RHODONEA CELL ACOUSTIC HYPERLENS FOR THRU-CASING ULTRASONIC SENSORS

摘要

Apparatus, systems, and methods for investigating a subsurface volume of interest from a borehole. Apparatus comprise an enclosure configured for conveyance along the borehole; an acoustic source in the enclosure configured to generate acoustic signals; a lens assembly disposed in the enclosure and next to the acoustic source, the lens assembly being formed of a plurality of cells, each cell formed as a column oriented transverse to a direction of travel of the acoustical signals. Each cell comprises a plurality of cell segments with each cell segment of the plurality comprising at least one arcuate wall and at least one radial finger, and wherein the cell segments are oriented in alignment with a rhodonea conformal mapping geometry in a plane transverse to the column to cause acoustic waves to travel at a different speed in each of three orthogonal directions.