Coiled tubing is a preferred remedial method of extending the flowing life for gas wells. but selection of a size that will accomplish the task of removing bottomhole liquids is not simple. The difficult, in predicting results that guide coiled tubing selectivity is partly caused by the changing gas to liquid flow rates in the wellbore as the accumulated liquid discharges. This paper provides a guide to the prediction making process, with emphasis on the modeling methods which are needed.
The variables that serve as indicators of the viability of each tubing size are velocity and liquid holdup. The values that should be used for criteria were reviewed in SPE 30197, Modeling Coiled Tubing Velocity Strings for Gas Wells. Those criteria are used with the prediction procedure to expand the selection process to cover a wider range of coiled tubing sizes and gas-liquid flow rates.
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