Importance

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Abstract

A sidewall contact parameter tool, adapted to be disposed in a mud-filled wellbore, includes a pad assembly, in accordance with the present invention, which is adapted to cut through mudcake and measure a parameter of a formation disposed under the mudcake. The wellbore wall includes a mudcake and an earth formation disposed under the mudcake. The pad assembly includes at least one formation parameter sensor, and the formation parameter sensor includes a base portion and a knife edge portion integrally connected to the base portion. The base portion of each formation parameter sensor is adapted to contact a surface of the mudcake but the knife edge portion is adapted to cut into the mudcake and contact or penetrate a surface of the earth formation disposed under the mudcake. The knife edge portion of each sensor includes an internal space or pinhole aperture, and a parameter sensing apparatus disposed within the internal space or aperture. When an arms assembly extends the pad assembly radially in the wellbore and the pad assembly contacts the wall of the wellbore in response to the force applied to the arms assembly by a spring in a hydraulics assembly, the sensing apparatus disposed within the internal space of the knife edge portion senses the parameter of the earth formation under the mudcake but not the parameter of the mudcake. The tool also includes a mud temperature sensor for sensing mud temperature and a mud pressure sensor for sensing mud pressure, the mud temperature and mud pressure being used to check and confirm the accuracy of the formation parameter measured by the parameter sensing apparatus in the knife edge portion of the formation parameter sensor.

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First Claim