The Physical Modelling laboratory is developing a range of measuring capabilities for basic acoustic measurements as well as simulating seismic acquisition. The capabilities in the laboratory now include 3 and 4D seismic acquisition with a variety of geometries and types of signals. A high pressure chamber can imitate thermodynamic conditions of condensable gases at close to reservoir conditions. Apparatus is being developed to perform acoustic tomographic experiments on simulated reservoirs to image the movement of fluids through porous rocks.
In addition to and combined with these basic experiments we are investigating the use of continuous repetitive signals aimed at improving the precision with which seismic travel times can be determined, and eventually give the ability to measure velocity dispersion in fluid-filled porous rocks. In the last two years physical modelling has been used to study the methodology and promise of the ‘Virtual Source Method’. In this technique strongly heterogeneous and scattering layer in the near surface can be nullified by using subsurface receivers to record seismic signals generated at the surface. By correlation of these recorded signals, the receivers can be simulated to be virtual source as signals received by the receivers continue to lower layers and, when back reflected, act as virtual sources. The cross correlation of the signals can simulate virtual shot records where each sub-surface receiver acts as both a virtual source and an actual receiver. The technique has been verified and brut stack record generated with suitable fold and after processing show the expected reflectors in the subsurface.
The program will also develop experimental tests of the theoretical rock physics and acoustic behaviour of fluid filled reservoirs.
Dr. Maxim Lebedev (M.Lebedev@exchange.curtin.edu.au)