Patent US5065818A successfully refreshed from Google Patents.
US5065818A
Expired / Lapsed
US
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Subterranean heaters
Assignee: Shell USA Inc
•
Filing: 1991-01-07
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Granted: 1991-11-19
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Expires: 2011-01-07
Abstract
Abstract An electrical resistance subterranean heater is provided which is cemented directly in a well borehole without a casing in the borehole within the zone to be heated. The absence of the casing results in an economical installation.
Inventors
- 👤 Cornelis F. H. Van Egmond
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:54
CPC Classifications
H; H05; H05B; H05B3/00; H05B3/40; H05B3/42; H05B3/48; E; E21; E21B; E21B36/00; E21B36/04
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
74 words
A subterranean heater with a well borehole in a formation to be heated, the heater comprising: a) at least one electrically resistive core; b) mineral insulation surrounding the core; c) a sheath surrounding the mineral insulation; d) cement securing the sheath in the well borehole, wherein a casing is not present within the well borehole in the formation to be heated; and e) a means to supply electrical power through the electrically resistive core.
Claim 2
Dependent Claim
74 words
A subterranean heater with a well borehole in a formation to be heated, the heater comprising: a) at least one electrically resistive core; b) mineral insulation surrounding the core; c) a sheath surrounding the mineral insulation; d) cement securing the sheath in the well borehole, wherein a casing is not present within the well borehole in the formation to be heated; and e) a means to supply electrical power through the electrically resistive core.
Claim 3
Dependent Claim
16 words
The heater of claim 1 wherein the sheath comprises an inner sheath and an outer sheath.
Claim 4
Dependent Claim
11 words
The heater of claim 1 wherein the sheath comprises INCOLOY 800.
Claim 5
Dependent Claim
20 words
The heater of claim 1 wherein the sheath is of a thickness of between about 0.125 and about 0.5 inches.
Claim 6
Dependent Claim
21 words
The heater of claim 1 wherein the heater comprises two electrically resistive cores within the sheath, separated by the mineral insulation.
Claim 7
Dependent Claim
21 words
The heater of claim 1 wherein the heater comprises three electrically resistive cores within the sheath separated by the mineral insulation.
Claim 8
Dependent Claim
22 words
The heater of claim 1 wherein the heater is capable of heating intervals of a subterranean formation up to 1000 feet long.
Claim 9
Dependent Claim
20 words
The heater of claim 1 wherein the heater is capable of an average useful life in excess of 20 years.
Claim 10
Dependent Claim
32 words
The heater of claim 1 wherein the heater is capable of supplying heat into the formation in an amount of from about 50 to about 250 watts per foot of heater length.
Claim 11
Dependent Claim
21 words
The heater of claim 1 wherein the heater is, prior to being cemented into the well borehole, a spoolable heater cable.
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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) | 1994-11-18 | 1995-05-20 | 1995-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-11-18 | 1999-05-20 | 1999-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-11-18 | 2003-05-20 | 2003-11-19 | $7700.00 | Window Closed / Lapsed |