Since the early 1980s, directional-drilling technology has become a vital tool for the drilling engineer. Supporting technologies such as the measurement-while-drilling, pressures-while-drilling, wire-line-steering-tool, and, as of late, rotary-steerable systems allow custom design of target intercepts. Directional-wellbore-profile types now include the build-and-hold, S-curve, horizontal, multi-lateral, radial drilling from a lateral, and “sump drilling,” which creates a “belly” or curved section vertically deeper than the reservoir total depth of the well. Sump drilling uses a pump in the belly portion to aid production and is specifically used for formations that contain heavy oil or that experience impeded formation feed-in. Regardless of which wellbore profile is chosen for development of the target reservoir(s), burning questions often go unanswered. How much target exposure is too much? How far should the lateral be extended before overextending the economic ability to recoup the investment? To answer these questions, mechanical aspects and production limits must be considered in addition to economic limits. The length of an extended-reach well may be limited by torque and drag or wellbore stability. The length of the lateral in a horizontal well in a 1-darcy-permeability sand may be production-tubing limited. The expense of drilling a 500-ft lateral in such a high-permeability sand may create the same production rate and ultimate recovery as a 1,500-ft lateral in the same target. Specific answers appear to be woven into the fabric of each directional application. Some parameters include matrix permeability, relative mobility of the produced hydrocarbon or water, wellbore stability, pressure drop from lateral toe to heel, production-tubing size, target pore pressure, anticipated depletion limits of the target formation, and existence of fractures or faults within the target. A thorough examination of all the appropriate factors may reveal a surprising truth: less exposure to the target may be better. Available from the SPE eLibrary: www.spe.org SPE 89848 “A Novel Approach to Production Logging in Multiphase Horizontal Wells,” by Vu-Hoang, D., SPE, Schlumberger, et al. SPE 92685 “U-Tube Wells—Connecting Horizontal Wells End to End Case Study: Installation and Well Construction of the World’s First U-Tube Well,” by Lee, D., SPE, Landmark Graphics Corp., et al. SPE 93986 “Evaluation of Two-Phase IPR Correlations for Horizontal Wells,” by Kamkom, R., Texas A&M U., et al. SPE 94945 “A Quantum Leap in Horizontal Gravel-Pack Technology,” by Mendez, A., SPE, BJ Services Co., et al. Available at the OTC Library: www.otcnet.org OTC 17548 “New Technology Applications To Extend Field Economic Life by Creating Uniform Flow Profiles in Horizontal Wells: Case Study and Technology Overview,” by Ratterman, E.E., Baker Oil Tools, et al.