Tonni Franke Johansen
Tonni Franke Johansen
Publications and responsibilities
A Study of the Flexural Attenuation Technique Through Laboratory Measurements and Numerical Simulations
Ultrasonic focusing through a steel layer for acoustic imaging
Ultrasonic tools are being used for imaging in a large variety of fields, spanning from medical applications in a hospital to applications deep down in oil and gas wells. When applying ultrasonic imaging techniques to image through elastic materials, such as steel, one of the main challenges these...
Design, Fabrication and Testing Highly Sensitive Single Element Doppler Transducers
LABORATORY SETUP FOR IMPROVED LOGGING BEHIND CASING
Sealing of new wells, and the increasing need of plug and abandonment (P&A) of old wells, has triggered research and development of new methods for saving time at this operation. Shale has proven to seal off the annulus in longer well sections; however, the detection and qualification of the...
Analysis of acoustic impedance matching in dual-band ultrasound transducers
Dual-frequency band probes are needed for ultrasound (US) reverberation suppression and are useful for image-guided US therapy. A challenge is to design transducer stacks that achieve high bandwidth and efficiency at both operating frequencies when the frequencies are widely separated with a...
Laboratory experiments on ultrasonic logging through casing for barrier integrity validation
Verification of annular barriers is essential for well integrity, with ultrasonic methods being central in well integrity testing for many decades. By doing ultrasonic pitch-catch measurements on a bench top laboratory setup developed to replicate an oil well casing, we were able to show that the...
Ultrasonic through-tubing well logging with an array of receivers
Simulation and inversion of ultrasonic pitch-catch through-tubing well logging with an array of receivers
Current methods for ultrasonic pitch-catch well logging use two receivers to log the bonded material outside a single casing. For two casings separated by a fluid, we find by simulation that increasing the number of receivers provides a better picture of the effect of the bonded material outside the...