CO2 SEQUESTRATION IN SALINE AQUIFER: GEOCHEMICAL MODELING, REACTIVE TRANSPORT SIMULATION AND SINGLE-PHASE FLOW EXPERIMENT by BINIAM ZERAI Submitted in partial fulfillment of the requirements For the degree of Doctor of Philosophy Dissertation Advisors: Dr. B. Saylor and Dr. J. Kadambi Department of Geological Sciences CASE WESTERN RESERVE UNIVERSITY January, 2006 CASE WESTERN RESERVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the dissertation of ______________________________________________________ candidate for the Ph.D. degree *. 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Dedicated to My family TABLE OF CONTENTS TABLE OF CONTENTS………………………………………………............................. i LIST OF TABLES……………………………………………………….......................... v LIST OF FIGURES...……………………………………………………………………vii ACKNOWLEDGEMENTS…………………………………………….......................... xii NOMENCLATURE……………………………………………………. .......................xiii ABSTRACT…………………………………………………………….......................xviii INTRODUCTION……………………………………………………… .......................... 1 PART I GEOCHEMICAL MODELING AND REACTIVE TRANSPORT SIMULATION CHAPTER 1: INTRODUCTION AND BACKGROUND 1.1. Introduction............................................................................................................ 6 1.2. Disposal in Geological Formation....................................................................... 10 1.3. Why Saline Aquifers............................................................................................ 12 1.4. Purpose and Objective of Study .......................................................................... 13 CHAPTER 2: MECHANISM FOR AQUIFER STORAGE OF CO2 AND THE GEOLOGY OF ROSE RUN SANDSTONE 2.1. Mechanism for Aquifer Storage of CO2 .............................................................. 16 2.1.1. Hydrodynamic Trapping........................................................................... 17 2.1.2. Solubility Trapping ................................................................................... 21 2.1.3. Mineral Trapping ...................................................................................... 23 2.2. Geologic Reservoir - Rose Run Sandstone.......................................................... 27 2.3. Structure and Hydrologic Parameters.................................................................. 30 2.4. Rose Run Brine Chemistry .................................................................................. 31 i CHAPTER 3: CO2 SOLUBILITY MODELS 3.1. Introduction.......................................................................................................... 33 3.2. CO2 Solubility Modeling ..................................................................................... 34 3.2.1. PG-CSM.................................................................................................... 36 3.2.2. DS-CSM.................................................................................................... 37 3.2.3. SP-CSM .................................................................................................... 41 3.2.4. Xu-CSM.................................................................................................... 42 3.2.5. MRK-CSM................................................................................................ 44 3.3. Modeling of CO2 Solubility................................................................................. 46 3.4. Comparison with Experimental Data................................................................... 48 3.5. Intermodel Comparison of CO2 Solubility Model............................................... 53 3.6. Discussion............................................................................................................ 57 3.7. Concluding Remark............................................................................................. 61 CHAPTER 4: BATCH GEOCHEMICAL MODELING 4.1. Introduction.......................................................................................................... 63 4.2. Geochemists’ Workbench.................................................................................... 64 4.3. Rose Run Rock Assemblage................................................................................ 67 4.4. Brine Chemistry................................................................................................... 68 4.5. Rate Constants ..................................................................................................... 69 4.6. Fugacity of CO2 ................................................................................................... 70 4.7. Reactive Surface Area ......................................................................................... 71 4.8. Activity Coefficients............................................................................................ 73 4.9. Thermodynamic Database ................................................................................... 73 CHAPTER 5: RESULTS AND DISCUSSION ON GEOCHEMICAL MODELING 5.1. Computer Simulation – GWB ............................................................................. 74 5.1.1. Equilibrium Modeling............................................................................... 74 5.1.2. Path of Reaction........................................................................................ 80 5.1.3. Kinetic Modeling ...................................................................................... 83 5.2. Discussion............................................................................................................ 90 5.3. Recommendations and Concluding Remarks...................................................... 96 CHAPTER 6: REACTIVE TRANSPORT CODE DEVELOPMENT 6.1. Introduction.......................................................................................................... 99 6.2. Brief Assessment of Existing Codes.................................................................. 100 6.3. Reactive Transport Modeling ............................................................................ 103 6.4. Conceptual Model.............................................................................................. 104 6.5. Theoretical Background..................................................................................... 105 6.6. Chemical, Hydrological and Physical Parameters............................................. 106 ii 6.6.1. Chemical Parameters and Thermodynamic Database............................. 107 6.6.2. Hydrological and Physical Parameters ................................................... 120 6.7. CO2 Solubility Models....................................................................................... 121 6.8. Mathematical Equations .................................................................................... 122 6.8.1. Flow and Transport................................................................................. 122 6.8.2. Chemical Reaction.................................................................................. 127 6.8.3. Integral Finite Difference Discretization ................................................ 130 6.9. Solution Method ................................................................................................ 135 CHAPTER 7: REACTIVE TRANSPORT SIMULATION RESULTS 7.1. Introduction........................................................................................................ 138 7.2. Rose Run Sandstone and CO2 Solubility Model ............................................... 139 7.2.1. CO2 Saturation, Pressure and pH............................................................ 140 7.2.2. Fugacity, CO2 Solubility and Free CO2 .................................................. 144 7.2.3. Mineral Precipitation and Dissolution .................................................... 147 7.2.4. Porosity Change and CO2 uptake............................................................ 157 7.3. Carbonate Aquifer ............................................................................................. 160 7.4. Silicate Aquifer.................................................................................................. 161 7.5. Sensitivity Analysis ........................................................................................... 166 7.5.1. Temperature and Pressure....................................................................... 168 7.5.2. Salinity and Reaction Rate...................................................................... 171 7.6. Concluding Remark........................................................................................... 175 CHAPTER 8: DISCUSSIONS AND CONCLUSIONS 8.1. Discusion ........................................................................................................... 176 8.2. Conclusion ......................................................................................................... 185 8.3. Future Work......................................................................................................