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US4559818A
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Thermal well-test method
Assignee: United States Department of Energy
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Filing: 1984-02-24
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Granted: 1985-12-24
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Expires: 2004-02-24
Abstract
Abstract A well-test method involving injection of hot (or cold) water into a groundwater aquifer, or injecting cold water into a geothermal reservoir. By making temperature measurements at various depths in one or more observation wells, certain properties of the aquifer are determined. These properties, not obtainable from conventional well test procedures, include the permeability anisotropy, and layering in the aquifer, and in-situ thermal properties. The temperature measurements at various depths are obtained from thermistors mounted in the observation wells.
Inventors
- 👤 Chin-Fu Tsang
- 👤 Christine A. Doughty
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:50
CPC Classifications
E; E21; E21B; E21B49/00; E21B49/08; E21B49/087; E21B47/00; E21B47/06; E21B47/07; G; G01; G01V; G01V9/00; G01V9/005
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
118 words
A well-test method for determining characteristics of a groundwater aquifer or geothermal reservoir, comprising the steps of: determining at least the horizontal permeability and storativity of an underground water containing area to be tested; installing temperature indicating means at different depths in at least one observation well located within the area to be tested; injecting into the water containing area a specified amount of water at a temperature different from the water in the area being tested; during injection of the water, obtaining temperature readings at different depths from the observation well; and plotting the temperature distributions for determining the general characteristics of the water containing area, heat capacity, porosity, effective thermal conductivity, permeability anisotropy and layering characteristics.
Claim 2
Dependent Claim
118 words
A well-test method for determining characteristics of a groundwater aquifer or geothermal reservoir, comprising the steps of: determining at least the horizontal permeability and storativity of an underground water containing area to be tested; installing temperature indicating means at different depths in at least one observation well located within the area to be tested; injecting into the water containing area a specified amount of water at a temperature different from the water in the area being tested; during injection of the water, obtaining temperature readings at different depths from the observation well; and plotting the temperature distributions for determining the general characteristics of the water containing area, heat capacity, porosity, effective thermal conductivity, permeability anisotropy and layering characteristics.
Claim 3
Dependent Claim
63 words
The method of claim 1 additionally including the steps of: withdrawing from the water containing area being tested a quantity of water equal to the amount of water injected; during withdrawal of the water, obtaining temperatures readings from the observation wells; obtaining the temperature of the water being withdrawn as a function of time; and processing the data to obtain the recovery factor.
Claim 4
Dependent Claim
24 words
The method of claim 2, wherein the water is withdrawn at the same rate at which water was injected into the water containing area.
Claim 5
Dependent Claim
78 words
The method of claim 2, additionally including the steps of: plotting a curve showing the temperature of the water withdrawn versus time; and calculating the recovery factor, by the formula ε=(T p -T o )/(T w -T o ), where T p is the average withdrawal temperature, T o is the temperature of the water in the area to be tested prior to injection of different temperature water, and T w is the temperature of the water injected.
Claim 6
Dependent Claim
14 words
The method of claim 1, wherein the water is injected at a specified rate.
Claim 7
Dependent Claim
38 words
The method of claim 1, wherein the temperature readings from the observation wells are obtained by locating thermistors at various depths in the observation wells, and backfilling the observation wells to minimize vertical thermal convection within the wellbore.
Claim 8
Dependent Claim
66 words
The method of claim 1, additionally including the steps of: drilling an injection/production well in the area to be tested which penetrates the area to be tested, drilling at least one observation well adjacent to but at a distance from the injection/production well and in the underground aquifer or geothermal reservoir to be tested, and positioning temperature indicating devices at selected depths in each observation well.
Claim 9
Dependent Claim
40 words
The method of claim 1, wherein the step of processing the data includes: forming a contour plot of temperature distribution at the end of the injection period; and making a contour plot of temperature versus time for each observation well.
Claim 10
Dependent Claim
129 words
In a well-test method, the improvement comprising the steps of: locating a plurality of observation wells in the area of the well being tested; positioning temperature sensing devices at different depths in each of the observation wells; injecting water at a constant, but different, temperature at a specified rate into the well being tested; producing water from the well being tested at the same rate as the water was injected thereinto; during injection and production, record the temperatures in the observation wells; during production record the temperature of the produced water; using time-sequence temperature data from the observation wells along with spatial temperature distributions for selected times based on data from the observation wells, and utilizing the data thus obtained to determine various characteristics of the well being tested.
Claim 11
Dependent Claim
129 words
In a well-test method, the improvement comprising the steps of: locating a plurality of observation wells in the area of the well being tested; positioning temperature sensing devices at different depths in each of the observation wells; injecting water at a constant, but different, temperature at a specified rate into the well being tested; producing water from the well being tested at the same rate as the water was injected thereinto; during injection and production, record the temperatures in the observation wells; during production record the temperature of the produced water; using time-sequence temperature data from the observation wells along with spatial temperature distributions for selected times based on data from the observation wells, and utilizing the data thus obtained to determine various characteristics of the well being tested.
Claim 12
Dependent Claim
22 words
The method of claim 9, additionally including the step of backfilling the observation wells for minimizing vertical thermal convection within the wellbores.
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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) | 1988-12-23 | 1989-06-24 | 1989-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-12-23 | 1993-06-24 | 1993-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-12-23 | 1997-06-24 | 1997-12-24 | $7700.00 | Window Closed / Lapsed |