This case-history paper presents the results of installing frac-pack [one-step tip screenout (TSO)1  fracture stimulation and gravelpack operations]2–5  completions in gas-storage wells in the West Clear Lake field of Harris County, Texas. With the frac-pack technique, operators have fracture-stimulated six wells (new drills and workovers) in the past 3 years as part of an overall facility upgrade. Gas is injected daily into the Frio formation (5,500 ft) of the field and withdrawn at high rates during peak demand periods. A strong waterdrive can "water-out" production at the end of peak-season gas withdrawal. The water recedes when withdrawal is ended and injection restores gas volume and pressure in the reservoir. The paper presents frac-pack installation techniques, performance comparison of conventional methods and frac packs, and completion-technique selection to achieve high production efficiency.

New wells that were completed with frac packs in 1994 have yielded rates up to 100 MMcf/D each with approximately 500 psi drawdown pressure. In 1995, a well capable of producing at 25 MMcf/D with a gravel pack was recompleted with a frac pack, which increased its rate capacity to 49 MMcf/D. Because of the performance of the first three wells, three more wells were completed with frac packs in 1997. The frac-pack completion has proven superior to other sand-control methods in providing highrate deliverability in the West Clear Lake field. Frac-pack completions have, in general, provided a two-fold increase in the daily production rate.

Frac-pack completions and recompletions can be applied in gas-storage wells where high production rates and sand-control measures are necessary for the life of the well.

This paper provides guidelines and results associated with frac packing by

  • Demonstrating the importance of selecting completion techniques that will provide high-efficiency production from gasstorage wells.

  • Presenting case histories of frac-pack-stimulated gas-storagewell performance over a relatively long time period.

  • Comparing well performance of conventionally completedand frac-pack-completed gas-storage wells producing at high rates.

  • Providing insight into the operational aspects of frac-pack completions.

Keywords:
assembly, operator, withdrawal, completion installation and operations, injection, spe drilling, gravel pack, gal crosslinked hpg, clear lake field, completion
Subjects:
Completion Installation and Operations, Frac and pack, Hydraulic Fracturing, Perforating, Sand Control, Completion Operations
Copyright 2002, Society of Petroleum Engineers
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