The main goal of this paper is to present the development of an ultrasonic tomograph that simulates the dynamic monitoring of CO2 injection into a hydrocarbon reservoir. It is proposed the use of ultrasonic tomography to detect sound velocity changes caused by a phantom inside a small-scale medium, in order to simulate the dynamic monitoring on field, since CO2 injection also causes sound velocity changes in the hydrocarbon reservoir. The real acquisition system simulated by this tomograph is comprised by acoustic sources evenly spaced along an approximately vertical well in parallel to another well, both drilled in the oilfield, where the acoustic receivers are evenly spaced. The acoustic signal propagates from each source and crosses the medium between wells to reach the receivers in another well. From traveltimes recorded at receivers, one can estimate the sound propagation velocity of the medium between sources and receivers. The subsurface image is then estimated by use of seismic tomography methods. That image is a graphical representation of the sound velocity field and yields the identification of CO2 plume contour injected into hydrocarbons reservoirs. Thus, one can automate the CO2 injection monitoring in order to preserve the field operation safety against undesirable and potentially lethal CO2 leaks.
tomography; digital signal processing; carbon capture and sequestration; reservoir monitoring; dynamic imaging; permanent acquisition systems; computational methods
