EP1112437B1 - Method for the in-situ extraction of gas from coal seams - Google Patents

Method for the in-situ extraction of gas from coal seams Download PDF

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Publication number
EP1112437B1
EP1112437B1 EP99953624A EP99953624A EP1112437B1 EP 1112437 B1 EP1112437 B1 EP 1112437B1 EP 99953624 A EP99953624 A EP 99953624A EP 99953624 A EP99953624 A EP 99953624A EP 1112437 B1 EP1112437 B1 EP 1112437B1
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Prior art keywords
gas
bore hole
coal
pressure
pressurization
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Expired - Lifetime
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EP99953624A
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German (de)
French (fr)
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EP1112437A1 (en
Inventor
Armin LÖVENICH
Hans-Joachim Doering
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EOn Ruhrgas AG
RAG AG
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RAG AG
Ruhrgas AG
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    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21BEARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/006Production of coal-bed methane

Definitions

  • the pressurization of the borehole can be exerted by injecting water or gas.
  • water used to pressurize the borehole
  • reservoir water present in the deposit can also be pressed into the borehole or the pore structure breathing can be generated by cyclically applied pressure via the pressure excitation of the reservoir water.
  • the gas flowing into and conveying the borehole can be pressed back into the borehole for pressurizing it; alternatively, the injection of CO 2 may be provided, which the advantageous effect is that the binding of the is reduced to be conveyed methane (CH 4) to the coal on admission of CO 2, so that the relied on for pressurizing CO 2 gas also acts as a subsidy.
  • CH 4 methane

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Geology (AREA)
  • Fluid Mechanics (AREA)
  • Physics & Mathematics (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Environmental & Geological Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Solid Fuels And Fuel-Associated Substances (AREA)
  • Artificial Fish Reefs (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Description

Die Erfindung betrifft ein Verfahren zur in-Situ-Förderung von Gas aus Kohleflözen, wobei zur Schaffung von Fließwegen in der Kohle die Struktur der gashaltigen Kohle mittels unter Druck in ein in das Kohleflöz niedergebrachtes Bohrloch eingebrachten Gasen und/oder Flüssigkeiten aufgeschlossen und anschließend für die Gasförderung ein kleiner als der jeweilige Desorptionsdruck bemessener Druck an der Bohrung angelegt wird.The invention relates to a method for in-situ funding of gas from coal seams, creating flow paths in the coal the structure of the gas-containing coal by means of under pressure into one brought into the coal seam Gases and / or liquids brought into the borehole open minded and then involved in gas production pressure smaller than the respective desorption pressure is created on the bore.

Die Gewinnungsmöglichkeit von in Kohleflözen anstehendem Methan aus bergmännisch nicht aufgeschlossenen Flözhorizonten mittels einer in-Situ-Förderung aus in das betreffende Kohleflöz niedergebrachten Bohrlöchern wird bestimmt durch die Parameter Gasinhalt, Permeabilität und Porosität der Kohle sowie durch den im einzelnen vom Gasinhalt der Kohle abhängigen Desorptionsdruck des Methans. Zur Förderung des Methans hat man im Rahmen von bisher bekannten Verfahren Stimulationstechniken angewendet, die aus der Erdölförderung an sich bekannt sind, indem das in das zur Gasförderung herangezogene Kohleflöz niedergebrachte Bohrloch kurzzeitig, d. h. über einen Zeitraum von weniger als einer Stunde bis zu wenigen Stunden, mittels Injektion von Wasser oder eines geeigneten Gases unter einen gleichmäßig hohen Druck, beispielsweise von 300 bis 350 bar, gesetzt wird.The possibility of extracting pending in coal seams Methane from non-mined mines Seam horizons by means of in-situ funding from the the coal seam in question is drilled determined by the parameters gas content, permeability and Porosity of the coal as well as by the in particular from Gas content of the coal dependent desorption pressure of the Methane. To promote methane, one has within previously known methods of stimulation techniques applied, which is known per se from oil production are by using that in the gas production Coal seam sunk temporarily, d. H. about a period of less than an hour to a few Hours, by injection of water or a suitable one Gases under a uniformly high pressure, for example from 300 to 350 bar.

Diese Druckbeaufschlagung führt zur Ausbildung eines sogenannten Fracs, mittels dessen die Makrostruktur der Kohle an ihren natürlichen mechanischen Schwachstellen wie Schlechten, Klüfte etc. aufgebrochen wird. Die Druckbeaufschlagung geschieht unter gleichzeitiger Einbringung eines geeigneten Materials, wie beispielsweise eines rolligen Sandes, mittels dessen die aufgeschlossene Makrostruktur offengehalten und gleichzeitig ein Gasströmungsweg entlang der aufgebrochenen mechanischen Schwachstellen hergestellt wird. Mit dem bekannten Verfahren wird insoweit lediglich die Zutrittsfläche in das Förderbohrloch vergrößert.This pressurization leads to the formation of a so - called Fracs, by means of which the macrostructure of the Coal at their natural mechanical weak points like Bad, fractures etc. is broken open. The Pressurization happens at the same time Introduction of a suitable material, such as of a rolling sand, by means of which the open Macro structure kept open and at the same time Gas flow path along the broken mechanical Vulnerabilities is created. With the well-known In this respect, the procedure is only the access area in the Production well enlarged.

Mit dem bekannten Stimulationsverfahren ist der Nachteil verbunden, daß damit in Kohleflözen mit einer geringen Permeabilität nur dann befriedigende Gasförderraten erzielbar sind, wenn die Kohle hochgesättigt an Methan ist und demzufolge der Desorptionsdruck relativ nahe an dem Beaufschlagungsdruck liegt. Ist eine geringpermeable Kohle dagegen untersättigt, so ergibt sich ausgehend von dem jeweils eingebrachten Frac nur eine geringe Eindringtiefe des bei Absenkung des Drucks für die Gasförderung sich einstellenden Drucktrichters. Der unterhalb des Desorptionsdrucks am Bohrloch einzustellende Förderdruck wirkt daher nur auf ein vergleichsweise kleines Kohlevolumen, nämlich dasjenige, welches unmittelbar senkrecht zum jeweiligen Frac ansteht. Damit beeinflußt die bekannte Stimulationstechnik nur vergleichsweise geringe Flözabschnitte; es findet zumindest kurzfristig keine volumetrische Flözbeeinflussung statt, und die Wanderungsgeschwindigkeit der Druckabsenkung im Flöz beim Förderbetrieb ist zu gering.The disadvantage with the known stimulation method connected that in coal seams with a low Permeability only satisfactory gas production rates can be achieved if the coal is highly saturated with methane and consequently the desorption pressure is relatively close to that Pressure is present. Is a low permeable coal on the other hand, undersaturated, it follows from that each Frac introduced only a small depth of penetration of when the pressure for gas production drops adjusting hopper. The below the Desorption pressure to be set at the borehole therefore only affects a comparatively small one Coal volume, namely that which immediately is perpendicular to the respective frac. This affects the known stimulation technology only comparatively low Flözabschnitte; it does not find any, at least in the short term volumetric seam control instead, and the Migration speed of the pressure drop in the seam at Funding operation is too low.

Infolgedessen ist bei einer geringen Permeabilität und einem geringen Desorptionsdruck der zur Gasförderung herangezogenen Kohle der zur Unterschreitung des Desorptionsdruckes in einem wirtschaftlich interessanten Kohlevolumen benötigte Zeitraum entsprechend lang; die erzielbaren Gasförderraten können dann so gering sein, daß eine wirtschaftliche Gasförderung nicht gegeben ist.As a result, with low permeability and a low desorption pressure for gas production Coal used to fall below the Desorption pressure in an economically interesting Coal volume required correspondingly long time; the achievable gas production rates can then be so low that there is no economic gas production.

US-A-5 411 098 beschreibt ein übliches Verfahren mit Kurzzeitigem, hohen und wechselndem Druck. In US-A-5 566 755 wird nach einiger Zeit die Drechbeaufschlagung durch das inerte Gas verringert und später wieder erhöht. Es gibt in US-A-5 566 755 jedoch keinen Hinweis, daß in dem jeweiligen Flözhorizont die Hauptspannung des Materials zu ermitteln, um demnach einen bestimmten Druck in der Bohrung einzustellen.US-A-5 411 098 describes a common method Short-term, high and changing pressure. In US-A-5 566 755 after some time the turning action is caused by the inert gas decreased and increased again later. There is, however, in US-A-5 566 755 no indication that the main stress in the respective seam horizon of the material to determine a certain pressure set in the hole.

Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren der eingangs genannten Art anzugeben, mittels dessen die Gasförderrate gesteigert werden kann.The invention is therefore based on the object To specify methods of the type mentioned at the beginning, by means of whose gas production rate can be increased.

Die Lösung dieser Aufgabe ergibt sich einschließlich vorteilhafter Ausgestaltungen und Weiterbildungen der Erfindung aus dem Inhalt der Patentansprüche, welche dieser Beschreibung nachgestellt sind. The solution to this problem is inclusive advantageous refinements and developments of Invention from the content of the claims, which this Description are reproduced.

Die Erfindung sieht in ihrem Grundgedanken vor, daß zum Aufschluß der Kohle eine über einen längeren Zeitraum wirksame Beaufschlagung des Bohrloches mit einem Druck eingestellt wird, der kleiner als die kleinste in dem jeweiligen zur Gasförderung herangezogenen Flözhorizont ermittelte Hauptspannung ist, wobei die Beaufschlagung des Bohrloches während des Aufschlußzeitraumes mit einem zyklisch wechselnden Druck erfolgt.The invention provides in its basic concept that Digestion of coal over a long period of time effective application of pressure to the borehole is set which is smaller than the smallest in that respective seam horizon used for gas production main voltage determined, the loading of the Borehole during the exploration period with a cyclically changing pressure occurs.

Mit der Erfindung ist der Vorteil verbunden, daß die Beaufschlagung des zur Gasförderung heranzuziehenden Kohleflözes mit einem Druck, der kleiner als die kleinste in dem entsprechenden Flöz ermittelte Hauptspannung ist, das in der Kohle vorhandene komplexe Rißsystem im Porenbereich von Makroporen bis hin zu Mikroporenstrukturen öffnet, ohne daß sich neue Risse im Bereich der Makrostruktur öffnen oder öffnen müßten. Im Anschluß an das Aufbrechen der Porenstruktur gehen die Mikrorisse nicht wieder in ihre dichte Ausgangslage zurück, da durch die länger andauernde Druckbeaufschlagung mit einem im Bereich der Hauptspannung liegenden Druck eine geringe Disloziierung der Mikrorißflächen gegeneinander und wegen der damit verbundenen Ablösung von Feinstpartikelchen ein bleibender Spalt auf der jeweiligen Rißfläche erzeugt wird, so daß in vorteilhafter Weise auch auf den Einsatz von Stützmitteln wie Sanden etc. verzichtet werden kann.The advantage of the invention is that the Acting on the gas to be used Coal seams with a pressure less than the smallest is the main stress determined in the corresponding seam, the complex crack system in the coal Pore range from macropores to microporous structures opens without new cracks in the area of the Macro structure should open or open. Following the The microcracks do not break open the pore structure back to their dense starting position, because of the Prolonged pressurization with one in the area the main stress is a low Dislocating the micro-crack surfaces against each other and because of the associated detachment of very fine particles permanent gap is created on the respective crack surface, so that advantageously on the use of Support agents such as sands etc. can be dispensed with.

Die Öffnung des Rißsystems im Porenbereich wird weiterhin dadurch unterstützt, daß erfindungsgemäß die Beaufschlagung des Bohrlochs während des Aufschlußzeitraumes mit einem zyklisch wechselnden Druck erfolgt, so daß es hierdurch zu einer Art Atmung im Porenbereich der aufzuschließenden Kohle kommt, weshalb sich einmal geöffnete Porenstrukturen nicht wieder schließen können. Hierdurch werden auch die Verschiebung der Mikrorißflächen gegeneinander und der Transport von abgelösten Feinstpartikelchen innerhalb der geöffneten Mikroporenstrukturen unterstützt.The opening of the crack system in the pore area continues supported by the fact that, according to the invention, the application the well during the exploration period with a cyclically changing pressure takes place, so that it thereby a kind of breathing in the pore area of the unlocked Coal comes, which is why once pore structures open cannot close again. This will also Displacement of the micro-crack surfaces against each other and the Transport of detached fine particles within the open micro-pore structures supported.

Somit wird mit dem erfindungsgemäßen Verfahren die Permeabilität der Kohle dauerhaft und über einen größeren Flächenbereich erhöht, ohne daß beim anschließenden Förderbetrieb ein größeres Kohlevolumen auf ein Druckniveau unterhalb des Desorptionsdruckes gepumpt werden müßte, so daß dieses größere Kohlevolumen mit der durch die erfindungsgemäße Maßnahme erhöhten Permeabilität für eine Gasförderung zur Verfügung steht.Thus, with the method according to the invention Permeability of the coal permanently and over a larger one Area increased without the subsequent Conveyor operation a larger coal volume to a pressure level would have to be pumped below the desorption pressure, so that this larger volume of coal with the by Measure according to the invention increased permeability for a Gas production is available.

Im einzelnen wird zur Bestimmung des im Einzelfall einzustellenden Druckes die in dem für die Gasförderung heranzuziehenden Kohleflöz herrschende niedrigste Hauptspannung gemessen, und es wird der Beaufschlagungsdruck niedriger als die ermittelte Hauptspannung eingestellt; die Druckbeaufschlagung erstreckt sich über einen längeren Zeitraum, der mit einem Tag bis mehreren Tagen oder Wochen angegeben werden kann. Diese lang andauernde Druckbeaufschlagung mit dem auf die gegebene Hauptspannung ausgelegten Druck führt zum erwünschten Aufschluß der Porenstruktur der Kohle, ohne daß sich Veränderungen in dem mechanischen Gefüge des Kohleflözes einstellen. In detail, is used to determine the individual the pressure to be set in the for gas production lowest coal seam to be used Main stress is measured, and it becomes the Actuation pressure lower than that determined Main tension set; the pressurization extends over a longer period of time with one Day to several days or weeks can be specified. This long-lasting pressurization with the on the given main stress designed pressure leads to Desired decomposition of the pore structure of the coal without changes in the mechanical structure of the Adjust coal seams.

Nach einem Ausführungsbeispiel der Erfindung kann vorgesehen sein, daß während des Aufschlußzeitraumes Perioden der Druckbeaufschlagung des Bohrloches und Perioden der Gasförderung zyklisch wechseln.According to an embodiment of the invention be provided that during the digestion period Well pressurization periods and Change periods of gas production cyclically.

Nach Ausführungsbeispielen der Erfindung kann die Druckbeaufschlagung des Bohrloches mittels Einpressen von Wasser oder von Gas ausgeübt werden. Soweit Wasser für die Druckbeaufschlagung des Bohrloches herangezogen wird, kann auch in der Lagerstätte anstehendes Lagerstättenwasser in das Bohrloch eingepreßt bzw. durch zyklisch aufgebrachten Druck die Atmung der Porenstruktur über die Druckanregung des Lagerstättenwassers erzeugt werden. In gleicher Weise kann nach einem Ausführungsbeispiel der Erfindung das dem Bohrloch zuströmende und zu fördernde Gas für die Druckbeaufschlagung des Bohrloches in dieses rückgepreßt werden; alternativ kann auch das Einpressen von CO2 vorgesehen sein, was die vorteilhafte Wirkung hat, daß bei Zutritt von CO2 die Bindung des zu fördernden Methans (CH4) an die Kohle verringert wird, so daß das für die Druckbeaufschlagung herangezogene CO2-Gas gleichzeitig als Förderhilfe wirkt.According to embodiments of the invention, the pressurization of the borehole can be exerted by injecting water or gas. Insofar as water is used to pressurize the borehole, reservoir water present in the deposit can also be pressed into the borehole or the pore structure breathing can be generated by cyclically applied pressure via the pressure excitation of the reservoir water. In the same way, according to one embodiment of the invention, the gas flowing into and conveying the borehole can be pressed back into the borehole for pressurizing it; alternatively, the injection of CO 2 may be provided, which the advantageous effect is that the binding of the is reduced to be conveyed methane (CH 4) to the coal on admission of CO 2, so that the relied on for pressurizing CO 2 gas also acts as a subsidy.

Claims (7)

  1. Method for the in-situ extraction of gas from coal seams, whereby to provide flow paths in the coal, the structure of the gas-containing coal is opened up by means of gases and/or liquids introduced under pressure into a bore hole sunk into the coal seam, and subsequently for the gas extraction a pressure is applied to the bore hole that is less than the respective desorption pressure, and whereby for the opening-up of the coal, a pressurization of the bore hole that is effective over a prolonged period of time like one day up to many days or weeks is established with a pressure that is less than the lowest principal stress determined in the respective seam layer from which gas is to be extracted, and whereby the pressurization of the bore hole during the opening-up period is effected with a cyclically fluctuating pressure.
  2. Method according to claim 1, characterized in that during the opening-up type period, periods of pressurization of the bore hole cyclically alternate with periods of gas extraction.
  3. Method according to claim 1 or 2, characterized in that the pressurization of the bore hole is carried out by pressing in water.
  4. Method according to claim 3, characterized in that as water, seam water that is present at the site is pressed in.
  5. Method according to claim 1 or 2, characterized in that the pressurization of the bore hole is effected by pressing in gas.
  6. Method according to claim 5, characterized in that the gas that flows to the bore hole and that is to be extracted is utilized for pressurizing the bore hole and is pressed back into the bore hole.
  7. Method according to claim 5, characterized in that as gas CO2 is pressed into the bore hole.
EP99953624A 1998-09-02 1999-08-27 Method for the in-situ extraction of gas from coal seams Expired - Lifetime EP1112437B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19839866A DE19839866A1 (en) 1998-09-02 1998-09-02 Process for in-situ production of gas from coal beds
DE19839866 1998-09-02
PCT/DE1999/002693 WO2000014379A1 (en) 1998-09-02 1999-08-27 Method for the in-situ extraction of gas from coal seams

Publications (2)

Publication Number Publication Date
EP1112437A1 EP1112437A1 (en) 2001-07-04
EP1112437B1 true EP1112437B1 (en) 2003-07-23

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EP99953624A Expired - Lifetime EP1112437B1 (en) 1998-09-02 1999-08-27 Method for the in-situ extraction of gas from coal seams

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US (1) US6571874B1 (en)
EP (1) EP1112437B1 (en)
CN (1) CN1097136C (en)
DE (2) DE19839866A1 (en)
ES (1) ES2204166T3 (en)
PL (1) PL346410A1 (en)
RU (1) RU2206718C2 (en)
WO (1) WO2000014379A1 (en)

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DE10159311B4 (en) * 2001-08-03 2007-02-01 Wolfgang Herr In-situ evaporation
US6877566B2 (en) * 2002-07-24 2005-04-12 Richard Selinger Method and apparatus for causing pressure variations in a wellbore
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AU2006279679B2 (en) * 2005-08-12 2011-08-04 University Of Wyoming Research Corporation D/B/A Western Research Institute Biogenic methane production enhancement systems
US8256282B2 (en) * 2007-07-19 2012-09-04 Schlumberger Technology Corporation In situ determination of critical desorption pressures
CN104342459A (en) 2008-07-02 2015-02-11 西里斯能源公司 Method For Optimizing In-Situ Bioconversion of Carbon-Bearing Formations
CN101539008B (en) * 2009-04-14 2012-04-04 赵万福 Ground stereoscopic discharge and mining method of coal bed methane
AU2010332294C1 (en) 2009-12-18 2015-06-18 Ciris Energy, Inc. Biogasification of coal to methane and other useful products
WO2013005082A1 (en) * 2011-07-07 2013-01-10 Seeden Foundation Device and method for enhancing oil production by generating shock waves
CN103670338B (en) * 2012-09-21 2016-06-15 新奥气化采煤有限公司 A kind of coal bed gas and coal mining method altogether
RU2524583C1 (en) * 2013-03-25 2014-07-27 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Национальный минерально-сырьевой университет "Горный" Intensification of natural gas extraction from coal seams via wells
RU2625829C2 (en) * 2015-12-30 2017-07-19 Федеральное государственное бюджетное учреждение науки Институт проблем нефти и газа Российской академии наук (ИПНГ РАН) Method of hydrocarbons deposit develompent in low-permeability sediments
CN109026128A (en) * 2018-06-22 2018-12-18 中国矿业大学 Multistage combustion shock wave fracturing coal body and heat injection alternation strengthen gas pumping method
CN115163021B (en) * 2022-07-13 2023-11-03 中国矿业大学 Water injection and nitrogen injection gas extraction hole sealing device and drilling arrangement method

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US6412559B1 (en) * 2000-11-24 2002-07-02 Alberta Research Council Inc. Process for recovering methane and/or sequestering fluids

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RU2206718C2 (en) 2003-06-20
US6571874B1 (en) 2003-06-03
PL346410A1 (en) 2002-02-11
WO2000014379A1 (en) 2000-03-16
CN1097136C (en) 2002-12-25
DE59906375D1 (en) 2003-08-28
ES2204166T3 (en) 2004-04-16
DE19839866A1 (en) 2000-03-09
EP1112437A1 (en) 2001-07-04
CN1320189A (en) 2001-10-31

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