Drilling a predetermined geometric horizontal well path does not lead to commercial success because the stratigraphic location of rock holding access to sought-after hydrocarbons is not accurately known geometrically at undrilled/unlogged depths. This structure mapping reality extends from nature's perpetual unpredictability and the economic unfeasibility to reduce 3D/global-coordinate control point location uncertainty of grid data to necessary accuracy levels. As a result, skilled horizontal payzone drilling is governed by correlation principles and regional experience to geometrically understand stratigraphy and to steer. ENTER, SES.