The DeepLook-EM electromagnetic crosswell reservoir imaging and monitoring system from Schlumberger is the first tool to successfully bridge the interwell information gap. At the reservoir scale, the system is capable of measuring interwell resistivity when the well bores are hundreds, or even thousands, of feet apart. In fields under waterflood, the tool tracks the distribution of injected fluid volumes and the resulting swept zone by measuring resistivity sensitivity to changes in fluid saturation and temperature. These measurements make it possible to infer structure, temperature distribution, and residual saturation of affected reservoir volumes. Operators can use the system to image and monitor the effects of steam or water saturation changes, thus helping to guide field development and enhance reserves estimates.