ABSTRACT: New Dimensions for Seismic Interpretation
VOZOFF, K., Macquarie University, Sydney, Australia, K.-M. STRACK, University of Cologne, Germany, A. M. ZIOLKOWSKI, Technical University of Delft, The Netherlands, and F. WENZEL, CSIRO Exploration Geoscience, Sydney, Australia
A variety of techniques have been applied to seismic reflection data in an effort to extract information such as lithology, porosity, and permeability. These techniques, including attribute analysis processing and AVO measurements, have met with partial success. The problem cannot yet be considered solved, probably because the seismic data lack the necessary sensitivity.
Another approach which has had some success is the augmentation of seismic data with independent geophysical data of a different kind. Augmentation with gravity and/or magnetic information is well-established for some kinds of problems. However, only electromagnetic methods have the resolution needed for relatively thin units and respond to porosity directly through conductivity.
We will show examples of surveys in which electromagnetic surveys were used to map lateral conductivity changes indicative of porosity enhancement in a tight carbonate (Australia), structure in a limestone which was not evident in seismic data (PRC), and a conductive horizon due to Mesozoic sediments beneath extensive basalt flows which were not penetrated by seismic (S. Asia).
In addition, we show results of modeling, indicating the limiting conditions under which electromagnetic data can be used to search for porosity trends in resistive horizons such as carbonates or tight clastics. Given accurate thicknesses from seismic data, and pore fluid conductivity from well logs, electromagnetic techniques are capable of mapping changes within some important reservoirs, in Australia and overseas. To do so demands special care in seismic acquisition and processing in order to obtain the necessary resolution.
AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)