Mining or in situ disintegration of hard material – Processes – Mine safety
Reexamination Certificate
1998-11-20
2001-08-28
Bagnell, David (Department: 3673)
Mining or in situ disintegration of hard material
Processes
Mine safety
C166S245000, C166S263000, C166S050000, C166S052000
Reexamination Certificate
active
06280000
ABSTRACT:
BACKGROUND OF THE INVENTION
Subterranean deposits of coal, whether of “hard” coal such as anthracite or “soft” coal such as lignite or bituminous contain substantial quantities of methane gas entrained in the coal deposits. Limited production and use of methane gas from coal deposits has occurred for many years. However there are substantial obstacles which heretofore have frustrated more extensive development and use of methane gas deposits in coal seams. The foremost problem is the fact that coal seams, while they may extend over large areas of up to several thousand acres, typically are fairly shallow in depth, varying from a few inches to several meters. While they often are relatively near the surface (a thousand feet or less), vertical wells drilled into the coal deposits for obtaining methane gas can drain only a fairly small radius around the coal deposits. Further, the coal deposits are not amenable to pressure fracturing and other methods often used for increasing methane gas production from rock formations, so that, once the gas easily drained by a vertical well bore into the coal seam is produced, further production tends to be quite limited in volume. Additionally, coal seams often are associated with subterranean water, which must be drained from the coal seam in order to produce the methane.
Horizontal drilling patterns have been tried in order to extend the amount of coal seam exposed to a drill bore for gas extraction. But removal of the entrained water has presented difficulties in these operations. Horizontal drilling techniques require the use of a radiused well bore portion and a horizontal bore. The most efficient method for pumping water from a subterranean well, a sucker rod pump, does not work well in horizontal bores or around radiused bores.
A further problem which has been encountered in prior art techniques for producing gas from coal seams is the difficulty presented by under balanced drilling conditions resulting from the porousness of the coal seam. During the well drilling operations, whether vertical or horizontal, drilling fluid used to remove cuttings to the surface presents a hydrostatic pressure on the formation which, if it exceeds the hydrostatic pressure in the formation, can result in a loss of drilling fluid into the formation. This results in entrainment of drilling fines in the formation, which tends to plug up the small cracks and fractures which are needed to produce the gas.
SUMMARY OF THE INVENTION
It is accordingly, the primary object of the present invention to provide a method and apparatus for removing water and producing gas from subterranean coal seams which overcome the disadvantages found in the prior art.
A further object is to provide such a method and apparatus in which two wells are drilled in tandem, a vertical well having a bottom cavity terminating at or below the target coal seam and an offset well having a substantially horizontal portion which intersects the bottom cavity in the vertical well. The vertical well provides means for exact identification, via logging, of the target coal seam, and for efficient sucker rod pumping of water from the formation, while the offset well provides means for drilling a substantially horizontal drainage pattern in the target coal seam which intersects the vertical well bottom cavity, for optimal drainage of water and gas from the coal seam.
A still further object is to provide such a method and apparatus in which the prior art problem of overbalanced pressure conditions is overcome by injection of aerating gas into the drilling fluid to reduce bottom hole hydrostatic pressure.
A further object is to provide such a method and apparatus which may be used advantageously in conjunction with subterranean coal mining operations, in order to remove dangerous gases and water from a coal seam in advance of mining the subterranean coal seam for extraction of the coal.
REFERENCES:
patent: 54144 (1866-04-01), Hamar
patent: 274740 (1883-09-01), Douglass
patent: 526708 (1894-10-01), Horton
patent: 639036 (1899-12-01), Heald
patent: 1189560 (1916-07-01), Gondos
patent: 1285347 (1918-11-01), Otto
patent: 1467480 (1923-09-01), Hogue
patent: 1485615 (1924-03-01), Jonas
patent: 1674392 (1928-06-01), Flansburg
patent: 1777961 (1930-10-01), Capeliuschnicoff
patent: 2018285 (1935-10-01), Schweitzer et al.
patent: 2069482 (1937-02-01), Seay
patent: 2150228 (1939-03-01), Lamb
patent: 2169718 (1939-08-01), Böll et al.
patent: 2335085 (1943-11-01), Roberts
patent: 2450223 (1948-09-01), Barbour
patent: 2490350 (1949-12-01), Grable
patent: 2679903 (1954-06-01), McGowen Jr., et al.
patent: 2726063 (1955-12-01), Ragland et al.
patent: 2780018 (1957-02-01), Lytie
patent: 2847189 (1958-08-01), Shook
patent: 2911008 (1959-11-01), Bois
patent: 2980142 (1961-04-01), Turak
patent: 3347595 (1967-10-01), Dahms, et al.
patent: 3443648 (1969-05-01), Dugay
patent: 3503377 (1970-03-01), Beatenbough et al.
patent: 3528516 (1970-09-01), Brown
patent: 3530675 (1970-09-01), Turzillp
patent: 3681011 (1972-08-01), Kammerer, Jr., et al.
patent: 3692041 (1972-09-01), Bondi
patent: 3757877 (1973-09-01), Leathers
patent: 3800830 (1974-04-01), Etter
patent: 3809519 (1974-05-01), Garner
patent: 3828867 (1974-08-01), Elwood
patent: 3874413 (1975-04-01), Valdez
patent: 3902322 (1975-09-01), Wantanbe
patent: 3934649 (1976-01-01), Pasini, III et al.
patent: 3957082 (1976-05-01), Fuson et al.
patent: 3961824 (1976-06-01), Van Eek, et al.
patent: 4037658 (1977-07-01), Anderson
patent: 4073351 (1978-02-01), Baum
patent: 4089374 (1978-05-01), Terry
patent: 4116012 (1978-09-01), Abe et al.
patent: 4156437 (1979-05-01), Chivens et al.
patent: 4160510 (1979-07-01), Melgs
patent: 4189184 (1980-02-01), Green
patent: 4220203 (1980-09-01), Steeman
patent: 4221433 (1980-09-01), Jacoby
patent: 4257650 (1981-03-01), Allen
patent: 4278137 (1981-07-01), Van Eed, deceased
patent: 4295785 (1981-10-01), Vitello et al.
patent: 4299295 (1981-11-01), Gossard
patent: 4312377 (1982-01-01), Knecht
patent: 4317492 (1982-03-01), Summers et al.
patent: 4366988 (1983-01-01), Bodine
patent: 4372398 (1983-02-01), Kuckes
patent: 4390067 (1983-06-01), Willman
patent: 4396076 (1983-08-01), Inoue
patent: 4397360 (1983-08-01), Schmidt
patent: 4401171 (1983-08-01), Fuchs
patent: 4407376 (1983-10-01), Inoue
patent: 4444896 (1984-04-01), Reale, et al.
patent: 4494010 (1985-01-01), McKee
patent: 4512422 (1985-04-01), Knisley
patent: 4527639 (1985-07-01), Kickinson, III et al.
patent: 4532986 (1985-08-01), Mims, et al.
patent: 4544037 (1985-10-01), Terry
patent: 4558744 (1985-12-01), Gibb
patent: 4566252 (1986-01-01), Campbell et al.
patent: 4600061 (1986-07-01), Richards
patent: 4605076 (1986-08-01), Goodhart
patent: 4611855 (1986-09-01), Richards
patent: 4618009 (1986-10-01), Carter et al.
patent: 4638949 (1987-01-01), Mancel
patent: 4674579 (1987-06-01), Geller et al.
patent: 4702314 (1987-10-01), Huang, et al.
patent: 4715400 (1987-12-01), Boxell et al.
patent: 4763734 (1988-08-01), Dickinsin et al.
patent: 4830105 (1989-05-01), Petermann
patent: 4842061 (1989-06-01), Parant
patent: 4852666 (1989-08-01), Brunet et al.
patent: 4978172 (1990-12-01), Schwoebel et al.
patent: 5016710 (1991-05-01), Renard, et al.
patent: 5035605 (1991-07-01), Dineman et al.
patent: 5036921 (1991-08-01), Pittard et al.
patent: 5074360 (1991-12-01), Guinn
patent: 5074365 (1991-12-01), Kuckes
patent: 5074366 (1991-12-01), Karlsson et al.
patent: 5111893 (1992-05-01), Kvello-Aune
patent: 5135058 (1992-08-01), Millgard et al.
patent: 5148875 (1992-09-01), Karlsson et al.
patent: 5168042 (1992-12-01), Wydrineski
patent: 5174374 (1992-12-01), Halley
patent: 5197553 (1993-03-01), Letumo
patent: 5197783 (1993-03-01), Thelmer et al.
patent: 5199496 (1993-04-01), Redus et al.
patent: 5201617 (1993-04-01), Hailey
patent: 5217076 (1993-06-01), Masek
patent: 5240350 (1993-08-01), Yamaguchi et al.
patent: 5242017 (1993-09-01), Hailey
patent: 5246273 (1993-09-01), Rosar
patent: 5255741 (1993-10-01), Alexander
patent: 5271472 (1993-12-01), Letuno
patent: 5301760 (1994-04-01), Graham
patent: 5363927 (
Bagnell David
Baker & Botts L.L.P.
Kreck John
LandOfFree
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