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This paper discusses the effect of completion interval on aquifer storage operations. The study was performed using a single-well, two-dimensional reservoir simulator model.
Results are presented for two reservoir geometries, a homogeneous and a highly stratified heterogeneous reservoir model. For both geometries, the effect of completion interval upon such parameters as water arrival time, injectivity and productivity indices, and gas bubble thickness were studied for two different rate schedules. Results showed that completion interval did not affect bubble thickness for the homogeneous model, but did show some effect for the heterogeneous model. For both models the depth and length of completion interval did affect such parameters as water arrival time, water parameters as water arrival time, water cut and productivity indices.
Well completion intervals and depths used in aquifer storage operations frequently consist of five or ten feet perforated intervals located immediately below the caprock. In some cases the gas bubble thickness as estimated from neutron logs seems to stabilize or at least grow very little from year to year when thickening would be expected due to gravity drainage and/or inventory growth during the early life of the storage operation.