A gas condensate reservoir in the Appalachian Basin has been converted into a gas storage reservoir. Te results of the first storage cycle are presented. When gas is injected into a depleted gas condensate reservoir, the remaining condensate will evaporate and enrich the injected gas. The degree of mixing among the residue gas, residue liquid, and the injected gas will determine the composition of the gas in the reservoir and the liquid yield at the surface when the gas is withdrawn. The results of the first storage cycle clearly indicated that complete mixing was not achieved in the reservoir. The storage gas compositional changes, due to partial mixing with the native fluids, have both positive and negative impact on the operation of storage field. The lower liquid yields reduce the requirements for liquid handling. However, the heavier hydrocarbons remain in the reservoir longer and the liquid production is extended to a greater number of storage cycles. The liquid yields were low initially because the withdrawn gas had been in the reservoir for a short period of time. Furthermore, this gas did not come into contact with significant liquid due to liquid evaporation. The liquid yields subsequently increased up to a maximum before they declined again. The decline in liquid yields was caused by retrograde condensation in the reservoir. The storage gas compositional changes reduced the storage capacity by 12 percent. The reduction in gas capacity was economically advantageous since it reduced the base gas requirements. Finally, the results of first storage cycles were utilized to optimize the liquid recovery at the surface facilities for the subsequent cycles to prevent liquid drop out by retrograde condensation in the pipeline.

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