USRE36244E - Well plugging apparatus and method - Google Patents

Abstract

An apparatus for plugging a burning or gushing well comprises a hollow tubular plug body (20) sized for insertion into a well casing (112). Provided on the plug body are a retainer module (54) for retaining the plug within the well casing; a sealing sleeve (46) provided for forming a seal between the plug body and the well casing; and a valve assembly (50) for selectively closing a hollow internal passageway of the tubular plug body. The plug body is loaded on a gantry assembly (21), which in turn is carried by a shielded vehicle (24). At the base of the gantry assembly are provided an alignment assembly (37) for aid in approach to the well casing and a cutter assembly (40) for sawing off inordinately protruding casings. In one embodiment, a protective break-away shell (118) circumferentially surrounds at least a portion of the plug body.

Description

This is a divisional of application Ser. No. 08/051,854, filed Apr. 26, 1993, . .and U.S. Pat. No. 5,367,840.!..Iadd.now U.S. Pat. No. 5,361,840.Iaddend..

BACKGROUND

1. Field of Invention

This invention pertains to the method apparatus and system for extinguishing and capping burning or gushing oil, gas, geothermal, or water wells.

2. Related Art and Other Considerations

Few things on earth are as awesome and dangerous as oil or gas well fires. The extremes of temperature, pressure, noxious/toxic fumes, acidic impurities in crude oil, slippery conditions, limited visibility, and difficult site conditions combine to make extinguishing and capping a burning or gushing well very difficult and hazardous. Many developments such as automatic shut-off valves, safety valves and blowout preventers attempt to eliminate wild wells before they get out of control. These methods certainly reduce the risk of wild wells, but several well fires still occur in an average year throughout the world. They may be caused by static electricity, lightning, human error, higher pressure than anticipated, accidents, sabotage, or other reasons.

The standard methods of oil well fire-fighting and capping were developed in the 1920's or earlier. The most popular and universal extinguishing method consists of driving a crane-like piece of equipment close to the burning well so that it suspends a container of hundred of pounds of high explosives near the apex of the flame. The equipment operator then dismounts his vehicle and immediately vacates the area of the well. The explosive is detonated and (usually) sufficiently deprives the fire of oxygen to extinguish the fire. This leaves a gushing well with a high danger of reignition. Gushing wells are usually capped by several men going to the wellhead and connecting a control valve (e.g., Christmas Tree valve). The valve connection is accomplished mostly by hand with the aid of some tools and equipment, but the men are covered with crude oil and struggle against pressures that may exceed 20,000 psi. If a gushing well reignites from a static spark, heat, or lightning, all personnel in the vicinity who are covered with oil are endangered by a possibility of being instantly incinerated.

As a result of the oil field fires in Kuwait in 1991, several new methods of extinguishing well fires have been used with varying success such as liquid nitrogen injection and blowing out the fire with the exhaust of a jet engine. However, they all place people with only limited protection in close proximity to the fire and all leave a gushing well to be capped. Additionally, they are limited when another burning well is close by. The only method that extinguishes and "CAPS" a well simultaneously consists of dropping a heavy dome over the wellhead. The dome is only a temporary cap that must be removed to place the well into production.

Up until now, no method has been able to extinguish, cap, and place a well into production in a matter of minutes and without exposing people to crude oil, heat, flame, fumes, and slippery conditions.

Accordingly, it is an object of the present invention to provide a method, apparatus, and system for extinguishing and capping burning or gushing wells with maximum safety and minimum exposure of personnel.

An advantage of the present invention is the provision of a method, apparatus, and system that renders a well usable a short time after plugging.

Another advantage of the present invention is the provision of method and apparatus for accomplishing the entire plugging operation by remote control from a distant position of safety, thus not endangering human life.

Yet another advantage of the present invention is the provision of apparatus and method that are operative on damaged well casings above ground, and even on casings that may be broken off below ground level.

Still another advantage of the present invention is the provision of apparatus and method that extinguishes and caps a well in a single process.

A further advantage of the present invention is the provision of apparatus and method which does not require explosives or an inordinate amount of time.

An even further advantage of the present invention is the provision of apparatus and method that extinguishes and caps a well right next to another burning well.

Another advantage of the present invention is the provision of apparatus and method which are more economical than alternative methods and equipment.

Another advantage of the present invention is the provision of apparatus and method which utilize components which are simple and reliable.

SUMMARY

This invention is a remote controlled, protected vehicle with an attached plug insertion apparatus and specially designed hot plug which, when inserted into a well casing, locks itself to the well casings' interior, seals itself to the well casing's interior, and closes its integral valve to shut off fluid flow and extinguish the fire, if any. The entire system can withstand the high heat, flame, pressure, and forces exhibited by uncontrolled wells. It does not endanger human life but does put the well rapidly into production. The system is self-aligning and can cut off a damaged well casing, if necessary.

The apparatus for plugging a burning or gushing well comprises a hollow tubular plug body sized for insertion into a well casing. Provided on the plug body are a retainer module for retaining the plug within the well casing; a sealing sleeve provided for forming a seal between the plug body and the well casing; and a valve for selectively closing a hollow internal passageway of the tubular plug body. The plug body is loaded on a gantry assembly, which in turn is carried by a shielded vehicle. At the base of the gantry assembly are provided an alignment assembly for aid in approach to the well casing and a cutter assembly for sawing off inordinately protruding casings. In one embodiment, a protective break-away shell circumferentially surrounds at least a portion of the plug body.

In accordance with a method of the invention, the plug body is inserted into the well casing and locked in place by actuating the retainer module. A seal is then formed between the peripheral surface of the plug body and the well casing. The hollow internal passageway of the tubular plug body is selectively closed by operation of the valve assembly, thereby extinguishing the fire.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of preferred embodiments as illustrated in the accompanying drawings in which reference characters refer to the same parts throughout the various views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

FIG. 1A is a side view of apparatus for plugging a burning or gushing well according to a first embodiment of the invention, the apparatus being carried upon a first type of military vehicle.

FIG. 1B is a side view of the apparatus of FIG. 1A being carried upon a second type of military vehicle.

FIG. 1C is a side view of the apparatus of FIG. 1A being carried upon a civilian vehicle such as a bull dozer or front-end loader.

FIG. 2 is a side view, partially sectioned, of a plug body of an embodiment of the invention.

FIG. 3 is a detailed side view, partially sectioned, of a cable-operated ball valve included in a well plug of the invention.

FIG. 4 is a side view of one embodiment of a retainer included in a well plug of the invention.

FIG. 4A is a partially sectioned side view of the retainer of FIG. 4.

FIG. 4B is a sectioned view taken along line 4--4 of FIG. 4A.

FIG. 5 is a detailed side view, partially sectioned, of a sealing sleeve usable in a well plug of the invention.

FIG. 6A is a schematic top view of an alignment assembly .Iadd.including a cut-off saw .Iaddend.usable with a well plug of the invention, the alignment assembly being in a operative orientation,

FIG. 6B is a schematic top view of the alignment assembly of FIG. 6A .Iadd.with the cut-off saw .Iaddend.in a storage orientation.

FIG. 7A is a side view, partially sectioned, of a plug body of a second embodiment of the invention

FIG. 7B is a cross-sectional view of the plug body of FIG. 7A taken alongline 7--7.

FIG. 8 is a partial longitudinal cross-section of another embodiment of a retainer usable in a well plug of the invention.

FIG. 9 is a partial longitudinal cross-section of yet another embodiment of a retainer usable in a well plug of the invention.

FIG. 10 is a sectional view of the apparatus of FIG. 1A taken alongline 10--10.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1A shows aninstallation apparatus 18 for installing a plug 20 (also known as the "hot plug") in acasing 112 of a burning oil or gas well or gushing water, geothermal, oil or gas well. The structure of thehot plug 20 per se will be described in further detail with reference to FIGS. 2-5.

As shown in FIG. 1A, the installation apparatus consists of gantry assembly 21 which includes an insertion ram 22 (also known as a plug insertion means); a track driven, self-propelled, heat-shieldedvehicle 24; aheat shield 30 carried by thevehicle 24; and, a plurality of connectingarms 31 for connecting the gantry assembly 21 to theheat shield 30 and ultimately to thevehicle 24 bystruts 140 and 142. The connectingarms 31 comprise steel struts. Although not shown as such, it should be understood that there are left and right lower struts 31 as well as left and right upper struts 31, and left andright struts 140 and 142.

On a front surface thereof, theheat shield 30 bears avideo camera 32 within aprotective enclosure 34. Theenclosure 34 has atransparent pyrex window 36 that is continuously cleaned on its exterior by a pressure jet spray of non-combustible gas such as nitrogen. In this regard, aspray port 35 is provided above thepyrex window 36 and is connected by hoses to a cylinder of compressed gas or a motor driven pump (mounted either in theenclosure 34 or on the vehicle 24) for supplying the non-combustible gas.

At its base, the gantry assembly 21 carries analignment assembly 37 including analignment fork 38, as well as acasing cutter 40. The casing cutter includes a cut-off saw 41. Thealignment assembly 37 and thecasing cutter 40 are described in greater detail hereinafter with reference to FIGS. 6A and 6B.

Theheat shield 30 comprises heavy steel plates which form an essentially inverted box-like enclosure having front, back, left side, right side, and top walls. The external surface of the heat shield is provided with a reflective coating such as aluminizing to reduce its heat absorption even further.

Theheat shield 30 has supporting members of steel and anaccess door 128 located on its left side near its rear. Theheat shield 30 is mounted on thevehicle 24 by a plurality of struts, including rear support struts 124. Rear support struts 124 includehydraulic cylinders 125 which allow theheat shield 30 to be raised or lowered. There is sufficient structural bracing (not shown on FIG. 1A for sake of clarity) internally in theheat shield 30 to maintain a rigid, box like structure.

The gantry assembly 21 comprises two heavy gantry vertical frame members ortower 144; two gantry guide rods 138 (only one being shown in FIG. 1A, the other being behind the rod shown in FIG. 1A); a very heavyhydraulic cylinder 136; a rigid horizontalgantry base plate 146; a horizontal gantrytop plate 147; and, movable plug guides 148. Theplates 147 and 146 are attached to (or integral with) the gantryvertical frame members 144. The lower ends of theguide rods 138 extend below thebase plate 146 and provide for rigid connection of thealignment assembly 37 and thecutter assembly 40. Thealignment assembly 37 andcutter assembly 40 are described in further detail with reference to FIGS. 6A and 6B.

FIGS. 1B and 1C show essentiallyidentical installation apparatuses 18 and plugs 20, and primarily differ in the type of vehicle upon which theheat shield 30 andinstallation apparatus 18 are mounted. In particular, FIG. 1B shows theinstallation apparatus 18 andheat shield 30 carried on an alternate type of military vehicle 26 (such as a military tank or self-propelled artillery piece), while FIG. 1C shows theinstallation apparatus 18 andheat shield 30 carried on a civilian vehicle 28 (such as a bull dozer, front-end loader, or other standard, commonly available, piece of construction equipment of sufficient weight). FIGS. 1B and 1C employ the same reference numerals as FIG. 1A for illustrating identical or comparable structure. Various structural details not shown in FIGS. 1B and 1C are understood with reference to FIG. 1A.

FIG. 2 shows ahot plug 20 inserted, locked, and sealed in awell casing 112. Theplug 20 includes an essentially hollowcylindrical plug body 42 comprised of two sections, in particularlower plug body 42A andupper plug body 42B. Plugbody 42 is formed from a heavy steel and is of a hollow tubular shape having an internal passageway therein. Plugbody 42 has a guide nose or guidepoint 43 at a lower end thereof. Also included in the plug body is a sealing module or sealingsleeve 46 and aball valve 50. The sealingmodule 46 is described in more detail with reference to FIG. 5, while the ball valve is described in more detail with reference to FIG. 3. Whether or not specifically stated hereinafter, it should be understood that portions of theplug body 42 above theball valve assembly 50 are of theupper plug body 42B, while portions of the plug body below theball valve assembly 50 are of thelower plug body 42A.

Theguide point 43 is comprised of a plurality of guide struts 44 which meet together to define a conical structure at a lower point. Since thestruts 44 are unconnected other than at the lower point, thestruts 44 provide aconical volume 45. Theguide point 43 serves not only to start thehot plug 20 easily into the well casing 112 upon insertion, but also centers theplug body 20 and thereby protects the sealingmodule 46 andball valve 50 from catching or snagging on the top of thewell casing 112. In addition, theguide point 43 allows a maximum fluid flow with minimum drag force through the open center of thehot plug body 42, thus assuring a minimum insertion force requirement.

Above theguide point 43 in FIG. 2 is the sealingmodule 46. The sealing module 46 (shown in more detail in FIG. 5) comprises an elastomeric, high temperature resistant, tubular sleeve orbladder 47. The sealingsleeve 47 is securely held in place on the outer peripheral surface of theplug body 42 bysteel retaining collars 48 which both seal it to thehot plug body 42 and prevent relative longitudinal motion. As described hereinafter with reference to FIG. 5, thesleeve 47 is inflatable with hydraulic fluid supplied through a high pressurehydraulic fluid line 49.

Above thesealing module 46 in FIG. 2 is a cable operatedball valve assembly 50, illustrated in more detail in FIG. 3. Aball valve case 52 is drilled and tapped for connection of the high pressurehydraulic fluid line 49 which passes through theball valve assembly 50 and which furnishes hydraulic fluid for inflation of the sealingmodule 46.

Above theball valve assembly 50 in FIG. 2 is aretainer module 54. In the embodiment illustrated in FIGS. 2, 4, 4B, and 4A, theretainer module 54 comprises three heavy jaw assemblies 70A, 70B, and 70C that bite into the well casing's 112 interior when theretainer module 54 is activated. As shown in FIG. 4B, the jaw assemblies 70A, 70B, and 70C are positioned around the periphery of theplug body 42, with each jaw assembly extending just shy of one third the circumference of the plug body and small gaps orspaces 73 being provided between the jaw assemblies. The jaw assemblies 70A, 70B, and 70C each haveteeth 71 provided thereon and are borne by afluid bladder 72 that inflates with hydraulic fluid when activated. Inflation of thebladder 72 causes thejaws 70 to engage thewell casing 112. Twoaxial collars 74 hold theretainer module 54 in place on theplug body 42.

Depending on the pressure expected at a wellhead, there may be two ormore retainer modules 54 used on ahot plug 20. Theretainer module 54 and two alternate configurations are described in further detail with reference to FIGS. 4, 8, and 9.

Near the top of thehot plug 20, and above the portion of thehot plug 20 that is inserted into thewell casing 112, is a steel radial arm orprotective sleeve 56. All hydraulic lines run through thesleeve 56 between themembers 144 of theinsertion ram 22 and ultimately through theheat shield 30 to thevehicle 24, 26, or 28.

At the very top of the hot plug is atop flange assembly 122 which is screwed onto thehot plug body 42 with standard pipe threads. Theflange assembly 122 mates with theinsertion ram 22 to hold thehot plug 20 in place during insertion and allows full inside diameter fluid flow through thehot plug 20 andinsertion ram 22. Theflange assembly 22 can be removed for connection of thehot plug 20 to a production pipe line after thehot plug 20 is inserted, locked, sealed, and theball valve 50 is closed. Upon connection to production piping theball valve 50 may be easily reopened, which reopening places the well immediately into production.

FIG. 3 shows in more detail the cable operatedball valve assembly 50. Thecase 52 of the ball valve consists of two halves, only one half being shown by virtue of the cross section illustration of FIG. 3. The halves of thecase 52 bolt together with four highstrength steel bolts 123. The mating faces of thecase 52 halves are precision machined to effect a seal without the use of gaskets. The lower ends of thecase 52 halves having tapering surfaces 53 on their exterior to prevent them from snagging on thewell casing 112 during insertion. The axial ends of thecase 52 halves are internally threaded for attachment to upper and lowerplug body sections 42B and 42A, respectively. Onecase 52 half is drilled from end to end (i.e., from top to bottom) for passage of thehydraulic fluid line 49 to thesealing module 46 for its activation. Thecase 52 halves may be welded together in addition to being bolted to effect greater strength and seal.

Theball valve assembly 50 includes aball 58 of precision machined steel. Theball 58 has protrudingtrunions 64 on opposite sides which fit into trunion sockets in thevalve case 52 halves and which allow theball 58 to pivot smoothly about the trunion's 64 axis. Attached to theball 58 are twosteel cables 60 & 62 which serve to rotate theball 58 to a closed position (cable 60) or open position (cable 62) when tensioned.Cable 60 has itsown raceway 68 machined into the side of the ball, andcable 62 has itsown raceway 66 machined into thecase 52 half. A central axial opening through theball 58 allows (when the ball is rotated to its open position) for a maximum, free flowing inside diameter for any given outside diameter. Theball 58 may or may not utilize sealing rings to effect a seal in its closed position depending on the anticipated conditions of use. A pivoted lever (not shown) near the top of the hot plug provides for onecable 60 or 62 to be slackened whenever theother cable 62 or 60 respectively is tensioned.Cable 60 is tensioned by a small hydraulic cylinder (not shown) located near the top of thehot plug 20.

FIG. 4A is a lateral view, partially sectioned, of theretainer module 54 which is built around the plug bodyupper section 42B. As explained above, theretainer module 54 consists of three toothed jaws assemblies 70A, 70B, and 70C placed circumferentially around thehydraulic bladder 72. Both thehydraulic bladder 72 and thejaws 70 are held in place byretainer rings 74 at their upper and lower ends. The retainer rings 74 are crimped tightly in place and their outer edges are welded circumferentially to the hot plugupper body 42B. Asmall steel tube 76 supplies hydraulic fluid to anannular space 78 between the hot plugupper body section 42B and thehydraulic bladder 72. The application of hydraulic fluid inflates the bladder and causes thejaws 70 to be driven radially outward to firmly engage the inside surface of thewell casing 112.

As shown in FIG. 4B, thespaces 73 between thejaws 70 allow the ball valve's 50operating cables 60 and 62 to travel up past thejaws 70. The third space between thejaws 70 is utilized for placement of thehydraulic line 49 which operates the inflation of the sealingmodule 46. The top ends of the hydraulicfluid supply tube 76 andline 49 have check valves (not shown) installed to prevent deflation due to loss of pressure anywhere in the hydraulic system and may operate at pressures that are stepped up from the output pressure of the vehicle if necessary for locking and sealing against the extremely high pressures found in some wells.

FIG. 8 is a lateral cross-section showing an alternate locking orretainer assembly 80 that employs multiple levels of pivotal engagement levers 82 in various planes and of sufficient number to assure the locking against a stated design pressure. Thelevers 82 extend throughslots 81 provided in the plug bodyupper section 42B. The engagement levers 82 have cam shaped outer lower profiles that allow them to be easily inserted into thewell casing 112. Their inner ends are long enough to prevent their travel past a locked position and havesteel cables 83 attached that travel up the interior of the upperhot plug body 42B. The multiple cables are joined as necessary and travel over an unillustrated pulley at the top of thehot plug 20 to a small hydraulic cylinder (not shown) on the exterior of the upperhot plug body 42B that applies or releases tension to thecables 83.

FIG. 9 is a lateral cross-section showing yet another alternate retainer or lockingassembly 84. This assembly utilizesspring 88 operated toothed cam locks 86 spaced alternately aroundring 85 between attachment brackets (not shown) which secure the ring to the upperhot plug body 42B. As few as eightcam locks 86 may be on aring 85 and more may be provided for larger diameter hot plugs 20. A sufficient number ofrings 85 are provided, as required, to resist the expected pressure of the well. Exterior cable and hydraulic lines, although not shown on FIGS. 5, 4A, 8, and 9, pass between engagement levers 82 or toothed cam locks 86 to prevent interference. Exterior cable and hydraulic lines are protected by steel tubing throughout their lengths.

FIG. 5 is a lateral cross-section of the sealingmodule 46 showing the lowerhot plug body 42A, the elastomeric, high temperature resistant,tubular sleeve section 47 in its inflated position, two retainingcollars 48,fluid reservoir 96, and hydraulicfluid supply tube 49. The retainingcollars 48 are crimped tightly in place and their outer edges may be welded to the lowerhot plug body 42A to provide a secure seal and to prevent sliding along the lowerhot plug body 42A under extreme loading conditions. The lowerhot plug body 42A is slotted or channeled as at 92 to provide an access space for thefluid supply tube 49 which is brazed into place for a complete seal and the surface is ground smooth and/or polished so that theupper collar 48 does not crush thetube 49 and effects a secure high pressure seal. It should be understood from FIG. 5 that when hydraulic fluid passes through hydraulicfluid supply tube 49 thesleeve section 47 inflates by virtue of fluid entering thereservoir 96 until the exterior surface of thebladder 47 seals tightly against the interior of thewell casing 112. The pressure of the hydraulic fluid supplied is stepped up to a pressure sufficiently greater than the fluid spewing from the uncontrolled well to generate a complete seal.

FIG. 6A is a top view partially sectioned, showing both thealignment assembly 37 and thecutter assembly 40. FIG. 6A shows thecutter assembly 40 with power cable cut-off saw 41 in an operating position and having completed the cutting-off of awell casing 112.

Thealignment assembly 37 comprises thealignment fork 38. Thealignment fork 38 has two heavyvertical rods 150 that attach to the lower ends of thegantry guide rods 138. Therods 150 hold thealignment fork 38 rigidly in place. Thealignment fork 38 has two fork members 160A and 160B connected to provide the fork with a V-shape. A plurality ofsensors 108 are provided on facing surfaces of the two fork members 160A, 160B. As shown in FIG. 6A, the two fork members 160A, 160B are oriented to accommodate the well casing 112 therebetween.

Themultiple sensors 108 indicate upon contact with well casing 112 or with a high pressure fluid flow if thewell casing 112 does not extend above ground level. In one embodiment, the sensor indications are displayed on a video display device within the vehicle for observation by the vehicle operator. In an alternate embodiment, particularly the case of remote control operation, the sensor indications are displayed at a remote control console. Electrical connection lines 109 (only some of which are shown) fromindividual sensors 108 pass through thealignment fork 38 and join to form a cable which passes through a thermallyprotective conduit 116 to thevehicle 24.

Thecutter assembly 40 includes a pivotinghorizontal plate 162 shaped in the form of a trapezoid. At one of its back corners thecutter pivoting plate 162 carries apivot collar 164 which rotatably surrounds a corresponding one of thevertical rods 150. At another of its back corners thecutter pivoting plate 162 carries a half-collar 166 which bears against a corresponding other one of thevertical rods 150 when thecutter assembly 40 is in its utilization configuration. The half-collar 166 has aradial connection flange 168 which has a pin hole therein for receiving aconnection pin 152. Further, theplate 162 has a first of threepulley wheels 102 rotatably mounted thereon.

Thecutter plate 162 has two horizontal support struts 104 which extend therefrom in a V-Shaped cantilevered fashion. Intermediate segments of thestruts 104 are connected by a cross-bar andspring tensioning assembly 106 to provide sufficient force for maintaining separation of thestruts 104. On their distal ends, the support struts 104 each have one of the other two of the threepulley wheels 102 rotatably mounted thereon. Thepulley wheels 102 are mounted in a horizontal plane so that a multistrand abrasive cable 98 (comprising saw 41) can be entrained thereabout.

Thecutter assembly 40 slides vertically downward onto the leftvertical rod 150. A firsthydraulic cylinder 110 is anchored to the fork member 160A and has its piston attached to theconnection flange 168 by thepin connection 152. Thehydraulic cylinder 110 extends until stopped by contact with the rightvertical rod 150 of thealignment fork 38, thereby moving the power cable cut-off saw 41 into its operating position and maintaining thesaw 41 in that utilization position. When thehydraulic cylinder 110 retracts, it moves the power cable cut-off saw 41 into its swing-away, or stored, position.

Theabrasive cable 98 travels on the three silicone rubber linedpulley wheels 102, two of which are held in place by pulley support struts 104 andspring tensioner 106. Thethird pulley 102, which is the drive pulley, is attached to and driven by ahydraulic motor 100. Thehydraulic motor 100 is served by hydraulic fluid supply and return lines that travel to the power cable cut-off saw 41 from the vehicle (24, 26, 28) in a thermally protectedflexible conduit 114.

FIG. 6B is a schematic top view of thealignment fork 38 with the power cable cut-off saw 41 attached and shown in its swing-away or stored position (with the swing-awayoperating cylinder 110 shown disconnected for illustration purposes only). Also shown are the hydraulic supply, return, andcontrol lines 114 which have thermal protection and carry hydraulic fluid from the vehicle to the hydraulic motor and return, as well as the thermally protectedsensor lines 116 which carry sensor indications to a video screen mounted within the vehicle or, alternatively, are sent by a computer on board the vehicle to a remote control console.

FIG. 7A is a lateral view, partially sectioned, of the lower part of ahot plug assembly 20 showing a protective break-awayshell 118 installed for additional thermal protection. Theshell 118 may be of potter's clay, ceramic, or other heat resistant material. The break-away shell is installed before theguide point 43 is welded in place and extends radially beyond theguide point 43 so that contact with the top of thewell casing 112 will cause it to break easily and have its pieces carried away by the stream of well fluid during the insertion process.

FIG. 7B is a cross-sectional view of the hot plug taken through the middle of the sealingmodule 46 with a protective break-awayshell 118 installed. There is anair space 170 between the sealingsleeve 47 and the protective break-awayshell 118. Formed-infault lines 120 which assist in breaking are shown in FIG. 7B. Also shown is the lowerhot plug body 42A.

FIG. 10 is a horiztonal cross section of the gantry 21 looking downwardly from above. FIG. 10 showsmovable plate 174, which travels up and down, being guided byguide rods 138 andvertical frame members 144 and driven by the double actinghydraulic cylinder 136.Plate 174 engagesflange 122 at the top of thehot plug 20, which is held securely by holdingplates 176 and 178 when they are pivoted to their closed positions as shown in FIG. 10.

OPERATION

The well plugging operation begins with collection of data. Data are collected on the inside diameter of the well casing, site conditions, pressure encountered in this particular field (or, if not available, in the general area), availability of safety and support services, and a variety of other information. From the data an operational plan is developed and implemented. Ahot plug 20 of the correct size range for the well casing is loaded onto the gantry assembly 21. Thesaw 41 is installed, if needed. The vehicle and all equipment are assembled at the site, checked and tested, fueled, and made ready.

If obstructions are present, or thecasing 112 extends to a troublesome height, the power cable cut-off saw 41 is pivoted to its utilization configuration by activation of thecylinder 110.

The vehicle withheat shield 30, gantry assembly 21,hot plug 20 andalignment assembly 37 in place is moved up the well head. The vehicle moves straight ahead so that thealignment assembly 37 contacts thewell casing 112. Maneuvering of the vehicle is aided by the sensor display which receives inputs from thesensors 108. The sensory input enables the operator to align perfectly thealignment assembly 37, and hence the entire gantry assembly 21 and theplug 20, over the well casing 112 or center of fluid flow.

When alignment is reached (in less than one minute), themotor 100 is activated to power the cable saw 41. The vehicle is driven to push thesaw 41 into the casing 112 (e.g., to the left in FIG. 1) until thesaw 41 has eaten completely through thecasing 112.

Upon completion of thecasing 112 cut-off operation, thehydraulic cylinder 136 of the gantry assembly 21 is activated to push thehot plug 20 into thewell casing 112. Thehot plug 20 is then locked into the well casing by activating its locking or retainingmodule 54. Then, hydraulic fluid is supplied to thebladder 47 of the sealingmodule 46 for sealing theplug 20 against the interior surface of thewell casing 112. Theball valve assembly 50 is then closed very slowly in order to minimize the hammer effect.

After installation, thehot plug 20 can then either be left in place as a temporary cap: be removed and replaced by a "Christmas Tree" type of control valve; or be epoxy grouted or welded permanently in place and connected to production piping (after removing the flange assembly 122). When permanently secured and connected, theball valve assembly 50 may be re-opened to place the well rapidly into production.

While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various alterations in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims (6)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An apparatus for plugging a burning or gushing well, the apparatus comprising:

a tubular plug body for sealing insertion and retention in a well casing, the plug body having a selectively closable hollow internal passageway;

a gantry assembly upon which the plug body is suspended above the well casing;

a sensor assembly provided at a lower end of the gantry assembly for sensing proximity to the well casing.

2. The apparatus of claim 1, wherein the sensor assembly comprises:

a fork which horizontally extends from the gantry assembly;

a plurality of sensors located on the fork in predetermined positions.

3. The apparatus of claim 2, wherein the fork has two fork members connected to provide the fork with a V-shape, and wherein the plurality of sensors are provided on facing surfaces of the two fork members, the two fork members being oriented to accommodate the well casing therebetween.

4. A method for plugging a burning or gushing well, the method comprising:

sensing with a sensor assembly a relative positioning between a well casing and a plug body to be inserted in the well casing, and providing a positioning signal from said sensor assembly in accordance with the sensed relative positioning;

inserting a tubular plug body into the well casing when the positioning signal indicates a proper relative positioning.

5. The method of claim 4, further comprising:

locking the plug body into the well casing by actuating a retainer;

forming a seal between the peripheral surface of the plug body and the well casing;

selectively closing the hollow internal passageway of the tubular plug body. .Iadd.

6. A ball valve assembly comprising:

a valve case having an interior space which communicates with first and second axial ports of the valve case;

a ball rotatably positioned within the valve case, the ball having an axial central opening therein;

a first cable having a first end attached within the interior space of the valve case to the ball to rotate selectively the ball to one of a first position and a second position, the first position having the axial central opening of the ball aligned with the axial ports of the valve case and the second position not having the axial central opening of the ball aligned with the axial ports of the valve case, a second end of the first cable being remotely positioned with respect to the valve case. .Iaddend..Iadd.7. The apparatus of claim 6, further comprising a second cable having a second cable first end attached within the interior space of the valve case to the ball and a second cable second end being remotely positioned with respect to the valve case for selectively rotating the ball from the second position to the first position. .Iaddend..Iadd.8. The apparatus of claim 7, wherein within the interior space of the valve case the ball has a raceway provided therein for at least one of the first cable and the second cable. .Iaddend..Iadd.9. The apparatus of claim 7, wherein the valve case has a raceway internally provided therein for at least one of the first cable and the second cable. .Iaddend..Iadd.10. The apparatus of claim 6, wherein within the interior space of the valve case the ball has a raceway provided therein for the cable. .Iaddend..Iadd.11. The apparatus of claim 6, wherein the valve case has a raceway internally provided therein for the cable. .Iaddend.

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