Ammunition and explosives – Blasting – Patterned blasting
Reexamination Certificate
1999-01-29
2002-01-08
Nelson, Peter A. (Department: 3641)
Ammunition and explosives
Blasting
Patterned blasting
C102S313000, C102S704000, C102S705000, C166S057000, C175S017000
Reexamination Certificate
active
06336408
ABSTRACT:
BACKGROUND
The invention relates to cooling systems for downhole tools.
A wellbore is typically a hostile environment, with downhole temperatures capable of reaching well over 500° F. Such elevated temperatures can damage heat-sensitive components of tools lowered into the wellbore to perform various activities, such as logging, perforating, and so forth. Examples of such heat-sensitive components include explosives and detonating cords used in a perforating apparatus or batteries and electronic circuitry in other devices.
Conventionally, to avoid damage to heat-sensitive components in tools lowered into wellbores having elevated temperatures, the tools must be quickly inserted and retrieved from the well to perform the desired activities. Generally, this is practical only in vertical wells. In highly deviated or horizontal wells, in which insertion and retrieval of tools are relatively slow processes, the length of time in which the tools are kept in the wellbores at elevated temperatures could cause damage to heat-sensitive equipment.
In some logging tools, dewar flasks have been used to protect heat-sensitive equipment. A dewar flask is generally tubular and contains a vacuum layer that reduces heat transfer. Heat-sensitive components are placed in the inner bore of the dewar flask. By using the dewar flask, the rate of temperature rise is reduced to allow the logging tools to stay downhole longer. However, a need continues to exist for more effective techniques of reducing the rate of temperature rise of components lowered into a wellbore.
SUMMARY
In general, in one embodiment, an apparatus for cooling a component inside a tool includes a heat sink positioned next to the component. An insulation layer surrounds the component to reduce heat transfer to the component.
Other features and embodiments will become apparent from the following description and from the claims.
REFERENCES:
patent: 3142336 (1964-07-01), Doscher
patent: 3444279 (1969-05-01), Dost
patent: 3700050 (1972-10-01), Miles
patent: 3731893 (1973-05-01), Stalmach, Jr.
patent: 4024919 (1977-05-01), Pujol
patent: 4513733 (1985-04-01), Braun
patent: 5153369 (1992-10-01), Hardt et al.
patent: 6015015 (2000-01-01), Luft et al.
Chen Kuo-Chiang
Parrott Robert A.
Song Haoshi
Nelson Peter A.
Trop Pruner & Hu P.C.
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