Advances for Improved Storage: Deliverability Enhancement and New Storage Facilities

摘要

Major studies completed by the U.S. Department of Energy/National Energy Technology Laboratory (NETL) have documentedor demonstrated advances for improved storagedeliverability and new storage facilities. These technologicaladvances are very important for maintaining the reliability of thenatural gas infrastructure since energy forecasts predict that theNation’s demand for natural gas is likely to exceed 30 Tcf peryear by 2015. The anticipated growth in electricity generationdemand for natural gas will require the delivery system to bere-optimized to meet larger off-peak swing loads as well as peakdayrequirements that could increase from 111 Bcf per day(1997) to 152 Bcf per day by 2015.Four new and novel fracture stimulation technologies - liquidCO2 with proppant, propellant, tip-screenout, and extreme overbalancedfracturing - were tested in eight different storage fields.In total, 29 fracture treatments were performed as part of theproject. Several of these new and novel stimulation technologiesprovided attractive deliverability enhancement results andaddressed the special concerns of gas storage operators. Threenew projects were started in the fall of 1999 to investigateimproved remedial treatment technologies.Studies of the technical and economic merits of fouradvanced storage concepts were also completed. Three of thesenew or improved storage methods can provide storage in areaswhere conventional storage is not available or does not meet therequirements of end-users. The large-scale projects, lined rockcaverns and refrigerated-mined caverns, have been shown to besuperior to LNG storage when using several cycles. A feasibilitystudy of storing gas as hydrates found that a single formation anddecomposition cycle could be achieved within 24 hours in a2.25-MMcf process. Using an advanced constitutive modeldeveloped for nuclear waste isolation in salt, the fourth studyfound that minimum working gas pressure in most existing saltcavern storage facilities can be lowered 10 percent withoutcompromising cavern stability. Extrapolating these results acrossthe salt cavern industry would result in a 17-Bcf increase instorage capacity with no changes to existing infrastructure. Afifth study, initiated in 1999, is investigating the feasibility ofstoring gas in basalt aquifers.