Vp/Vs and AVO analysis used in monitoring heavy-oil cold production
Duojun (Albert) Zhang, Laurence R. Lines
Vp/Vs and AVO analysis were researched to monitor the recovery process of heavy-oil cold production in this paper. Reference horizons were selected based on synthetic seismograms and interpreted on 3D PP and PS seismic volumes. The target formation is surrounded by picked reference top and bottom horizons. To enhance the similarity of PP and PS seismic volumes, a band-pass filter was designed based on the frequency spectrum of PS volume and applied to the PP seismic volume. Vp/Vs calculated from PS and filtered PP seismic volumes were compared with that from PS and unfiltered PP seismic volumes. The primary result is encouraging and further research should be done to reveal the direct effect of heavy-oil cold production on Vp/Vs. Meanwhile, AVO modeling was done for one oil well based on fluid substitution modeling. In unconsolidated sand reservoirs, cold production of heavy-oil will create a typical Class III AVO response. The indicator A*B (intercept*gradient) value of post-production from the pay zone is obviously distinguished from other cases.