US3892128A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods for thermal well logging
Assignee: Texaco Inc
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Filing: 1973-08-06
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Granted: 1975-07-01
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Expires: 1993-08-06
Abstract
Abstract A method for thermal well logging of earth formations in cased or open boreholes to produce logs of temperature, specific heat and formation thermal conductivity is disclosed. A well logging tool employing a constant output heat source and three temperature sensors is utilized. A first temperature sensor measures the ambient borehole temperature at a given depth level. The constant output heat source then heats the formation at the investigated depth level. A second temperature sensor located relatively near the heat source then measures the temperature increase at the depth level due to the heating. This provides a measure of the formation specific heat. A third temperature sensor located a spatially separated distance from the second temperature sensor is then moved past the depth level being investigated some time interval later and the amount of cooling since the heat source has passed is measured. This provides a measure of the formation thermal conductivity. A further embodiment which utilizes the three temperature sensors and a heat source which is utilized also as a drilling tip is also disclosed.
Inventors
- 👤 Jr Harry Davis Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 00:18
CPC Classifications
G; G01; G01N; G01N25/00; E; E21; E21B; E21B47/00; E21B47/06; E21B47/07
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
208 words
A method for thermal logging of a well borehole to provide a measure of the specific heat, the borehole ambient temperature, and the thermal conductivity of earth formations in the vicinity of the borehole comprising the steps of: measuring the ambient temperature of earth formations in the vicinity of the borehole at a selected depth level; heating the earth formations at said selected depth level by imparting a predetermined quantity of heat thereto; measuring a first temperature of the earth formations at said selected depth level substantially simultaneously with said heating step and determining the temperature increase therein due to said heating step; measuring, after a predetermined time interval, a second temperature of earth formations at said selected depth level and determining the temperature decrease therein due to thermal conductivity losses of heat to other surrounding formations; combining said ambient temperature measurement and said first temperature measurement according to a first predetermined relationship and deriving an indication of the specific heat of earth formations at said selected depth level; and combining said first and second temerature measurements according to a second predetermined relationship and deriving an indication of the ratio of thermal conductivity to the square of the specific heat of earth formations at said selected depth level.
Claim 2
Independent Claim
208 words
A method for thermal logging of a well borehole to provide a measure of the specific heat, the borehole ambient temperature, and the thermal conductivity of earth formations in the vicinity of the borehole comprising the steps of: measuring the ambient temperature of earth formations in the vicinity of the borehole at a selected depth level; heating the earth formations at said selected depth level by imparting a predetermined quantity of heat thereto; measuring a first temperature of the earth formations at said selected depth level substantially simultaneously with said heating step and determining the temperature increase therein due to said heating step; measuring, after a predetermined time interval, a second temperature of earth formations at said selected depth level and determining the temperature decrease therein due to thermal conductivity losses of heat to other surrounding formations; combining said ambient temperature measurement and said first temperature measurement according to a first predetermined relationship and deriving an indication of the specific heat of earth formations at said selected depth level; and combining said first and second temerature measurements according to a second predetermined relationship and deriving an indication of the ratio of thermal conductivity to the square of the specific heat of earth formations at said selected depth level.
Claim 3
Dependent Claim
27 words
The method of claim 1 wherein the heating step is performed by applying heat from a relatively constant output heat source for a predetermined length of time.
Claim 4
Dependent Claim
48 words
The method of claim 1 wherein the steps are performed repetitively at a plurality of such selected depth levels and a log of the earth formation specific heat, ratio of thermal conductivity to square of specific heat and ambient temperature is recorded as a function of borehole depth.
Claim 5
Dependent Claim
47 words
The method of claim 1 and further including the step of combining said specific heat indication and said ratio of thermal conductivity to the square of specific heat indication of formation thermal conductivity and recording said indication of formation thermal conductivity as a function of borehole depth.
Claim 6
Dependent Claim
33 words
The method of claim 4 and further including the steps of recording simultaneously as a function of borehole depth said specific heat indication, said indication of formation thermal conductivity and the ambient temperature.
Claim 7
Dependent Claim
42 words
The method of claim 4 and further including the step of comparing said formation thermal conductivity indication with known values of such for water and oil saturated sands to derive an indication of the location of oil sands in a well 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) | 1978-06-30 | 1978-12-30 | 1979-07-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-30 | 1982-12-30 | 1983-07-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-30 | 1986-12-30 | 1987-07-01 | $7700.00 | Window Closed / Lapsed |