Apparatus for rotating a transducer assembly of a borehole logging tool in a deviated borehole
This patent describes a borehole logging tool for acoustic shear wave logging of an unconsolidated subsurface formation penetrated by a deviated borehole. It comprises: a dipole acoustic energy source mounted for rotation about the axis of the borehole tool to focus the directivity of acoustic energy such that it is perpendicular to the axis of the borehole tool, at least one axially spaced-apart dipole acoustic energy receiver mounted for rotation about the axis of the borehole tool to focus the reception of acoustic energy in the same direction as the focusing of the source, a motor mechanically coupled to the source and the receiver for rotating the source and the receiver about the axis of the borehole tool, means for providing a first signal representing the source and receiver rotational positions relative to a vertical direction, means for providing a second signal having a fixed reference level representing the vertical direction, a comparator for providing a third signal of the difference between the first and second signals representing the difference between the first and second signals, and means for applying the third signal to the motor to cause it to rotate the source and the receiver to a position that minimizes the third signal so as to maintain the focus of the source and the receiver in a horizontal direction that is perpendicular to the direction of eccentricity of the borehole tool with respect to the borehole axis.
- Assignee:
- Mobil Oil Corp., Fairfax, VA (United States)
- Patent Number(s):
- US 5159578; A
- Application Number:
- PPN: US 7-824921
- OSTI ID:
- 6878235
- Resource Relation:
- Patent File Date: 23 Jan 1992
- Country of Publication:
- United States
- Language:
- English
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