Patent Publication Number: US-2012024533-A1

Title: Apparatus for collecting oil escaped from an underwater blowout

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an apparatus for collecting oil escaped from an underwater wellhead into a surrounding body of water. More particularly this invention relates to an apparatus for channeling escaped oil from a point near the seabed to a floating oil collection facility. 
     In recent years, the exploitation of oil and gas deposits in geological layers deep beneath the sea surface has become more and more common. The exploitation of these energy resources comprises several phases from the drilling of test wells up to and including the establishment of production facilities. Test drilling as well as production is often conducted from offshore structures, such as floating rigs, semi-submersible vessel and bottom-secured platforms. 
     Several problems accompany deep-sea drilling and production, one of which is position of the wellhead a mile or more below the water surface. When the production pipe is damaged, the steel casings and the underlying rock formations are leaking oil, under a considerable pressure into the water. To solve this problem, the wellheads are provided with blowout preventers (BOP), which are typically large valves at the top of a well that may be closed if the drilling crew in an event of loss of control of formation fluids. By closing this valve (usually operated remotely via hydraulic actuators), the drilling crew usually regains control of the reservoir, and procedures can then be initiated to increase the mud density until it is possible to open the BOP and retain pressure control of the formation. If the BOP fails, a catastrophic blowout can occur, as a result of which the wellhead and the formation around it starts leaking oil. 
     In the offshore drilling or production of oil and gas, accidents such as equipment malfunctions or the like occasionally result in a condition known as a blowout. In such instances, the fluids under substantial underground pressure flow uncontrollably to the surrounding body of water. The contamination caused by a blowout disastrously affects the environment. A non-checked oil spill can kill every sea inhabitant and wildlife along a nearby shoreline. 
     Well blowouts should be capped as quickly as possible in order to prevent a further loss of the valuable resource, as well as to prevent pollution of the environment. However, to control the flow from a burning or damaged well, it is necessary to close the wellbore at a location where the casing and tubing are still undamaged and accessible. 
     The industry proposes several solutions to this problem. In one commonly used method, additional wellbores are drilled to intersect the uncontrolled wellbore so that plugging cement can be used to seal the gushing well. Another method suggests pumping a heavy drilling mud into the formation to kill the well. These procedures, however, are hazardous, costly and time consuming. As the additional wellbores are drilled, which can take several months in an offshore location, the oil continues to flow onto and pollute the surrounding area. Moreover, in an offshore operation, heavy wave action severely limits the available options. 
     In spite of advanced technology and substantial safety measures, there is always a risk of accidents caused by e.g. human error, material fatigue, system malfunctioning or the influence of forces of nature. The catastrophic explosion that caused an oil spill from a British Petroleum offshore drilling rig in the Gulf of Mexico in April of 2010 demonstrates the need for improvements in safety of the offshore operations. As a consequence of the explosion, the oil and gas, or a combination of these components flow uncontrolled into the Gulf of Mexico. The escaped oil rises to the surface and disperses with resulting pollution and detrimental effects to bird life and the environment of marine biology. 
     The difficulty of collecting oil from the water surface and land are further exacerbated by icing of the methane gas and solidification of paraffin in the collectors. Furthermore, the blown pipe may have uneven edges, which makes sealing of the pipe even more difficult. 
     The present invention contemplates elimination of drawbacks associated with convention solutions provision of an additional layer in the safety system for oil drilling and producing wells. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide an apparatus for channeling escaped oil from an underwater location to the surface-floating collection vessel. It is another object of the invention to provide an apparatus that allows to catch escaped oil and direct the oil toward the surface within a tubular conduit body. 
     It is a further object of the invention to provide an apparatus for channeling the escaped oil via a tubular conduit that minimizes icing of the methane gas and solidification of paraffin in the collection channels. 
     These and other objects of the invention are achieved through a provision of an apparatus for collecting oil and gas escaped from a sea-bottom wellhead. The apparatus has a ring-shaped weighted base configured for positioning on a sea bottom in a generally surrounding relationship to the wellhead. A tubular conduit is secured to the sea bottom and extends through the opening in the base below the bottom surface so as to anchor the tubular member and resist displacement by water currents. 
     The tubular member has an open top, which facilitates pressure equalization between the water and the interior of the tubular member. Escaped oil and gas ascend to the water surface being guided by the tubular member. To reduce solidification of paraffin and methane icing, a portion of the tubular conduit if formed from polyvinyl chloride. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made to the drawings, wherein like parts are designated by like numerals, and wherein 
         FIG. 1  is a perspective view of the oil collection apparatus of the present invention. 
         FIG. 2  is a plan view of the oil collection apparatus of the present invention. 
     
    
    
     DETAIL DESCRIPTION OF THE INVENTION 
     As apparent from  FIGS. 1 and 2 , the apparatus  10  comprises a ring-shaped base  12  configured to rest on a sea bottom  14  in a surrounding relationship to a wellhead  16 . The base has a central opening configured to receive a tubular channeling member  20  therethrough, as will be explained in more detail hereinafter. 
     The wellhead  16  can be in the form of a conventional subsea Christmas tree, with a plurality of valves for regulating a flow of liquids to and from a drill pipe or production pipe  18 . Conventionally, the drill/production pipe  18  penetrates the formation to reach a producing zone (not shown), while the Christmas tree  16  is mounted in the upper part of the drill/production pipe  18 . 
     The base  12  is preferably formed as a weighted non-buoyant member that resists displacement by the water current. If one aspect of the invention, the base  12  is a ring-shaped hollow body filled with concrete to assure an appropriate seal between a bottom surface  15  of the base  12  with the sea bottom  14 . If necessary, the base  12  may be anchored to the sea bottom  14  by conventional anchors. 
     A large diameter tubular member  20  is affixed to the collar  12  and extends upwardly therefrom. The tubular member  20  has an open top  21 , which does not create any significant pressure differential between the area around a well and the top of the tubular member  20 . 
     The tubular member  20  comprises a lower portion  22 , a middle portion  24 , and an upper portion  26 . A part  23  of the lower portion  22  is configured to penetrate to a distance into the sea bottom  14  of the body of water, thus stabilizing position of the tubular member  12  in relation to the bottom  12 . The lower portion  22  is positioned in a surrounding relationship to the tree  16 , as shown in  FIG. 2 , protecting the tree  16  and establishing a boundary for any liquids that may escape from the well. 
     The base  12  is positioned in a surrounding relationship to the lower portion  22  and further prevents displacement of the lower portion  22 . A suitable seal may be formed at the intersection of the lower portion  22  and the base  12  to prevent leaking of oil into the water. In one aspect of the invention, the lower portion  22  is formed from a non-corrosive material, such as stainless steel. Of course other materials may be used depending on the manufacturing preferences. 
     The middle portion  24  of the tubular member  20  is fixedly connected in a liquid-tight manner to the lower portion  22 . The lower portion  22  and the middle portion  24  are fluidly connected, forming a path for escaped oil from the well. The lower portion  24  can be formed from a strong non-corrosive nonmetal material, such as for instance, polyvinyl chloride (PVC). In one aspect of the invention, the wall of the tubular member that defines the middle portion  24  is about 4 inches thick. It is believed that the non-metal conduit for guiding escaped oil to the surface prevents icing of the methane gas that is released when oil spills from a well and solidification of paraffin. 
     The upper portion  26  of the tubular member  20  is fixedly secured to an upper end  28  of the middle portion  24 . The upper portion  26  engages the middle portion  24  in a liquid-tight manner with appropriate seals between the walls of the two conduits. The upper portion  26  can be formed from a non-corrosive material, such as stainless steel. 
     A spout  30  is secured to the wall of the upper portion  26  and is fluidly connected to the interior opening in the upper portion  26 . The oil rising through the openings of the lower portion  22 , the middle portion  24  and the upper portion  26  is guided into the spout  30  for collection in a collection vessel, such as a barge  32 . The barge  32  is a conventional floating structure suitable for collecting oil and transporting it to an onshore facility or a pipeline. 
     The tubular member  20  is wide enough to capture all of the flow that is coming out of the pipeline  16 . The tubular member is expected to catch the oil/gas mixture escaping from the well, while significantly reducing the pressure in the wellhead with the tree  16 . The methane gas icing and paraffin solidification are eliminated, or significantly reduced due to the larger portion of the tubular member being made of a nonmetallic material. 
     It is envisioned that a pump may be connected to the tubular member  20  to further facilitate in withdrawing of oil and gas from the spill location. 
     In operation, the apparatus  10  will channel oil and gas as it escapes from the well bore, directing it to the top of the well site where it can be pumped to container ships. Even without the use of auxiliary pumps it is expected that the oil and gas will rise to the surface through the tubular member  20 . Since the oil cannot escape the tubular member  12  it cannot escape into the open water and contaminate the surrounding area. 
     If desired, a gas collection conduit can be connected to the upper portion to divert the escaped gas into a collection area. Alternatively, the gas trapped by the tubular member can be allowed to rise to the surface and then ignited in an uncontrolled combustion. 
     The invention enables collection of oil and gas from a blowout at all water depths at which it is feasible to drill for oil or gas. The apparatus can operate under the most extreme variations in tidal water, and in consideration of given operational conditions it may be designed for very large wave heights as well as the more moderate conditions which normally will occur. 
     Many changes and modifications can be made in the design of the present invention without departing from the spirit thereof. I, therefore, pray that my rights to the present invention be limited only by the scope of the appended claims.