Multicomponent seismic imaging of sand reservoirs: Middle Magdalena Valley, Colombia.

Many current resource exploration targets are more difficult to image and assess than in the past; thus, more complete and sophisticated techniques, such as the multicomponent (3C) seismic method, are needed. The scope of this work is to image the sand reservoirs present in the Tenerife Field in the Middle Magdalena Valley, Colombia. The analyzed data include a migrated 3D-3C volume, raw shot gathers from two 2D-3C test lines acquired with different source sizes and depths, and varying receiver depths. Additionally, well logs and VSP from three wells in the field were incorporated into this study. For the 2D-3C processing, a conventional processing workflow was followed except for some steps in the radial channel, such as refraction statics and velocity picking. Better results were obtained with refraction statics computed from manually-picked S-wave first breaks and with semblances generated separating positive from negative offsets. The effect of the different acquisition parameters was more evident in PS-waves, observing an improvement in the stack when increasing the fold, and source size and depth. On the other hand, PP-waves showed nearly the same stack quality with the different acquisition parameters. Vp/Vs maps at the top of the target-horizon showed low values around one of the producing wells (Tenerife-2), which is known to have a good stack of clean sands, based on log data. The other two wells presented no Vp/Vs anomalies; in Tenerife-1 the gross thickness is far below conventional seismic resolution and in Tenerife-3 the shale-content is very high. Thus, in the Tenerife Field, there seems to be a direct correlation between low Vp/Vs values and good quality reservoir sands.