US3786858A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of extracting heat from dry geothermal reservoirs
Assignee: United States Atomic Energy Commission
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Filing: 1972-03-27
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Granted: 1974-01-22
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Expires: 1992-03-27
Abstract
Abstract Hydraulic fracturing is used to interconnect two or more holes which penetrate a previously dry geothermal reservoir, and to produce within the reservoir a sufficiently large heat-transfer surface so that heat can be extracted from the reservoir at a usefully high rate by a fluid entering it through one hole and leaving it through another. Introduction of a fluid into the reservoir to remove heat from it and establishment of natural (unpumped) convective circulation through the reservoir to accomplish continuous heat removal are important and novel features of the method.
Inventors
- 👤 R Potter
- 👤 E Robinson
- 👤 M Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:26
CPC Classifications
F; F24; F24D; F24D12/00; F24T; F24T10/00; F24T10/20; Y; Y02; Y02E; Y02E10/00; Y02E10/10
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
103 words
A method of extracting energy from a dry igneous rock geothermal reservoir comprising: a. drilling a hole to such a depth as is required to encounter hot igneous rock in the range of 150* to 500* C; b. hydraulically fracturing from this hole to produce a large crack system in the rock; c. pumping cold fluid down the hole to establish underground circulation through the crack system; d. extracting thermal energy from the pressurized hot fluid rising in a shallower flow passage and then to a heat-exchanger at the surface; and e. re-introducing the cooled fluid from the heat-exchanger into the crack system.
Claim 2
Independent Claim
103 words
A method of extracting energy from a dry igneous rock geothermal reservoir comprising: a. drilling a hole to such a depth as is required to encounter hot igneous rock in the range of 150* to 500* C; b. hydraulically fracturing from this hole to produce a large crack system in the rock; c. pumping cold fluid down the hole to establish underground circulation through the crack system; d. extracting thermal energy from the pressurized hot fluid rising in a shallower flow passage and then to a heat-exchanger at the surface; and e. re-introducing the cooled fluid from the heat-exchanger into the crack system.
Claim 3
Dependent Claim
27 words
The method of claim 1 in which the said cold fluid causes a second crack system to develop which is in communication with the initial crack system.
Claim 4
Dependent Claim
19 words
The method of claim 1 in which the said hole contains both the cold and hot fluid flow passages.
Claim 5
Dependent Claim
17 words
The method of claim 1 in which the temperature of said hot rock is about 300* C.
Claim 6
Dependent Claim
12 words
The method of claim 1 in which the said fluid is water.
References Cited (Backward Citations)
US3640336A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-21 | 1977-07-23 | 1978-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-21 | 1981-07-23 | 1982-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-21 | 1985-07-23 | 1986-01-22 | $7700.00 | Window Closed / Lapsed |