Abstract:
Disclosed herein in example embodiments is a simple Drill-Through-Equipment (DTE) system for deep water drilling of oil, to intervene in the event of Blowout Preventer (BOP) failure, and mitigate spill disaster. Example embodiments of systems and methods of failed BOP intervention, and oil spill disaster mitigation disclosed herein may be used to mount a housing within the existing BOP below the blind shear ram, whereby the failed BOP is made accessible just below the blind shear ram through access ports, opening or closing in the housing. Through these ports blowout is diverted, thus protecting the rig. Through these same ports access is granted to the drill pipe allowing external manipulation or cutting of the drill pipe in effort to render the BOP operational. Once this is accomplished, the access ports are closed, and normal BOP and/or drilling operations are resumed. Example embodiments integrate and make use of existing BOP machinery.

Description:
PRIORITY CLAIM TO RELATED US PATENT APPLICATIONS 
       [0001]    To the full extent permitted by law, the present U.S. Non-provisional Patent Application is made pursuant to, and hereby claims priority to and the full benefit of, U.S. Provisional Application entitled “Systems and Methods for Catastrophe Mitigation for Deep Water Oil Drilling during Blowout Preventer Failure,” having assigned Ser. No. 61/816,405 filed on Apr. 26, 2013, incorporated herein by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure is generally related to subsea blowout preventers (BOPs) used in deep water drilling for oil, and, more particularly, mitigating disaster in the event of BOP failure. 
       BACKGROUND 
       [0003]    Protocol for any oil drilling effort in deep water requires the use of a blowout preventer (BOP), which is designed to stop oil well gushers occurring due to unanticipated peaks in well pressure. These gushers can reach the rig, causing death, damage to property, and harm to the environment. Many examples of this scenario are documented, the most notable of which is the event that occurred in April of 2010 with British Petroleum (BP) and Transocean&#39;s Deep-water Horizon drill rig vessel over the Macondo Well located in the Mississippi Canyon 252 site of the Gulf of Mexico. Eleven men died and estimates of oil spill rates climbed steadily from 5,000 barrels per day up to a stunning 60,000 barrels per day. 
         [0004]    Subsea BOPs are used extensively for the drilling of oil and natural gas, and are designed to operate in environments subject to unexpected peaks in pressure. A BOP is basically a system of valves, called rams, annular valves, or annular BOPS. These are of various types, arranged in series to form a safety redundancy. The drill column is the flow channel within the BOP and riser pipe, i.e. the piping leading from the BOP to the rig hundreds, or even thousands of feet above, and leads up to the rig. The drilling tool, called the drill pipe, leads from the rig, through the drill column and BOP, and into the earth below. To prevent blowout flows from advancing up the drill column and reaching the rig, each valve is designed to close off blowout flow in one of various manners, depending on if the drill pipe is still present in the drill column. When all these measures fail to seal in blowout flow, the last line of defense is the blind shear ram, which cuts the drill pipe, subsequently to be removed, and seals in blowout. Under such high pressure peaks the BOP can fail to operate, usually by failing to seal the flow while the drill pipe is present, or by failing to cut the drill pipe, subsequently failing to shut off blow out flow. One common failure mechanism is the drill pipe being located off center from the drill column, rendering the rams and shears inoperable. Another failure mechanism occurs when a BOP ram attempts to seal around, or cut through, the drill pipe at its tool joint. In these situations the BOP rams cannot operate properly. In the case of the Macondo Well incident, the drill pipe broke into two sections, both of which occupied the blind shear ram. These conditions presented the blind shear ram with a scenario for which it was not even designed. For these reasons, BOPs can fail. Though a small percentage of failure incidents are catastrophic, these catastrophes are costly to life, property and the environment. If a BOP fails, then the oil and natural gas escape onto the rig and into the surrounding water. 
         [0005]    The BOP is an enclosed system, and the failed mechanisms are therefore inaccessible during such a crisis event. The depth under water further complicates efforts to reach a failed BOP. Intervention is usually possible only using remotely operated vehicles (ROVs). There is an enormous need for a means that is minimally intrusive into current BOP architecture, which provides immediate access to the failure mechanism at the BOP, simultaneously diverting the blowout spill at this location far below the rig until the BOP is rendered operable, and the spill is stopped. 
       PRIOR ART 
       [0006]    Prior art provides blowout diverters at or near rig levels which allow for diversion of low pressure blowout flows. These diverters exist for land operations, as well as jack-up and floating rigs. But they provide a limited barrier between the rig and workers, and the dangerous hazards of the approaching high pressure flow. Furthermore, they offer no remedy to the failure mechanisms of the failed BOP. A means of diverting blowout at higher pressure a safer distance relative to the rig, while simultaneously providing for the mitigation of the causes of BOP failure is needed in order to assure safety to rig and crew, and gain control of the blowout. 
       SUMMARY 
       [0007]    Example embodiments of the present disclosure provide systems and methods of accessing and remedying a failed BOP, diverting blowout flow away from the rig, and minimizing spill duration due to BOP failure during a blowout. Briefly described, in architecture, one example embodiment of the system among others can be implemented as follows: a housing assembly, consisting of upper and lower parts, each having an integrated casing, i.e. boss, on which to mount existing BOP ram systems; an annular sealing ram positioned within the housing and between the ram block systems and able to slide within the housing, the annular ram configured to abut to a surface within one end of the housing, and the annular ram also configured to open and close a side opening in the housing ; A guide pin to keep the annular ram oriented properly for locking position; a locking mechanism configured to lock the annular ram in the closed position; a hydraulic chamber within the housing, the chamber configured for sliding the annular ram within the housing to open it, or seal it shut on the surface of the housing; and a system of seals to contain hydraulic and well pressures within and without the system. 
         [0008]    Example embodiments of the present disclosure can also be viewed as providing methods for systems and methods of accessing and remedying a failed BOP, diverting blowout flow away from the rig, and minimizing duration of spill from a blowout caused by BOP failure. In this regard, one embodiment in such a method, among others, can be broadly described by the following: a housing mounted in the BOP stack system, consisting of upper and lower parts, each consisting of an integrated BOP ram, the upper part having a blind shear ram, and the lower part having a casing shear ram; a sealing annular ram positioned to slide within the housing to open and close the housing, to provide access into the drill column below the blind shear ram, to remedy the failure mechanism, and to provide egress for blowout flow. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1(   a ) Cross section of an example embodiment for a  19  inch well, using existing BOP ram systems (indicated in phantom line) showing annular ram closed, upper housing and lower housing cap 
           [0010]      FIG. 1(   b ) Full view of an example embodiment with annular ram open, showing upper housing, lower housing cap, and side opening 
           [0011]      FIG. 2(   a ) Typical BOP system showing stack and LMRP 
           [0012]      FIG. 2(   b ) The BOP with the invention installed, showing access into the BOP drill column and drill pipe, and egress for blowout diversion 
           [0013]      FIG. 3(   a ) Cross section view of example embodiment integrated into the BOP, showing normal drilling operation with annular ram closed 
           [0014]      FIG. 3(   b ) Cross section view showing emergency blowout operation following BOP failure, opening annular ram to allow blowout diversion and access to the problematic drill pipe (not shown in this figure) responsible for BOP failure 
           [0015]      FIG. 4(   a ) An example embodiment installed on BOP stack, shown open giving access to drill column and problem drill pipe 
           [0016]      FIG. 4(   b ) Drill column and drill pipe shown in cutaway view 
           [0017]      FIG. 5  Exploded view of an example embodiment, showing use of existing BOP rams, ram cases being one piece with housing parts 
           [0018]      FIG. 6  exploded view of an example embodiment without BOP ram equipment 
           [0019]      FIG. 7(   a ) Exploded view of housing assembly showing upper housing and lower housing cap, looking from above 
           [0020]      FIG. 7(   b ) Exploded view of housing assembly looking from below 
           [0021]      FIG. 8(   a ) Exploded view of housing cap and annular ram with related seals looking from above 
           [0022]      FIG. 8(   b ) Exploded view of housing cap and annular ram with related seals looking from below 
           [0023]      FIG. 9(   a ) Exploded view looking from above, showing annular ram, and cutaway section of housing, with related seals, locking components, and guide pin 
           [0024]      FIG. 9(   b ) Exploded view looking from below, showing annular ram, cutaway section of housing, related seals, locking components, and guide pin 
           [0025]      FIG. 10(   a ) Annular ram piston geometry looking from above, showing proper design 
           [0026]      FIG. 10(   b ) Annular ram piston geometry looking from below 
           [0027]      FIG. 11(   a ) Cutaway and enlarged views of locking mechanism for annular ram, looking from above, showing operation of locking lugs and guide pin sliding in housing slot to keep ram features aligned to receive locking lugs when ram closes 
           [0028]      FIG. 11(   b ) Looking at cutaway view of locking mechanism from below 
           [0029]      FIG. 12  System assembled with standard BOP ram devices, and surfaces shown to be machined/ drilled/ tapped as needed 
           [0030]      FIG. 13(   a ) Computer analysis of deformations for designing stiffening geometry to minimize deformation of housing under load 
           [0031]      FIG. 13(   b ) Stiffening geometry resulting from computer analysis 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    Embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings in which like numerals represent like elements throughout the several figures, and in which example embodiments are shared. Embodiments of the claims may, however, be embodied in many different forms and should not be construed to be limited to the embodiments set forth herein. The examples set forth herein are non-limiting examples, and are merely examples among other possible examples. System parts are indicated by leader lines with arrowheads pointing to the part, or leader lines with dots touching the part. Part features, such as surfaces, embossments, debossments, or similar are indicated by leader lines only, touching the feature. The system disclosed herein integrates with existing systems. 3-digit numerals are used to represent elements of the invention. 2-digit numerals represent elements of existing machinery with which the invention integrates. In some cases these elements are shown in phantom line. 
         [0033]    Protecting oil rigs from unexpected peaks in well pressure is of paramount importance. When the BOP fails under these extreme pressures, the rig, crew, and environment are almost certain to suffer loss, as in the case of the British Petroleum (BP)/Deep-water Horizon event where eleven men died and estimates of oil spill rates climbed steadily from 5,000 barrels per day up to a stunning 60,000 barrels per day. 
         [0034]    Mitigating disastrous effects due to BOP failure is almost impossible with current drilling architecture. Proactive methods to deal with this scenario are virtually nonexistent, limited to reactive, post disaster methods for cleanup, and ad hoc methods for spill terminating. This disclosure provides a proactive solution for mitigating disaster when a BOP fails and emergency scenarios ensue. Disclosed herein in example embodiments is a minimally intrusive system to be installed into current BOP architecture for mitigating such disasters. This mitigation process is proposed as diverting blowout flow at a safe location away from the rig, while, at the same time, providing access into the drill column inside of the failed BOP. Example embodiments of systems and methods of diverting blowout flow at the failed BOP, and opening the drill column therein, are disclosed herein and may be used to install below the blind shear ram within the BOP stack, a housing unit within which a sliding annular ram opens and closes the housing. In example embodiments of this system, the current drilling protocol operates as usual, until occasion when a blowout occurs and the BOP fails. Then, the sliding annular ram opens the housing to allow blowout to flow out at this location, instead of upwards towards the rig. This opening simultaneously provides access to the drill pipe inside the drill column of the failed BOP, allowing external manipulation of the drill pipe to center it in the BOP rams for proper BOP ram function; or, if necessary, to cut the pipe, subsequently removing it from the BOP and allowing the BOP to resume normal function. Example embodiments include a hydraulic chamber within the housing to move an annular ram pipe through the housing to open and close the housing, thereby sealing the blowout flow once the failed BOP is remedied. 
         [0035]      FIG. 1(   a ) shows a cross sectional view of a system for catastrophe mitigation for deep water oil drilling during BOP failure. The system includes three main parts: the housing upper part  100 ; the housing lower cap part  200 ; and the annular ram part  300 . The system includes a plurality of threaded fasteners to retain assembly between housing and housing cap parts. The system also includes a plurality of pressure seals to maintain fluids and pressures from within and without. The annular ram part  300  is shown in closed position. This system is used in conjunction with existing BOP rams, and shown in phantom line. In this example embodiment the top ram is a blind shear ram, and the bottom ram is the casing shear ram. 
         [0036]      FIG. 1(   b ) shows the system in full view with the annular ram in open position. In this view one can see feature  110 , referred to herein as the “access-diverter port”, “egress port”, or “side opening”. The annular ram  300  opens in the event of BOP failure to allow diversion of blowout flow at this location, instead of allowing the blowout to proceed to the rig. Simultaneously, access is allowed at this location to enter the drill column and the drill pipe inside (not shown in this figure) in an effort to restore function to the BOP and drilling operation. Overall width is 65 inches, and height is about 13 feet. In the preferred embodiment overall weight is about 50 tons, however net weight increase to the standard BOP is only about 35 tons for reasons to be discussed next. 
         [0037]      FIG. 2(   a ) provides a view of a typical BOP system like that used on the Macondo Well. The typical BOP consists of a series of horizontal gate type valves of various types and called “rams” or “BOP rams”, located in the stack  20 . These are commonly the blind shear ram  21 , casing shear ram  22 , and variable bore rams  23 . These are powered hydraulically by hydraulic piston systems such as those indicated by  21 A and  22 A. Above the stack is the Lower Marine Riser Package (LMRP)  10  consisting of an Emergency Disconnect System (EDS)  14 , connected to the EDS flange  15 ; and upper and lower elastic donut shaped valves, or “annular BOPs”  12  and  13  respectively, also called “annular valves”. At the top is the flexible joint, also called the flex joint  11 . When a blowout occurs the annular BOPs attempt to close around the drill pipe to close the drill column, to block the passage of blowout flow. Likewise the variable bore rams attempt to as a backup measure. When these fail the blind shear ram attempts to cut the pipe which can then be removed. The blind shear then shuts off blowout. The blind shear ram is the last stopping force to blowout flow. If this fails, an uncontrolled blowout approaches the rig. 
         [0038]      FIG. 2(   b ) shows the same BOP system with invention installed. Example embodiments add a nominal 35 tons, and 5½ feet of height to the current architecture. A preferred embodiment employs “built in”, i.e. “integrated” BOP ram systems available on the market today. This example embodiment provides a “window” or “access port” into the drill column. Through this port, one may access the problematic drill pipe with any available cutting or forcing device. Example embodiments provide the side opening  110  which is about 36 inch wide by 24 inch high. In a preferred embodiment, well pressure containment capacity is 20,000 pounds per square inch (psi) total pressure, overall width and diameter is about 65 inches, and overall height is about 13 feet. The gross weight is nominally 50 tons. However, a preferred embodiment using integrated rams as one piece with the housing unit results in only a 5½ feet height increase, and weight increase of 35 tons, nominally because it already consists of two BOP rams. Example embodiments and other dimensions are contemplated herein for smaller wells and BOPs. 
         [0039]      FIG. 3(   a ) shows a cross sectional view of an example embodiment in operation, with annular ram  300  in closed position for normal drilling or BOP operations. Surfaces  120 ,  311 , and  207  are the diameter of the drill column through the BOP. If a blowout occurs, the annular BOPs  12  and  13  try to close around the drill pipe (drill pipe not shown) to close the drill column. If needed the variable bore rams  23  will ensue. If these fail the blind shear ram  21  attempts to cut the drill pipe and seal in flow. If this fails, as it did in the case of the Macondo Well with British Petroleum and Transocean, total BOP failure has occurred, and the following operation ensues. 
         [0040]      FIG. 3(   b ) shows operation for Systems and Methods for Catastrophe Mitigation for Deep 
         [0041]    Water Oil Drilling during Blowout Preventer Failure. The annular ram  300  opens while the annular BOPs  12  and  13  above it close. This relieves static pressure in the BOP and diverts blowout through the side openings  110 , rendering the rig completely safe and in control of remedying the situation. The drill pipe is rendered accessible through the side opening  110 , such that the drill pipe may be accessed directly beneath the blind shear ram by a cutting or forcing device via ROV(s) or other means, and either cut, or centered whereby allowing the blind shear ram to cut the pipe, or other rams to seal around it to properly seal the blowout flow. Some other possible fringe benefits are retention of expensive drill mud above the annular LMRP valves; minimal downtime; and possible near term resuming of the drilling operation. 
         [0042]      FIG. 4(   a ) shows a close up of an example embodiment bolted between the EDS flange and the lower ram stack of three BOP rams. As discussed, a preferred embodiment makes use of integrated blind shear and casing shear rams. 
         [0043]      FIG. 4(   b ) more clearly shows the drill column and drill pipe in a cutaway view, with the tool joint adversely located near a given BOP ram. In this view the annular ram is shown open. As seen here, this example embodiment not only integrates well with existing BOP systems, it makes use of additional existing BOP ram equipment currently available. 
         [0044]      FIG. 5  shows the exploded view of an example embodiment using off-the-shelf existing BOP blind shear rams and casing shear rams  21  and  22  respectively. The locking lugs  400  are actuated by hydraulic ram systems like, or similar to, those aforementioned, and chosen commensurate with lug geometry such as, length, diameter, or end geometry. 
         [0045]      FIG. 6  shows an example embodiment as in  FIG. 5 , but without BOP rams, where surfaces  103 ,  105 , and  203  are to be machined specifically for the BOP ram systems of choice. This example embodiment consists of the housing unit  100 , housing cap  200 , annular ram  300 , a plurality of locking lugs  400 , a plurality of threaded fasteners  705  and  710 , housing cap seal  600 , a plurality of inner annular ram seals  601 , a plurality of outer annular ram seals  602 , a plurality of housing seals  603 , and annular ram guide pin  500 . In a preferred embodiment, the lower ram is a casing shear ram mounted to surface  203 , and the upper ram is a blind shear ram with locking bonnet, and mounted on surface  103 . This preserves the stack arrangement like the architecture shown in  FIG. 2(   a ). The middle BOP ram mounts to surface  105  and is chosen as needed to actuate the locking lugs  400 . Preferred embodiments for the housing  100 , housing cap  200  and annular ram  300  are preferably machined or forged from materials such as high strength steel, stainless steel, chrome molybdenum or other similar steel in which the elastic modulus is no less than 30e6 psi, and minimum yield strength is 75,000 psi. Like materials are contemplated for the locking lugs  400  and guide pin  500 . In an example embodiment the face seal  600  may be naval bronze, brass, or similar material suitable for sealing purposes for pressures not less than 5000 psi. Anti-corrosive coatings are considered for all embodiments, and may include silver coating, carburizing, painting, epoxies, or other methods to prevent corrosion of surfaces exposed under deep sea or salt water conditions. 
         [0046]      FIG. 7  shows an example embodiment of housing part  100  assembling with housing cap  200 . Outer diameter of surface  101  and  201  are equal. Surface  208  mates against surface  112 , with housing cap seal  600  between them. This assembly is retained with threaded fasteners  710  and  705 , through hole features  104  and tapped holes  204 . Surface  206  fits concentric with surface 113 . The housings  100  and  200  embody special geometries  102 ,  202 , and  108  to provide stiffness in needed areas. Features  102  and  202  also provide encasements for existing BOP ram valve assemblies. Throughout this disclosure it is emphasized that preferred embodiments use features  102  and  202  as casings, or cases, to house blind shear ram valve assemblies and casing shear ram valve assemblies respectively. In this manner existing BOP ram systems, such as features  21  and  22  shown in  FIG. 2(   a ) are “built in”, i.e. integrated into the system disclosed herein. This results in a smaller increase in height being introduced into current BOP architecture. The width across surface  103  to the opposite side  103  is commensurate with off-the-shelf BOP ram cases. Surfaces  103 ,  105 , and  203  are to be machined specifically to accept selected BOP ram systems. Overall height is a nominal 13 feet, and diameters of this example embodiment are 65 inches at surface  109  and 50 inches at surface  111 . The side opening  110  is about 36 inches wide and 24 inches tall in this example embodiment. A facing or grove  205  is provided and sized as needed for generic face seal  600 , about 50 inches in diameter. Diameter  207  makes up the drill column in this portion of the BOP overall drill column, and matches it in diameter of about 19 inches. Other dimensions are contemplated in the disclosures herein. 
         [0047]      FIG. 8  shows an example embodiment of the inner annular ram seals  601 , the housing cap  200 , and annular ram  300 . In a preferred embodiment, diameters of surfaces  301  and  206  are about 28 inches plus or minus clearance tolerance. The overall height of ram  300  is about 65 inches, and overall height of the cap  200  is about 74 inches. The inner diameters of surfaces  311  and  207  match that of the drill column. The cap  200  has grooves  209  into which seals  601  install. The annular ram  300  slides over surface  206  of the cap  200 . The seals  601  form a pressure barrier across the surfaces  301  and  206 . Hydraulic clearance exists between surfaces  301  and  206 . A preferred embodiment has these clearances at 0.0015 inches, but other clearances are contemplated herein. Seals  601  are arranged for bidirectional pressure. In this case however, the upper seal is on the side of the well pressure. Hence this seal must contain well pressures commensurate with current BOP capacities of 20,000 psi. Though the lower seal  601  does not have this requirement, a preferred embodiment makes use of like seals for ease of assembly and standardization. These seals are about  28  inches in diameter for this example embodiment. Other dimensions to the foregoing discussion are contemplated herein. 
         [0048]      FIG. 9(   a ) and  FIG. 9(   b ) show, from different viewpoints, an example embodiment of the annular ram  300  inserted into the housing  100 . The annular ram  300  has grooves  310  recessed into surface  304 . Seals  602  fit into these grooves, providing a seal across the annular ram surface  304  and surface  113  of the housing  100 . Seals  603  fit into grooves  114  recessed into surface  115 , providing a seal across the housing surface  115  and the annular ram surface  306 . Diameter of surface  120  matches that of the drill column; 19 inches in this example embodiment. Diameters of surfaces  113  and  115  of the housing  100  are about 42 inches and 40 inches, respectively, plus needed clearances to accept the annular ram  300 . The diameter of the seals  602  and  603  are about 42 inches nominal. The diameter of surface  304  is slightly larger than that for surface  306 , providing the shoulder surface  305 , on which hydraulic pressure, entering through port  116 , forces the annular piston type ram  300  downward, to the open position. Conversely, hydraulic pressure entering through port feature  117  applies force to the annular ram surfaces  307  and  308  forcing the annular ram  300  upward into the closed position. This forms a seal across surface  309  and surface  119 , closing the drill column. As an example embodiment, surfaces  309  and  119  are conical at 37.5° from axis, and form a metal to metal contact seal. Other seal geometries and materials are contemplated herein. Hydraulic clearance exists between surfaces  304  and  113  and surfaces  306  and  115 . A preferred embodiment has these clearances at 0.0015 inches, but other clearances are contemplated herein. Seals  602  form a pressure barrier in both directions of hydraulic force acting on surface  305 , or surfaces  307  and  308 . In this example embodiment seals are designed for pressures of 1500 psi, though other pressure values may be considered herein. Likewise, seals  603  are arranged for bidirectional pressure. In this case however, the upper seal is on the side of the water pressure at ocean depth. Hence this seal must contain depth pressures commensurate with current drilling practices. A preferred embodiment sets this value to about 5,000 psi, though higher values are contemplated herein. Though the lower seal  603  does not have this requirement, a preferred embodiment makes use of like seals for ease of assembly and standardization. The housing  100  has an insertion hole,  107 , through which the annular ram guide pin  500  is inserted into the threaded hole  302  of the annular ram  300 . This pin in turn slides in the guide slot  118  of the housing  100 . This slot resides outside of the hydraulic chamber formed below the seals  603  in the grooves  114 . This pin  500  serves to keep the annular ram  300  properly oriented such that the locking recesses  303  align with, and receive, the locking lugs  400  when the annular ram closes its surface  309  against surface  119  of the housing  100 . The locking lugs  400  install and operate through the hole features  106  of the housing  100  and are actuated by available external rams mounted as previously discussed. Thee lugs are about 5 inches diameter. Other dimensions to the foregoing discussion are contemplated herein. 
         [0049]      FIGS. 10(   a ) and ( b ) show annular ram geometry from top and bottom respectively, and illustrate what happens if the annular piston ram is not properly designed. If surface area  313  is larger than surface area  312 , then well pressures in the drill column  120  and  311  can create a force differential which acts against hydraulic closing pressures entering  117  to prematurely open the annular ram  300 . Conversely, if surface area  312  is greater than surface area  313 , well pressures can create a force differential against the hydraulic opening force entering  116 , preventing opening the annular ram  300 . The forgoing applies only when the annular ram is in the closed position, when well total pressures are contained. Hence, example embodiments require surface areas  312  and  313  to be equal. This cancels any adverse forces that might otherwise prematurely open, or prevent opening, the annular ram  300 . 
         [0050]      FIG. 11  shows an example embodiment of a locking mechanism consisting of locking lugs  400  and guide pin  500 . Locking lugs  400  are actuated by external BOP ram systems of choice, available as off-the-shelf items. In a preferred embodiment these lugs  400  move inward to engage the locking lug surface  401  with annular ram surface  303 A, a surface feature within the slot feature labeled  303  in  FIG. 9 . In example embodiments the lug surface  401  and the slot surface  303 A are at a slight angle which provides a wedge cam effect to “tighten” the annular ram surface  309  against the housing surface  119 , shown here, and also shown in  FIG. 9 . This angle is determined in general to provide the optimum force for maintaining adequate seal between the aforementioned surfaces  309  and  119 . Thus different angles are contemplated herein for example embodiments. The lugs are about 5 inches in diameter, and the length and end geometry are to be determined based upon actuating ram of choice. In this figure we see the guide pin  500  sliding along the housing guide groove  118  to maintain proper alignment of the annular ram locking slots  303  with the locking lugs  400 , when the annular ram  300  moves to closed position. Dimensions to the foregoing discussion are for example embodiments, and other values are contemplated herein. 
         [0051]      FIG. 12  shows an example embodiment fully assembled. This invention makes use of existing rams. In a preferred embodiment indicated surfaces  103 ,  105 , and  203  are intended to accommodate general BOP ram systems, and are therefore to be machined/drilled/tapped as needed. Likewise surfaces  121  and  210  are machined to accommodate any connections desired. In example embodiments herein surface  121  is drilled and tapped for an EDS connection flange, while surface  210  is drilled and tapped for a BOP ram flange connection. A preferred embodiment consists of a casing shear ram for the lower ram and a blind shear ram with locking bonnet for the upper ram system. Other choices may be contemplated herein. A preferred embodiment is shown using a ram system with locking bonnets on the middle rams. 
         [0052]      FIG. 13  shows an example embodiment of housing  100  assembled with housing cap  200 , bringing attention to stiffening geometry  108 . This feature allows the housing assembly  100  and  200  to undergo tensions typical in drill risers. A preferred embodiment allows tensions of one million pounds without deforming the housing, to prevent compromise of internal hydraulic clearances between housing  100  and annular ram  300  (see  FIG. 9 , for example). Geometric features  108  maintain needed geometric integrity of the device hydraulics for this purpose. This is confirmed by computer analysis, which gives convergent results for numeric values of stress and deformations. In a preferred embodiment deformations are found to be less than 0.0008 inches, which are less than the aforementioned designed hydraulic clearances of 0.0015. 
         [0053]    Referring now to  FIGS. 1 through 13 , by way of example, and not limitation, there is illustrated a system of mitigating blowout disaster when BOP failure occurs. Specifically, these disclosures are for a well and BOP having a nominal inside diameter of 19 inches, and it is recognized that alternative well and BOP sizes are available, resulting in varied dimensions, materials, and manufacturing techniques for the configuration of a system of mitigating blowout disaster when BOP failure occurs, to match such well and BOP configurations, and such varied dimensions, materials, and manufacturing techniques are understood by one skilled in the art and are contemplated herein. Preferably, the dimensions, materials, and manufacturing techniques herein include other suitable characteristics, such as strength, durability, water-resistance, light weight, temperature-resistance, chemical inertness, oxidation resistance, ease of workability, or other beneficial characteristic understood by one skilled in the art. The foregoing description and drawings comprise illustrative embodiments. Having thus described exemplary embodiments, it should be noted by those skilled in the art that the disclosures within are exemplary only, and that various other alternatives, adaptations, dimensions, materials, and modifications may be made within the scope of the present disclosure. Many modifications and other embodiments will come to mind to one skilled in the art to which this disclosure pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Although specific terms may be employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. Accordingly, the present disclosure is not limited to the specific embodiments illustrated herein, but is limited only by the claims following.