Tube-wave Effects in Cross-Well Seismic Data at Stratton Field

The analysis of crosswell seismic data for a gas reservoir in Texas revealed two newly detected seismic wave effects, recorded 2000 feet above the reservoir. The first is that the dominant late phases on the records are the tube waves generated in the source well and later converted into laterally propagating waves through the reservoir in gas/water saturated layers, which convert back to tubewaves in the receiver well. The tube-wave train showed good correlation with multilayered reservoir zone structure, suggesting that the recorded wave field has strong dependence on the reservoir parameters. The second effect is that the recorded field is composed of multiple lowvelocity tube-waves. The modeling results suggest that imperfect cementation is the likely cause of this phenomenon.