Importance

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Abstract

An inertial borehole survey system is disclosed. The survey system of the present invention includes a probe suitable for insertion into a borehole. The probe includes a plurality of temperature sensitive inertial measuring instruments which are utilized to survey the borehole during the descent or ascent of the probe. Accuracy of these instruments is maintained by enclosing the instruments in a thermal insulating package and by providing a mass of isothermal heat absorbing material which exhibits a phase change at a temperature well above most ambient temperatures. In a preferred embodiment of the present invention, a heat absorbing material is utilized which exhibits a phase change at a temperature of 116.degree. F. The probe also includes a longitudinal air passage which permits ambient temperature air to be utilized to cool the isothermal heat absorbing material by passing air through the length of the probe. Currently the instrument cluster is mounted on a member formed of a single billet of metal to form a thermally conductive, small diameter, stiff structure which permits the inertial measurement instruments to be spaced longitudinally in a cluster in order to minimize the diameter to approximately the largest diameter of any single instrument and yet which permits heat generated by the instruments to be absorbed by the heat absorbing material.

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First Claim