Improved sucker-rod system design and optimization

A new sucker-rod simulator saves computer run time and provides sufficient accuracy for conceptual sucker-rod-system design.; A new method expands the scope of the American Petroleum Institute's Recommended Practice (RP) 11L for up to seven tapers (including sinker bar) of any rod material that obeys Hooke's Law.; Secondary findings apply to the creation of a consistent sucker-rod nomenclature, a procedure for history matching field data, and the potential for saving computer run and getting preliminary accuracy from an existing simulator.; The new sucker-rod simulator developed by this research saves run time and meets the 20% error tolerance normally associated with conceptual design. The new simulator uses the method of characteristics and nondimensional partial differential equations. Prior to 1990, no sucker-rod design method met the error tolerances for conceptual, preliminary and final system design. Also prior to 1990, the only sucker-rod simulators that ran profitably fast did so by using a coarse grid. A coarse grid saves run time by minimizing the number of rod subdivisions (elements). The number of rod elements directly affects simulation accuracy. Minimizing the number of elements reduces accuracy.; Improving the methodology behind RP 11L expands 11L's scope to include composite sucker-rod materials and sinker bar.; The specific examples are for fiberglass-steel rod strings and for rod strings with up to seven tapers. RP 11L was originally intended for all steel rod strings without sinker bar.; This research resolves the literature's chaotic sucker-rod notation by creating a sucker-rod nomenclature that is consistent with the Society of Petroleum Engineers' standard.; Since field data validates an existing simulator, a history-matching procedure is developed. The validated simulator validates the new (conceptual-quality) simulator.; While validating the conceptual-quality simulator, the existing simulator demonstrated the ability to save computer time and to meet the 10% error tolerance normally associated with preliminary design. Initially, this was considered a coincidence. However, a review of previous work revealed a consistent pattern. The pattern includes constant motor rpm, averaging the results of the second and third cycles, and 10 to 20 rod elements.