Abstract: A well bore is inspected to detect cement defects that can give rise to leakage. The well bore comprises an inner metal pipe. Outside the inner metal pipe its configuration may vary with distance from the top of the well bore in terms of concentric pipes outside the inner metal pipe and presence of cement between the pipes. A probe with is lowered through the inner metal pipe. An ultrasound signal is transmitted from the probe into the inner metal pipe and responses to the transmitted signal are received at a series of ultrasound receivers at different axial positions. A selection of a spatial frequency of waves arriving along the axial direction at the ultrasound receivers and/or the apparent velocity of said waves is retrieved dependent on the configuration. The received responses are band pass filtered accordingly.

Abstract: Improved imaging is provided for structures under test that have propagation direction dependent ultrasound propagation speed or position dependent ultrasound propagation speed due to fibrous, coarse grain or single crystalline material. A set reflection points is selected in the structure under test and ultrasound propagation time delays between the reflection point or points on one hand and the plurality of positions on the other hand that fit an observed time delay of the detected reflections are computed. This may be done by means of an iterative method. In the iterative method a synthetically focused ultrasound beam is realized by summing measurements after compensation for propagation time delay from different transmitting transducers to the reflection points.

Abstract: A well bore is inspected to detect cement defects that can give rise to leakage. The well bore comprises an inner metal pipe. Outside the inner metal pipe its configuration may vary with distance from the top of the well bore in terms of concentric pipes outside the inner metal pipe and presence of cement between the pipes. A probe with is lowered through the inner metal pipe. An ultrasound signal is transmitted from the probe into the inner metal pipe and responses to the transmitted signal are received at a series of ultrasound receivers at different axial positions. A selection of a spatial frequency of waves arriving along the axial direction at the ultrasound receivers and/or the apparent velocity of said waves is retrieved dependent on the configuration. The received responses are band pass filtered accordingly.

Abstract: Improved imaging is provided for structures under test that have propagation direction dependent ultrasound propagation speed or position dependent ultrasound propagation speed due to fibrous, coarse grain or single crystalline material. A set reflection points is selected in the structure under test and ultrasound propagation time delays between the reflection point or points on one hand and the plurality of positions on the other hand that fit an observed time delay of the detected reflections are computed. This may be done by means of an iterative method. In the iterative method a synthetically focused ultrasound beam is realized by summing measurements after compensation for propagation time delay from different transmitting transducers to the reflection points.