sufficiently well anchored to the sea bed and or the wellhead so as to not be displaced by the pressure of escaping oil and gas, or by currents or other disturbances. 
     In accordance with still another aspect of the invention, there is provided a blowout containment device which is deployed and anchored using the same techniques and equipment used to prepare the wellhead and deploy the BOP. 
     The present invention addresses all of the known issues and more. It is relatively inexpensive, it is always available and in place, it does not interfere with normal drilling operations, it will capture all of the oil and gas emitted by the blowout, it does not require special or unique sea surface apparatus or vessels, it does not have any operational requirements that are different than those with which drilling crews are familiar, and if it needs to be activated, the required actions are the same as those normally used for drilling operations. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
         FIG. 1  is a side cut view of a blowout containment device in its rest configuration around the wellhead. The BOP is shown already in place. The blowout containment device is in its standby configuration, available for future use. 
         FIG. 2  is a side cut view of a blowout containment device deployed to contain oil and gas. 
         FIG. 3A  is a top view of the blowout containment device with the iris valve closed. 
         FIG. 3B  is a top view of the blowout containment device with the iris valve open. 
         FIG. 3C  is a top view illustrating how the blades of the iris valve close the top of the blowout containment device. 
         FIG. 4  is a pictorial representation of one iris valve blade showing the pivot axle, the slot in the blade, and the drive pin that rides in the slot. 
         FIG. 5  shows a closure apparatus comprising a clam shell type structure. 
     
    
    
     Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims. 
     The world wide need for energy and the depletion of shore side reserves has driven oil drilling to ever deeper waters. Leaks or blowouts at any depth, even on land, can be very difficult to deal with, but the difficulty increases with increasing depth where drilling operations are at the leading edge of existing technology. The present invention is a blowout containment device for addressing subsea leaks. 
     The present invention includes telescoping steel cylinders that contain the flowing oil and gas, and direct it from ports through pipes to an existing manifold for transfer to tankers or undersea pipelines. Its function is to prevent oil and gas from venting into the ocean in the event of a failure of the BlowOut Preventer (BOP) or any apparatus or structure beneath the BOP. 
       FIG. 1  is a side view cut-away of the blowout containment device  10  in position around wellhead apparatus including the blowout preventer  12  (“BOP”) and the drill pipe  14 . The device consists of a telescoping cylindrical steel housing  16  and a top closure  18 . The cylindrical housing surrounds the wellhead and drilling apparatus including the BOP  12 . The blowout containment device  10  is anchored to the sea bed by means of an anchor plate  20  which may be secured to the wellhead and or the sea bed. One of the several oil extraction ports and valves  22  is shown in  FIG. 1 .  FIG. 1  and the others are intended to convey the concept and should not be construed as accurate from a design point of view. For example, there will most likely be more than three nested (or telescoping) cylinders  16 , but only three are shown in  FIG. 1  for clarity. 
     In  FIG. 1  the steel cylinders  16  are fully collapsed and the top closure  18  is fully open. The vertical height of the collapsed device  12  is low enough that it will not prevent work on the valves, ports, and other access points on the BOP  12 . The diameter of the inner most cylinder  16  is larger than the horizontal reach of the BOP  12  in its operating configuration with the bonnets closed. In this normal operating configuration, that is, with the cylinders  16  collapsed within one another, the blowout containment device  10  will not hamper opening the BOP bonnets if required during the well drilling process. The actual physical dimensions of the blowout containment device  10  vary with the size of the BOP  12 . 
       FIG. 2  is a side view cut-away of the blowout containment device  10  in its deployed configuration. The telescoping cylinders  16   a ,  16   b , and  16   c  are fully extended and locked into position. The joints between pairs of cylinders are closed by seals  17 . The various cylinders  16   a ,  16   b ,  16   c  are automatically fixed in this fully extended position by latches  26  that are automatically tripped when full vertical extension is reached. The top closure  18  is closed tightly around the drill pipe  14 . Escaping oil and/or gas are thus contained within the volume defined by the cylinders  16   a ,  16   b , and  16   c , and the top closure  18 . Pressure in excess of the design operating limit of the blowout containment device  10  is relieved in normal operation by the several outlet ports in the lower cylinder to which transfer pipes or tubes  24  are connected. The pipes  24  deliver the oil and/or gas to an existing manifold, typically present during drilling operations, and from there to surface vessels or an undersea pipe line. 
     Pressure surges or pressure buildup is relieved by one or more of the several pressure relief valves  28  also located around the periphery of the largest cylinder  16   a  at the base of the blowout containment device  10 . In this over pressure condition oil and/or gas would be vented to the sea. However, attaching more pipes  24  or opening the valves  22  more fully will return the pressure relief valves to their seated position, once again directing all oil and gas to the manifold. 
     When the nested set of cylinders  16   a ,  16   b ,  16   c  is expanded vertically to the maximum design height, the top of the blowout containment device  10  is above the height of the BOP  12 . With the latches engaged, this is a mechanically stable configuration. 
       FIGS. 3A ,  3 B, and  3 C are top views of a top closure  18  comprising an iris valve  30 .  FIG. 3A  shows the iris valve  30  completely closed around the drill pipe  14 .  FIG. 3B  shows the iris valve  30  completely open, leaving the BOP  12  and the drill pipe  14  clear of obstruction.  FIG. 3C  shows some of the blades  32  closed around the drill pipe  14 . 
     The iris valve  30  is composed of a multitude of individual, overlapping steel blades  32 , preferably eight to twenty in number, although the number may be greater or fewer and more preferably about twelve. When the blades  32  are in their fully open position as in  FIG. 3C , the clear inner diameter is approximately equal to the inner diameter of the smallest of the steel cylinders  16   c . When the blades are closed as in  FIG. 3A , they can close the top of the cylindrical shell completely in the case where the drill pipe  14  is missing, or can seal around the outer diameter of the drill pipe  14  when it is present. The outer diameter of the iris valve assembly  30  is typically larger than the outside diameter of the largest of the collapsible cylinders  16   a.    
     As shown in  FIG. 2 , the center iris valve  30  is canted downward (i.e., concave down) in the preferred embodiment. This design feature increases the pressure holding capacity of the blowout containment device  10 . Although it is not intended as a pressure vessel, by design it will withstand nominal overpressure adequate to force the oil through the oil extraction pipes  24  as shown in  FIG. 2 , and through them to the manifold (not shown, as it is not part of this invention and is normally present during drilling operations). Increasing pressure pushes upward on the iris valve blades from the inside, tightening the grip of the blades on the drill pipe or, if the pipe  24  is absent, this pressure will increase the force with which the ends of the valve blades  32  are pressed together, which action will increase the pressure holding capacity of the blowout containment device  10 . 
     Several methods of closing the iris valve  30  are contemplated. In the first preferred method a pair of axially co-located rings  40  and  42  (see  FIG. 4 ) serve as both iris valve blade  32  supporting structure and valve closing mechanism. One ring  40  is stationary, the other ring  42  is rotatable as shown conceptually in  FIG. 4 . The stationary ring  40  contains the blade axles  38 , about which the blades  32  pivot. The rotatable ring  42  contains pins  36  that drive each valve blade  32 . Each pin  36  slides in a slot  34  in the iris valve blade  32 . As the ring  42  with the pins  36  is rotated along arrow  44 , the motion of the pin  36  in the slot  34  forces the blade  32  to rotate about the pivot axle  38 . 
     Alternatively, the pins may be fixed in the blades, in which case the pins would slide in slots in the rotatable disc, the rotation of which will cause the blades to move inward toward the closed position when the disc is rotated in one direction, and to move outward toward the open position when the disc is rotated in the opposite direction. 
     The movable ring may be driven by hydraulic cylinders, or the ring may incorporate gear teeth on the outer periphery which are driven by a hydraulic motor or manually by a shaft that is rotated by a remotely operated underwater vehicle. 
     While the method of closing the valve described above is preferred, alternative methods are also feasible. Among the alternatives, the one most preferred is the use of hydraulic cylinders to position each blade individually. Various cam and lever arrangements are also obvious alternatives. 
     An alternative to the iris valve is a clamshell type closure  50  shown in  FIG. 5 . In this embodiment the inner cylinder  16   a  is stationary and fixed to the base ring, and the outer cylinders  16   b  and  16   c  slide up over one another during deployment. Attached to the outer cylinder  16   c  are a set of shell-like ellipsoidally shaped steel surfaces  54 . In  FIG. 5 , only one shell  54  is shown for clarity. Following full deployment of the cylinders, these shells, which at rest hug the outer periphery of the outer cylinder, glide on angularly oriented tracks  52  attached to the outer cylinder  16   c  and upon full deployment curve up and over the open end of the outer cylinder  16   c . These shells would be at least two in number, but most preferably four or more. 
     The shell form can be visualized as a section of a tapered cylinder, akin to the necked-down portion of a water bottle. When this shell is canted at an angle, then a traverse upward from its stowed location on the outside of the outermost cylinder will result in the necked-down portion moving inward over the open cylinder top. 
     While closure devices  18  comprising an iris device and a clamshell device are described above, a blowout containment device having any closure device is intended to come within the scope of the present invention. 
     While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.