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Publication numberUS2788956 A
Publication typeGrant
Publication dateApr 16, 1957
Filing dateAug 3, 1955
Priority dateAug 3, 1955
Publication numberUS 2788956 A, US 2788956A, US-A-2788956, US2788956 A, US2788956A
InventorsErnest F Pevere, Howard V Hess
Original AssigneeTexas Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Generation of carbon monoxide and hydrogen by underground gasification of coal
US 2788956 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

E. F- PEVERE ET AL GENERATION OF CARBON MONOXIDE AND HYDROGEN 4 April 16, 1957 2,788,956

BY UNDERGROUND GASIF'ICATION OF COAL I Filed Aug. 3, 1955 med SmePuefO GENERATION 01 MONOXIDE' HYDROGEN BY UNDERGROUND GASIFICA- TION F COAL I a Ernest'F. Pevere, Reac ing-mu Hom ny. Hess, Glenliam, N". Y., assignurs-to The. Texas Company; New York, N. Y., a corporation. of Delaware Application August 3, 1955, Serial No. 526,163 fiGlaiins". '(Cl.-262-"-$) This application relates-tothe partial combustionof coal inunderground seams. in one of itsmore specific aspects, the invention relates to a method for preparing coal beds for'underground gasification. 7

Since 1933', the underground gasification-of coal has been seriously investigated and exploited by a special Russian trust, Podzem, and extensive Russian literature has grown out of this work. A reviewin-English by Chel-tin was published in Collary Garden 162, 1193-6 (1936) and Fuel Economist ll, 331- (l 936). Since. the end of World War II, this problem has been seriously examined in England, France, Belgium and the UnitedSta'tes. A review by M. L. Kastems'appeared in Chemical and Engineering News, March 24,. 1952.

Underground gasification of coal hasbeen carried out in a number of cases with encouraging results. In preparing the coal seam forgasification, it is generally necessary to drive two parallel main drifts through .the:coal seam, one as an inlet andthe other as an outlet, and to connect these shafts with one or more-lateral drifts at right angles to the main drifts. A combustion-supporting gas, e. g. air, oxygen or'other gas' con'taining'free oxygen is introduced through one of the main drifts and products of combustion are withdrawn through the other. Steam or carbon dioxide may be used in conjunction with air, oxygen, or a mixture of air and oxygen as the gasifying medium or combustion-supporting gas. Combustion is initiated by igniting the .co'al along the path of flow, usually at the lateral cross drifts. The main drifts may be used alternately as inlets and outlets. Afterthe coal seam is fired, air or oxygen is blown through the corridorto bring the surface of the coal tofthe desired temperature, and then steam is blown in either alone or withair or oxygen. If steam alone is used, the flow of steam must be periodically interrupted and the coal seam'firedwith combustionsupporting gas to maintain .the required temperature. A mixture of steam with oxygen or air may be used for continuous gasification. Thegas produced generallyhas a low B. t. u. value, a result which is not unexpected due to poor contact of the coal with the steam and oxygen.

It has been proposed previously to prepare a portion of a coal seam for gasification by breaking the coal loose from the bed by mining methods and then passing the reacting gases through the lumps ofcoal. Although this procedure results in effective contact between thecoai and thegases it obviously is a costly one. By the process of this invention the coal seam is prepared for underground g'asifica'tion insuch-a way that intimate contact between the coal and the gaseous reactants isobtained without the necessity of mining the coal from the seam.

In accordance with this inventiona mineral acid having solvent power for one or more' of the constituents of the coal is brought into contact with theicoal seameffecting solution of coal substance; Preferably, theacidi. is permitted to drip onto the coal at a pluarlity of points. The acid forms a multitude of passages through the coal which are irregular in shape and which are very permeable to gaseous reactants used for the gasification of coal.

In a specific embodiment of. the presentinvention a main channel or passageway is drilled throughan upper portion of the coal seam, preferably as near as possible to the top-of the seam, while a second-"main passageway Patented Apr. 16; 1957 stantially parallel to the upper passageway. In general, the passageways are parallel to the bedding; plane of the coal seam. Theprocess of the invention remains the samefor an inclined seam as for a horizontal seam. The acid is introduced through the upper main passageway or drift. The acid percolates downward through. the coal seam and eventually reaches the lower main passageway. Intermediate .passagewaysparallel to the main passageways may be :provided and are particularly-advantageous in thick beds.

In .a preferred embodiment of. the present invention strong sulfuric acid containing percent sulfuric acid by weight is introduced slowlyinto contact with the coal in the=upper partof. the. seam- Strong sulfuric acid may be introduced through the passageway-into contact with the coalseam through a steel .tube. The tube may be perforated to distribute the acid along the desired section of the passageway. With other acids other types of acid resistant tubing. are required, e. g. plastic or synthetic rubber tubes.

St-rongmineral acids, e. g. hydrochloric, hydrofluoric, nitric, and sulfuric acids, are useful in the processof this invention. The acid concentration should exceed 30 weight percent. Higher concentrations of sulfuric and nitric acids are desirable. Sulfuric acid in. excess. of 90 weight percent is preferred.

Selective gasification of'the coal seam may be accomplished'by treating. sections of the seam with acidv and leaving pillar-s or untreated sections of the coal seam between treated sections. One or more of the treated sections may be ignited while others are blocked off.

Preferably the-reaction is initiated in an upper passageway, the gasification proceeding downwardly through the c'oal b'ed to a lower passageway. As indicated above, exit passageways may be provided at varying depths and are particularly useful inthick seams of coal.

Firing of the coal may be initiatedin any of a number of ways, fo'rexample by pumping a colloidal or semicolloidal dispersion of phosphorus in water, or phosphorus in carbon disulfide into the upper part of the pretreated section of the coal. As the carrier liquid trickles downwardly through the treated section, phosphorus is deposited on .thelco'al. Afterthe bed has been pretreated with the phosphorus solution, an oxygen-containing gas is'introduced which, upon contact with the phosphorus, ignites simultaneously and thereby ignites the coal. Once the reaction commences it isself sustaining so long as an adeguate supply of oxygen-containing gas is provided.

The" figure is a diagrammatic sectional view through a section of the earth illustrating the application of the process of this invention to underground gasification of coal.

With reference to the figure, a well 1 is drilled into or through the coalseam. A main passageway 2 is then drilled along the upper part of the coal seam. Means for horizontal drilling and directional drilling-are known in the art. Generally, a deflecting device known as a whipstock is positioned in the well 'at the desired depth and a rotating drill bit on a flexible conduit is operated fromth'e whipstock' to effect horizontal 'or near-horizontal drilling. After a horizontal bore Zof the desired length. has been drilled, the bit is removed, the whipstock is lowered and a second bore 3 is drilled through the coal seam parallel to and below bore 2. Bore 3 forms the second main passageway. Obviously a number of such passageways may be drilled through the coat seam. The portion of well 1 below bore 2 is then filled with cement 4. A second well 6 is drilled into the coal seam to intersect passageway 3-. Well 6 may be enlargedat its lower end'b'y means of explosive charges.

A conduit 7, closed at its end andprovid'e'd witha series ofperforations 8; is; theniutr'oduced into the-upper main passageway 2. Strong mineral acid, e. g. sulfuric acid, is

pumped through conduit 7 from which it escapes through perforations 8 into section AA' of the coal seam. The 7 necting the upper main passageway 2 with the lower main passageway 3. Similarly, other sections of the coal seam, e. g. section BB' may be acid treated. Following acid treatment, an ignition agent may be introduced through pipe 7. Following preparation pipe 7 is withdrawn from the well bore. A combustion supporting gas is then introduced through one of the wells, preferably through well 1 into the upper horizontal pasageway 2. The coal seam is, ignited at the top of the treated section. The oxygen-containing gas stream passes down through channels formed by the acid in the treated section. As the coal is consumed, combustible gas comprising carbon monoxide and hydrogen is generated. The combustible gas, together with volatile constituents distilled from the coal, is collected in the lower pasageway 3 and produced through well 6 to the surface.

The coal seam may be ignited initially in any suitable manner, as by electrical means or by a squib or incendiary shell, placed in contact with the coal in the horizontal passageway 2.

Air or relatively pure oxygen may be employed as the source of oxygen-containing gas. Relatively pure oxygen is preferred from the standpoint of producing gas which contains a minimum amount of nitrogen and other inert constituents. Once combustion is well established, steam may be introduced either continuously, in admixture with oxygen or oxygen-containing gas, or intermittently as in gas making apparatus with alternate blast and blow gas make cycles. Steam helps to control the temperature in the formation and produces hydrogen.

It will be understood that although passageway 2 is preferred as the input passageway for the combustionsupporting gas, either main passageway 2 or 3 may be used as the input pasageway while the other is used as the outlet passageway. It will also be understood that either of the main passageways may be drilled through well 6.

i In an alternative procedure, channels between passageways 2 and 3 are first made by hydraulic fracturing of'the coal seam between the passageways. In this case, hydraulic fluid under pressure, suitably water or oil with or without thickeners or viscosity increasing additives, is introduced through well 6 into passageway 3 under sufficient pressure to fracture the coal seam and form cracks extending upwardly toward or even as far as passageway 2. Similarly, hydraulic fluid under pressure may be introduced through well 1 into the upper passageway 2,

fracturingthe coalseam between bores 2 and 3. The

liquid is withdrawn, the grains of sand or gravel serve to help prevent thecracks from closing. Following hydraulic fracturing, acid is introduced through passageway 2 onto the top of the coal seam. The acid per- .colates down through the fissures, forming auxiliary passageways'interconnecting the main passageways. The gasifying medium may be readily passed through the auxiliary passageways.

Spent acid may be withdrawn from the coal seam through passageway 3 and well 6. Ordinarily it is not necessary to separately withdraw the spent acid. Acid recovery is efiected by processing the product gas. Fresh acid thus may be made up for additional treatment opcrations. Sulfuric acid is a preferred acid because of the natural occurrence of sulfurin coal. Obviously, many modifications and variations of the invention, as herein'before set forth, may be made without departing from the spirit and scope thereof and therefore only such limitations should:be made as are'indicated in the appended claims.

Weclaimz. 1. In a process forthe underground gasification of coal in which an exothermically-reacting gas is introduced into contact with the coal in situ, the coal is reacted with said gas, and gaseous products of reaction are withdrawn from the coal bed, the improvement which comprises forming a first main passageway through an upper portion of the 'coal bed along the seam, forming a second main passageway through a lower portion of the coal bed along the seamsubstantially parallel to and below said first passageway, fonning aum'liary passageways interconnecting said main passageways by introduction of strong mineral acid through said first passageway into contact with said coal eifecting solution of coal substance in said acid, and

thereafter supplying reactant gas to one of said main passageways, and withdrawing gaseous products from the other of said main passageways.

2. A process as defined in claim 1 wherein said acid is sulfuric acid.

3. A process as defined in claim 1 wherein said acid is nitric acid.

4. A process as defined in claim 1 wherein said acid is hydrochloric acid.

5. In a process for the underground gasification'of coal wherein a combustion-supporting gas is introduced into contact with the coal in situ, the coal is ignited, and gaseous products of reaction are withdrawn from the coal bed, the improvement which comprises forming a first main passageway through an upper portion of the coal bed along the seam, forming a second main passageway through a lower portion of the coal bed along the seam substantially parallel to and below said first passageway, and introducing strong mineral acid through said first main passageway into contact with the bed of coal at a plurality of selectedpoints along said first main passageway thereby effecting solution .of coal substance and forming auxiliary vpasageways interconnecting said main passageways,

. 6. In a'pro'cess for .the underground gasification of coal wherein a combustion-supporting gas isintroduced into contact with the coal in situ, the coal is ignited, and gaseous products of reaction are withdrawn from the coal bed, the improvement which comprises forming a first main passageway through an upper portion of the coal bed .along the seam, forming a second main passageway through a lower portion of the coal bed along the seam substantially parallel to and below said first passageway, introducing liquid under pressure through at least one of said mainpassageways eflecting fracturing of said coal seam and forming fluid permeable channels interconnecting said main passageways, withdrawing said fracturing liquid and introducing a strong mineral acid into said first main passageway and through said channels into said secondmain passageway effecting solution of coal substance in said strong mineral acid, withdrawing reaction products of said acid from said coal bed, introducing combustion-supporting fluid through one of said main passageways, and withdrawing gaseous products of reaction from the other of said main passageways.

References Cited in the file of this patent UNITED STATES PATENTS 2,630,306 I Evans Mar. 3', 1953

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2630306 *Jan 3, 1952Mar 3, 1953Socony Vacuum Oil Co IncSubterranean retorting of shales
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3223158 *Dec 10, 1962Dec 14, 1965Socony Mobil Oil Co IncIn situ retorting of oil shale
US3233668 *Nov 15, 1963Feb 8, 1966Exxon Production Research CoRecovery of shale oil
US3250327 *Apr 2, 1963May 10, 1966Socony Mobil Oil Co IncRecovering nonflowing hydrocarbons
US3285335 *Dec 11, 1963Nov 15, 1966Exxon Research Engineering CoIn situ pyrolysis of oil shale formations
US3285350 *Apr 23, 1964Nov 15, 1966Keller Henderson JohnMethod and apparatus for controllably drilling off-vertical holes
US3298434 *May 27, 1964Jan 17, 1967Graham Thomas TGasification of coal
US3344856 *Mar 18, 1965Oct 3, 1967Deutsche Erdoel AgProcess for the extraction of liquid and solid bitumens from underground deposits
US3352355 *Jun 23, 1965Nov 14, 1967Dow Chemical CoMethod of recovery of hydrocarbons from solid hydrocarbonaceous formations
US3386508 *Feb 21, 1966Jun 4, 1968Exxon Production Research CoProcess and system for the recovery of viscous oil
US3457996 *Jul 30, 1968Jul 29, 1969Phillips Petroleum CoThermal oil recovery process utilizing decomposition of co
US3513913 *Apr 19, 1966May 26, 1970Shell Oil CoOil recovery from oil shales by transverse combustion
US3599714 *Sep 8, 1969Aug 17, 1971Becker Karl EMethod of recovering hydrocarbons by in situ combustion
US3856084 *Jun 7, 1973Dec 24, 1974Continental Oil CoAn improved blind borehole back-reaming method
US3954140 *Aug 13, 1975May 4, 1976Hendrick Robert PRecovery of hydrocarbons by in situ thermal extraction
US4010801 *Oct 6, 1975Mar 8, 1977R. C. TerryMethod of and apparatus for in situ gasification of coal and the capture of resultant generated heat
US4022279 *Dec 23, 1974May 10, 1977Driver W BFormation conditioning process and system
US4026356 *Apr 29, 1976May 31, 1977The United States Energy Research And Development AdministrationMethod for in situ gasification of a subterranean coal bed
US4032193 *Mar 28, 1974Jun 28, 1977Shell Oil CompanyCoal disaggregation by basic aqueous solution for slurry recovery
US4095650 *Aug 10, 1977Jun 20, 1978The United States Of America As Represented By The United States Department Of EnergyMethod for increasing the calorific value of gas produced by the in situ combustion of coal
US4130164 *Aug 11, 1977Dec 19, 1978Syracuse Research CorporationProcess for coal gasification
US4168752 *Nov 23, 1977Sep 25, 1979Karol SabolFlexible conduit for effecting lateral channelling in coal or oil shale beds
US4197911 *May 9, 1978Apr 15, 1980Ramcor, Inc.Using a lower alcohol
US4220203 *Dec 6, 1978Sep 2, 1980Stamicarbon, B.V.Method for recovering coal in situ
US4221433 *Jul 20, 1978Sep 9, 1980Occidental Minerals CorporationRetrogressively in-situ ore body chemical mining system and method
US4223729 *Jan 12, 1979Sep 23, 1980Foster John WMethod for producing a geothermal reservoir in a hot dry rock formation for the recovery of geothermal energy
US4230181 *Aug 31, 1978Oct 28, 1980Pennington James RIn situ method of processing bituminous coal
US4279301 *Dec 13, 1979Jul 21, 1981Texaco Inc.Method for improving the effective permeability of formations
US4296809 *Jul 21, 1980Oct 27, 1981Gulf Research & Development CompanyInjection of air
US4299285 *Jul 21, 1980Nov 10, 1981Gulf Research & Development CompanyUnderground gasification of bituminous coal
US4313499 *Jul 21, 1980Feb 2, 1982Gulf Research & Development CompanySubterranean gasification of bituminous coal
US4484629 *Sep 28, 1982Nov 27, 1984In Situ Technology, Inc.Movable oxidizer injection point for production of coal in situ
USRE37867May 22, 1997Oct 8, 2002Halliburton Energy Services, Inc.Downhole equipment, tools and assembly procedures for the drilling, tie-in and completion of vertical cased oil wells connected to liner-equipped multiple drainholes
USRE38616Sep 4, 2001Oct 12, 2004Halliburton Energy Services, Inc.Downhole equipment, tools and assembly procedures for the drilling, tie-in and completion of vertical cased oil wells connected to liner-equipped multiple drainholes
USRE38636Apr 4, 2001Oct 26, 2004Halliburton Energy Services, Inc.Downhole equipment, tools and assembly procedures for the drilling, tie-in and completion of vertical oil wells connected to liner-equipped multiple drainholes
USRE38642Jun 4, 2001Nov 2, 2004Halliburton Energy Services, Inc.Downhole equipment, tools and assembly procedures for the drilling, tie-in and completion of vertical cased oil wells connected to liner-equipped multiple drainholes
USRE39141Sep 21, 2001Jun 27, 2006Halliburton Energy ServicesDownhole equipment, tools and assembly procedures for the drilling, tie-in and completion of vertical cased oil wells connected to liner-equipped multiple drainholes
USRE40067Apr 8, 2005Feb 19, 2008Halliburton Energy Services, Inc.Downhole equipment tools and assembly procedures for the drilling, tie-in and completion of vertical cased oil wells connected to liner-equipped multiple drainholes
Classifications
U.S. Classification166/259, 48/DIG.600, 48/210, 175/12
International ClassificationE21B43/30, E21B43/247
Cooperative ClassificationE21B43/247, Y10S48/06, E21B43/305
European ClassificationE21B43/30B, E21B43/247