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Geology 490M 3D Seismic Workshop Looking at our prospect in depth tom.h.wilson [email protected] Department of Geology and Geography West Virginia University Morgantown, WV A combination of Geometrical and Velocity anomalies Recall this generalized structural model of the Summit field north of Morgantown, WV from earlier in the semester. The blue colored anticlines are cored by salt, which also served as a detachment interval or decollement zone. The deeper strata dip gently to the east. How will the distribution of fast and slow rocks affect the appearance of the seismic time section? Remember what a buried focus event is? The buried focus Velocity “Pull-Up” What doesn’t look right in this seismic section? Why does it appear? Travel time is reduced to the lower reflector beneath the anticline. Reef Scattered ray-paths produce the geometrical distortions What would you expect to happen here? Note the subtle velocity anomaly beneath the channel reflections. In most exploration endeavors you will have some well log information, and formation depth information scattered through the area. With horizon depths from wells and travel times form the seismic data it is easy to compute velocity. Velocities derived over our survey area. Where are the most likely structural traps located? Recall possible interpretation based on the set of “2D” lines ... 5 millisecond contour interval Where are the most likely structural traps located? In 2-way traveltime we had weak prospects with limited and questionable closure Before we forget … Let’s decide when to get together for our oral presentations The 8:30 to 9:30 MWF classes have exams scheduled for 11:00 am to 1:00 pm on Wednesday, May 8th. All in favor ...