Adaptive imaging processing for reducing ultrasonic ringdown interference pattern

Abstract

In the oil and gas industry, ultrasonic imaging tools are actively used in stress identification and fracture detection. Pulse-echo transducers measure the properties of the echoes reflected from the formation, and the signal peak amplitude and travel time are typically displayed as a circumferential image of the borehole wall. A well-known problem is that the pulse-echo transducers have internal ringdown which constantly modulates formation echoes. As a result, the acquired image is often dominated by a “wood-grain” interference pattern which degrades image quality. Traditional ringdown reduction methods try to remove the ringdown effect by estimating the ringdown waveform. However, the ringdown signal varies versus borehole conditions, which make it inadequate for traditional methods to efficiently reduce the image interference pattern. In this paper, we proposed an image processing method which significantly reduces the interference pattern. This new image processing method does not require any ringdown waveforms. It adaptively estimates the ringdown modulation template and after that constructs the interference amplitude pattern. Examples shows promising results and have proven the propose method is more efficient than traditional ringdown reduction methods on the ringdown interference pattern reduction.