Underground ultrasound probing for monitoring carbon dioxide flooding in oil producing reservoirs

The problem of identifying the position and location of immiscible or miscible layers is a critical issue in methods of carbon dioxide injection for oil producing bodies. Accurate knowledge of the position could lead to an ability to control the position of the carbon dioxide front affecting production, efficiency, economy, and, in the end, profitability. The approach of studying the progress of carbon dioxide in reservoirs using ultrasound is new and may lead to unique and powerful ways of monitoring the position of carbon dioxide, as well as visualizing the reality of the oil producing area. Firstly in this paper, some basic experiments to investigate the acoustic properties in many situations are described. These experiments include the ultrasound reflection properties of stationary water-air, water-oil, air-oil, oil-oil interfaces, as well as those of moving interfaces. Secondly, experiments of ultrasound reflection properties in porous mediums combined with air, water and oil are described. These experiments include reflection of air-water interfaces in porous mediums, oil-water interfaces in porous mediums, and air-oil interfaces in porous mediums. Thirdly, measures of digital signal processing are introduced to obtain position information of interfaces in porous mediums and improve the resolution and accuracy of the location. Ultrasound has many advantages as a tool in underground probing, such as small size, low power consumption and safety.