Preliminary results of the AVO analysis at Pike's Peak

Jonathan E. Downton, Laurence R. Lines

An AVO study was performed to determine the potential of AVO to map the steam chamber, to aid in the enhanced oil reservoir production of the Pike's Peak Thermal Project. The study consisted of three phases: a rock physics study, a modeling study and a template seismic study. The rock physics study helped determine the relationship between the elastic properties of the reservoir and the extrinsic variables: temperature and pressure. This understanding was used along with log control to do a forward modeling study. Synthetic gathers were generated under a variety of reservoir conditions to model the seismic response of the reservoir. The knowledge gained from the modeling study was used to design and interpret the AVO study.

Two AVO inversion techniques were found helpful in describing reservoir changes. The bandpassed reflectivity estimate of lambda and the fluid stack react anomalously to the high temperatures and low fluid modulus associated with the steam front. This was predicted based on forward modeling and observed on the actual seismic. This offers the potential for 4D AVO studies to map the steam front as a function of time.