Wells – Processes – Specific pattern of plural wells
Patent
1979-06-21
1984-04-03
Suchfield, George A.
Wells
Processes
Specific pattern of plural wells
48DIG6, 166261, E21B 43243, E21B 4330
Patent
active
044402244
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to mining combustible minerals, and has particular reference to a method of underground fuel gasification.
DESCRIPTION OF THE PRIOR ART
Two methods of underground fuel processing are known in the present state of the art, of which one is based upon filtering the blast gas blown through the boreholes drilled in the seam of the mineral, say, coal bed, while the other method makes use of the gasification process occurring in special ducts prepared in the seam of the mineral to be processed, e.g., coal bed.
More explicitly the filtration method incorporates drilling a number of boreholes in a coal bed, setting fire to the latter, and alternative blowing of an oxygen-containing blast gas, such as air, steam, carbon dioxide, etc., whereupon the reaction products of said blast gas are withdrawn from the same borehole that has served as a blow-down one, or from adjacent boreholes. However, application of the above method involves inescapably substantial irrecoverable losses of the blast gas and heat evolved, occurring in the coal bed and its enclosing rock. Furthermore, said method may be realized only at restricted flowrates of the blast gas. Thus, both of the aforesaid features of the method described above affect adversely the efficiency thereof.
The other of the afore-discussed methods proved to be more promising, viz., the method of duct gasification. To carry said method into effect a number of boreholes are drilled in the coal bed and interconnected by resorting to one of the conventionally practised methods of cross-cutting (fire-type filtration breakthrough of bore-holes, hydraulic coal bed fracturing, drilling boreholes on bed strike). Next the coal bed fired up, and an oxygen-containing blast gas is blown into one of the boreholes, which reacts with carbon or the walls of the ducts to yield generator gas. In addition, steam is blown into the borehole along with the oxygen-containing blast gas to enrich the producer gas with combustible elements. The generator gas is withdrawn through gas-discharge boreholes located at the other end of the duct.
The abovesaid method suffers from the disadvantages that it fails to yield generator gas having a calorific value in excess of 1000 kcal/m.sup.3 resorting to air-blast technique, and that a great deal of irrecoverable losses of physical heat of the generator gas is involved.
Both of the aforesaid disadvantages render said method impracticable for processing coal beds less than 2.0 m thick.
There has been developed in the recent years one novel method of coal gasification in ducts, wherein the process of drilling boreholes, their interconnecting and setting fire to the coal bed remains the same as in the preceding method. A substantial distinguishing feature of the novel method resides in that the feed of an oxygen-containing blast gas is periodically ceased, and a carbon- and/or hydrogen-containing blast gas is fed in the thus-occurred time intervals to obtain a producer gas rich in gaseous and liquid combustible substances (cf., e.g., U.S. Pat. No. 4,059,151 filed on Mar. 4, 1976 and granted on Nov. 11, 1977).
A disadvantage inherent in said method resides in an intermittent character of the process being carried out and its poor controllability and in the fact that the final products widely differ in the composition due to alternating feed of an oxygen- and carbon- and/or hydrogen-containing blast gas, which requires separate withdrawal and application of each of the products yielded.
DISCLOSURE OF THE INVENTION
It is a primary object of the present invention to carry out such an interaction of the producer gas and a gas enriching the latter with combustible elements as to provide most complete utilization of the heat withdrawn by the generator gas, as well as better conditions for control of the gasification process.
Said object is accomplished due to the fact that in an underground fuel gasification, incorporating the drilling a plurality of boreholes intercommunicating through gasification ducts, se
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Fedorov Nikolai A.
Kreinin Efim V.
Zvyagimtsev Kirill N.
Suchfield George A.
Vesojuzny Nauchno-Issledovatelsky Institut Ispolzovania Gaza V N
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