Lateral length : The length of the lateral part of the well, usually in the pay zone. The departure length is the horizontal distance from the surface penetration point to the furthest distance reached by the drill bit
George E. King Engineering, 5000 Oilfield Terms: A Glossary of Petroleum Engineering Terms, Abbreviations and Acronyms, US 2010. http://gekengineering.com/Downloads/Free_Downloads /Glossary_of_Petroleum_Engineering_Terms_25_August _2010.pdf, (Oil - Amer) {593}