Greater erosion occurs during fracturing of the four perforations in cluster 5 (heel side on top row) than in cluster 1 shown at bottom (toe side, bottom row). Fracturing leaves its mark on each of the perforations penetrating the steel casing. The array of perforations above (Figure 1) were eroded by water and sand surging through these entry holes, some more than others. Dave Cramer, senior engineering fellow for ConocoPhillips, said pictures shot after fracturing are full of telling details when combined with other diagnostics. These shots were created by EV, an in-well imaging and analysis company, for ConocoPhillips.