Columbia Gas Transmission operates two groups of natural-gas storage fields approximately 50 miles northeast ofColumbus, Ohio. The Silurian-age Clinton sandstoneformation in both fields varies significantly in thickness andreservoir quality. Although the gross Clinton interval is fairlyuniform, it can include one to three separate sand members.Reduction in storage-well performance over time dictatesthe need to periodically stimulate, or even re-stimulate thewells. Fracture stimulation is often required to restore wellperformance. The objective of the hydraulic fracturingtreatments in these wells is to obtain a short, highly conductivepropped fracture past the damaged area. Fracturing models areused to determine the optimum tip-screenout treatment designbased on individual well characteristics.Several fracturing fluids have been used in the attempt toachieve the optimum fracturing treatment. Previously, the bestresults were seen with borate-crosslinked fluids using nitrogenassist. With recent advances in fracturing-fluid technology,conventional borate-crosslinked fluids can be replaced withhigh-performance viscoelastic fluids, which reduce fluiddamage to the proppant pack and formation. The viscoelasticfluid has excellent proppant-transport properties andpredictable break times.Three wells, two in Group I and one in Group II, wereselected as candidates for fracturing with the viscoelasticfracturing fluid. Fracturing models were used to design atreatment that would result in similar fracture geometry as theborate-crosslinked fluids. This resulted in up to 40%reductions in total fluid requirements and up to 65%reductions in pad fluid volumes. All three wells were fracture-treatedwith the designs obtained from the fracture models.Fluid volumes recovered, flowing pressures, and choke sizewere all recorded during flowback and compared to valuesfrom offset wells. This paper details the properties of the viscoelasticfracturing fluid, fracture designs, and post-fracture results ofthe wells stimulated with the viscoelastic fluid.
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