Geomechanical Analysis and Design Considerations for Thin-Bedded Salt Caverns
The bedded salt formations located throughout the United States are layered and interspersed with non-salt materials such as anhydrite, shale, dolomite and limestone. The salt layers often contain significant impurities. GRI and DOE have initialized this research proposal in order to increase the gas storage capabilities by providing operators with improved geotechnical design and operating guidelines for thin bedded salt caverns. Terralog has summarized the geologic conditions, pressure conditions, and critical design factors that may lead to: (1) Fracture in heterogeneous materials; (2) Differential deformation and bedding plane slip; (3) Propagation of damage around single and multiple cavern; and (4) Improved design recommendations for single and multiple cavern configurations in various bedded salt environments. The existing caverns within both the Permian Basin Complex and the Michigan and Appalachian Basins are normally found between 300 m to 1,000 m (1,000 ft to 3,300 ft) depth depending on local geology and salt dissolution depth. Currently, active cavern operations are found in the Midland and Anadarko Basins within the Permian Basin Complex and in the Appalachian and Michigan Basins. The Palo Duro and Delaware Basins within the Permian Basin Complex also offer salt cavern development potential. Terralog developed a number of numerical models for caverns located in thin bedded salt. A modified creep viscoplastic model has been developed and implemented in Flac3D to simulate the response of salt at the Permian, Michigan and Appalachian Basins. The formulation of the viscoplastic salt model, which is based on an empirical creep law developed for Waste Isolation Pilot Plant (WIPP) Program, is combined with the Drucker-Prager model to include the formation of damage and failure. The Permian salt lab test data provided by Pfeifle et al. 1983, are used to validate the assumptions made in the material model development. For the actual cavern simulations two baseline models are developed for single and multiple caverns, respectively. Different parameters that affect damage propagation and deformation of salt cavern, such as cavern pressure, operating conditions, cavern height/diameter ratio, overburden stiffness and roof thickness are analyzed and the respective results summarized. For multiple horizontal caverns numerical models are developed to determine the cavern interaction and the minimum safe center to center distance. A step by step methodology for operators to assess critical cavern design parameters for thin bedded salt formations is also presented.
- Research Organization:
- Terralong Technologies USA
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FC26-03NT41813
- OSTI ID:
- 850502
- Country of Publication:
- United States
- Language:
- English
Similar Records
Preliminary feasibility study of the coal-bed methane resource in Pennsylvania
Thermo-mechanical Modelling of Pebble Beds in Fusion Blankets and its Implementation by a Return-Mapping Algorithm