Successful placement of a horizontal well requires the driller to land the BHA in a position that will then permit maximum wellbore exposure to the reservoir. The consequences of suboptimal landings are lost lateral exposure and lost attic oil, among other issues. Using deep, directional electromagnetic measurements, the GeoSphere service precisely maps the reservoir top. With a clear, real-time view of the reservoir, operators can land optimally and avoid losing lateral exposure or creating sumps.