Geophysical Imaging For CO₂ Monitoring of OBPP

Abstract

The Australian Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) has developed a demonstration pilot project for all aspects of geosequestration of CO2. In preparation for acquiring a time lapse 3DVSP for this project we carried out an extensive series of vertical seismic profiles to assess source performance, operational efficiency, target imaging using a range of zero offset, walkaway, offset source and shear seismic VSPs. We were able to image the target reservoir at 2 km with resolution bandwidth of greater than 140 Hz. Analysis of shear energy in both zero and offset surveys showed the main stress direction consistent with other data. We will review these surveys and the subsequent baseline 3DVSP.We will also review the design of an integrated sampling and geophysical completion for the monitoring well. This completion is configured to provide geochemical sampling at 3 distinct levels, as well as three types of geophysical monitoring activities; an array of geophones centred at 1470 m will be used to acquire walkaway VSP data during injection, a set of three triaxial geophones just above the reservoir will be set to monitor microseismic events, and a set of hydrophones and geophones within the reservoir will be deployed for high resolution travel time measurements.