Improving the Efficiency of Gas Storage Well Completions Using UnderbalancedDrilling With Coiled Tubing

摘要

A key element of maximizing injection and withdrawal ratesin gas storage fields is minimizing skin damage of thecompletions. A highly efficient completion technique canreduce the number of storage wells required to produce andrefill a storage zone. It also reduces the cost of installationand operation of the compression equipment required toachieve commercial injection and withdrawal rates. Thecurrent completion methodology involves conventionaloverbalanced drilling through to the target zone. Casing is runand cemented from TD with communication to the reservoirachieved by perforating. Skin damage is typically reduced byflowback and acid stimulation of the well to remove drillingmud and filter cake. A different approach utilizingunderbalanced vertical deepening, or “well finishing” withcoiled tubing was employed in the Huntsman Storage Field,Nebraska and the Sayre Storage Field, Oklahoma in an effortto further reduce skin damage. The wells were conventionallydrilled and cased to the cap rock of the storage zone then thefinal stage of drilling to TD was performed underbalanced bya coiled tubing unit. The storage zone was completedopenhole.