The elasto-plastic response of underground excavations in rock masses that satisfy the Hoek-Brown failure criterion

In this study underground hydrogen storage in various storage types (aquifers, depleted deposits of natural gas and oil, salt caverns) is examined. A road map for the implementation of underground hydrogen storage is presented. Underground hydrogen storage does not significantly differ from natural gas storage. Nevertheless, it is not yet an available and technically feasible manner of storing energy and it will not prove to be one in the near future. The lower cost of hydrogen production through electrolysis will be the decisive factor for the implementation of this method of energy storage on an industrial scale. Numerous problems and challenges in this field are presented. The fact that specific properties of gaseous hydrogen will have to be handled adequately to provide tightness during underground storage, transport and withdrawal has been noted. The choice of geological structures for underground hydrogen storage should be based on a detailed geological analysis, taking geological and engineering criteria into account. Any possibility of hydrogen escape beyond the limits of an underground storage facility should result in the rejection of the hazardous location. The factors related to the surface installations should be considered only after the selection based on geological criteria has been conducted. Geological, technological, economic, legal and social obstacles have to be overcome before the underground hydrogen storage is implemented on a full scale. As a result of the complexity of the issue coupled with the lack of experience in this kind of operations a prolonged period of studies can be expected. Any future implementations will have to be preceded by extensive studies aimed at a better understanding of the processes of hydrogen interaction with ambient rocks and the installations. Plans to reduce all the hazards involved should be prepared. These activities should proceed in well-defined time frames.

Underground hydrogen storage: Characteristics and prospects

Simulation and analysis of different adiabatic Compressed Air Energy Storage plant configurations

Development of damage and permeability in deforming rock salt

Discontinuous fatigue of salt rock with low-stress intervals

Thousands of salt caverns (100 in France alone) are being used to store hydrocarbons. This is the safest way to store large quantities of hydrocarbons: salt formations are almost perfectly impermeable, and fire or explosion is impossible underground. However, a small number of accidents (blow-out, product seepage, cavern instability) have occurred in the past. Cavern abandonment is also a concern in some cases. This paper describes several accidents and the lessons that have been drawn from them, leading to considerable improvements in storage design and operation.

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Safety of salt caverns used for underground storage: Blow out; mechanical instability; seepage; cavern abandonment

A salt cavern abandonment test

Very slow creep tests on rock samples

Thousands of caverns have been leached out from salt formations. They are used for storing a variety of fluid products ranging from compressed air and hydrogen to LPG, natural gas and crude oil, which requires that the caverns be tight. The main factors in the onset of well leakage and its prevention are discussed: fluid pressure distribution, geological environment, cementing workmanship and well architecture. The Mont Belvieu accident is described to illustrate the importance of periodic cavern testing. Test methods are discussed; apparent, corrected and actual leaks are distinguished. Factors contributing to apparent leaks are described, as are two actual in situ tests that use fuel oil and nitrogen as test fluids. It is proven that a thorough test analysis allows good estimations of actual leaks.

/pdf/tightness-tests-in-salt-cavern-wells-ebeaypmf17.pdf

Pierre Berest

Papers

Safety of salt caverns used for underground storage: Blow out; mechanical instability; seepage; cavern abandonment

A salt cavern abandonment test

Very slow creep tests on rock samples

Tightness Tests in Salt-Cavern Wells

The 1873 collapse of the Saint-Maximilien panel at the Varangeville salt mine