Abstract:
An apparatus and method for the creation of an impermeable pile in the vicinity of a dysfunctional oil well are provided. The impermeable pile is sealed and impervious to sea water and of sufficient strength to sustain the oil pressure to prevent oil leakage into the sea. The impermeable pile is configured for receiving oil from the well and discharging oil through a pipe leading to the surface.

Description:
RELATIONSHIP TO OTHER APPLICATIONS AND PATENTS 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/344,352, filed Jul. 6, 2010. 
    
    
     TECHNICAL FIELD 
     The present invention relates to underwater drilling of oil wells in fresh or salt water (referred to herein collectively as “sea”); more particularly, to methods for dealing generally with an oil well exhibiting uncontrolled flow into the sea; and most particularly, to a method and apparatus for capping such a well to stop leakage into the sea whilst optionally continuing to produce crude oil from the well. 
     BACKGROUND OF THE INVENTION 
     In petroleum exploration and production, it is well known to drill for oil in a sub-sea environment. It is also known that during drilling or production, unanticipated pressure surges may occur at the well head, leading to an uncontrolled flow condition known in the art as a “blow-out” wherein flow control of the emerging crude oil is lost. Such blow-outs are costly at least in terms of lost time and production; and when a blow-out continues for an extended period of time or in very deep water, as has been seen recently in the BP blow-out incident in the Gulf of Mexico on Apr. 20, 2010, the environmental and financial consequences can be catastrophic. 
     Typically, wells that are drilled on land or underwater are drilled through a generally cylindrical safety device mounted at the well head known as a “blow-out preventer” (BOP). A typical BOP includes a compressible collar that can be clamped about a drill stem to seal the well should a potential blow-out occur with the drill stem in place, and further includes a plurality of redundant valves that can be closed to shut off a blow-out or other leakage from a producing or exhausted well. However, in blow-out instances wherein no BOP was employed or wherein the BOP was inoperative, additional control is required. For land-based drilling operations, it is well known to seal a blown-out well with heavy equipment and/or explosives. For underwater blow-outs, these options are not generally available, especially in very deep water where all remediation must be conducted remotely, in darkness, and at greatly elevated pressures. 
     What is needed in the art is a simple method and apparatus to shut off uncontrolled flow of crude oil from an underwater oil well, preferably to allow continued production to the sea surface from the well. 
     It is a principal object of the present invention to stop the uncontrolled flow of crude oil from an underwater oil well into the surrounding sea environment. 
     It is a further object of the invention to capture and recover crude oil continuing to flow from the well. 
     SUMMARY OF THE INVENTION 
     Briefly described, in accordance with the present invention an apparatus and method for capping an underwater oil well comprises a pipe equipped with a pervious collection head extending from the vicinity of the oil well head to the sea surface. Optionally, the pipe may be further equipped with a pump for lifting oil collected by the pervious collection head from the well head to a point of controllable discharge at the sea surface. 
     A pile of objects, which may be rocks or metals, or combinations thereof, is disposed around the pervious collection head and the lower end of the pipe. In a presently preferred embodiment, a mix of smaller objects is disposed on and around larger objects, forming a first canopy. Still a mix of smaller objects is disposed on and around the first canopy to form a second canopy. A plurality of additional canopies of progressively smaller objects, such as for example, smaller boulders, cobbles, pebbles, granules, and sand are disposed in substantially concentric layers about the second canopy, defining a graded pile. A mixture of cement that is settable under water may be included in one or more of the successive canopy mixes. An impermeable membrane may be included within or on the outer surface of the graded pile. The size and weight of the graded pile is sufficient to prevent leakage of oil to the sea. The entire flow from the well head thus may be drawn through the pipe by the optional pump, or the well may be shut in by closing one or more valves in the flow path. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described, by way of example, with reference to the accompanying drawing, in which: 
         FIG. 1  is an elevational cross-sectional view (not to scale) of a presently preferred embodiment of an apparatus for capping an underwater oil well in accordance with the present invention. 
     
    
    
     The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , an apparatus  10  in accordance with the present invention is shown resting on the sea floor  12  and surrounding the well head  14  of an oil well  16 . Apparatus  10  comprises a pipe  18  extending from the vicinity of well head  14  at a first end to a point of controllable discharge, such as above the surface  20  of the sea  22 , at a second end. Optionally, a pump  24  is coupled to pipe  18  and shown at the upper pipe end  26  but may be installed anywhere in pipe  18  in accordance with the invention. A pervious collection head  28  may be connected to the lower pipe end  30  in proximity to well head  14 . A pile  32  of objects surrounds well head  14 , pervious collection head  28 , and the lower portion of pipe  18 . Preferably, pile  32  is graded in size with the largest objects  34  emplaced first to form a core pile  36 , then smaller objects  38  emplaced in a first canopy  40  over and around pile  36 , then still smaller objects  42  emplaced in a second canopy  44  over and around first canopy  40 . A plurality of additional canopies, exemplified by a third canopy  46 , may be emplaced sequentially in the same fashion, terminating in a canopy of finest objects  48 . The number of canopies, the progressive gradation in size of the objects, and the relative size of the objects may be varied at will within the scope of the present invention. Optionally, one or more impermeable membranes  50  may be incorporated in pile  32 , either on the outside as shown in  FIG. 1 , or internally between successive canopies. 
     In a presently preferred embodiment, at least some of objects  34 , 38 , 42 , 48  are formed of rock, metals, or other suitable materials. Preferred sizes of progressive canopy objects are selected from the group consisting of boulders, cobbles, pebbles, granules, and sand in accordance with the internation Wentworth scale of sizes. It will be seen that as additional canopies are formed, the newly-emplaced smaller objects will settle into some of the interstices of the previous canopy, thereby partially blocking oil flow and creating additional desirable pressure drops to inhibit oil flow radially through pile  32  and to help redirect the flow of oil upward through pipe  18  toward surface  20 . 
     Optionally, wet concrete  52  may be included within pile  32  during construction thereof to fill interstices and further reduce the permeability of pile  32 . Optionally, a choke valve  54  may be included at an appropriate location along pipe  18  to eventually cut off the flow of oil upward through pipe  18 , if so desired. 
     As successive canopies are added to form pile  32 , the pile creates an increasing back pressure of oil in the immediate vicinity of well head  14  and pervious collection head  28 . Preferably, optional pump  24  is energized during construction of pile  32  to remove at least a part of the oil flowing from well head  14 , along with surrounding sea water, thereby reducing any tendency for oil to flow radially through or around pile  32  before construction of the pile is finished. Preferably, the capacity of optional pump  24  and the size of pipe  18  are selected to be able to pump at the flow rate of oil flowing from well head  14 . 
     The following description is believed to explain the basis for success of the present invention in capping an undersea oil well. 
     Pipe  18  is necessary for apparatus  10  to function successfully. Initially during construction, pipe  18  is placed near well head  14 . Without anything further being done, oil will continue to spew uncontrolled from the well head to the surface  20 ; and some of the oil may rise by density difference to the surface through pipe  18 . Placement of large objects  34 , such as boulders, around well head  14  and pipe  18  begins to create some back pressure above the well head such that pipe  18  offers a path of lesser resistance for the oil to flow. Some oil will flow up pipe  18  but most of the oil will continue to flow around the large-size objects  34  during the initial stages of build of pile  32 . As more canopies of smaller-sized objects are added on top of the larger objects, more back pressure is created around the well head and more of the oil will flow through the pipe as the path of less resistance. Eventually, as more and more objects of even smaller size are place on the pile  32 , most of the oil will flow through pipe  18  because of the increased back pressure through pile  32  and, if necessary, the operation of pump  24 . At that point, if pipe  18  were choked off (i.e., dead-headed), the pressure inside pile  32  will eventually equal the pressure at the well head and, unless pile  32  is made essentially impermeable, oil will again begin seeping out through pile  32  uncontrollably. 
     However, if pile  32  can be made impermeable, the pile by itself can stop the oil leakage without resort to optional pump  24 . That is, pipe  18  may be closed off entirely thereby sealing the well. Cement mixed with the objects, or a membrane of plastic or rubber of sufficient thickness, can help to make the pile monolithic and impermeable. If a cement is used, it can be added during application of subsequent layers of objects when the pipe  18  is capable of carrying a sufficient amount of the well head flow in the pile. Until pile  32  is made impermeable, the vent pipe may need an optional choke valve  54 . The valve may remain open during the early stages of object piling; then, as the pile becomes less permeable with the additional of smaller objects and with setting of the cement, pipe  18  may be gradually choked off. If pile  32  can contain the full pressure of well head  14 , the pipe  18  may be choked off completely, thereby shutting off the flow of oil from the well in accordance with the primary object of the present invention. If some leakage remains through pile  32 , valve  54  may be re-opened and oil pumped to the surface so that no oil flows through pile  32 . This may continue until the well itself is tapped down by the vent pipe to a head pressure that pile  32  can accommodate with pipe  18  closed, until another well head can be installed into the existing well or until pile  32  can be made impermeable. Alternatively, the well may be placed into production through pipe  18 , thereby reducing the well head pressure and forestalling further leakage through pile  32  into the sea. 
     Whether pile  32  has been made impermeable can be determined by a simple calculation based on measurable factors such as the oil pressure at the well head, the depth of the water, and the oil pressure at the top of the pipe. 
     A method in accordance with the present invention for capping an underwater oil well comprises the steps of:
         a) providing a pipe extending from the immediate vicinity of the well head to the surface; and   b) forming a pile of objects resting on the sea floor and surrounding the lower end of the pipe, wherein the pile is graded in size and weight of the objects progressively outward from the well head, the largest of the objects being placed nearest the well head and the smallest of the objects being placed farthest from the well head.       

     The method may comprise the further step of shutting off oil flow through the pipe when the pile has been made impermeable enough to offset the oil pressure at the well head. 
     The method may also comprise the further step of passing oil through the pipe during and after completion of construction of the pile. 
     It is believed that by providing a thick impermeable layer at the top-side of the pile, a large surface area is provided to oppose the pumping pressures at the well head. 
     While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims.