US3814480A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of controlling gas accumulation in underground mines
Assignee: Consolidation Coal Co
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Filing: 1973-03-23
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Granted: 1974-06-04
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Expires: 1993-03-23
Abstract
Abstract A method of preventing gas communication between a gas producing formation and a mine passage located therebelow. The method includes the drilling of a well bore into a fracturable rock formation disposed between the gas producing formation and the mine passage. The rock formation is then fractured and the fracture formed thereby is extended to the extent that the shear cracks to be formed by the subsidence of the overburden due to the collapse of the roof of the mine passage during the mining operation will intersect the extended fracture. Gas from the gas producing formation is allowed to flow through the shear cracks in the overburden to and through the fracture to the well bore where it is then vented to the atmosphere or otherwise suitably produced.
Inventors
- 👤 H Dahl
- 👤 J Davis
- 👤 P Ehlers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 12:11
CPC Classifications
E; E21; E21F; E21F7/00
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
179 words
A method of preventing gas communication between a gas producing formation and a mine passage having a roof and lying in a position below the gas producing formation, with at least one fracturable rock formation interposed between the gas producing formation and the mine passage, when the roof of the mine passage is allowed to collapse during the mining operation thereby forming shear cracks in the overburden communicating between the gas producing formation and the mine passage resulting from subsidence of the overburden, comprising the steps of: drilling a well bore into a selected rock formation; fracturing the selected rock formation to form a fracture therein intermediate the gas producing formation and the mine passage and communicating with the well bore, so that the shear cracks formed by allowing the roof of the mine passage to collapse will intersect the fracture; and allowing gas from the gas producing formation to flow from the gas producing formation through at least one shear crack communicating between the gas producing formation and the fracture, and through the fracture to the well bore.
Claim 2
Independent Claim
179 words
A method of preventing gas communication between a gas producing formation and a mine passage having a roof and lying in a position below the gas producing formation, with at least one fracturable rock formation interposed between the gas producing formation and the mine passage, when the roof of the mine passage is allowed to collapse during the mining operation thereby forming shear cracks in the overburden communicating between the gas producing formation and the mine passage resulting from subsidence of the overburden, comprising the steps of: drilling a well bore into a selected rock formation; fracturing the selected rock formation to form a fracture therein intermediate the gas producing formation and the mine passage and communicating with the well bore, so that the shear cracks formed by allowing the roof of the mine passage to collapse will intersect the fracture; and allowing gas from the gas producing formation to flow from the gas producing formation through at least one shear crack communicating between the gas producing formation and the fracture, and through the fracture to the well bore.
Claim 3
Dependent Claim
29 words
The method as defined in claim 1 wherein the step of fracturing the rock formation is characterized further as including the application of hydraulic pressure to the rock formation.
Claim 4
Dependent Claim
98 words
The method as defined in claim 1 characterized further to include the additional steps of: fracturing at least one additional fracturable rock formation to form a fracture therein intermediate the gas producing formation and the mine passage and communicating with the well bore so that shear cracks formed by allowing the roof of the mine passage to collapse will intersect the additional fracture; and allowing gas from the gas producing formation to flow through at least one shear crack communicating between the gas producing formation and the additional fracture, and through the additional fracture to the well bore.
Claim 5
Dependent Claim
53 words
The method as defined in claim 1 characterized further to include the additional step of: extending the fracture to the extent that at least a portion of the shear cracks formed by the subsidence of the overburden resulting from the collapse of the roof of the mine passage will intersect the extended fracture.
Claim 6
Dependent Claim
36 words
The method as defined in claim 4 characterized further to include the additional step of: propping the extended fracture with a propping agent to retain the fracture in an open condition and facilitate gas flow therethrough.
Claim 7
Independent Claim
178 words
A method of preventing gas communication between a gas producing formation and an underground mine passage having a roof and extending beneath the gas producing formation, with at least one fracturable rock formation interposed between the gas producing formation and the mine passage, when the roof of the mine passage is allowed to collapse during mining operations, thereby forming shear cracks in the overburden communicating between the gas producing formation and the mine passage resulting from subsidence of the overburden, comprising the steps of: drilling a borehole into a selected fracturable rock formation; fracturing the selected rock formation to form a fracture therein communicating with the borehole; extending the fracture to the extent that at least a portion of the shear cracks to be formed by the subsidence of the overburden resulting from the collapse of the roof of the mine passage will intersect the fracture; and allowing gas from the gas producing formation to flow through at least one shear crack communicating between the gas producing formation and the fracture, and through the fracture to the borehole.
Claim 8
Independent Claim
178 words
A method of preventing gas communication between a gas producing formation and an underground mine passage having a roof and extending beneath the gas producing formation, with at least one fracturable rock formation interposed between the gas producing formation and the mine passage, when the roof of the mine passage is allowed to collapse during mining operations, thereby forming shear cracks in the overburden communicating between the gas producing formation and the mine passage resulting from subsidence of the overburden, comprising the steps of: drilling a borehole into a selected fracturable rock formation; fracturing the selected rock formation to form a fracture therein communicating with the borehole; extending the fracture to the extent that at least a portion of the shear cracks to be formed by the subsidence of the overburden resulting from the collapse of the roof of the mine passage will intersect the fracture; and allowing gas from the gas producing formation to flow through at least one shear crack communicating between the gas producing formation and the fracture, and through the fracture to the borehole.
Claim 9
Dependent Claim
36 words
The method as defined in claim 6 characterized further to include the additional step of: propping the extended fracture with a propping agent to retain the fracture in an open condition and facilitate gas flow therethrough.
Claim 10
Dependent Claim
29 words
The method as defined in claim 6 wherein the step of fracturing the rock formation is characterized further as including the application of hydraulic pressure to the rock formation.
Claim 11
Dependent Claim
107 words
The method as defined in claim 6 characterized further to include the additional steps of: fracturing at least one additional fracturable rock formation to form a fracture therein communicating with the borehole; extending each additional fracture to the extent that at least a portion of the shear cracks to be formed by the subsidence of the overburden resulting from the collapse of the roof of the mine passage will intersect each additional fracture; and allowing gas from the gas producing formation to flow through at least one shear crack communicating between the gas producing formation and each additional fracture, and through each additional fracture to the borehole.
Claim 12
Dependent Claim
21 words
The method as defined in claim 6 characterized further to include the additional step of: producing the gas from the borehole.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-03 | 1977-12-03 | 1978-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-03 | 1981-12-03 | 1982-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-03 | 1985-12-03 | 1986-06-04 | $7700.00 | Window Closed / Lapsed |