EP0229434A1 - Process for the improvement of the conditioning of gasification agents utilized in an underground coal-gasification process - Google Patents

Process for the improvement of the conditioning of gasification agents utilized in an underground coal-gasification process Download PDF

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Publication number
EP0229434A1
EP0229434A1 EP86202396A EP86202396A EP0229434A1 EP 0229434 A1 EP0229434 A1 EP 0229434A1 EP 86202396 A EP86202396 A EP 86202396A EP 86202396 A EP86202396 A EP 86202396A EP 0229434 A1 EP0229434 A1 EP 0229434A1
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gasification
water
foam
conditioning
gasifying
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EP86202396A
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German (de)
French (fr)
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EP0229434B1 (en
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Pierre Ledent
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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B33/00—Sealing or packing boreholes or wells
    • E21B33/10—Sealing or packing boreholes or wells in the borehole
    • E21B33/13—Methods or devices for cementing, for plugging holes, crevices, or the like
    • E21B33/138—Plastering the borehole wall; Injecting into the formation
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
    • E21B21/14—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor using liquids and gases, e.g. foams
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
    • E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
    • E21B43/243—Combustion in situ

Definitions

  • the choice and packaging of the gasifying agent is an important element in the industrial development of underground gasification processes for coal.
  • the oxygen + water vapor mixture was successfully used in the U.S.A. in the first underground gasification trials carried out on a pilot scale, in coal deposits located at shallow depths.
  • the use of water vapor, in mixture with an oxygen-containing gas has many drawbacks for the industrial development of underground gasification of coal in large deposits located at medium or great depth.
  • gasifying agent preheated to a temperature of the order of 200 ° C to 250 ° C also has the effect of causing the auto-ignition of the coal as soon as the gasifying agent comes into contact with it. , which excludes any possibility of developing an underground gasification process in which the gasification front would move against the flow direction of the gasifying agent.
  • Patent AU-A-64329/80 proposes to use, as gasifying agent, air or oxygen at ambient temperature and to inject liquid water, continuously or intermittently, into the wells of injection of the gasifying agent to minimize the auto-ignition reactions of the carbon and control the position of the gasification zone.
  • the primary objective of the present invention is to remedy these difficulties, by avoiding the segregation of the water and the gas which make up the gasifying agent.
  • the water injected continuously or intermittently is added with a small dose of foaming agent.
  • the water and the oxidizing gas are then treated in a foam generator, operating under high pressure, before being jointly injected into the deposit in the form of a foam constituting a stable and homogeneous two-phase mixture.
  • the foaming agent can be a proteinaceous substance, of the kind which are used in the fight against fires and which consist of hydrolysed proteins obtained from natural substances such as: horns, hoofs of cattle, feathers, hair, fish scales ... It can also be a synthetic chemical, such as triethanolamine laurysulfate, sodium laury-ether sulfate or any other surfactant product, foam stabilizer, which makes it possible to maintain the homogeneity of the two-phase mixture during the duration of the gasifier's underground route.
  • a synthetic chemical such as triethanolamine laurysulfate, sodium laury-ether sulfate or any other surfactant product, foam stabilizer, which makes it possible to maintain the homogeneity of the two-phase mixture during the duration of the gasifier's underground route.
  • the distance between the foam generator and the gasification area will be minimized.
  • each injection well is equipped with two concentric tubes: the external casing 1, used for injecting the oxidizing gas, ends at a short distance from the vein to be gasified by one or more filter screens 2 with mesh one to two millimeters in diameter.
  • each injection well is fitted with a casing 5.
  • a foam generator installed at the head of each of the injection wells is connected to this casing via a shut-off valve 6. Closing this valve allows the foam generator to be isolated, for maintenance operations, without decompressing the underground gasifier.
  • the foam generator comprises a metal casing 7, capable of withstanding the gas injection pressure, one or more filter screens 8 with mesh of one to two millimeters in diameter and one or more sprayers, such as 9, located at a few decimetres upstream of the filter screens 8.
  • the oxidizing gas under pressure is supplied via line 10 and the mixture of water and foaming agent through line 11.
  • the second objective of using a gasifying agent in the form of foam is to avoid self-ignition of the coal in the presence of a gas with a high oxygen content, by ensuring a uniform distribution of water and gas and continuously maintaining a film of water on the surface of the coal which inhibits oxidation reactions.
  • the third objective of using a gasifying agent in the form of foam is to promote the circulation of gas along the carbon front during gasification and to prevent a large fraction of the gasifying agent from bypassing the reaction, filtering through the cracks and cavities that remain between the rocky scree of the already carbonated area. This result is the consequence of the different behavior of the foam, depending on the temperature. In the hot zone near the reaction front, the rise in temperature evaporates the foam bubbles and the gasifying agent circulates along the carbon front in the form of a homogeneous gas phase.
  • the evaporation of the water contained in the bubbles of foam causes a rapid decline in temperature and, after a relatively short time, the presence of the foam realizes the filling of the cracks and cavities that remain between the scree.
  • a gasifying agent in the form of foam prepared from water added with a foaming agent and from a gas containing oxygen can be adapted to all underground coal gasification processes. .
  • FIG. 3 shows, in a section passing through a vertical plane, an underground gasification process by filtration without prior connection, at the level of the vein, in which the well 12 is used for the injection of a gasifying agent, under high pressure, and the well 13 for the recovery of the gas produced.
  • the gasification begins with the firing of the coal at the bottom of the well 13 and it progresses against the flow direction of the gasifying agent.
  • the preconditioning of the gasifying agent in the form of foam ensures a uniform distribution of the water and the oxidizing gas, in the layer of carbon, and maintains on the surface of the carbon a film of water which inhibits the oxidation reactions. , which makes it possible to use a gasifying agent with a high oxygen content, without causing self-ignition of the coal in the vicinity of the injection well.
  • FIG. 4 shows, in a section passing through a vertical plane, a gasification process in which the gasifying agent with high oxygen content is injected into a very long borehole 14, drilled in the thickness of the vein and coated with a steel casing, the gas produced being evacuated by the well 15.
  • the gasification begins with the ignition of the coal, at a point located at a short distance from the well 15.
  • the gasification operation includes alternating periods during which the injection point of the gasifying agent remains fixed and periods during which the injection point is retracted, by controlled combustion of the casing.
  • the preconditioning of the gasifying agent in the form of foam prevents backburning of the casing.
  • the retraction operations of the injection point of the gasifying agent are controlled by temporary interruptions of the water supply to the foam generator, going hand in hand with an adjustment of the gas flow rate to a value which allows the backburning of the casing. .
  • FIG. 5 shows, in a section passing through the thickness of the layer, an underground gasification process in which the gasification operation takes place between an injection borehole 16 and a recovery borehole 17, along a channel 18 , open in the thickness of the layer, and which is limited on one side by the coal being gasified and on the other side by rock scree from the caving of the roof, in the zone 19 already gasified.
  • the gasifying agent injected in the form of foam ensures the filling of the cracks and cavities that remain between the rocky scree of the blasted zone, which has the effect of channeling the flow of gases along the coal gasification front, in the area where the rise in temperature evaporates the bubbles that make up the foam.

Abstract

1. Method of improving the conditioning of gasifying agents, used in methods for the underground gasification of coal, and consisting of water in the liquid state, by an oxygen-containing gas and by a low dosage of a tensio-active agent promoting the production of foam, characterized in that the production of foam is performed at the bottom of the injection wells, equipped with two concentric casings (1, 3), the outer casing (1), used for the injection of the oxydizing gas, terminating in one or more filtering sieves (2) with meshes of approximately one or two millimetres diameter, and the inner casing (3), used for the injection of the mixture of water and a foaming agent, terminating in one or more vaporisers (4) or by a device made from perforated sheet metal dispersing the water in fine droplets.

Description

Le choix et le conditionnement de l'agent gazéifiant constituent un élément important du développement indus­triel des procédés de gazéification souterraine du char­bon.The choice and packaging of the gasifying agent is an important element in the industrial development of underground gasification processes for coal.

Le mélange oxygène + vapeur d'eau a été utilisé avec succès aux U.S.A. lors des premiers essais de gazéification sou­terraine réalisés à l'échelle pilote, dans des gisements de houille situés à faible profondeur. Cependant, l'uti­lisation de vapeur d'eau, en mélange avec un gaz contenant de l'oxygène, présente de nombreux inconvénients pour le développement industriel de la gazéification souterraine du charbon dans des gisements de grande étendue situés à moyenne ou à grande profondeur.The oxygen + water vapor mixture was successfully used in the U.S.A. in the first underground gasification trials carried out on a pilot scale, in coal deposits located at shallow depths. However, the use of water vapor, in mixture with an oxygen-containing gas, has many drawbacks for the industrial development of underground gasification of coal in large deposits located at medium or great depth.

Contrairement à ce qui se passe dans les installations de gazéification du charbon extrait, la vapeur ne peut pas être produite par récupération des pertes de chaleur des gazogènes. Il en résulte que la production de vapeur ne contribue pas à l'amélioration du bilan énergétique du procédé mais qu'elle entraîne une augmentation du prix de revient du gaz, par les investissements en générateurs de vapeur et par la consommation de combustible qu'elle nécessite.Contrary to what happens in gasification plants for extracted coal, steam cannot be produced by recovering heat losses from gas generators. It follows that the production of steam does not contribute to the improvement of the energy balance of the process but that it leads to an increase in the cost price of the gas, by the investments in steam generators and by the consumption of fuel which it need.

Par ailleurs, le développement de la gazéification souter­raine dans les gisements profonds implique un allongement des circuits de distribution des agents gazéifiants et une augmentation de la pression de gazéification. Dans ces conditions, la nécessité de maintenir la température de l'agent gazéifiant au-dessus du point d'ébullition de l'eau entraîne une forte augmentation du coût des con­duites de distribution et des puits d'injection, dont le diamètre doit être augmenté et pour lesquels il faut pré­voir des compensateurs de dilatation et des revêtements isolants de forte épaisseur.In addition, the development of underground gasification in deep deposits involves an extension of the distribution circuits for gasifying agents and an increase in gasification pressure. Under these conditions, the need to maintain the temperature of the gasifying agent above the boiling point of water leads to a sharp increase in the cost of distribution pipes and injection wells, the diameter of which must be increased. and for which expansion compensators and thick insulating coatings must be provided.

L'utilisation d'un agent gazéifiant préchauffé jusqu'à une température de l'ordre de 200° C à 250° C a également pour effet de provoquer l'auto-inflammation du charbon dès que l'agent gazéifiant entre en contact avec lui, ce qui exclut toute possibilité de développement d'un procé­dé de gazéification souterraine dans lequel le front de gazéification se déplacerait à contre courant du sens d'écoulement de l'agent gazéifiant.The use of a gasifying agent preheated to a temperature of the order of 200 ° C to 250 ° C also has the effect of causing the auto-ignition of the coal as soon as the gasifying agent comes into contact with it. , which excludes any possibility of developing an underground gasification process in which the gasification front would move against the flow direction of the gasifying agent.

Le brevet AU-A-64329/80 propose d'utiliser, comme agent gazéifiant, de l'air ou de l'oxygène à température am­biante et d'injecter de l'eau liquide, de façon continue ou intermittente,dans les puits d'injection de l'agent ga­zéifiant pour minimiser les réactions d'auto-inflammation du charbon et contrôler la position de la zone de gazéifi­cation.Patent AU-A-64329/80 proposes to use, as gasifying agent, air or oxygen at ambient temperature and to inject liquid water, continuously or intermittently, into the wells of injection of the gasifying agent to minimize the auto-ignition reactions of the carbon and control the position of the gasification zone.

Cette façon de procéder évite les difficultés résultant de l'utilisation de la vapeur d'eau mais elle entraîne d'au­tres difficultés. En effet, l'eau et le gaz constituent deux phases de densités très différentes et, si la couche à gazéifier présente d'importantes différences de niveau en raison de son épaisseur ou de son pendage, les deux constituants de l'agent gazéifiant peuvent se séparer par gravité, avant que l'eau ait eu le temps de s'évapo­rer, cette séparation ayant pour conséquence l'arrêt des réactions dans la partie basse de la couche et la sur­chauffe des parties hautes.This procedure avoids the difficulties resulting from the use of water vapor but it causes other difficulties. Indeed, water and gas constitute two phases of very different densities and, if the layer to be gasified has significant differences in level due to its thickness or its dip, the two constituents of the gasifying agent can separate by gravity, before the water has had time to evaporate, this separation having the consequence of stopping the reactions in the lower part of the layer and overheating of the upper parts.

La présente invention a pour premier objectif de remé­dier à ces difficultés, en évitant la ségrégation de l'eau et du gaz qui composent l'agent gazéifiant. A cet effet, préalablement à son introduction dans le circuit souterrain, l'eau injectée de façon continue ou inter­mittente est additionnée d'une faible dose d'agent mous­sant. L'eau et le gaz oxydant sont ensuite traités dans un générateur de mousse, fonctionnant sous haute pression, avant d'être injectés conjointement dans le gisement sous la forme d'une mousse constituant un mélange diphasique stable et homogène.The primary objective of the present invention is to remedy these difficulties, by avoiding the segregation of the water and the gas which make up the gasifying agent. To this end, prior to its introduction into the underground circuit, the water injected continuously or intermittently is added with a small dose of foaming agent. The water and the oxidizing gas are then treated in a foam generator, operating under high pressure, before being jointly injected into the deposit in the form of a foam constituting a stable and homogeneous two-phase mixture.

L'agent moussant peut être une substance protéinique, du genre de celles qui sont utilisées dans la lutte contre les incendies et qui sont constituées par des protéines hydrolysées obtenues à partir de substances naturelles telles que : cornes, sabots de bovins, plumes, poils, écailles de poissons... Il peut également être un produit chimique de synthèse, tel que le laurysulfate de triétha­nolamine, le laury-éther sulfate de sodium ou tout autre produit tensioactif, stabilisateur de mousse, qui per­mette de maintenir l'homogénéité du mélange diphasique pendant la durée du parcours souterrain de l'agent gazéi­fiant.The foaming agent can be a proteinaceous substance, of the kind which are used in the fight against fires and which consist of hydrolysed proteins obtained from natural substances such as: horns, hoofs of cattle, feathers, hair, fish scales ... It can also be a synthetic chemical, such as triethanolamine laurysulfate, sodium laury-ether sulfate or any other surfactant product, foam stabilizer, which makes it possible to maintain the homogeneity of the two-phase mixture during the duration of the gasifier's underground route.

Pour réduire la consommation d'agent moussant, la distance entre le générateur de mousse et la zone de gazéification sera réduite au minimum.To reduce the consumption of foaming agent, the distance between the foam generator and the gasification area will be minimized.

L'invention est décrite maintenant sur la base des dessins annexés, à titre d'exemples uniquement, montrant en :

  • Figure 1 une première variante d'application du procédé suivant laquelle la production de mousse est réalisée au fond des puits d'injection des agents gazéifiants ;
  • Figure 2 une seconde variante d'application, suivant la­quelle la production de mousse est réalisée en surface ;
  • Figures 3 à 5 l'application du procédé suivant l'inven­tion respectivement à trois procédés de gazéification, pour lesquels le conditionnement de l'agent gazéifiant sous forme de mousse présente un intérêt particulier.
The invention is now described on the basis of the appended drawings, by way of examples only, showing in:
  • Figure 1 a first alternative application of the method according to which the production of foam is carried out at the bottom of the injection wells of the gasifying agents;
  • Figure 2 a second application variant, according to which the production of foam is carried out on the surface;
  • Figures 3 to 5 the application of the process according to the invention respectively to three gasification processes, for which the packaging of the gasifying agent in the form of foam is of particular interest.

Dans la première variante chaque puits d'injection est équipé de deux tubes concentriques : le tubage extérieur 1, utilisé pour l'injection du gaz oxydant, se termine à faible distance de la veine à gazéifier par un ou plu­sieurs tamis filtrants 2 à mailles de un à deux milli­mètres de diamètre. Le tubage intérieur 3, utilisé pour l'injection du mélange d'eau et d'agent moussant, se ter­mine à quelques décimètres en amont des tamis filtrants 2, par un ou plusieurs pulvérisateurs tels que 4 ou par un dispositif en tôle perforée, qui assure la dispersion de l'eau en fines gouttelettes.In the first variant, each injection well is equipped with two concentric tubes: the external casing 1, used for injecting the oxidizing gas, ends at a short distance from the vein to be gasified by one or more filter screens 2 with mesh one to two millimeters in diameter. The inner casing 3, used for injecting the mixture of water and foaming agent, ends a few decimeters upstream of the filter screens 2, by one or more sprayers such as 4 or by a perforated sheet device, which ensures the dispersion of water into fine droplets.

Dans la deuxième variante, chaque puits d'injection est équipé d'un tubage 5. Un générateur de mousse, installé en tête de chacun des puits d'injection est relié à ce tubage par l'intermédiaire d'une vanne d'arrêt 6. La fermeture de cette vanne permet d'isoler le générateur de mousse, pour procéder à des opérations d'entretien, sans décomprimer le gazogène souterrain. Le générateur de mousse comporte une enveloppe métallique 7, capable de résister à la pression d'injection du gaz, un ou plu­sieurs tamis filtrants 8 à mailles d'un à deux milli­mètres de diamètre et un ou plusieurs pulvérisateurs, tels que 9, situés à quelques décimètres en amont des tamis filtrants 8. Le gaz oxydant sous pression est ali­menté par la conduite 10 et le mélange d'eau et d'agent moussant par la conduite 11.In the second variant, each injection well is fitted with a casing 5. A foam generator, installed at the head of each of the injection wells is connected to this casing via a shut-off valve 6. Closing this valve allows the foam generator to be isolated, for maintenance operations, without decompressing the underground gasifier. The foam generator comprises a metal casing 7, capable of withstanding the gas injection pressure, one or more filter screens 8 with mesh of one to two millimeters in diameter and one or more sprayers, such as 9, located at a few decimetres upstream of the filter screens 8. The oxidizing gas under pressure is supplied via line 10 and the mixture of water and foaming agent through line 11.

L'utilisation d'un agent gazéifiant sous forme de mousse a pour deuxième objectif d'éviter l'auto-inflammation du charbon, en présence d'un gaz à haute teneur en oxygène, en assurant une répartition uniforme de l'eau et du gaz et en maintenant continuellement à la surface du charbon un film d'eau qui inhibe les réactions d'oxydation.The second objective of using a gasifying agent in the form of foam is to avoid self-ignition of the coal in the presence of a gas with a high oxygen content, by ensuring a uniform distribution of water and gas and continuously maintaining a film of water on the surface of the coal which inhibits oxidation reactions.

L'utilisation d'un agent gazéifiant sous forme de mousse a pour troisième objectif de favoriser la circulation du gaz le long du front de charbon en cours de gazéifica­tion et d'éviter qu'une fraction importante de l'agent gazéifiant contourne la zone de réaction, en filtrant à travers les fissures et les cavités qui subsistent entre les éboulis rocheux de la zone déjà gazéifiée. Ce résul­tat est la conséquence du comportement différent de la mousse, suivant la température. Dans la zone chaude proche du front de réaction, l'élévation de la tempéra­ture assure l'évaporation des bulles de mousse et l'agent gazéifiant circule, le long du front de charbon, sous la forme d'une phase gazeuse homogène. Dans la zone gazéi­ fiée, remplie d'éboulis rocheux, l'évaporation de l'eau contenue dans les bulles de mousse provoque un rapide déclin de la température et, au bout d'un temps relative­ment court, la présence de la mousse réalise le colmatage des fissures et des cavités qui subsistent entre les é­boulis.The third objective of using a gasifying agent in the form of foam is to promote the circulation of gas along the carbon front during gasification and to prevent a large fraction of the gasifying agent from bypassing the reaction, filtering through the cracks and cavities that remain between the rocky scree of the already carbonated area. This result is the consequence of the different behavior of the foam, depending on the temperature. In the hot zone near the reaction front, the rise in temperature evaporates the foam bubbles and the gasifying agent circulates along the carbon front in the form of a homogeneous gas phase. In the gas zone folded, filled with rocky scree, the evaporation of the water contained in the bubbles of foam causes a rapid decline in temperature and, after a relatively short time, the presence of the foam realizes the filling of the cracks and cavities that remain between the scree.

L'utilisation d'un agent gazéifiant sous forme de mousse préparé à partir d'eau additionnée d'un agent moussant et à partir d'un gaz contenant de l'oxygène, peut s'adapter à tous les procédés de gazéification souterraine du char­bon.The use of a gasifying agent in the form of foam prepared from water added with a foaming agent and from a gas containing oxygen, can be adapted to all underground coal gasification processes. .

La figure 3 montre suivant une coupe passant par un plan vertical un procédé de gazéification souterraine par fil­tration sans liaison préalable, au niveau de la veine, dans lequel le puits 12 est utilisé pour l'injection d'un agent gazéifiant, sous haute pression, et le puits 13 pour la récupération du gaz produit. La gazéifica­tion débute par la mise à feu du charbon au fond du puits 13 et elle progresse à contre courant du sens d'écoulement de l'agent gazéifiant. Le conditionnement préalable de l'agent gazéifiant sous forme de mousse assure une répar­tition uniforme de l'eau et du gaz oxydant, dans la couche de charbon, et maintient à la surface du charbon un film d'eau qui inhibe les réactions d'oxydation, ce qui permet d'utiliser un agent gazéifiant à haute teneur en oxygène, sans provoquer l'auto-inflammation du charbon au voisi­nage du puits d'injection.FIG. 3 shows, in a section passing through a vertical plane, an underground gasification process by filtration without prior connection, at the level of the vein, in which the well 12 is used for the injection of a gasifying agent, under high pressure, and the well 13 for the recovery of the gas produced. The gasification begins with the firing of the coal at the bottom of the well 13 and it progresses against the flow direction of the gasifying agent. The preconditioning of the gasifying agent in the form of foam ensures a uniform distribution of the water and the oxidizing gas, in the layer of carbon, and maintains on the surface of the carbon a film of water which inhibits the oxidation reactions. , which makes it possible to use a gasifying agent with a high oxygen content, without causing self-ignition of the coal in the vicinity of the injection well.

La figure 4 montre, suivant une coupe passant par un plan vertical, un procédé de gazéification dans lequel l'agent gazéifiant à haute teneur en oxygène est injecté dans un sondage de grande longueur 14, foré dans l'épaisseur de la veine et revêtu d'un tubage en acier, le gaz produit étant évacué par le puits 15. La gazéification débute par la mise à feu du charbon, en un point situé à une petite distance du puits 15. L'opération de gazéifica­tion comporte une alternance de périodes durant lesquelles le point d'injection de l'agent gazéifiant reste fixe et de périodes durant lesquelles le point d'injection est ré­tracté, par combustion contrôlée du tubage. Le condi­tionnement préalable de l'agent gazéifiant sous forme de mousse empêche la rétrocombustion du tubage. Les opéra­tions de rétraction du point d'injection de l'agent ga­zéifiant sont contrôlées par des interruptions tempo­raires de l'alimentation en eau du générateur de mousse, allant de pair avec un ajustement du débit de gaz à une valeur qui permette la rétrocombustion du tubage.FIG. 4 shows, in a section passing through a vertical plane, a gasification process in which the gasifying agent with high oxygen content is injected into a very long borehole 14, drilled in the thickness of the vein and coated with a steel casing, the gas produced being evacuated by the well 15. The gasification begins with the ignition of the coal, at a point located at a short distance from the well 15. The gasification operation includes alternating periods during which the injection point of the gasifying agent remains fixed and periods during which the injection point is retracted, by controlled combustion of the casing. The preconditioning of the gasifying agent in the form of foam prevents backburning of the casing. The retraction operations of the injection point of the gasifying agent are controlled by temporary interruptions of the water supply to the foam generator, going hand in hand with an adjustment of the gas flow rate to a value which allows the backburning of the casing. .

La figure 5 montre suivant une coupe passant dans l'épais­seur de la couche un procédé de gazéification souterraine dans lequel l'opération de gazéification se déroule entre un sondage d'injection 16 et un sondage de récupération 17, le long d'un chenal 18, ouvert dans l'épaisseur de la couche, et qui est limité d'un côté par le charbon en cours de gazéification et de l'autre côté par des éboulis de roche provenant du foudroyage du toit, dans la zone 19 déjà gazéifiée. L'agent gazéifiant injecté sous forme de mousse assure le colmatage des fissures et des cavités qui subsistent entre les éboulis rocheux de la zone fou­droyée, ce qui a pour effet de canaliser l'écoulement des gaz le long du front de gazéification du charbon, dans la zone où l'élévation de la température assure l'évaporation des bulles qui constituent la mousse.FIG. 5 shows, in a section passing through the thickness of the layer, an underground gasification process in which the gasification operation takes place between an injection borehole 16 and a recovery borehole 17, along a channel 18 , open in the thickness of the layer, and which is limited on one side by the coal being gasified and on the other side by rock scree from the caving of the roof, in the zone 19 already gasified. The gasifying agent injected in the form of foam ensures the filling of the cracks and cavities that remain between the rocky scree of the blasted zone, which has the effect of channeling the flow of gases along the coal gasification front, in the area where the rise in temperature evaporates the bubbles that make up the foam.

Claims (8)

1. Procédé d'amélioration du conditionnement des agents gazéifiants, consistant en de l'eau à l'état liquide et en un gaz contenant de l'oxygène, utilisés dans les pro­cédés de gazéification souterraine, caractérisé en ce que,préalablement à son injection dans le gisement, l'eau est mélangée à une faible dose d'agent moussant et en ce que l'eau et le gaz oxydant sont traités dans un généra­teur de mousse, fonctionnant sous pression, avant d'être injectés conjointement dans le gisement, sous la forme d'une mousse constituant un mélange diphasique stable et homogène.1. A method for improving the conditioning of gasifying agents, consisting of water in the liquid state and an oxygen-containing gas, used in underground gasification processes, characterized in that, prior to its injection in the deposit, the water is mixed with a low dose of foaming agent and in that the water and the oxidizing gas are treated in a foam generator, operating under pressure, before being jointly injected into the deposit, in the form of a foam constituting a stable and homogeneous two-phase mixture. 2. Procédé d'amélioration du conditionnement des agents gazéifiants suivant la revendication 1, caractérisé en ce que l'agent moussant utilisé est constitué par des protéines hydrolysées obtenues à partir de substances naturelles telles que : cornes, sabots de bovins, plumes, poils, écailles de poisson.2. A method for improving the conditioning of gasifying agents according to claim 1, characterized in that the foaming agent used consists of hydrolysed proteins obtained from natural substances such as: horns, hoofs of cattle, feathers, hair, fish scales. 3. Procédé d'amélioration du conditionnement des agents gazéifiants suivant la revendication 1, caractérisé en ce que l'agent moussant est un produit chimique de syn­thèse tel que le laurysulfate de triéthanolamine, le laury-éther sulfate de sodium ou tout autre produit tensioactif, stabilisateur de mousse, qui permette de maintenir l'homogénéité du mélange diphasique pendant la durée du parcours souterrain de l'agent gazéifiant.3. Method for improving the conditioning of gasifying agents according to claim 1, characterized in that the foaming agent is a synthetic chemical such as triethanolamine laurysulfate, sodium laury-ether sulfate or any other surfactant, foam stabilizer, which makes it possible to maintain the homogeneity of the two-phase mixture for the duration of the underground course of the gasifying agent. 4. Procédé d'amélioration du conditionnement des agents gazéifiants suivant la revendication 1, caractérisé en ce que la production de mousse est réalisée au fond des puits d'injection équipés de deux tubages concentriques, le tubage extérieur (1), utilisé pour l'injection du gaz oxydant, étant terminé par un ou plusieurs tamis fil­trants (2) à mailles de un à deux millimètres de dia­mètre et le tubage intérieur (3), utilisé pour l'injec­tion du mélange d'eau et d'agent moussant, étant termi­né par un ou plusieurs pulvérisateurs (4) ou par un dis­positif en tôle perforée, qui assure la dispersion de l'eau en fines gouttelettes (figure 1).4. Method for improving the conditioning of gasifying agents according to claim 1, characterized in that the production of foam is carried out at the bottom of the wells injection pipes equipped with two concentric casings, the external casing (1), used for injecting the oxidizing gas, being terminated by one or more filter screens (2) with mesh of one to two millimeters in diameter and the internal casing ( 3), used for injecting the mixture of water and foaming agent, being terminated by one or more sprayers (4) or by a perforated sheet device, which ensures the dispersion of the water into fine droplets (figure 1). 5. Procédé d'amélioration du conditionnement des agents gazéifiants suivant la revendication 1, caractérisé en ce que la production de mousse est réalisée en surface, dans un générateur de mousse (7) installé en tête de chacun des puits d'injection, au sommet d'un tubage (5), auquel il est relié par l'intermédiaire d'une vanne (6) (figure 2).5. A method of improving the conditioning of gasifying agents according to claim 1, characterized in that the production of foam is carried out on the surface, in a foam generator (7) installed at the top of each of the injection wells, at the top a casing (5), to which it is connected via a valve (6) (Figure 2). 6. Procédé d'amélioration suivant revendication 1 pour le conditionnement des agents gazéifiants utilisés dans les procédés de gazéification souterraine, dans lesquels un agent gazéifiant, injecté sous haute pression, filtre à travers une couche de charbon pour alimenter un front de gazéification se déplaçant à contre courant du sens d'écoulement de l'agent gazéifiant, caractérisé en ce que l'agent gazéifiant sous forme de mousse est condi­tionné de manière à assurer une répartition uniforme de l'eau et du gaz dans la couche de charbon et à maintenir à la surface du charbon un film d'eau qui inhibe les réactions d'oxydation (figure 3).6. Improvement method according to claim 1 for the conditioning of gasifying agents used in underground gasification processes, in which a gasifying agent, injected under high pressure, filters through a layer of carbon to feed a gasification front moving at against the flow direction of the gasifying agent, characterized in that the foaming gasifying agent is conditioned so as to ensure a uniform distribution of water and gas in the carbon layer and to maintain the surface of the coal a film of water which inhibits oxidation reactions (Figure 3). 7. Procédé d'amélioration suivant revendication 1 pour le conditionnement des agents gazéifiants utilisés dans les procédés de gazéification souterraine, dans lesquels un agent gazéifiant à haute teneur en oxygène est injec­té à travers un sondage en veine (14) garni d'un tubage, l'opération de gazéification comportant une alternance de périodes durant lesquelles le point d'injection reste fixe et de périodes durant lesquelles le point d'injec­tion est rétracté par combustion contrôlée du tubage, caractérisé en ce que le contrôle de la rétraction du point d'injection de l'agent gazéifiant est assuré par des interruptions temporaires de l'alimentation en eau du générateur de mousse, allant de pair avec un ajuste­ment du débit de gaz (figure 4).7. Improvement method according to claim 1 for the conditioning of the gasifying agents used in underground gasification processes, in which a gasification agent with high oxygen content is injected through a vein borehole (14) fitted with a casing, the gasification operation comprising alternating periods during which the injection point remains fixed and for periods during which the injection point is retracted by controlled combustion of the casing, characterized in that the control of the retraction of the injection point of the gasifying agent is ensured by temporary interruptions of the supply of water from the foam generator, along with an adjustment of the gas flow rate (Figure 4). 8. Procédé d'amélioration suivant revendication 1 pour le conditionnement des agents gazéifiants utilisés dans les procédés de gazéification souterraine, dans lesquels l'opération de gazéification se déroule le long d'un chenal (18) ouvert dans l'épaisseur de la veine et qui est limité d'un côté par le charbon en cours de gazéifi­cation et de l'autre côté par des éboulis de roche pro­venant du foudroyage du toit, dans la zone déjà gazéifiée (19), caractérisé en ce que le colmatage des fissures et des cavités qui subsistent entre les éboulis rocheux de la zone foudroyée est assuré par l'agent gazéifiant in­jecté sous forme de mousse de manière à canaliser l'é­coulement des gaz, le long du front de gazéification du charbon, dans la zone où l'élévation de la température assure la vaporisation des bulles de mousse (figure 5).8. Improvement method according to claim 1 for the conditioning of gasifying agents used in underground gasification processes, in which the gasification operation takes place along a channel (18) open in the thickness of the vein and which is limited on one side by the coal in the course of gasification and on the other side by rock scree from the caving of the roof, in the already gasified zone (19), characterized in that the clogging of cracks and cavities which remain between the rocky scree of the blasted zone is ensured by the gasifying agent injected in the form of foam so as to channel the gas flow, along the front of gasification of coal, in the zone where the elevation of the temperature ensures the vaporization of the foam bubbles (Figure 5).
EP19860202396 1986-01-16 1986-12-30 Process for the improvement of the conditioning of gasification agents utilized in an underground coal-gasification process Expired - Lifetime EP0229434B1 (en)

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BE6/48181A BE904055A (en) 1986-01-16 1986-01-16 PROCESS FOR IMPROVING THE CONDITIONING OF GASIFYING AGENTS USED IN SUBTERRANEAN GASIFICATION PROCESSES.

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EP1298280A1 (en) * 2001-09-28 2003-04-02 Halliburton Energy Services, Inc. Fracturing with downhole foam mixing
EP1298281A1 (en) * 2001-09-28 2003-04-02 Halliburton Energy Services, Inc. Acid stimulating with downhole foam mixing
US6725933B2 (en) 2001-09-28 2004-04-27 Halliburton Energy Services, Inc. Method and apparatus for acidizing a subterranean well formation for improving hydrocarbon production
WO2006018306A1 (en) * 2004-08-17 2006-02-23 Dew Pitchmastic Plc Bioremediation foam and delivery method
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EP1298280A1 (en) * 2001-09-28 2003-04-02 Halliburton Energy Services, Inc. Fracturing with downhole foam mixing
EP1298281A1 (en) * 2001-09-28 2003-04-02 Halliburton Energy Services, Inc. Acid stimulating with downhole foam mixing
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WO2006018306A1 (en) * 2004-08-17 2006-02-23 Dew Pitchmastic Plc Bioremediation foam and delivery method
GB2518626A (en) * 2013-09-25 2015-04-01 Venture Engineering Services Ltd Well apparatus and method for use in gas production
US9702224B2 (en) 2013-09-25 2017-07-11 Venture Engineering Services Limited Well apparatus and method for use in gas production
CN107401393A (en) * 2017-07-31 2017-11-28 山西晋城无烟煤矿业集团有限责任公司 Water pumping gas production integration goaf gas extraction well casing programme and its construction method
CN107401393B (en) * 2017-07-31 2023-07-25 山西晋城无烟煤矿业集团有限责任公司 Drainage and gas production integrated goaf gas extraction well body structure and construction method thereof

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