This book introduces the science of deviating a well along a planned course to workers who are already familiar with basic drilling practices and terms. Directional drilling expert Joao Luiz Vieira of Halliburton shares current information about the types of directional holes, how a well is planned, the equipment and data needed, and some of the special applications and challenges associated with controlled directional drilling. Updated text, colorful new graphics, and a self-test help readers comprehend this increasingly relevant topic.