Study of tapered internal diameter tubing string well completion for enhanced production
Affanaambomo, Bertrand O.
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Conventional Well Completion involves usually a single, internal diameter (ID) tubing for producing oil from the subsurface reservoir. As the oil flows vertically upward, the flowing pressure decreases as a function of depth. This reduction in flowing pressure causes more and more dissolved gases to come out. Consequently, the flow stream, especially free gas, expands in volume per unit mass flow rate. The motivation of the present study is to investigate the effect of gradually increasing the tubing inside diameter (ID) as the fluid moves up the string. We call this Tapered ID Tubing Well Completion (TTWC), which is expected to gives higher flow rates of oil. Apparently the TTWC involves a slight increase in capital expenditure (CAPEX) for the additional cost accrued from using a section of larger ID tubing. Therefore, we performed numerous studies using nodal analysis for various tubing size combinations, and also economic analysis over the entire producing life of the well. The study reveals that the higher flow rates possible through TTWC not only offsets the additional CAPEX, but also gives significant economic benefits compared to the conventional single tubing completion.