MXPA01006758A - Method for removing condensables from a natural gas stream - Google Patents

Abstract

A method for removing condensables from a natural gas stream upstream of a wellheadchoke connected to a subterranean formation, the method comprising the steps of:(A) inducing the natural gas stream to flow at supersonic velocity through a conduit and thereby causing it to cool to a temperature that is below a temperature at which condensables will begin to condense forming separate droplets and/or particles;(B) separating the droplets and/or particles from the gases;(C) collecting the gas from which the condensables have been removed;(D) and transporting the gas and/or the condensables to a wellhead and/or re-injecting it into the subterranean formation from which it has been produced, or into a different formation, with the proviso that not all of the collected gas and condensables are re-injected into the same reservoir zone of the same formation, and a well completion system for producing gas from a subterranean formation wherein said method is applied.

Description

METHOD FOR EXTRACTING CONDENSABLE MATERIALS FROM A NATURAL GAS CURRENT FIELD OF THE INVENTION The present invention relates to a method for extracting condensable materials from a natural gas stream and to a well termination system to produce gas from an underground formation where the method is applied.

BACKGROUND OF THE INVENTION Natural gas, produced from a gas, subsurface or subsea production formation (hereinafter underground formation), requires the separation of components that are normally liquid or have relatively high condensation temperatures. These components, collectively referred to in the claims and in the description, with the expression "condensable materials" include water, propane, butane, pentane, propylene, ethylene, acetylene and others such as carbon dioxide. , hydrogen sulfide, nitrogen gas and the like. Typically, the gas stream is treated, on the surface, downstream REF .: 131234 from a well head that is connected to an underground gas producing formation, through a primary borehole that contains a pipe that extends down the hole from the wellhead. This is not very cost effective, particularly for multilateral wells (ie, well completion systems that contain a borehole system with multiple branches, which connects the reservoir of a production formation with one or more different deposits) in which the natural gas and / or the condensable materials, or part of any of them, is reinjected from one formation to another or within the formation of one area of the deposit to another. This is done, for example, to stimulate a new well or revive an existing well; or to store natural gas or condensable materials for later use, etc. The separators that are effective to reduce the dew points of the gases, generally require complex equipment and instrumentation, such as absorbers of fluffy oils or glycols, refrigerated. These operations are generally too complex to be located in the wellheads such as in the heads of the wells of the seabed, and too expensive to be placed in heads of individual wells in a gas producing field.

Spacers located downstream to extract water from the gas as it is produced are known, for example, in U.S. Patent No. 5,444,684. This device uses flotation balls that float upwards and block a flow path when the water level in the borehole rises, and then a gas pressure and force is formed at the water level downward, allowing the production of the gas is free of liquid water. This device is only able to keep liquid water separate from the gas produced. It is not able to extract condensable materials or water from the gas produced. U.S. Patent Application No. 5,794,697"also discloses a downhole separator for capturing gas from a mixture of liquids and gas produced in a borehole This patent focuses on gas compression, downhole, and the reinjection of the gas into a layer of gas above the oil remaining in the formation A separator is shown and described as a helix that imparts a swirling motion to the fluids, and then the extraction of the gas from the center of the swirl. The separator also does not reduce the temperature of the dew point of the gas (ie extract the condensable materials), but only separates the existing phases.The separation method and the inertial separator according to the preamble of claims 1 and 7 are known to From the International Patent Application WO 95/09970 The known separator includes a cyclone in which the water produced is separated from the produced gas and the water vapor is separated a of the gas in a membrane separated at high pressure. It would be desirable to have a simpler separator for extracting condensable materials and / or water from a stream of natural gas located upstream of the choke of the wellhead., that is, before entering surface or underwater installations, with nominal, typical, lower pressure values that are in the order of 15 MPa (15 MN / m2) or less. First of all, this is because a greater pressure drop for the separation is still available, upstream of the well head choke, making better use of the available potential energy, which is otherwise dissipated in the choke. of the head of the well. Secondly, this is because as the gas flows up the borehole, it can be cooled by heat transfer to the shallower formations surrounding the borehole, and by adiabatic expansion of the gas, as it flows towards it. above the well. When the gas cools, the condensable materials and / or water can then be condensed from the previously saturated gas stream. Liquids condensed in a gas producing well can cause many problems. The separated liquid phase could considerably increase the hydrostatic head within the borehole, and thus reduce the pressure in the wellhead and / or gas production. Depending on the resulting flow regime, liquids could be formed until the bottom of the borehole is exposed to an additional, substantial, hydrostatic head. Also, the water could be combined with hydrocarbons and / or with hydrogen sulfide to form hydrates in the borehole. These hydrates could clog the well. To prevent this, it is common to inject alcohols or glycols into the gas producing wells to prevent plugging with solid hydrates. This injection is relatively expensive, and also results in more liquids being present in the borehole. The spills of these liquids can cause particular environmental concerns, because by their nature they are miscible with water. There are numerous methods and devices for separating components from gaseous fluids or other types of fluids. Examples of conventional separation devices include distillation columns, filters and membranes, settling tanks, centrifuges, electrostatic precipitators, dryers, coolers, cyclones, vortex tube separators and adsorbers. In addition, several inertial spacers equipped with a supersonic nozzle have been described in the art. JP-A-02, 017, 92I refers to the separation of a gas mixture by the use of supersonic flow. The device includes a swirl generator located upstream of a supersonic nozzle. The eddy fluid stream then passes through an axially symmetric expansion nozzle to form fine particles. The swirl is maintained across a longitudinal, axial distance, creating a large pressure drop. U.S. Patent Application No. 3,559,373 relates to a supersonic flow separator that includes a high pressure gas inlet, a rectangular shaped throat, and a channel with a U-shaped rectangular cross section. The channel includes a curved wall outer, permeable. A gas stream is provided at the gas inlet, at subsonic velocities. The gas converges through the throat and expands in the channel, increasing the speed to a supersonic speed. The expansion of the flow in the supersonic region results in the union of the small droplets and larger droplets passing through the permeable outer wall and being collected in a chamber.

EP-A-O, 496, 128 relates to a method and device for separating a gas from a gas mixture. The device includes a cylinder that converges in a nozzle and then diverges in a swirling zone. The gas enters an inlet of the cylinder, at subsonic speeds, and flows through a converging section of the nozzle. The flow expands out of the convergence section, towards the divergence section of the cylinder, at supersonic velocity. A pair of deltoid plates impart a whirlpool to the supersonic flow. The combination of the supersonic velocities and the vortex helps to condense and separate a condensed component from the gaseous components of the flow stream. An outlet tube is centrally positioned inside the cylinder, to allow discharge of the gaseous components from the flow stream, at supersonic velocity. The liquid components continue to pass to a second divergence section, which reduces the speed to a subsonic speed, and through a fan, finally exiting the cylinder, through a second outlet. WO 99/01194 describes a similar method and corresponding device, for extracting a selected gaseous component, from a fluid stream containing a plurality of gaseous components. This device is equipped with a shock-flow inductor located downstream of the collection zone, to decrease the axial velocity of the current to a subsonic velocity. The application of a shock wave in this manner results in a more efficient separation of the formed particles. These references describe several inertial, supersonic separators. However, none describe or suggest its use in a site located upstream of a well head choke, a well termination system, and / or instead of the well head choke.

BRIEF DESCRIPTION OF THE INVENTION According to the invention there is provided a method for extracting condensable materials from a natural gas stream, upstream of a choke of the well head, connected to an underground formation in accordance with the unique features of claim 1. The invention also concerns to a well termination system, for producing gas from an underground formation in accordance with the unique features of claim 7.

DETAILED DESCRIPTION OF THE INVENTION The supersonic inertial separators referenced hereinabove require a predominantly gaseous stream (ie, containing less than 10% by weight of either solids or liquids) at a pressure sufficient to undergo supersonic acceleration when pass through the convergent-divergent Laval nozzle of the same. The pressures in the well and before the choke of the head of the well, can be in the same interval as in the underground formation, and are usually more than adequate. Therefore, the method can be used in the borehole of a unilateral well; in the main borehole or in one or more of the branching boreholes of a multilateral borehole, or in place of the choke of a wellhead. Therefore the method can be used on the surface, but it can also be used under the surface or under the sea. It will be understood that if the supersonic inertial separator is used in place of a choke, that in an elegant manner the natural gas is free of condensable materials while the reduction in pressure to the level required for a distribution network occurs. One of the most attractive advantages of the present invention concerns the minimum number or even the lack of moving parts in the supersonic inertial separator, allowing its use in sites that commonly require remote controls. The preferred supersonic inertial separator is one of the type described in EP-A-0, 496, 128, that is, where the supersonic stream containing small droplets and / or particles, is forced into a vortex motion, thereby causing the small droplets and / or particles to flow into a radially outer section of a collection area in the stream, followed by the extraction of these small droplets and / or particles in a supersonic collection zone. In another preferred embodiment of the present invention, a shock wave occurs which is caused by the transition from supersonic to subsonic flow, upstream of the separation of the small droplets and / or particles from the collection zone. It was found that the separation efficiency is significantly improved if the collection of the particles, in the collection area, is carried out after the shock wave, ie, in the subsonic flow rather than in the supersonic flow. It is believed that this is because the shock wave dissipates a substantial amount of kinetic energy from the current and therefore greatly reduces the axial component of the fluid velocity, while the tangential component (caused by the medium that imparts eddies) remains substantially unchanged. As a result, the numerical density of the particles in the radially outer section of the collection zone is significantly greater than anywhere in the conduit where the flow is supersonic. It is believed that this effect is caused by greatly reduced axial fluid velocity and therefore a reduced tendency for the particles to be entrained by a central "core" of the stream, where the fluid flows at a higher axial velocity than in a place closer to the wall of the canal. In this way, in the subsonic flow regime, the centrifugal forces acting on the condensed particles are not counteracted to a large extent by the dragging action of the central "core" of the current, in such a way that the particles are allowed to flow. they agglomerate in the radially outer section of the collection area from which they are extracted. Preferably the shock wave is created by the induction of the fluid stream to flow through a diffuser. An appropriate diffuser is a supersonic diffuser. A diffuser can be, for example, one of divergent volume, or one of convergent volume, and then divergent. In an advantageous embodiment, the collection zone is located at a site adjacent to the exit end of the diffuser. The present invention may be practiced in combination with other operations to effect the drying of the fluid stream, it may be practiced in front of conventional separators in order to reduce the size and / or capacity required of the latter. Also, either the stream containing liquids from the collection zone or the stream from which the liquids have been separated, could be subjected to an additional separation step, for example, a dryer or separator. Advantageously, any gaseous fraction separated together with the condensable materials, for example from the radially outer section of the collection area, in the case of a supersonic inertial separator of the type described in EP-A-0, 496, 128 or WO 99 / 011994, can be recycled back to the inlet preferably using an inductor to increase the pressure again to the value of the pressure of the inlet stream. Another alternative in practice. of the present invention, is to channel the condensable materials to a liquid-liquid separator, where, for example, a liquid hydrocarbon phase is isolated from an aqueous phase. The liquid water phase could be, for example, injected back into the same formation, in a more or less deep area of the reservoir, or to a different formation. The liquid hydrocarbon phase could be produced with any of the gases, instead of the gases, or separately from the gases. The reinjection of the liquid hydrocarbon phase, for example for subsequent production, is also an option. Conveniently, the means for inducing current to flow at supersonic velocity comprises a Laval type inlet of the conduit, wherein the flow area with smaller cross section of the diffuser is preferably larger than the cross sectional flow area smaller, of the entrance type of Laval. The present invention can also be used to reinject gas separately from the condensable materials within a borehole. For example, when multiple reservoirs are present (for example, stacked reservoirs or different reservoirs penetrated by different wells of a multilateral well) and you want to produce only gas condensates. The gases can be re-injected to prevent spreading or to maintain reservoir pressure. A separator of the present invention could extract the condensable fluids from the gas and the gas could be re-injected from the same borehole.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows schematically a longitudinal cross section of a first preferred embodiment of the separator useful in the practice of the present invention. Figure 2 schematically shows a longitudinal cross section of a second embodiment of the device useful in the practice of the present invention. Figure 3 schematically shows a device in accordance with the present invention within a well bore of a well termination system. Figure 4 schematically shows a device used to demonstrate the device useful in the practice of the present invention. Figures 5A and 5B schematically show a device according to the present invention in a well head of a well termination system. The . Figure 6 is a schematic drawing of an embodiment of the present invention, wherein the liquid stream coming from the separator of the present invention, is channeled to a liquid-liquid separator, and an aqueous phase is separated from a hydrocarbon phase, and the aqueous phase is reinjected into the formation.

Figure 7 is a schematic drawing of an embodiment of the present invention, where condensate is produced and the gas is re-injected into the formation.

DESCRIPTION OF A PREFERRED MODALITY In Figure 1 there is shown a conduit in the form of a tubular housing 1 with open ends. An inlet 3 for fluid is provided at one end of the housing, a first outlet 5 for a fluid loaded with liquid near the other end of the housing, and a second outlet 7 for the fluid substantially free of liquid, at the other end of the housing. The flow direction in the device 1 is from the inlet 3 to the first and second outlets 5, 7. The inlet 3 is an acceleration section containing a Laval type device, which has a longitudinal cross-section of convergent-divergent shape in the direction of flow, to induce a supersonic flow rate to a fluid stream that will flow into the housing through the inlet 3. The housing 1 is further provided with a main cylindrical part 9 and a diffuser 11 by the which main cylindrical part 9 is located between the inlet 3 and the diffuser 11. One or more (for example, four) delta-shaped fins 15 project radially inward from the interior surface of the main cylindrical part 9, each fin 15 is disposed at a selected angle with respect to the direction of flow, in the housing, in order to impart a swirling motion to the fluid flowing at supersonic velocity at through the main cylindrical part 9 of the housing 1. The diffuser 11 has a longitudinal section of convergent-divergent shape in the flow direction, defining an inlet 16 of the diffuser and an outlet 19 of the diffuser. The smaller cross section flow area of the diffuser is larger than the smaller cross section flow area of the 3 Laval type inlet. The housing 1 further includes a secondary cylindrical part 17 which has a greater flow area than the main cylindrical part 9 and which is disposed downstream of the diffuser 11 in the form of a continuation of the diffuser 11. The secondary cylindrical part 17 is provided with longitudinal outlet slits 18 for the liquid, slits 18 which are arranged at an appropriate distance from the outlet 19 of the diffuser. An outlet chamber 21 encloses the secondary cylindrical part 17, and is provided with the first outlet 5 mentioned above, for a stream of concentrated liquids.

The secondary cylindrical part 17 opens into the second outlet 7 mentioned above substantially for gas. The normal operation of device 1 is now explained for the mode using subsonic spacing. A current containing particles of micron sizes is introduced to the Laval type 3 input. When the current flows through the input 3, the current is accelerated up to the supersonic speed. As a result of the very increasing velocity of the current, the temperature and pressure of the current can be reduced to below the dew point of the heavier gaseous components of the stream (for example, water vapors) whereby they condense to form a plurality of liquid particles. When the current flows along the delta-shaped fins 15, a swirling motion is imparted to the stream (which is schematically indicated by the spiral 22) in such a way that the liquid particles are subjected to centrifugal forces radially towards outside. When the current enters the diffuser 11 a shock wave is created near the output 19 located downstream of the diffuser 11. The shock wave dissipates a substantial amount of kinetic energy from the current, whereby the axial component is mainly reduced of fluid velocity. As a result of the greatly reduced axial component of the fluid velocity, the central part of the stream (or "core") flows at a reduced axial velocity. This results in a reduced tendency of the condensed solids and particles to be entrained by the central part of the stream flowing in the secondary cylindrical part 17. The condensed particles can then agglomerate in a radially outer section of a collection zone of the stream, in the secondary cylindrical part 17. The agglomerated particles form a layer of liquid that is extracted from the collection zone through outlet slits 18, the outlet chamber 21, and the first outlet 5 substantially for liquid. However, it is also within the spirit of this invention to extract the condensed particles, at supersonic velocity, without a shock wave located upstream. The stream from which the condensable vapors have been removed is discharged through the second outlet 7 substantially for the liquid-free gas. In Figure 2 a second embodiment of the device for carrying out the invention is shown. This device has a tubular housing 23 with open ends, with a fluid inlet, Laval type, 25, at one end, and a first outlet 27 for the stream containing the solids and any liquid condensed at the other end of the housing. The address of the. flow for the fluid in the device is indicated by the arrow 30. The housing has, from the inlet 25 to the outlet for liquid 27, a substantially cylindrical main part 33, a divergent diffuser 35, a secondary cylindrical part 37 and a diverging part 39. A delta-shaped fin 41 projects radially inwardly into the primary cylindrical portion 33, the fin 41 being disposed at a selected angle to the direction of flow in the housing, in order to impart a swirling motion to the fluid which flows at supersonic velocity through the housing 23. A second outlet 43 in the form of a tube, substantially for gas, extends through the first outlet 27 coaxially within the housing, and has an inlet 45 in the current end down the secondary cylindrical part 37. The outlet 43 can be internally provided with a straightener (not shown), for example, a paddle type straightener, to change the flow with eddies, of the gas, to a straight flow. The normal operation of the second mode is substantially similar to the normal operation of the first mode. The swirling, supersonic flow occurs in the main cylindrical part 33 and a shock wave, if any, occurs near the transition from the diffuser 35 to the secondary cylindrical part 37. The subsonic flow occurs if a diffuser is used in the secondary cylindrical part 37. The stream containing the solids particles and any condensed liquids is discharged through the first outlet 27, and the dry gas is discharged through the second outlet 43 in which the eddy flow, of the gas, is converted to straight flow by the straightener. In the detailed description above, the housing, the main cylindrical part, the diffuser and the secondary cylindrical part, have a circular cross-section. However, any other appropriate cross section can be selected from each of these parts. Also, the main and secondary parts may alternatively have a different shape than the cylindrical one, for example, a frusto-conical shape. In addition, the diffuser can have any other suitable shape, for example without a convergence part (as shown in Figure 2) especially for applications at lower supersonic fluid velocities. Instead of each fin being disposed at a fixed angle relative to the axial direction of the housing, the fin may be disposed at a changing angle with respect to the flow direction, preferably in combination with a spiral shape of the fin. A similar result can be obtained by arranging flat fins along a path of increasing angle with respect to the axis of the initial flow. In addition, each fin may be provided with a raised fin tip (also referred to as aletlet). Instead of the diffuser having a divergent shape (Figure 2), the diffuser alternately has a diverging section followed by a converging section when viewed in the direction of flow. An advantage of this diffuser with divergent-convergent form, is that in the diffuser there is less increase in the temperature of the fluid. Referring now to Figure 3, a device of the present invention is shown in a borehole. A formation from which hydrocarbons 301 are being produced is below a cover 302, and is penetrated by a borehole 303. The borehole provides communication from the formation, through the perforations 305 shown Packed with 306 sands to prevent the collapse of the formation inside the perforations. A tubing 307 is placed in the borehole and is secured with cement 308 which is placed by circulation from the inside of the tubing and outwards to provide support. The cement is followed by a cement plug 309 that remains at the bottom of the tubing, and is retained by a lip 310 provided in the lower segment of the tubing for that purpose. The gas flowing from the formation is forced through the separator of the present invention by a shutter 311 which is effective to isolate the borehole in the region of the producing formation. The gas from the production formation travels through the Laval 312 inlet nozzle, where supersonic speeds are created and the fin 313 induces a vortex to the supersonic flow. A sufficiently long flow path 314 is provided for the supersonic flow region. A section 315 of the diffuser, if any, is provided to create a sonic shock wave, preferably just upstream of the separation of the liquids from the radially outer section, of the vapors, which are captured in a vortex finder 316 and canalized to the surface through a production line 317. The flow from the radially outer section of the portion of the collection section 318 is shown channeled to the outside of the production line to an annular volume between the tube 307 and the production line 317 through a tangential outlet 319. The tangential outlet can help separate liquids from the vapors in the liquid stream.

Although the current that is removed from the radially outer section of the collection section is initially liquid, considerable vaporization can occur when the gas is re-compressed in the shock wave induced by the diffuser. But the liquid could be sufficiently concentrated so that even this rise in temperature does not vaporize all the condensable materials in the stream. A pump with a typical pump rod or an electric pump 320 located downstream is shown removing liquid water that has fallen behind the insulation plug 311. It is also possible to reinjection the formation for both liquids and gases, possibly with the help of submersible electric pumps, if required by the pressure regime of the formation, or in the case of multilateral wells. The concentrated stream of water and / or heavy hydrocarbons preferably has a composition such that the addition of components to prevent the formation of hydrates is not necessary. Even if the inhibition of hydrates is desirable, the amount of the compound for hydrate inhibition, necessary, will be considerably reduced due to the need to treat only the smallest volume of the fluid to be treated. Referring now to Figure 5A, a device of the present invention is shown schematically in the head of an underwater well. A submarine well 501, in a body of water 513 is shown with a tubing 502, with perforations 503 providing communication from a formation 512 to the interior of the borehole 504. The typical equipment 505 of the well head is shown schematically. The separator of the present invention 506 separates a stream 507 mainly from the liquid, from a dry steam stream 508. The temperatures at the seabed 509 approach the freezing temperatures, and the formation of hydrates along the pipe in the bed is therefore a serious concern. The present invention provides a simple, inexpensive and low maintenance dehydration system. Separate liquids can be provided with an additive 510 for hydrate inhibition, through a controlled injection 511. Referring now to Figure 5B, another embodiment is shown, with a borehole 550 located on a surface 551. The borehole is enclosed with a tubing 554 provided with perforations 555. Typical equipment 552 of the well head can be provided. A liquid-vapor separator 553 is provided with an outlet 556 for liquids and a level control system 557. A vapor outlet from the vapor-liquid separator 563 is piped to the dehydrator of the present invention 558. The vapors from the outlet 559 of the separator of the present invention are dry gas 560 having a dew point less than the dew point of the gases produced. The liquid of the separator of the present invention 564 may contain vapors that will be saturated, and therefore preferably are channeled to a second vapor-liquid separator 561. The liquids from this second separator 562 may be combined with liquids from the first separator, or they can be piped separately to the surface equipment. Alternatively, liquids from the second separator can be re-injected into the formation for effective disposal. The liquids from the second separator can be pumped to a reservoir at higher pressure, which can be connected through a different borehole of a multilateral well, or flow through the available pressure drop, towards a lower pressure formation. The liquids from the second separator, if reinjection is desirable, can be collected and re-injected, or they can be re-injected into the borehole from which the gas is produced. Referring now to Figure 6, an embodiment of the present invention is shown, wherein a separator of the present invention 601 is within a borehole 602 that is drilled in a hydrocarbon gas producing formation 603. The borehole is shown enclosed with a tubing 604 that is cemented with cement 605, with a cement shoe 606. A plug 607 isolates the production portion of the borehole, forcing the gas produced into an inlet 608 to the separator of the present invention. A flap 609 induces a vortex to the supersonic gases that have passed through the Laval 610 nozzle, and the condensable materials are collected and leave the separator from a 611 outlet for liquids. Liquids from the outlet for liquids pass to a liquid-liquid separator 612. The liquid-liquid separator can be of any type known in the art. The liquids are separated in a hydrocarbon phase, which is channeled to a well head 613 on the surface 614, through a pipe 618 such as a coiled tubing. An aqueous, liquid phase 615 is channeled through the perforations 613 into a formation. A second set of shutters 619 is shown isolating a section of the borehole for reinjection of the aqueous phase. The steam from which the contaminants have been extracted including the water, is piped through a production line 617 to the well head, where the produced gas 620 and the hydrocarbon liquids produced 621 are collected separately. Referring now to Figure 7, a borehole 701 is shown with a tubing 714 drilled through bores 702. The cement 703 secures the tubing in a formation 704 from which the hydrocarbons are produced, the cement has been forced down the cased by the pressure behind a cement shoe 715. The hydrocarbons are forced through a separator 705 of the present invention. The separator of the present invention has an outlet 706 for liquids and an outlet 707 for steam. The outlet for liquids is in communication with a production line 708. The steam outlet is in communication with a segment of the volume that is inside the tubing 709 that is in communication with a second formation 710 to which they are going to return to. injecting the vapors through further perforations 711. The segment of the volume that is inside the tubing in communication with the second formation, is isolated by an upper shutter 712 and a lower shutter 713. The use of a device as described is not shown in any of Figures 6 or 7, in a multi-branching borehole system. If it is used in a branching borehole system, the device is preferably used at the point of attachment of the boreholes. In that arrangement, the condensable or part thereof, or instead part of the treated gas stream, can be directed through the branching well, either to a different formation or to a different area of the deposit. This system would be used, for example, to avoid the production of water on the surface, which would require additional processing. It can also be used to flow gas to an area of the reservoir used for pressure maintenance or an underground gas reservoir. The means for imparting swirls can be arranged in the inlet part of the duct, rather than downstream of the inlet part.

EXAMPLE A test device for the present invention was prepared, and demonstration was made in the separation of water vapor from the ambient air conditions. Obviously, in the case where the device is used below the surface, under the sea or in the well head, different temperatures, pressures and Mach numbers may apply. However, one skilled in the art will have no difficulty in making the necessary adaptations. Reference is made to Figure 4 for the general configuration of the device used. In this example the air 425 was pressurized to 140 Kpa (1.4 bar (a)) by a blower 401 to provide pressurized air 426. After the blower the air was cooled to a temperature of about 25 to 30 ° C by a fin cooler 402, located in a container 418, and water 419 was sprayed into the vapor space below the cooler 420 to ensure that the air was very close to saturation with water (RV = 90%). This air 427 saturated with water was fed to the liquid-vapor aliphatic separator 403, where the water was separated with a small amount of air displaced in a humid stream 421, together with this stream of liquid water and dry air 422. In In this example, the device was provided with tubular conduits for flow, although the same results can be achieved for cross sections of the conduit, rectangular or asymmetric. Therefore, the diameters of the devices are mentioned, always referring to the internal diameter. The typical conditions at the entrance are summarized below: 1. Mass flow: 1.2 Kg / s 2. Pressure at the entrance: 140 KPa (1400 mbar (a)) 3. Temperature at the entrance: 25 ° C 4. Humidity at the entrance: 90% The device condensed water vapor, resulting in a mist flow that contained a large number of small water droplets. The final temperature and pressure in the supersonic zones 428 were, as found, -28 ° C and 68 KPa (680 mbar (a)), resulting in a fraction of water vapor that was negligibly small. The diameter 404 of the throat of the nozzle was 70 millimeters. The input diameter 405 was 300 millimeters, although its value is not significant with respect to the operation of the device. The outlet diameter 400 of the nozzle was 80 millimeters in order to obtain supersonic flow conditions; typically the corresponding Mach number is M = 1.15. The lengths of the nozzle are determined by the cooling speed, which in this case is 19000 K / s. Persons of ordinary skill in the art can determine the pressure and temperature profiles for the flow through the device, and therefore the cooling rate. The cooling speed determines the size distribution of the small drops. The reduction of the value of the cooling rate results in larger average sizes of the small drops. The lengths of the nozzle were: Ll, 406: 700 mm: from the nozzle inlet to the nozzle throat. L2, 407: 800 mm: from the throat of the nozzle to the outlet of the nozzle. In order to decrease friction losses, the roughness of the wall was small, preferably 1 micron or less. Depending on the application, any rigid material can be used for the nozzle device, as long as the aforementioned design parameters are respected. The vortex tube 408 was connected between the outlet of the nozzle and the diffuser. In the vortex tube was present an internal component type fin 409 that imparted whirlpool. At the edge of this internal component a vortex was created on the upper side (low pressure) and detached from the plane, preferably at the trailing edge. The root cord of this flap plate was attached to the inner wall of the vortex tube. The entrance diameter of the vortex tube 400 was 80 millimeters. In this case the vortex tube was slightly conical; the diameter was linearly increased to 84 millimeters (423) through a length of approximately the length of the fin rope. After the conical section of the vortex tube 410, the diameter of the vortex tube was constant of 84 millimeters over the entire length where the small droplets were deposited on the inner wall (separation length). These two lengths were: L3, 410: 300 millimeters: from the tip of the fin to the rear edge of the fin L4, 412: 300 millimeters: from the rear edge of the fin to the diffuser. The sizing of the inner fin component depends on the preferred circulation or the integral vorticity. This circulation is typically 16 m2 / s resulting from a fin length of 300 millimeters, a span of the fin, at the rear edge, of 60 millimeters, and an incidence of the fin line, at the axis of the 8 ° tube. The backward tilt angle of the anterior edge (perpendicular to the flow) was 87 ° and the backward inclination angle of the trailing edge was 40 °. The edges of the fin were sharp. The plane of the fin was flat and its profile was extremely scarce. The thickness of the fin was approximately at the root. The fin was found at an angle of 8o with respect to the axis of the tube. In the drainage section, the extraction of the liquids out of the vortex tube was achieved. The drainage section is not a device that is distinguished very clearly, but is an integral part of the vortex tube, for example by slits, porous materials, holes in the walls of the vortex tube; or, as shown in Figure 4 is an integral part of the diffuser by a vortex finder 413 (a coaxial conduit). In this example a vortex finder (a coaxial conduit) was centrally placed in the conduit after the shock wave, which was present directly after the vortex tube in the part 414 of the first diffuser. The dimensioning of the vortex tube depends on the ratio of diameters between the diameter of the diffuser at that site 424 (90 millimeters at the entrance) and the diameter of the entrance of the vortex seeker at that point 425 (85 millimeters at the entrance). The difference of cross-sectional areas between the last two influences the minimum flow that is extracted from the main stream containing the liquids. In this case the minimum flow was 10% of the main flow, that is 0.12 kg / s. The length of the 433 diffuser was 1500 millimeters. In the diffuser, the kinetic energy remaining in the flow is transformed into potential energy (increase in static pressure). It is desirable to avoid separation of the boundary layer, which can cause flow detachment, resulting in low efficiency. Therefore the average divergence angle of the diffuser in the test array, of the present, should preferably be less than 5 ° and in this case 4 ° was used. The inlet diameter of the diffuser was the same as the diameter of the vortex finder input (85 millimeters). The outlet diameter 415 of the diffuser was 300 millimeters and the dry air at this point was at approximately atmospheric pressure. The operating characteristics of this device were measured by means of two humidity sensors (capacitive principle: manufacturer "Vaisala") one at input 416 for air and the other at output 417 for dry air, and both were corrected for temperature and Pressure. The typical values of water fractions at the inlet were 18-20 grams of water vapor per kilogram of dry air. The typical water values at the outlet were 13-15 grams of water vapor per kilogram of dry air. This can be expressed as separation efficiencies of approximately 25% steam extraction at the inlet. This also corresponds to the separation of condensed liquids in the supersonic region, because most of the liquid water present in the inlet stream condenses at that point.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (12)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A method for extracting condensable materials from a stream of natural gas, upstream, from a choke of the wellhead connected to an underground formation, using an inertial separator located downstream, in which the small droplets and / or particles are separated from each other. the gases, and the gas from which the condensable materials have been extracted, is collected, characterized in that the method further comprises the steps of: (A) inducing the flow of natural gas to flow at supersonic velocity through a separator Inertial comprising a conduit having an acceleration section in which the gas stream is accelerated to a supersonic velocity whereby it is caused to cool to a temperature which is below a temperature at which condensates start to condense. condensable materials, forming small droplets and / or particles, separated; and (B) transporting the gas and / or condensable, condensed materials, to a wellhead and / or re-injecting it into the underground formation from which it has been produced, or to a different formation, with the proviso that not all gas and condensable materials, collected, are re-injected into the same reservoir zone of the same formation. The method according to claim 1, characterized in that in a section for imparting eddies, a swirling movement is induced to the supersonic fluid stream, whereby the small droplets of the liquid are caused to flow to a radially outer section from a collection zone in the stream, followed by subsonic or supersonic extraction of the liquids, in an outlet stream, from the radially outer section of the collection zone. The method according to claim 2, characterized in that the vortex motion induced to the supersonic fluid flow causes the condensable materials to flow towards a radially outer section of a collection zone in the stream, followed by the extraction subsonic or supersonic of the condensable materials, in an exit stream, from the radially outer section of the collection zone. The method according to claim 3, characterized in that the shock wave is created by inducing the fluid stream to flow through a diffuser. 5. The method according to any of claims 1 to 4, characterized in that the transport of the gases from which the condensable materials have been extracted, to a different well head or reservoir area, is carried out through a production pipeline and the condensable materials or part of the condensable materials are transported to the surface through a different flow path. 6. The method according to claim 1, characterized in that the water is removed from the gas as a condensable component. 7. A well termination system for producing gas from an underground formation comprising a well head, a borehole containing a pipe extending downhole from the wellhead, and an inertial separator comprising: optionally , a section for imparting eddies, which imparts a swirling movement to the gas; and a collection section where a stream of gas containing a reduced amount of condensable materials is collected; characterized in that the inertial separator comprises: an acceleration section in which the gas in use coming from the underground formation, is accelerated to a supersonic speed and the condensable materials are condensed. 8. A well termination system, according to claim 7, characterized in that it comprises a supersonic inertial separator in a borehole. 9. A well termination system, according to claim 7, characterized in that it comprises a supersonic inertial separator in the wellhead. 10. A well termination system, according to any of claims 7 to 9, characterized in that it comprises a borehole system with multiple branches, which connects the reservoir of a production formation, with one or more different reservoirs. 11. A well termination system, according to any of claims 7 to 10, characterized in that it also comprises one or more submersible pumps. 1

2. A well termination system, according to claim 7, characterized in that the collecting section for collecting the gas stream containing a reduced amount of condensable materials is formed by a second outlet extending coaxially through the a first outlet for the condensable materials, towards the tubular housing of the inertial separator. METHOD FOR EXTRACTING CONDENSABLE MATERIALS FROM A NATURAL GAS CURRENT SUMMARY OF THE INVENTION A method for extracting condensable materials from a natural gas stream, upstream of a choke of a well head, connected to an underground formation, the method comprises the steps of: (A) inducing the flow of natural gas to flow to a supersonic velocity through a conduit and therefore causing it to cool to a temperature that is below a temperature at which condensable materials begin to condense, forming small droplets and / or separate particles; (B) separating the small droplets and / or particles from the gases; (C) collecting the gas from which the condensable materials have been extracted; (D) and transporting the gas and / or condensable materials to a well head and / or re-injecting it into the underground formation from which it has been produced, or to a different formation, with the proviso that not all of the gas and condensable materials, collected, are injected back into the same reservoir area of the same formation, and a well termination system to produce gas from an underground formation where the method is applied.