Well integrity evaluation depends on reliable assessment of cement placement and casing condition throughout the life of the well. For decades, conventional rotatinghead mono-element ultrasonic tools have been widely used for this purpose and have provided reliable cement and casing evaluation across a broad range of well conditions. These tools remain an industry standard for pulse-echo cement and casing evaluation. However, when applied in slim tubulars, restricted-access completions, and highly deviated wellbores, the mechanical architecture of these tools can become a limitation. The rotating head, motor assembly, and relatively larger tool body may restrict access, increase sensitivity to eccentering, and reduce measurement stability in geometrically challenging well sections.

This paper compares conventional mono element mechanically scanned ultrasonic cement evaluation with an electronically steered phased-array approach through laboratory qualification and a same-well field application. The phased-array system was developed as a slim, non-rotating ultrasonic imager for cement and casing evaluation in environments where conventional rotating-head tools may face deployment or data-quality limitations.

Ultrasonic pulse-echo measurements are routinely used to generate azimuthal images and quantitative outputs, including acoustic impedance behind casing, internal radius, and casing thickness. In conventional imagers, circumferential coverage is obtained by mechanically rotating a mono-element transducer. In contrast, the phased-array tool replaces mechanical rotation with electronic circumferential scanning. Multiple transducer elements arranged around the tool are fired in controlled apertures, and delay-law phasing is used to shape and direct the acoustic field for cement and casing measurements. The resulting 2-1/8-in. tool can pass through smaller restrictions, operate on monoconductor or multiconductor wireline, and evaluate multiple casing sizes in a single run without hardware change.

Performance was first assessed in NORCE cemented test cells and wedge-based channel-detection fixtures. In these laboratory trials, the phased-array tool reproduced the impedance contrast, axial boundaries, and azimuthal defect responses observed with a conventional rotating mono-element reference tool. The comparison was then extended to a same-well field application in a deviated well containing both 7-in. casing and a 5-1/2-in. liner. In the 7-in. interval, the phased-array and rotating-head measurements showed close agreement in average radius, casing thickness, and repeated azimuthal features. In the 5-1/2-in. liner, particularly across the sidetrack kick-off interval, the phased-array tool achieved better centralization, resulting in less eccentering effect on the measurements and more continuous circumferential imaging.

The results demonstrate that electronically steered ultrasonic imaging preserves the quantitative outputs required for cement and casing evaluation while improving deployment flexibility and measurement quality in slim and geometrically challenging well sections. In addition, the phased-array tool broadens conveyance options by enabling deployment on either monoconductor or multiconductor wireline and supports integration with a wide range of complementary measurements, including production logging, leak detection, multifinger caliper, and electromagnetic thickness evaluation.