Evaluation of tar deposits using neutron tomography, Canning Basin, Western Australia

Abstract

Tar or bitumen deposits in the Canning Basin, Western Australia, indicate possible paths of petroleum migration. Neutron and X-ray tomography is applied to rocks containing biodegraded tar in order to investigate the distribution of petroleum within the pore system of the samples. Neutron tomography allows the imaging of hydrogen-rich components, such as tar and bitumen, within a sample, whereas X-ray tomography assists density analysis of the grains and pore space. The results indicate that the methodology discriminates excellently between tar and the other rock matrix and open void components. The images permit analysis of the connectivity of pore paths and enable conclusions to be drawn about petroleum migration. In the case history presented, the images demonstrate the injection of petroleum into a dilated fault zone, and the interaction of the petroleum with the fault gouge material. The images also demonstrate the nature of petroleum movement into sandstone beds, which were in communication with this fault zone.