Patent Application
20160102519
The present invention relates to an emergency valve assembly for managing extraction wells—such as, for example, wells for the extraction of petroleum and/or natural gas—under emergency conditions, for example in the case of blow-outs. The invention also relates to a well equipped with said valve and a process for managing an extraction well with said valve under emergency conditions.
The environmental disaster of the Deepwater Horizon platform, which took place in 2010 in the Gulf of Mexico, reiterated the necessity of improving systems for blocking the blow-out of hydrocarbons or natural gas from reservoirs under emergency conditions. In particular, the Deepwater Horizon disaster revealed how safety systems against blow-outs of hydrocarbons from reservoirs, with which current wells, either in the drilling phase or already in production, are equipped, can at times prove to be inadequate.
Apart from this incident, also the positioning of well-heads on sea or ocean floors at depths which have now reached 3,000 meters, and the difficulty of intervening to block gas or oil leakages at these depths, are such that the necessity is even more strongly felt for additional safety systems with respect to the current blow-out preventers (BOP) installed on Christmas trees, or safety valves at present inside the well head.
An objective of the present invention is to overcome the drawbacks of the state of the art mentioned above, and in particular provide a safety system for preventing or blocking blow-outs of hydrocarbons or natural gas from extraction wells, capable of intervening when the current safety systems have proved to be ineffective or are unable to operate.
This objective is achieved, in a first aspect of the present invention, with an emergency valve assembly having the characteristics according to claim 1.
In a second aspect of the invention, this objective is achieved with an extraction well having the characteristics according to claim 10.
In a third aspect of the invention, this objective is achieved with a process for managing an extraction well under emergency conditions, having the characteristics according to claim 12.
Further characteristics of the device are object of the dependent claims.
The advantages obtained with the present invention will appear more evident, to a technical expert in the field, from the following detailed description of a particular non-limiting embodiment, illustrated with reference to the following schematic figures.
In the present description, the expressions “upstream” and “downstream” indicate positions respectively closer to and further away from the reservoir to be exploited; analogously, the expressions “from upstream” and “from downstream” indicate movements with directions in accordance with and contrary to the flow of the fluid which is extracted from the reservoir.
The assembly 1 can comprise the actual well head 3, the assembly of the emergency valve 5 and the completion tree—also called Christmas tree—7.
The well head 3 can be of the known type and comprise for example a low-pressure housing and a high-pressure housing anchored to the seabed with a conductor pipe, which is generally a pipe having a thickness of 36″×1.5″ cemented with another 20″ pipe having the function of an anchoring column. More generically, the well head 3 can comprise an anchoring pipe 30 cemented, or in any case anchored or fixed to the seabed or other geological formation in which an underground reservoir to be exploited, lies, where the pipe 30 is close to the surface of the seabed or other geological formation in question; as shown in
The Christmas tree 7 can also be of the known type.
According to an aspect of the invention, the emergency valve assembly 5 comprises:
an external housing 50 inside which a pass-through duct 52, preferably straight, is arranged;
a rotating stopper 54 which forms, in its interior, a section 520 of the pass-through duct, wherein the pass-through duct 52, including its section 520 arranged in the rotating stopper, is arranged for the passage of a production and/or drilling line arranged for containing and carrying, through one pipe 9, extraction fluids such as, for example petroleum, oil, water, sludge, rock debris and/or earth, natural gas, or other fluids to be extracted from an underground reservoir;
a stopper drive 56 arranged for actuating the rotating stopper 54 making it rotate so as to shear the production or drilling line passing through it, in particular shearing the pipe 9 and closing the pass-through duct 52, preferably sealed or in any case so as to block or at least withhold the outflow of the fluid to be extracted from the pass-through pipe 52 as much as possible (
The pipes 9 can be so-called production tubing or pipe strings in technical jargon.
The rotating stopper 54 is preferably of the rotating ball type. The pass-through duct 52, when open, preferably has a substantially straight axis.
The rotating stopper 54 is arranged for shearing the pipe 9, or drilling or production line, rotating on itself around an axis AR transversal, and more preferably perpendicular, to the same pipe 9.
Again according to an aspect of the invention, the pass-through duct 52, 520 has a minimum passage section having a diameter equal to or greater than seven inches, so as to allow the passage of a drilling or production line having an adequate diameter and preferably less than seven inches, so as to leave adequate radial clearances between the internal walls of the pass-through duct 52, 520 and the drilling or production line, facilitating the shearing of the latter.
The internal diameter of the pass-through duct 52, 520 preferably corresponds to the maximum internal diameter envisaged on the basis of the nominal diameter of the BOPs or well head, high pressure housing, generally ranging from 13.625-18.625 inches. The internal diameter of the pass-through duct 52, 520 is more preferably equal to or greater than 13.625 inches, and more preferably equal to or greater than 18.625 inches. The internal diameter of the pass-through duct 52, 520 can, for example, be equal to 13-14 inches.
The emergency valve 5 is preferably arranged for receiving in the pass-through duct 52 and shearing both the intermediate sections of the drilling rods and also the tool joints connecting them. The drilling rods can have external diameters which reach 5-6.625 inches, thicknesses up to 0.29-0.36 inches and steel grades often equal to or greater than 80 Kpsi, for example within the range of 95-135 Kpsi; the corresponding tool joints can have maximum external diameters or transverse dimensions of up to 6.625-8.25 inches.
The external housing 50 preferably forms a stopper seat in which the rotating stopper 54 can rotate so as to shear the pipe 9 of the production or drilling line—or more generally the tubular material inside the same line—which passes through the rotating stopper 54 itself, and close the extraction fluid duct, and the assembly valve 5 is arranged for shearing the production and/or drilling line, and in particular its pipe 9, by crushing it between at least a first edge 540 of the section of pass-through duct arranged on the rotating stopper, also referred to as “first cutting edge”, and at least a second edge 500 arranged on the stopper seat, also referred to as “second cutting edge” (
The stopper drive 56 advantageously comprises an expansion chamber 57 and is arranged for driving the rotating stopper 54, making it rotate so as to shear the pipe 9 of the production line which passes through the rotating stopper, and so as to close to the extraction fluid duct, expanding an explosive charge in the expansion chamber 57—in this case, the expansion chamber 57 is an explosion chamber—preferably not more than five times, more preferably not more than three times and even more preferably only once. The stopper drive 56 is arranged for actuating the rotating stopper 54, exploding, in the explosion chamber 57, an explosive preferably selected from the following group: a solid explosive product, a pyrotechnical charge. The stopper drive can be possibly equipped with a hydraulic drive (not shown) arranged for driving the rotating stopper 54 and in turn actuated by explosion gases generated in the chamber 57.
Alternatively, the explosion chamber 57 can be substituted by an expansion chamber (not shown) in which a suitable chemical substance is expanded, more slowly with respect to an explosion or a detonation, by gasifying, for example, a liquid or solid substance, which provides the driving energy for actuating the rotating stopper 54.
The stopper drive 56 is advantageously neither fed nor driven by possible hydraulic or electrical power systems which feed possible blow-up preventers downstream of the emergency valve 5. The transmission lines of signals from and towards the valve 5 are advantageously independent of those for the transmission of signals from and towards the adjacent blow-up preventers, so that the valve 5 represents a further and independent safety measure in the case of failure of the BOPs.
An example of the use and functioning of the emergency valve assembly previously described, is described hereunder.
The emergency valve assembly 5 can be assembled on a known well head 3, and more specifically for example, between the well head 3, the well head high pressure housing and the stack of BOPs. If the well is still in the drilling phase, one or more blow-out preventers of the known type can be assembled above the emergency valve 5; if, on the other hand, the well is already completed and in production, a Christmas tree, per se known, can be assembled above the emergency valve 5. As it is positioned between the well head and Christmas tree, the emergency valve 5 can also be used as a safety valve during work-overs, or at the annulus during production.
The pipes 9 of a production or drilling line are passed through the pass-through hole 542 of the rotating stopper 54. When the flow of oil, natural gas or other fluids leaving the well must be interrupted in an emergency situation, and the other blow-out preventers or other safety valves onboard the Christmas tree, if present, have not been able to intervene or have proved to be inefficient, the emergency valve 5 can be actuated, by activating in particular the stopper drive 56, by means of an acoustic command, for example, or the mechanical arm of a ROV 11 (Remotely Operated Vehicle,
For this purpose, the stopper 54 can rotate for example by about 90° (
The fact that the rotating stopper 54 acts by shearing, and that the stopper drive 56 is capable of assisting the stopper 54 in completing its shearing run, exploiting the expansion of the explosion gases of a limited number of explosions—from one to five, and preferably from one to three—allows the stopper 54 to be actuated also at considerable underwater depths, for example at depths of 1,000-4,500 metres, at which it is not possible or in any case extremely difficult to resort for example to complicated hydraulic, electric actuations or alternative combustion engines for providing the high torques necessary for shearing the pipe 9; the shearing preferably takes place without chip removal. The valve 5 is arranged for remaining blocked in closure after shearing the production or drilling line, and is possibly equipped with suitable mechanical, hydraulic or electric blocking systems. These blocking systems preferably allow the valve 5 to be subsequently to be unblocked and reopened, by means of ROVs, once the upper barrier formed by conventional BOPs has been restored.
The authors of the present invention have estimated that the shear force for each section, i.e. in correspondence with each of the two torques of first cutting edge 540/second cutting edge 500, must be in the order of 1,000 tons, corresponding to a drive torque of about 106 Nm, assuming an arm of one metre. At present, there are no reducers capable of supporting drive torques in the order of 106 Nm.
The stopper drive 56, on the contrary, is capable of housing onboard, in extremely reduced spaces, the pyrotechnical charges or in any case the necessary explosives, which in turn allow extremely simple drive mechanisms to be effected, which are therefore reliable and suitable for being situated on seabeds FM which are deep and isolated for extremely long periods of time, ideally for the whole operating life of the well. The above pyrotechnical charges or in any case explosives can also be preserved at considerable depths for extremely lengthy periods, possibly replacing them after pre-established periods within programmed maintenance interventions, or after use for recharging the system.
As the emergency valve 5 can be installed outside the well head 3, however, it can be produced with fewer design constraints with respect for example to current safety valves situated inside the well head.
The embodiment examples previously described can undergo numerous modifications and variations, all included in the protection scope of the present invention. The rotating stopper 54, for example, can be not only a ball stopper, but also a disc stopper or rotating drum stopper. The emergency valve 5 can be better integrated in the well head or in the blow-out preventers downstream thereof or assembled thereon, by ensuring, for example, that the external housing 50 is formed integrally in a single piece by the/an external housing of the well head or by the/an outer housing of the blow-out preventers; in the former case, the outer housing 50 can be formed integrally, for example, in a single piece by the external housing of the tubing head or of a casing head of the well head. The emergency valve 5 can be provided with a lever transmission system arranged for transmitting the mechanical power developed in the expansion or explosion chamber 57 to the rotating stopper 54, actuating the latter. The levers of this transmission system are advantageously at least partially outside the external housing 50 of the emergency valve, so as to impose fewer dimensional and project constraints and therefore facilitate a simple and reliable embodiment of the same valve. Furthermore, all the details can be substituted by technically equivalent elements. The materials used, for example, as also the dimensions, can vary according to technical requirements. It should be specified that an expression such as “A comprises B, C, D” or “A is composed of B, C, D” also comprises and describes the particular case in which “A consists of B, C, D”. The examples and lists of possible variants of the present patent application should be considered as being non-exhaustive lists.
| Number | Date | Country | Kind |
|---|---|---|---|
| MI2013A 000845 | May 2013 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB14/61660 | 5/23/2014 | WO | 00 |
