Well and method for preventing or stopping a blowout

Abstract

A well (1), especially an oil or gas well (1), has a casing (2) and at least a blowout preventer (4) attached thereto. An ejector (5) is connected to the casing (2) or to a spool attached to said casing (2) via a lateral access opening (6) in the casing (2) or in the spool. The lateral access opening (6) and therefore the ejector (5) is arranged vertically below the blowout preventer / s (4).

Description

[0001] WELL AND METHOD FOR PREVENTING OR STOPPING A BLOWOUT

[0002] The invention relates to a well , especially an oil or gas well , with a casing and at least a blowout preventer attached thereto .

[0003] Furthermore , the invention relates to a method for preventing or mitigating the ef fects of a well blowout and a method for fully or at least partly control a blowout of a well .

[0004] When drilling wellbores through geologic structures a layer may be penetrated which has a formation pressure considerably higher than the pressure in the wellbore or well . The following influx of formation fluids ( such as gas or oil ) is referred to as a " kick" . The high-pressure kick influx rises to the upper end of the well . I f the kick reaches the surface there are two extremely serious well control situations in drilling :

[0005] • drilling fluid, downhole tools , and other drilling structures may be blown out of the well (blowout ) , and

[0006] • the blowout fluid may ignite and explode (blazing or burning well ) .

[0007] In the first well control situation (based on the world well control standards ) it is highly crucial to seal the well in case of deep wells , or in case of shallow wells , to divert the blowout flow immediately to prevent conversion of the blowout to an explosion and a burning well . Due to high blowout velocity and pressure shock, there is some chance that the blowout preventers (BOPs ) which are usually part of the well may not completely seal the well ( in deep-holes ) as was the case in some blowout incidents . In shallow-holes , where a diverter is a mandatory equipment , there is furthermore some little possibility that the diverter' s annular preventer does not completely seal the well . In the second well control situation it is necessary to stem the flow of blowout fluid to the upper end of the well to enable killing (permanent sealing) of the well.

[0008] To manage and mitigate potential damage to people working at the well and to the environment, controlling blowouts from oil and gas wells is of great importance. There are several known methods to control blowouts as discussed below.

[0009] U.S. Pat. No. 3, 647,000 (Rowley et al., 1972) discloses a method for offshore well capping of the uncontrolled flow of oil and gas from oil and gas wells, by a procedure performed below the level of the water surface in a location which is free from wave action and safe from the danger of fire or explosion. The method involves the tapping of a window or access opening into the well casing or tubing through which the well fluids are flowing below the surface of the well, crimping the casing or tubing above the point of the tap and injecting solid plugging bodies which lodge within the constriction in the production tubing string and form a plug blocking the flow. Heavy non-combustible mud is then pumped into the production tubing through the tapped-in access line until the weight of the injected mud overcomes the formation pressure, thus terminating well flow. The nature of the plugging and the heavy mud is not disclosed. The issue with this method is that it is only suitable for permanently killing a borehole.

[0010] U.S. Pat. No. 3,926,256 (McCall, 1975) discloses a method for preventing blowouts in offshore wells. There is an apparatus in which pins extend into the passage through which oil or gas are flowing. The uncontrolled flow is stopped by the injection of a sealer material (such as balls of rubber, fiber, Fiberglas, aluminum, shredded Teflon, and the like) into the pin-containing region, followed by the injection of a mastic which acts as the sealing agent . This method does not seem to practically apply to aggressive high-pressure blowouts .

[0011] US Pat Number 4 , 489 , 784 (Messenger, 1984 ) introduces pumping special alloy metallic balls via hot-taps in the casing which melt at a temperature below that of the formation at the bottom end of the active casing or tubing string . Alternatively, liquid alloy is introduced into the active string which will cool and solidi fy in the well to form a plug of solid alloy in the string to stop the flow of fluid . The nature and possible high cost of such special alloy balls or liquid alloy are not disclosed . As the balls may not practically descend to the bottom due to the up- flow, the method seems not to be practical .

[0012] An obj ective of the invention is to provide a well , especially an oil or gas well , of the type mentioned above which avoids the problems mentioned as far as possible . In particular, a well is to be provided which is ef fectively protected against the ef fects of a blowout . Further obj ectives of the invention are to provide a method for preventing or mitigating the ef fects of a well blowout as well as to provide a method for controlling a blowout of a well respectively extinguishing a burning well (blazing well ) .

[0013] These obj ectives are solved according to the invention by a well having the features of claim 1 , a method having the features of claim 5 and a method having the features of claim 8 .

[0014] Preferred and advantageous embodiments of the invention are the subj ect of the dependent claims .

[0015] According to the invention an ej ector is connected to the casing - particularly the upmost or last casing - or to a spool attached to said casing via a lateral access opening in the casing or in the spool , and said lateral access opening ( and therefore the ejector) is arranged vertically below (e.g. upstream) the blowout preventer / s .

[0016] The ejector preferably has a conventional design, which is sufficiently well known. For example, such an ejector has a suction chamber, a blowout fluid inlet connecting said suction chamber with the access opening, a motive fluid inlet with a nozzle leading into said suction chamber and a tubular diffuser with an outlet, wherein the tubular diffuser is connected to and leading out of said suction chamber.

[0017] The diffuser preferably comprises a convergent tubular section attached to the suction chamber and a divergent tubular section ending with the outlet and attached to the convergent tubular section, either directly or indirectly via a constant tubular section .

[0018] A well designed in this way is particularly well protected against a blowout, since the ejector allows blowout fluids to be diverted from the casing of the well (and therefore away from the upper end of the well and the surface) before they can escape the well. Since the ejector is located below the blowout preventer / s (BOP / BOPs) or blowout preventer stack (BOP stack) , it provides additional safety and - in case of a well blowout - enables the crew to take the most suitable blowout prevention measurements for the occasion without being under hard time pressure .

[0019] In exploratory drilling or possible gas-cap drilling (or even other types of drilling) , if a sudden unexpected (gas) blowout occurs, due to the high blowout velocity and the pressure shock, the BOPs may not be able to seal the well (in deep-holes) or a malfunction may occur to the surface facilities. In top-holes, there is a chance that the high-velocity gas flow may prevent the diverter' s annular preventer to close and seal the well before the vent line can open . Such diverters are essentially used in top holes since sealing the well using BOPs may cause fracturing of the top-hole formations and occurrence of a seepage issue . After blowout flow detection, the diverter' s annular preventer requires 30 seconds ( for 18 ts-in and lower diverter si zes ) or 45 seconds ( for > 18 ts-in si zes ) to close and seal the well .

[0020] To prevent the ef fect of a blowout high velocity and pressure shock on the performance of a BOP or a conventional diverter, the well and the method according to the invention allow the flow to be diverted below the BOP or conventional diverter by use of the ej ector .

[0021] The ej ector can be connected and installed to the lower side of the BOP or BOPs or a drilling or spacer spool ( located between the upper end of the casing - particularly the upmost or last casing - and the BOP / BOPs ) so that it is protected from damage due to possible explosions .

[0022] Preferably, with a well according to the invention a gas detector sensor and / or an ultrasonic sensor is / are connected to the casing - particularly the upmost or last casing - or the spool and is / are set up to automatically activate the ej ector in case a gas blowout is detected by the sensor / s . This allows immediate action to be taken against a blowout .

[0023] In case of a blowout of drilling muds (where a blowout detection by the sensors may not be possible ) which may prevent safe operation of the BOP, a driller' s alarm of emergency must activate the ej ector to operate . Therefore , the ej ector is preferably connected to a control system which is set up to automatically activate the ej ector in case the driller' s alarm is manually or automatically triggered in the control system . According to the invention it is possible , that a motive fluid inlet of the ej ector is connected to a compressor, especially providing high pressuri zed air and an outlet of the ej ector is connected to a burn-pit . This embodiment is preferred, i f a gas well is drilled and the blowout fluid to be expected is gas . The gas-air mixture (blowout-motive fluid mixture ) can be burned in the burn-pit .

[0024] Alternatively, the motive fluid inlet of the ej ector is connected to a pump, especially providing high pressuri zed water, and the outlet of the ej ector is connected to a separator . This embodiment is preferred, i f an oil well is drilled and the blowout fluid to be expected is oil . The separator can be used to separate the oil from the oil-water mixture (blowout-motive fluid mixture ) .

[0025] It is advantageous i f the ej ector is connected to the lateral access opening of the casing - particularly the upmost or last casing - or the spool via a connector made of hard- faced material so that the connector does not get disconnected or broken due to high velocity and pressure of the blowout fluid . For example , such a connector can be made of tungsten-carbide .

[0026] It is highly recommended, that the ej ector is aligned in such a way, that the least bends exist in the flow path of the blowout fluid through the access opening in the ej ector and out of the outlet of the ej ector .

[0027] The invention also relates to a method for preventing or mitigating the ef fects of a well blowout , wherein the well , especially an oil or gas well , has a casing and at least a blowout preventer attached thereto . An ej ector (preferably of conventional design respectively of a design described above ) is connected to the casing or to a spool of the well via a lateral access opening in the casing or in the spool . The lateral access opening and therefore the ejector is arranged vertically below (e.g. upstream) the blowout preventer so that the ejector is protected against explosions occurring at the upper end of the well .

[0028] In case of an actual or immanent blowout the ejector is automatically activated by injecting high pressurized motive fluid into the ejector, thereby blowout fluid is sucked from the casing into the ejector and a blowout-motive fluid mixture is emitted out of the outlet of the ejector. Thereby the blowout fluid flow is diverted out of the casing and away from the upper end of the well where the BOP is (or the BOPs are) directly or indirectly (for example via the spool) attached to the casing.

[0029] Preferably, after the activation of the ejector the blowout preventer or at least one of the blowout preventers (or a diverter's annular preventer if such a conventional diverter is part of the well) is activated, especially automatically, and after the successful activation of the blowout preventer or at least one of the blowout preventers (or the annular preventer) the well is sealed and the ejector is deactivated.

[0030] When using a conventional ejector, the ejector is automatically activated by injecting high pressurized motive fluid through the nozzle of the motive fluid inlet into the suction chamber towards the diffuser of the ejector. The motive fluid thus injected escapes from the suction chamber through the diffuser, creating a vacuum in the suction chamber. The vacuum sucks the blowout fluid from the casing through the blowout fluid inlet (which is connected to the access opening in the casing) into the suction chamber and the blowout fluid is entrained with the escaping motive fluid through the outlet of the diffuser.

[0031] If the method is used with a gas well, the motive fluid can be air provided by a compressor and the motive-blowout fluid mixture is burned in a burn-pit . I f the method is used with an oil well the motive fluid can be water provided by a pump and the blowout-motive fluid mixture is separated in a separator into blowout fluid (which can be burned or stored) and water .

[0032] The method described above is preferably used with a well as described above .

[0033] The well and the method for preventing or mitigating the ef fects of a well blowout according to the invention has / have the following advantages : the detection and immediate diversion of blowout fluid and prevention of a gas or oil explosion and the consequent danger to the crew, since the ej ector is quick to function ( it can operate immediately) especially in top-holes whereas some time is required for conventional diverters to operate , the elimination of the adverse ef fects of blowout high velocity and pressure shock on the ef ficient performance of BOPs or diverter' s annular preventers , and the provision of suf ficient time and prevention of mental stress for the drilling crew due to the elimination of the hazards , so that the crew can choose and perform the best suited well control procedures ( including the activation of BOPs ) .

[0034] The invention also relates to a method for stopping a blowout of a well respectively extinguishing a burning well .

[0035] The well to be brought under control ( e . g . the well suf fering a blowout which has to be stopped) has a casing through which blowout fluid flows upwards . The blowout fluid (which can be unignited or ignited and already burning) flows out from an upper end of the well . The following is an example of how the procedure is carried out :

[0036] First a tunnel is provided between the ground level and a section of the casing which is below the upper end of the well and also below the ground level .

[0037] Preferably, a control room is provided at the beginning of the tunnel right below ground level .

[0038] The distance between the starting point of the tunnel at ground level and the upper end of the well , and the depth of the tunnel ( e . g . the distance between the upper end of the well and the section of the casing to which the tunnel is provided) should be large enough for protection against heat of fire from burning well and related hazards .

[0039] The tunnel is preferably dug by using a tunnel boring machine ( TBM) . Furthermore , it is preferred i f the height of the tunnel is large enough to allow humans or robots to later enter it and to carry out the following and further operations . Therefore , the tunnel can be dug with a height of at least 100 cm, preferably at least 150 cm, especially at least 200 cm .

[0040] The next step comprises hot-tapping of the casing in the section below ground level wherein the blowout fluid (which maintains high pressure ) flows upwards . Through the hot-tapping at least one lateral access opening in the casing - particularly the upmost or last casing - is created . To provide a large enough opening area in the casing for easier gas or oil flow outside , one or more access opening / s with suf ficient diameter / s should be made in the casing to provide enough flow area . Hot-tapping is an already known technique to create one or more opening / s in a pressuri zed pipe using special devices suitable for this purpose . I f necessary, before the hot-tapping, further casings and / or cement sheaths surrounding the section of the casing where the access opening is to be created can be removed .

[0041] In a next step an ej ector is connected to the lateral access opening / s of the casing . The ej ector can be connected by a human or a robot .

[0042] The ej ector is also connected to a provision pipe , for the provision of a motive fluid, and a deposition pipe , for the deposition of a blowout-motive fluid mixture , each pipe leading through the tunnel , preferably up to the ground level .

[0043] It is very advantageous i f the tunnel has a first part , leading on one side from the ground level ( i f applicable by starting with the control room) to the section of the casing below the ground level and a second part , leading on another side from the section of the casing below ground level back up to the ground level . With such a tunnel , the provision pipe can be arranged in the first part of the tunnel and the deposition pipe in the second part or vice versa . In this way, the pipes manage without large bending radii or kinks .

[0044] In a next step, the ej ector is activated by inj ecting high pressuri zed motive fluid from the provision pipe into the ej ector, whereby blowout fluid is sucked from the casing into the ej ector and a blowout-motive fluid mixture is emitted out of an outlet of the ej ector which is connected to the deposition pipe . By activating the ej ector, the blowout fluid flow is diverted out of the casing which stops the outflow of potentially burning blowout fluid from the upper end of the well . A burning or blazing well can be controlled in such a way .

[0045] The method is preferably performed by use of a conventional ej ector which has a vacuum ej ector with a suction chamber, a blowout fluid inlet (which is connected to the access opening or access openings created through the hot-tapping) and a motive fluid inlet with a nozzle both leading into the suction chamber and a tubular diffuser with an outlet. The tubular diffuser is connected to and leading out of said suction chamber. Such an ejector is activated by injecting high pressurized motive fluid through the motive fluid inlet into the suction chamber towards the diffuser. The motive fluid injected in such a way escapes from the suction chamber through the diffuser while simultaneously creating a vacuum in the suction chamber. Due to the vacuum in the suction chamber, blowout fluid from the casing is sucked through the blowout fluid inlet into the suction chamber and entrained with the escaping motive fluid through the outlet of the diffuser. This leads to the diversion of the blowout fluid flow away from the upper end of the well, so that the burning of the well is extinguished and / or prevented.

[0046] With the well already extinguished, as the ejector is running, the crew can complete clearing away the remaining damaged equipment. To save time, if possible, some equipment should be already removed, before the burning of the well is extinguished. Generally, damaged equipment ranges from broken-down BOPs, draw works, rig floor, top drive, etc.

[0047] If a blowout preventer or blowout preventers attached to the upper end of the well have been damaged due to the blowout, after activation of the ejector remains of this or those can be cleared away (if necessary) and at least a new blowout preventer, a blowout preventer stack or a flange with two sideoutlet valves can be attached to the upper end of the well.

[0048] For example, a BOP stack can be raised by a crane, placed and installed on the upper end of the well to kill / bullhead the well. Another alternative is that a flange with two side-outlet- valves (a so-called mud-cross) is installed on the upper end of the well , with pump trucks or ships connected to the side- outlet-valves . It is also possible to arrange both a BOP and a flange with two side-outlet-valves at the upper end of the well , with the BOP preferably positioned downstream of the flange ( i . e . vertically above it ) .

[0049] After the BOP has been ( respectively the BOPs have been) installed and / or the flange has been installed, the ej ector can be deactivated while simultaneously heavy fluids are pumped through the blowout preventer or through the flange to bullhead the well and thereby bringing the well blowout under control by stemming the blowout fluid flow . The heavy fluids are provided by pump trucks or ships .

[0050] I f production from the well is possible and intended, as soon as the well is under control , the BOP / BOPs , the BOP stack or the flange can be replaced with a permanent wellhead, so that the well can be used for production . The use of a coiled tubing unit or even a drilling rig may be necessary to clean the well first .

[0051] Otherwise the well can be permanently killed . For example , several plugs , especially cement plugs , can be positioned in the casing for permanent closure of the well , after which the tunnel will preferably be filled with soil and strengthened .

[0052] The method for stopping a blowout of a well respectively extinguishing a burning well according to the invention has the following advantages :

[0053] • with the method it is not required to drill any relief wells ( only to dig a relatively short tunnel ) and thus tremendous expenses will be saved,

[0054] • with the method there will be no need for storing a huge amount of water in surface water pools ; digging water pools and storing the water before commencement of blowout control operations is timely, costly and can be a challenge ( especially in arid areas ) ,

[0055] • via this method, the fire is extinguished while the blowout fluid is diverted away from the upper end of the well ( or the rig) , and the top-kill operations can be implemented safely (with minimal risks ) and with less mental stress for the crew than with conventional top killing methods , and

[0056] • the top-kill method after using the ej ector is the quickest and least costly well control method .

[0057] Features described in combination with the methods according to the invention can be applied in an analogous manner to the well according to the invention and vice versa .

[0058] Further details , features and advantages of the invention will be apparent from the following description with reference to the accompanying drawings , in which preferred embodiments are shown .

[0059] Fig . 1 shows a well according to the invention in a side view,

[0060] Fig . 2 shows the well according to Fig . 1 in a top section view,

[0061] Fig . 3 shows a well which is brought under control with one of the methods according to the invention,

[0062] Fig . 4 shows a flow diagram of one of the methods according to the invention, and

[0063] Fig . 5 shows a flow diagram of the other method according to the invention .

[0064] Fig . 1 shows a well 1 according to the invention in a very basic side view .

[0065] The well 1 comprises a casing 2 that extends in a longitudinal direction L of the well 1 and ends at ground level G at an upper end 3 of the well 1 . Mounted on the upper end 3 ( e . g . downstream behind the casing 2 - particularly the upmost or last casing 2) is a blowout preventer 4 also known as BOP.

[0066] An ejector 5 - which is shown cut for better illustration in Fig. 1 - is arranged laterally at the casing 2 and beneath (e.g. upstream) the blowout preventer 5.

[0067] In the area where the ejector 5 is arranged or located on the casing 2, there is an access opening 6 in the casing 2 which is connected to the ejector 5.

[0068] In case a spool is attached to the upper end 3 of the well 1, the lateral access opening 6 can be a side opening in said spool, and the ejector 5 can be arranged or located laterally on the spool.

[0069] Fig. 2 shows the well 1 according to Fig. 1 in a top section view, with the sectional plane II-II running orthogonally to the longitudinal direction L of the well 1 and centrally through the ejector 5.

[0070] The ejector 5 as shown in the Figs. 1 to 3 has a suction chamber 8, a blowout fluid inlet 9 connecting said suction chamber 8 with the access opening 6, a motive fluid inlet 11 with a nozzle 12 leading into said suction chamber 8 and a tubular diffuser 13 with an outlet 14. The tubular diffuser 13 is connected to and leading out of said suction chamber 8.

[0071] The motive fluid inlet 11 is connected - preferably via a pipe - to a source for a motive fluid FM(like a compressor for gas or a pump for water) which is not shown in the Figs.

[0072] The outlet 14 of the tubular diffuser 13 of the ejector 5 is connected - preferably via a pipe - to a disposal installation for disposal of a blowout-motive fluid mixture Fx(comprising of blowout fluid FBand motive fluid FM) , which for example can be a burn-pit for burning gas or a separator for separating oil from water .

[0073] When motive fluid FMis inj ected into the suction chamber 8 and towards the tubular di f fuser 13 via the noz zle 12 of the motive fluid inlet 11 , the motive fluid FMleaves the ej ector 5 through the di f fuser creating a negative pressure (vacuum) in the suction chamber 8 .

[0074] The negative pressure inside the suction chamber 8 sucks or draws blowout fluid FB, which flows through the casing 2 in the direction of the upper end 3 of the well 1 , into the suction chamber 8 through the access opening 6 via the blowout fluid inlet 9 .

[0075] The blowout fluid FBsucked in is entrained by the motive fluid FMwhich is leaving respectively escaping the di f fuser 13 so that a blowout-motive fluid mixture Fxcontaining both fluids FM, FBis leaving or escaping the ej ector through the outlet 14 of the tubular di f fuser 13 . The ej ector 5 is therefore emitting the blowout-motive fluid mixture Fxout of its outlet 14 .

[0076] In such a manner, the flow of the blowout fluid FBcan be diverted from the casing 2 and away from the upper end 3 of the well , e . g . out of the access opening 6 and out of the ej ector 5 .

[0077] The tubular di f fuser 13 comprises a convergent tubular section 17 directly attached to the suction chamber 8 and a divergent tubular section 18 ending with the outlet 14 . The divergent tubular section 18 is attached to the convergent tubular section 17 either directly or by means of a constant tubular section 19 . A gas detector sensor 21 and an ultrasonic sensor 22 are connected to the casing 2 and are communicating ( either wired or wireless ) with a control system 23 .

[0078] Fig . 3 shows a well 1 after it is brought under control with the method for stopping a blowout of a well respectively extinguishing a burning well by use of the ej ector 5 as described above .

[0079] The well 1 comprises a casing 2 leading to an upper end 3 of the well 1 .

[0080] To access the casing 2 below the upper end 3 and suf ficiently below ground level G to be outside the danger zone of the burning well 1 , first a control room 24 is dug as part of a tunnel 25 and then the tunnel 25 is continued from the control room 24 to a section S of the casing 2 below ground level G . From this section S of the casing 2 the tunnel 25 is dug back up to ground level G .

[0081] In the section S of the casing 2 to which the tunnel 25 is leading an access opening 6 has been created in the casing 2 via hot-tapping . Further casings 26 and cement sheets 27 have been removed in an area around this hot-tapped section S before the hot-tapping took place .

[0082] The ej ector 5 is connected to the casing 2 , by connecting the suction chamber 8 of the ej ector 5 with the access opening 6 via the blowout fluid inlet 9 of the ej ector 5 .

[0083] The ej ector 5 is shown in an active state due to the inj ection of the motive fluid FMinto the ej ector 5 . As already described to Figs . 1 and 2 , the activated ej ector 5 sucks in the blowout fluid FBwhich is flowing through the casing 2 in the direction of the upper end 3 of the well 1 and emits a blowout-motive fluid mixture Fx(comprising of the motive fluid FMand the entrained blowout fluid FB) out of the outlet 14 of its diffuser 13. Therefore, the blowout fluid FBflow is diverted away from the upper end 3 of the well 1 so that a fire at the upper end 3 is extinguished (if there is a burning well) and action can be taken to control or even top-kill the well 1.

[0084] In Fig. 3 a flange 15 with two side-outlet-valves 16 has already been mounted on the upper end 3 of the well 1, so that the well 1 is ready to deactivate the ejector 5 while simultaneously pump heavy fluids through the side-outlet-valves 16 of the flange 15 to take control of the well 1 (e.g. to bullhead the well) .

[0085] The motive fluid inlet 11 of the ejector 5 is connected via a provision pipe 28 with a source for motive fluid FM, like a compressor (for gas) or a pump (for water) .

[0086] The blowout-motive fluid mixture Fx(containing the motive fluid FMand the diverted blowout fluid FB) is channeled away via a deposition pipe 29 leading to a deposition installation, like a burning-pit (especially for gas) or a separator (to separate oil from water) .

[0087] Fig. 4 shows a flow diagram of a first method according to the invention, which is suitable for preventing or mitigating the effects of a well blowout and is preferably used with a well according to Figs. 1 and 2.

[0088] In a detection and activation step after detection of an actual or immanent blowout in a well 1 (especially due to a gas detector 21 and / or an ultrasonic sensor 22 attached to the casing 2 or a the spool of the well 1) the ejector 5 is automatically activated by injecting high pressurized motive fluid FMinto the ejector 5. In a subsequent continuous diverting step 32 the blowout fluid FBis sucked out of the casing 2 into the ej ector 5 and a blowoutmotive fluid mixture Fxis emitted out of the outlet 14 of the ej ector 5 thereby diverting the blowout fluid FBflow out of the casing 2 and away from the upper end 3 of the well 1 . The blowout fluid FBis therefore diverted out of the well 1 .

[0089] In an optional sealing step which occurs after the activation of the ej ector 5 , the blowout preventer 5 or at least one of the blowout preventers 5 or a diverter' s annular preventer i f available is activated, especially automatically . This seals the well 1 .

[0090] In an optional deactivation step after the success ful activation of the blowout preventer 5 or at least one of the blowout preventers 5 or the diverter' s annular preventer the ej ector 5 is deactivated .

[0091] Fig . 5 shows a flow diagram of a variant of the second method according to the invention, which is suitable for stopping a blowout of a well 1 respectively extinguishing a burning well 1 .

[0092] In step a . a tunnel 25 is provided between the ground level G and a section S of the casing . The section S being below ground level G and suf ficiently below the upper end 3 of the well 1 .

[0093] I f necessary, further casings 26 and / or cement sheets 27 surrounding the casing 2 are removed in a step bO .

[0094] In step b . the casing 2 is hot-tapped in the section S ( therefore : hot-tapping section S ) below ground level G to create a lateral access opening 6 .

[0095] In a following step c . an ej ector 5 is connected to the access opening 6 . The ej ector 5 is also connected to a provision pipe 28 and a deposition pipe 29 each of which are leading from ground level G to the ejector 5.

[0096] In a subsequent step d. the ejector 5 is activated. Due to the active ejector 5 the blowout fluid FBis sucked out of the casing 2 (e.g. diverted away from the upper end 3 of the well 1) and channeled through the deposition pipe 29 to a deposition installation like a burn-pit or a separator.

[0097] If necessary, in a step e. remains of a BOP 4 or BOPs 4 are cleared away and at least a new blowout preventer 4, a blowout preventer 4 stack or a flange 15 with two side-outlet valves 16 is attached to the upper end 3 of the well 1, for example with a crane .

[0098] In a step f. the ejector 5 is deactivated and heavy fluids are pumped simultaneously through the blowout preventer / s 4 or the flange 15 into the casing 2, thereby bringing the well 1 under control .

[0099] In a final step g. the blowout preventer / s 4, the blowout preventer 4 stack or the flange 15 is replaced with a permanent wellhead, so that the well 1 can be used for production.

[0100] Alternatively, in step g. (and in possible further steps, not described in detail) the well 1 is permanently killed.

[0101] Reference sign

[0102] 1 well

[0103] 2 casing

[0104] 3 upper end of the well

[0105] 4 blowout preventer BOP

[0106] 5 e j ector

[0107] 6 access opening

[0108] 7

[0109] 8 suction chamber

[0110] 9 blowout fluid inlet

[0111] 10

[0112] 11 motive fluid inlet

[0113] 12 noz zle

[0114] 13 tubular di f fuser

[0115] 14 outlet

[0116] 15 flange

[0117] 16 side-out let- valve

[0118] 17 convergent tubular section

[0119] 18 divergent tubular section

[0120] 19 constant tubular section

[0121] 20

[0122] 21 gas detector sensor

[0123] 22 ultrasonic sensor

[0124] 23 control system

[0125] 24 control room

[0126] 25 tunnel

[0127] 26 further casing

[0128] 27 cement sheet

[0129] 28 provision pipe

[0130] 29 deposition pipe

[0131] L longitudinal direction

[0132] G ground level

[0133] S hot-tapping section FBblowout fluid

[0134] FMmotive fluid

[0135] Fxblowout-motive fluid mixture

Claims

Claims :

1. Well (1) , especially an oil or gas well (1) , with a casing (2) and at least a blowout preventer (4) attached thereto, characterized, in that an ejector (5) is connected to the casing (2) or to a spool attached to said casing (2) via a lateral access opening (6) in the casing (2) or in the spool, and in that the lateral access opening (6) and therefore the ejector (5) is arranged vertically below the blowout preventer / s (4) .

2. Well according to claim 1, characterized, in that a gas detector sensor (21) and / or an ultrasonic sensor (22) is / are connected to the casing (2) or the spool and is / are set up to automatically activate the ejector (5) in case a gas blowout is detected by the sensor / s (21, 22) .

3. Well according to claim 1 or 2, characterized, in that a motive fluid inlet (11) of the ejector (5) is connected to a compressor, especially providing high pressurized air, and an outlet (14) of the ejector (5) is connected to a burn-pit or that the motive fluid inlet (11) of the ejector (5) is connected to a pump, especially providing high pressurized water, and the outlet (14) of the ejector (5) is connected to a separator.

4. Well according to one of claims 1 to 3, characterized, in that the ejector (5) is connected to the lateral access opening (6) of the casing (2) or the spool via a connector (5) made of hard-faced material, especially tungstencarbide .

5. Method for preventing or mitigating the effects of a well blowout, wherein the well (1) , especially an oil or gas well (1) , has a casing (2) , at least a blowout preventer (4) attached thereto and an ejector (5) connected to the casing (2) or to a spool of the well (1) via a lateral access opening (6) in the casing (2) or in the spool, whereby the lateral access opening (6) and therefore the ejector (5) is arranged vertically below the blowout preventer (4) , characterized, in that in case of an actual or immanent blowout the ejector (5) is automatically activated by injecting high pressurized motive fluid (FM) into the ejector (5) , thereby blowout fluid (FB) is sucked from the casing (2) into the ejector (5) and a blowoutmotive fluid mixture (Fx) is emitted out of the outlet (14) of the ejector (5) thereby diverting the blowout fluid (FB) flow out of the casing (2) .

6. Method according to claim 5, characterized, in that the motive fluid (FM) is air provided by a compressor and the motive-blowout fluid mixture (Fx) is burned in the burn-pit or that the motive fluid (FM) is water provided by a pump and the blowout-motive fluid mixture (Fx) is separated in a separator into blowout fluid, which can be burned or stored, and water.

7. Method according to claim 5 or 6, characterized, in that after the activation of the ejector (5) , the blowout preventer (4) or at least one of the blowout preventers (4) or a diverter's annular preventer if available is activated, especially automatically, and after the successful activation of the blowout preventer (4) or at least one of the blowout preventers (4) or the diverter's annular preventer the ejector (5) is deactivated.Method for stopping a blowout of a well (1) respectively extinguishing a burning well (1) , wherein the well (1) has a casing (2) through which blowout fluid (FB) flows and wherein the potentially burning blowout fluid (FB) flows out from an upper end (3) of the well (1) , characterized by the following successive steps: a. providing a tunnel (25) between the ground level (G) and a section (S) of the casing (2) below the upper end (3) of the well (1) and the ground level (G) , b. hot-tapping the casing (2) in the section (S) below ground level (G) to create a lateral access opening (6) in the casing (2) , c. connecting an ejector (5) to the lateral access opening (6) of the casing (2) where the ejector (5) is also connected to a provision pipe (28) and a deposition pipe (29) each leading through the tunnel (25) , d. activating the ejector (5) by injecting high pressurized motive fluid (FM) from the provision pipe(28) into the ejector (5) , whereby blowout fluid (FB) is sucked from the casing (2) into the ejector (5) and a blowout-motive fluid mixture (Fx) is emitted out of an outlet (14) of the ejector (5) which is connected to the deposition pipe (28) , thereby diverting the blowout fluid (FB) flow out of the casing (2) and stopping the outflow of potentially burning blowout fluid (FB) from the upper end (3) of the well (1) .

9. Method according to claim 8, characterized, in that a control room (24) is provided at the beginning of the tunnel (25) right below ground level (G) .

10. Method according to claim 8 or 9, characterized, in that the tunnel (25) leads on one side from ground level (G) to the section (S) of the casing (2) below ground level (G)and on another side from the section (S) of the casing (2) below ground level (5) back up to ground level (5) .

11. Method according to one of claims 8 to 10, characterized, in that the tunnel (25) is dug with a height of at least 100 cm, preferably at least 150 cm, especially at least 200 cm.

12. Method according to one of claims 8 to 11, characterized, in that around the section (S) of the casing (2) where the access opening (6) is to be created, further casings (26) and / or cement sheaths (27) surrounding the casing are removed in a step bO. before step b.

13. Method according to one of claims 8 to 12, characterized, in that after step d. if a blowout preventer (4) or blowout preventers (4) attached to the upper end (3) of the well (1) have been damaged due to the blowout, in a step e. remains of this or those are cleared away if necessary and at least a new blowout preventer (4) , a blowout preventer (4) stack or a flange (15) with two side-outlet valves (16) is attached to the upper end (3) of the well (1) .

14. Method according to claim 13, characterized, in that after step e. in a step f. the ejector (5) is deactivated and heavy fluids are pumped simultaneously through the blowout preventer / s (4) , the blowout preventer (4) stack or the flange (15) into the casing (2) , thereby bringing the well (1) under control.

15. Method according to claim 14, characterized, in that after step f. in step g. the blowout preventer / s (4) , the blowout preventer (4) stack or the flange (15) is replaced with a permanent wellhead, so that the well (1) can be used for production, or the well (1) is permanently killed.

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