This Record of Study summarizes a Doctor of Engineering Internship undertaken with the Ocean Drilling Program at Texas A&M University. It covers activities related to improved understanding of the structural behavior and limitations of long drill strings suspended from a drilling vessel without the benefit of a riser. The intern incorporated prior analytical and experimental results and added his own analysis to develop a system for designing drill strings for sites ranging from a few hundred to over nine thousand meters of water depth and several thousand meters of penetration.; The system incorporates bottom hole assemblies, casing, guide bases, three types of drill pipe, pipe protectors, and varying operational conditions. The system evaluates overload due to dynamic effects, overpull combined with torque and internal pressure, and vessel up heave without heave compensation. This Record of Study includes a computer program exceeding 5,000 lines of source code and a spreadsheet to automate the implementation of this design system. These are intended for drill string analysis and design as well as site evaluation and planning. The program greatly simplifies a task which would be impractical by hand calculation.
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