Researchers will create equipment with the precision of milliseconds, as well as software for analyzing data that is collected
Researchers from the FAPESP Shell Research Centre for Gas Innovation (RCGI) plan to use ultrasound images to detect and quantify leakages of CH4 and CO2 on the seabed. The ultrasound visualization technique, which is widely applied in such fields as medicine and engineering, will help scientists map the temporal distance of the monitored phenomena and put together a framework to identify and quantify possible gas leaks. According to Marcos de Sales Guerra Tsuzuki, Coordinator of RCGI’s Project 35 (Leakage detection of CH4 and CO2 gases in the seabed by using ultrasound images with multiple elements), the big challenge is to use the ultrasound technology for this new application.
“Our team is knowledgeable about ultrasound and we have equipment on the seabed, at the pre-salt level, operating under high pressure to detect corrosion in ducts and pipelines. But this is the first time we are using this technique to detect the presence of gases. Therefore, we first describe the problem, in order to understand the physical phenomena involved and, then, take steps to develop a product that will help us with that specific problem,” Tsuzuki explains, who is a Professor in the Department of Mechatronic Engineering and Mechanical Systems of the Polytechnic School of the University of São Paulo (Poli-USP).
To that end, the team, formed by four instructors and three post-Doctoral candidates, is using laboratory tests to help understand, for example, how a bubble passes through water. “We want to know how we can observe and measure groups of bubbles in the water, in order to quantify the lead. We are creating models and tests in water, using tanks and simulating the environment to reach that understanding. We are also developing a numerical simulator that shows how air escapes in water,” the Professor added. By describing the environment, it will be possible to determine what frequency of the ultrasound waves is most adequate for perceiving the leakage present in the environment, its power, and at what depth it is located.
Sound and the time factor – He states that the technique follows the same principle of the ultrasound used in medicine. “We emit a sound wave, it returns, and we measure the echo of the sound that comes back to us.” But, according to Tsuzuki, most of the equipment in existence today uses static data. “Our equipment will be on a ship, or on a buoy, which is being towed. That is: we will be in motion, going and returning. And neither is what we want to observe in a static state: it is dynamic. So, if the ship is in motion, that has to be taken into account. If not, the information gathered will be wrong.”
Determining the variation of the echo, in terms of time, and how much time that echo takes to return, will provide more data and allow the discernment of false positives, such as the presence of fish, for example, or if the data that arrived is related to the seabed, a rock, or leaking gas. “We have a number of possible false positives, which is what we will attempt to differentiate via this temporal effect, since we will not be making a direct observation. That is a type of information that we will need to interpret. The correct interpretation is the key, and the hardest part: that is, understanding information that is coming from down below.”
He repeats that there already are products for monitoring the seabed with ultrasound, but the group wants to differentiate both the acquisition of sonar information with the hardware, and the analysis of the material. “We will create the interpretive software, as well. This is something in which we already have expertise, and there are several already on the market, but the new application of the technology requires that the post-processing software be specific in its own way.”