Patent ID: 6021093
Filing Date: 2000-02-01
Classification: G01V

Abstract:
An acoustic sensing tool for determining the consistency of a first medium disposed behind a casing and between an acoustically reflective layer having a greater acoustic reflectivity than the first medium and a second medium, the sensing tool including a rotating head comprising:first, second and third transducer pairs in a spaced apart configuration, each pair comprising a transmitting transducer for transmitting an acoustic radiation signal in a near field collimated zone or a far field main lobe, and a receiving transducer having a receiving radiation pattern in a main lobe, the transmitting and receiving transducers in each pair being arranged in the rotating head so as to allow the transmitting and receiving main lobes to intersect behind the casing but not in the acoustically reflective layer to null reverberation energy therefrom, each transducer pair being arranged in the rotating head to transmit a centerline of radiation that propagates and refracts through the acoustically reflective layer such that all the transmitted centerlines of radiation intersect in an intersection voxel;the transmitting transducer of the first transducer pair transmitting the acoustic radiation signal at a counterclockwise angle relative to a normal of the casing, the transmitting transducer of the second transducer pair transmitting the acoustic radiation signal at a clockwise angle relative to the normal of the casing and the transmitting transducer of the third transducer pair transmitting the acoustic radiation signal perpendicularly with respect to the normal of the casing; andwherein the intersection voxel is interrogated by all three transducer pairs substantially simultaneously at nearly a single azimuthal head position, such that any occlusion is interrogated from three different incident directions, thereby facilitating determination of occlusion surface orientation.