Abstract:
A system including a combined plug and valve device that may be precisely delivered to and inserted into an uncontrolled undersea oil well. Once positioned in the well, the device is operated in graduated fashion to anchor the plug to the well and gradually stanch the flow of oil from the well.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 61/502,016, filed Jun. 28, 2011, the disclosure of which is incorporated herein in its entirety by reference thereto. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates in general to oil well control systems and, in particular, to systems for managing the flow of crude oil and natural gas discharge from an uncontrolled undersea well. 
     BACKGROUND OF THE INVENTION 
     The 2010 crude oil spill in the Gulf of Mexico was a human and environmental disaster of epic proportions. It was the largest oil spill in history. From its beginning on Apr. 20, 2010 with the deadly explosion of the Deepwater Horizon oil drilling rig to Jul. 15, 2010 when the gushing well was effectively capped, the spill resulted in an estimated release of nearly 5 million barrels of crude oil that caused extensive damage to marine and wildlife habitats as well as the Gulf&#39;s fishing and tourism industries. 
     Several futile attempts were made to control the relentless flow of oil from the gushing undersea well which was located some 5000 feet beneath the water surface. These included remote underwater vehicles which failed to close blowout preventer valves on the damaged well head, a 140 ton containment dome, and pumping heavy drilling fluids into the well head. As noted, the well was capped in July and, from early August through September 2010, the well was permanently sealed with cement. 
     Ancillary to the human, environmental and tourism losses related to the disaster, but nonetheless highly economically significant, was the permanent encasement of crude oil and natural gas that might otherwise have been recovered from the sealed well had it performed as designed throughout its expected service life. To date, it is believed there is no known rapidly deployable system for effectively capping a gushing deep-sea oil well, let alone one which enables the damaged well to remain functional, if desired, after capping. 
     SUMMARY OF THE INVENTION 
     The present invention provides a system including methods and apparatus for effectively managing the flow of crude oil and natural gas from an uncontrolled undersea oil well. 
     The apparatus preferably comprises a combined well plug and valve device disposed within a cage-like housing. The housing desirably carries propulsion and steering means in the form of one or more biaxially rotatable electric propellers or hydraulic propulsion jets that propel and steer the cage and plug and valve device from or near the water&#39;s surface to the site of the damaged wellhead. Global positioning technology may aid in positioning of the apparatus to the general vicinity of the damaged wellhead. The apparatus also desirably has at least one on-board camera that provides visual images of the affected site that may be used to assist in precisely positioning and lowering the cage over the center of the damaged wellhead. 
     The combined well plug and valve device is preferably constructed with a hollow conical head portion and a hollow finned tail portion, both having rearwardly directed jets or nozzles. The head and tail portions are preferably connected to a hollow central tube or pipe via mating threading. The hollow central tube is provided with helical means on and/or in its outer surface. A plurality of threaded plates are screwed onto the helical means. Leading ones of the plates are separated by spacer means formed from consumable material such as thermite which is combustible even in underwater environments. Additionally, each plate includes at least one fluid passageway through which seawater and well fluid is intended to pass. The plates are slightly smaller in diameter than the inside diameter of the well to be plugged and the entire design is easily scalable to fit a well bore, pipe or tube of any diameter in order to control natural gas and crude oil being discharged at any flow rate and pressure. 
     Prior to launching the apparatus from an oil rig, ship barge or other structure or vessel situated at or beneath the surface of a body of water in which an uncontrolled oil spill is occurring, the fluid passageways of the plates are aligned to form at least one flow channel through which seawater may pass freely as the apparatus travels downwardly through the water toward the uncontrolled well. That is, the fluid passageways of the plates are desirably aligned in order to reduce fluid resistance against the apparatus as it is propelled downwardly through the seawater and into the gushing wellhead. 
     A hose is releasably attachable to the trailing end or tail portion of the combined plug and valve device. Once the device is in alignment with the well opening, fluid is injected at high pressure into the hose. The pressurized fluid enters the combined plug and valve device and is discharged through the aforesaid jets or nozzles whereby the device is propelled into the well against the pressure of upwardly flowing crude oil and natural gas. Upon insertion of the device to a desired depth within the damaged well, an optional dense stopper such as a ball-like stop may be inserted into the hose whereby it may descend through the hose and into the device until it comes to rest in a socket at the leading end or head portion of the device. With the stop seated in the socket, fluid flow through the leading propulsion jets is obstructed whereby propulsion fluid flow is limited to the set of trailing jets. And, with propulsion flow limited to the rear jets, such flow may be relatively easily sustained at a level sufficient to counteract the flow of gushing crude oil and gas in order to maintain the combined plug and valve device in an essentially static position with respect to the well bore so that the device may be anchored or affixed to the interior of the well. 
     Upon achieving the desired depth of insertion of the combined plug and valve device into the well, the device may be selectively actuated to gradually and incrementally close the device and to affix it to the affected well bore, tube or pipe and establish a desired degree of upward oil and gas flow through the device. That is, once the combined plug and valve device is positioned in the well as described above, at least some of the plate passageways are brought into misalignment in order to restrict pressurized gas and oil flow through the passageways. To achieve that effect, the consumable material above the lowermost or first leading plate is ignited and the space between that plate and the next plate is vacated. As this is occurring, pressure from the rising oil and gas plume pushes upwardly on the first plate, causing it to rotate and partially obstruct the flow channel established by the previously aligned plate flow passageways. Thereafter, the next consumable spacer layer is ignited and the first and second plates rotate upwardly as a unit until they contact the third plate. This procedure continues until the desired number of spacer layers have been consumed and the flow channels have been partially or completely blocked. As described in greater detail hereinbelow, incremental closing of the combined plug and valve device prevents damage to the device during the process of constricting the flow of gushing crude oil and natural gas while also enabling effective control of the well fluid flow should it be desired to preserve the well as a viable oil and or natural gas production site. 
     According to a first embodiment, the rotatable and axially movable plates squeeze at least one resilient anchor member that is operable to bulge radially outwardly in order to tightly seal itself against the inner wall of a well bore, tube or pipe upon axial compression exerted by the plates. 
     According to a second embodiment, at least one of the plates is substantially rigid but has sufficient flexibility such that when compressed between other plates it is caused to flatten and expand into sealed contact with the inner wall of the damaged well bore, tube or pipe. 
     Other details, objects and advantages of the present invention will become apparent as the following description of the presently preferred embodiments and presently preferred methods of practicing the invention proceeds. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will become more readily apparent from the following description of preferred embodiments thereof shown, by way of example only, in the accompanying drawings wherein: 
         FIG. 1  is a schematic view of an apparatus according to the invention being deployed from an off-shore oil rig; 
         FIG. 2  is an elevational, partial cross-section view of an apparatus according to the invention positioned above a damaged oil wellhead on the seafloor; 
         FIG. 3  is an elevational view of a first embodiment of a combined well plug and valve device according to the invention in its pre-anchored state; 
         FIG. 4  is an elevational cross-section view of the device taken along line  4 - 4  of  FIG. 3 ; 
         FIG. 5  is a perspective cross-section view of the device similar to  FIG. 4 ; 
         FIG. 6  is a top plan view of the device in its pre-anchored state; 
         FIG. 7  is a partially exploded elevational view of the device; 
         FIG. 8  is a partially exploded perspective view of the device; 
         FIGS. 9   a - 9   j  are elevational and top plan views depicting sequential closure of a combined plug and valve device according to the invention; 
         FIG. 10  is an elevational view of a first embodiment of a combined plug and valve device according to the invention in an anchored state; 
         FIG. 11  is an elevational cross-section view of the device taken along line  11 - 11  of  FIG. 10 ; 
         FIG. 12  is a perspective cross-section view of the device similar to  FIG. 11 ; 
         FIG. 13  is a top plan view of the device in a deployed state; and 
         FIGS. 14-16  are elevational cross-section views showing sequential deployment of a second embodiment of a well plug according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings, wherein like or similar references indicate like or similar elements throughout the several views, there is shown in  FIG. 1  an offshore oil rig from which an apparatus  12  according the present invention is suspended by a hose and cable arrangement  14 . As seen in that figure, apparatus  12  is in the process of being deployed to control a gushing, uncontrolled undersea oil well, the head  16  of which is located at seafloor  18  and from which there is seen a rising plume of crude oil and gas  20 . 
       FIG. 2  illustrates on an enlarged scale apparatus  12 , hose and cable arrangement  14  and oil wellhead  16 . As seen in that figure, wellhead  16  is shown as having a severed top end  22  such as might occur following a catastrophic failure or blowout of the well. Apparatus  12  includes a housing  24  and a combined plug and valve device  26 , which is schematically depicted in  FIG. 2 . Housing  24  is operable to protect and transport device  26  from a point of deployment at or near the water surface, i.e., from an oil rig, ship or other sea vessel, to the damaged well  16  on seafloor  18 , which distance may be as much as several hundred to several thousand feet. 
     Housing  24  is preferably formed from high-strength material such as steel, reinforced plastic or the like that can be fabricated into a three-dimensional shape. While the walls of housing  24  may be fully enclosed, it is preferred that they be constructed as a cage since a cage-like structure renders the housing lighter in weight and therefore more easily manipulated both above and beneath the water surface. In addition, the open spaces of the cage permit fluid flow therethrough. As a consequence, the apparatus passes easily through the seawater as it descends to the damaged wellhead  16  and is less susceptible to being displaced by the oil and gas plume  20  as it is placed over the wellhead. 
     Housing  24  carries at least one propulsion and steering means  28 . Means  28  preferably comprise biaxially movable, electrically driven propellers or hydraulically operated jets  30 . Propellers or jets  30  receive their power, whether electrical or hydraulic, from cables or hoses  32 , as the case may be, that form part of the cable and hose arrangement  14 , which cables or hoses provide input to conventional electrical or hydraulic motors and actuators  34  that drive the propellers or jets  30  as well as control their biaxial positioning. According to a preferred embodiment, means  28  include at least one set of propellers or jets  30 . More preferably, for optimum maneuverability and transport speed, a set of propellers or jets  30  is desirably provided at or near both the top and the bottom of the housing  24 . 
     For clarity of illustration, cables or hoses  32  are shown exteriorly of housing  24 . However, it will be understood that such cables or hoses may be situated interiorly of housing  24  for their protection during transport and operation of apparatus  12 . 
     It is preferable that housing  24  be formed with a first shoulder  36  against which the trailing end of combined plug and valve device  26  may rest during transport of apparatus to a damaged wellhead. Such shoulder may be located anywhere along the length of housing  24  so long as it provides a stable seat for device  26  during transport. Housing  24  may also be provided with additional unnumbered shoulders for accommodating the upper edges/regions of the of the exposed structure of damaged wellhead  16 . The bottom of housing  24  is open-bottomed and preferably outwardly flared or funnel-shaped as indicated at  38  to assist in placement of the housing over the wellhead  16 . Additionally, although not illustrated, housing  24  also desirably carries a global positioning system transmitter and at least one video camera for coarse and fine positioning, respectively, of the housing  24  over the wellhead  16 . 
       FIGS. 3-8  illustrate on an enlarged scale a presently preferred construction of a combined plug and valve device according to the invention. Device  26  is preferably constructed with a hollow conical head portion  40  and a hollow tail portion  42 , both having rearwardly directed jets or nozzles  44  and  46 , respectively. The tail portion is preferably provided with a plurality of fins  47  for guiding the device  26  as it is propelled into a damaged well as described below. The head and tail portions may be securely connected to a hollow central tube  48  via mating threading, welding or other suitable attachment means. The hollow central tube  48  is provided with helical means  50  on and/or in its outer surface. Prior to attaching the head and tail portions  40 ,  42  to the central tube  48 , a plurality of flat or curved leading plates  52 , each having a central opening  158  ( FIG. 9   a ) with threading corresponding to that of the helical means  50  of tube  48 , are screwed onto the tube. Except where otherwise specified, components  40 ,  42 ,  48 ,  50  and  52  (and subsequently described elements  64 ,  68  and  72 ) of device  26  are desirably, although not necessarily, formed from metal such as, for example, steel, aluminum, copper, brass, or the like. As seen in  FIG. 5 , plates  52  are preferably slightly bowl-shaped in elevational cross-section so that the plates may flex slightly radially outwardly as they contact other plates in order to increase inter-plate friction and, therefore, reduce the likelihood of slippage between plates as they progress through the incremental flow channel closing process discussed below. 
     Each plate  52  includes at least one fluid passageway  54  through which seawater and well oil is initially intended to pass. The plates  52  are slightly smaller in diameter than the inside diameter of the well bore, pipe or tube to be plugged. In this connection, it will be understood that the entire system design, including the already-described components as well as those described below, is easily scalable to fit a well bore of any diameter to control natural gas and crude oil being discharged at any flow rate and pressure. 
     Leading plates  52  are separated by consumable spacer means  56 , preferably an annular or ring-like spacer. A preferred spacer material is thermite which burns at predictable rates and is combustible under water. A further advantage of thermite is that it can be ignited simply by electrical resistance heating via application of a sufficiently high electrical current. It does not require a dedicated igniter mechanism which could be problematic in underwater environments. In this regard,  FIG. 5  shows an electrical ignition cable  58  which may be carried by a pressurized fluid supply hose  60  ( FIGS. 1 and 2 ) that leads from a launching rig or vessel to the apparatus  12 . Situated within the ignition cable  58  are several ignition lines  62  each of which leads to a consumable spacer  56 . As described in greater detail below, each ignition line  62  may be independently operated to selectively and progressively ignite the spacers  56 . 
     Situated rearwardly of the rearmost spacer  56  is the final leading plate  64  that likewise has at least one fluid passageway  54 . Plate  64  is preferably convex on both its forward and rearward surfaces. Following installation of plate  56 , a first yieldable member  66  is placed over the tube  48 . Like plates  52  and  64 , anchor member  66  is provided with at least one fluid passageway  54 . According to a preferred embodiment, yieldable member  66  is preferably constructed as a resilient or elastomeric disk-like element that both anchors device  26  to a well bore, tube or pipe, but also effectively seals the perimeter of the device against upwardly flowing well fluid. 
     Following placement of anchor member  66 , a first threaded backing plate  68  is then installed. Like plate  64 , plate  68  has at least one fluid passageway  54  and is preferably convex on both its forward and rearward surfaces. Following installation of plate  68 , a second yieldable anchor member  70  having at least one fluid passageway  54  is placed over the tube  48 . Following placement of anchor member  70 , at least one other threaded backing plate  72  is screwed onto helical means  50  and preferably secured to tube  48  such as by welding or other suitable affixation means. Plate  72  has at least one fluid passageway  54  and may be generally similar in construction to any of plates  52 ,  64  and  68 . However, it is preferred that the final backing plate be formed of especially high strength material and/or rigidified by gussets or the like in order to bear the full mass and momentum of the upwardly moving plates as well as the fluid pressure of the gushing well. In addition or in the alternative, additional backing plates may be added to tube  48  in order to bear the potentially tremendous upwardly directed forces exerted by the well fluid and the leading plates of the device itself. 
     Lastly, the head and tail portions  40 ,  42  are secured to central tube  48  to complete the assembly of the combined plug and valve device  26 . Prior to deployment of device  26 , however, the fluid passageways  54  of the several components are brought into alignment in the manner shown in  FIGS. 3 ,  5  and  6  so as to establish one or more substantially unobstructed flow channels through which seawater may freely pass as apparatus  12  is lowered through the water and through which gushing crude oil and natural gas may pass as the apparatus is positioned over an uncontrolled well. 
     It will be appreciated that the combined plug and valve device  26  shown in  FIGS. 3-8  is exemplary only and should not be construed as limiting. It is illustrative of but one version of myriad arrangements of plates and anchor members that may be suitable for plugging damaged undersea wellheads of any diameter and any fluid flow and/or pressure conditions. For instance, there may be as few as one or more than two anchor members depending on well size and conditions. Similarly, there may be more or less leading plates  52  and spacers  56  than as depicted in the drawing figures. Indeed, if well flow and pressure is modest, it is conceivable that as few as one anchor member, one backing plate, and as few as two leading plates  52  and a single spacer means  56  may be employed to effectively control well fluid flow and anchor the combined plug and valve device  26  to a bore, tube or pipe of a damaged well. 
     Following assembly of combined plug and valve device  26 , the tail portion  42  thereof is desirably detachably connected to hose  60  such as by a releasable clamp or the like, either before or after device  26  is placed in housing  24 . In this regard, housing  24  may be provided with an unillustrated access door or hatch on a side wall or top wall thereof in order to facilitate placement of the device  26  within the housing as well as to free tangled, kinked or snagged hoses and/or cables. 
     Referring again to  FIG. 2 , once housing  24  is stably positioned over wellhead  16  and the combined plug and valve device  26  is aligned with the well bore, pipe or tube to be plugged, water or other fluid is then pumped under pressure into hose  60 . The pressurized fluid enters the combined plug and valve device  26  and is discharged through jets or nozzles  44 ,  46  whereby the device is propelled into the well against the pressure of upwardly flowing crude oil and natural gas. Upon insertion of the device to a desired depth within the damaged well bore or tubing such as shown in dashed line in  FIG. 2 , an optional dense stopper such as a ball-like stop  74  ( FIGS. 4 ,  5 ,  11  and  12 ) may be inserted into the hose whereby it descends through the hose and into the plug and valve device whereupon it settles into a socket  76  at the head portion of device  26 . With the stop  74  seated in the socket  76 , fluid flow through the leading propulsion jets  44  is obstructed such that propulsion fluid flow is limited to the set of trailing jets  46 . And, with propulsion flow limited to the rear jets, such flow may be relatively easily sustained at a level sufficient to counteract the flow of gushing crude oil and gas in order to maintain the combined plug and valve device in an essentially static position with respect to the well bore so that device  26  may be anchored or affixed to the interior wall of the well bore, tube or pipe. 
     Upon achieving the desired depth of insertion of the combined plug and valve device  26  into the well, the well shutoff and anchorage procedure can begin. As schematically represented in  FIGS. 9   a - 9   j , device  26  may be incrementally closed in order to affix the device to the damaged well and establish a desired degree of oil and gas flow through the device. That is, once the combined plug and valve device  26  is positioned in the well bore as described above, at least some of the plate passageways are brought into misalignment in order to restrict pressurized gas and oil flow through the passageways. 
     To achieve that effect, the consumable material above the forwardmost leading plate  52  is ignited and the space between the first plate and second plates is vacated. As this is occurring, pressure from the rising oil and gas pushes upward on the first plate, causing it to rotate and partially obstruct the flow channel established by the previously aligned plate flow passageways. Thereafter, the next consumable spacer is ignited and the first and second plates rotate upwardly as a unit until they contact the third plate. This procedure continues until the desired number of spacers have been consumed and the flow channels have been partially or completely blocked. Furthermore, as shown in  FIGS. 10-13 , as the mass of the stack of leading plates comes into contact with the forwardmost anchor member  66 , the anchor members  66  and  70  become compressed between plates  64 ,  68  and  72  whereby they expand or bulge outwardly into contact with the inner wall of the surrounding well bore, tube or pipe. 
     By way of example, the uncontrolled Deepwater Horizon well was believed to have produced a gushing well plume with a highly powerful fluid pressure of some 6000 psi. Such high pressure would be more than sufficient to push several heavy steel plates upwardly along a helical path to achieve the objectives of the present invention. Furthermore, gradual or incremental closing of the combined plug and valve device  26  against such potentially destructive fluid force serves to prevent damage to the device during the process of constricting the well fluid flow while also enabling effective flow control should it be desired to preserve the well as a viable petroleum production site. As to the latter, by virtue of the present invention a previously uncontrolled well may be effectively converted into one producing less flow than in its original state but still constituting a manageable and commercially viable producer of crude oil. 
     Turning to  FIGS. 10-13 , the combined plug and valve device  26  is depicted as it would appear at the completion of step  9   j . That is to say, all plate passageways  54  are in misalignment and the anchor members  66 ,  70  are in their expanded well-contacting state. So disposed, the device is fully closed wherein all well fluid flow is stopped and the well is effectively “killed”. 
     At this point, hose  60  may be released from clamping engagement with the tail portion  42  of device by introducing a pulse of highly pressurized fluid through the hose, which pulse is not be readily dispersible through jets  46 . As such, the sudden pulse or slug of fluid creates a burst of back pressure within the hose which is sufficient to dislodge the hose from clamping engagement with the device  26 . 
       FIGS. 14-16  reveal an anchorage arrangement in accordance with an alternative embodiment of a combined plug and valve device according to the invention. For brevity, only those features that depart materially in structure and/or function from their counterparts in  FIGS. 3-13  or are otherwise necessary for a proper understanding of the invention will be described in detail in connection with  FIGS. 14-16 . 
       FIGS. 14-16  schematically illustrate how an alternative anchor member  166  may be deployed to anchor, and preferably seal, a combined plug and valve device to the interior wall of a well bore, tube or pipe  16 . As shown in those figures, a leading plate  152  and a backing plate  172  are positioned at opposite faces of an anchor member  166 . According to this embodiment, anchor member is formed from yieldable metal, is generally bowl-shaped in cross-section, and has a radius of curvature less than backing plate  172 . So constructed, as leading plate  152  moves upwardly against anchor member  166  in the direction of arrow  200  during a sequential passageway closure and anchorage procedure of the kind described above, anchor member  166  is compressed and flattened whereby its outer perimeter becomes radially enlarged. Indeed, the material, unstressed diameter and cross-sectional curvature of metal anchor member  166  are desirably selected such that, when the anchor member is properly compressed between leading and backing plates  152 ,  172 , it desirably comes into tight compressive contact with and, most preferably, slightly embedded in the interior wall of the well bore, tube, or pipe  16  from which crude oil and natural gas is flowing. Once in contact with the well, plate  166  (or plates  166 , if more than one such plate may be necessary to achieve desired anchoring and sealing) effectively anchors the combined plug and valve device and permits either no flow or some limited flow through the device as may be desired and as described above in connection with  FIGS. 3-13 . 
     Although the invention has been described in detail for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention as claimed herein.