Underground solution mining in salt deposits has a long – over hundred years old tradition. In recent years, the main application of this technology is in creating underground storage volumes for crude oil, gas and fuels rather, than in brine production for chemical industry, as before.
Therefore, the leaching technology was significantly modified, utilizing computer simulations and sophisticated sonar surveys, to provide creation of caverns with proper, stable shape, which can be used for storage during long years.
Underground solution mining is a very narrow specialization, distinguishing a lot from borehole exploitation of other raw resources (crude oil, gas, sulfur). There is no more than few hundreds of solution mining specialists worldwide, working in salt leaching technology.
In present situation (2006), the high prices of oil and gas, as well as uncertainty of supplies are arousing anew the interest of oil concerns in salt cavern storage – similarly as 30 years ago. And also as 30 years ago, there will be necessity to train a new generation of solution mining specialists and to transfer to them the knowledge collected up to now.
This textbook is aimed at filling the gap in the solution mining literature. Its main goal is to easily and concisely present the problems connected with the solution mining and to describe their basics.
- Spis treści
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Introduction 7
1. Outline of salt deposits geology 11
1.1. Origin of salt deposits 11
1.2. Minerals and rocks in salt deposits 12
1.3. Lithostratygraphy of salt deposits 14
1.4. Shapes of salt deposits 16
1.5. World distribution of salt deposits 18
Bibliography 22
2. Cavern location within the salt deposit 23
2.1. Geological and mining conditions for the cavern location 23
Bibliography 28
3. Drilling, construction and well completion for solution mining 29
3.1. Drilling 29
3.2. Running and cementing the casing 31
3.3. The leaching completion 34
3.4. Tightness tests 37
Bibliography 39
4. Review of solution mining technologies 40
4.1. Short description of most frequently applied leaching technologies 41
4.1.1. Shape of the mined excavations 41
4.1.2. Methods of injecting the leaching medium into the cavern and removing the brine 44
4.1.3. Development of caverns walls and methods of its modification 48
4.1.4. Cavern development - the initial cavern 50
4.2. Leaching technologies 52
4.3. Examples of solution mining systems applied in Poland to brine exploitation and storage caverns 53
Bibliography 55
5. Brine properties 56
5.1. Solubility of sodium chloride in water 56
5.2. Density of brine 59
5.3. Concentration of brine 60
5.4. Relation between brine density and concentration 61
5.5. Determining of salt content in brine 63
5.6. Industrial standards for brine 67
Bibliography 68
6. Leaching process 69
6.1. Soluble content and concentration distribution 69
6.2. Thermal effects 72
6.3. Insoluble content 74
6.4. Relation between salt production and cavern net volume 76
6.5. Leaching rate 77
6.6. Laboratory tests of the leaching rate 82
6.7. Physical models in salt blocks 84
Bibliography 86
7. Geomechanical aspects of cavern dimensioning 87
7.1. Mechanical properties of rock salt 88
7.2. Stability of excavations made in rock salt 91
7.3. Cavern dimensioning 93
7.4. Laboratory tests 95
7.5. In-situ tests 97
7.6. Other phenomena 99
Bibliography 99
8. Hydraulic aspects of solution mining 101
Bibliography 104
9. Designing of leaching technology 105
9.1. Conceptual study 105
9.2. Technical design of cavern leaching 106
9.3. Choosing of leaching technology 106
9.4. Remarks about errors in leaching technology 109
Bibliography 112
10. Computer modeling of leaching process 113
Bibliography 117
11. Monitoring of the cavern leaching process 119
11.1. Measurements and recording of leaching data 119
11.2. Technical design versus real leaching 120
11.3. Sonar surveying of cavern shape 121
11.4. Adjustment of the model parameters to sonar survey results 124
11.5. Short-term predictions for further leaching stages 126
Bibliography 126
12. Salt caverns for storage and waste disposal 127
12.1. Rock salt as a place for storage and disposal 127
12.2. Storage of usable substances 128
12.3. Examples of storage: Poland – storage of natural gas in KPMG Mogilno, storage of oil and fuels in PMRiP Gora 134
12.4. Example of disaster caused by wrong storage technology 136
12.5. Waste disposal 137
Bibliography 138
13. Solution mining impact on the surface 140
Bibliography 144
14. Caverns and wells abandonment 146
14.1. The brine volume in cavern to be abandoned 146
14.2. Why solution mined caverns cannot be tightly closed 148
14.3. Conclusions concerning cavern abandonment 150
Bibliography 151