US4465401A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Minimizing subsidence effects during production of coal in situ
Assignee: In Situ Technology Inc
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Filing: 1983-04-25
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Granted: 1984-08-14
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Expires: 2003-04-25
Abstract
Abstract Coal is reduced to ash in place by gasification using in situ production techniques, resulting in significant void space underground, which in turn causes roof fall and subsidence. Overburden collapse is stabilized by backfilling with foaming mud cement that hardens into an expanded solid, which quenches and fills the production module and seals residual ash. Rubble volumes and subsidence cracks are sealed against water incursions and contaminated water excursions. Surface facilities above barrier pillars are protected from destructive forces of subsidence draw.
Inventors
- 👤 Xerxes T. Stoddord
- 👤 Vesper A. Vaseen
- 👤 Xerxes T. Stoddard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 09:40
CPC Classifications
E; E21; E21F; E21F15/00; E21B; E21B33/00; E21B33/10; E21B33/13; E21B33/138; E21B43/00; E21B43/16; E21B43/24; E21B43/243; E21B43/247
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
90 words
A method of limiting the ground surface effects of subsidence draw on surface facilities used in the production of coal in situ, comprising the steps of establishing the outer and inner limits of a barrier pillar within the perimeter of the project area, then digging a subsidence draw protective trench within the periphery of the inner limits of the barrier pillar to a depth corresponding to the lowermost portion of the foundations for structures located within the barrier pillar area, with the resultant providing a discontinuity in the surface rock.
Claim 2
Independent Claim
90 words
A method of limiting the ground surface effects of subsidence draw on surface facilities used in the production of coal in situ, comprising the steps of establishing the outer and inner limits of a barrier pillar within the perimeter of the project area, then digging a subsidence draw protective trench within the periphery of the inner limits of the barrier pillar to a depth corresponding to the lowermost portion of the foundations for structures located within the barrier pillar area, with the resultant providing a discontinuity in the surface rock.
Claim 3
Dependent Claim
42 words
The method of claim 1 further including the steps of placing explosive charges in the bottom of the trench, filling the trench with material removed from the trench, then detonating the explosive charges, with the resultant further discontinuity in the surface rock.
References Cited (Backward Citations)
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Cited
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-08-14 | 1988-02-13 | 1988-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-08-14 | 1992-02-13 | 1992-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-08-14 | 1996-02-13 | 1996-08-14 | $7700.00 | Window Closed / Lapsed |