Basic Research Needs for Geosciences - Energetics Meetings and ...

More documents

Recommendations

Info

PANEL REPORT: CHEMICAL MIGRATION PROCESSES IN GEOLOGIC MEDIAThe objective of this panel is to identify important basic science challenges that, if met, wouldgreatly enhance the reliability and scientific credibility of predictions of chemical migration ingeologic media. These science challenges target five principal areas:• Colloid migration• Coupled chemical-hydrologic processes• Complex and dynamic interactions at the mineral-water interface• Biogeochemistry• Reaction equilibria and kinetics in perturbed geochemical environmentsThe significance of each area in the overall context of chemical migration processes and specificproposed principal research directions are described in detail below.BASIC SCIENCE CHALLENGES, OPPORTUNITIES AND RESEARCH NEEDSColloids as a critical mode of radionuclide mobilityColloids, which range in size from 1 nm to 1 μm, are chemically, structurally, and temporallycomplex species that are critically important to understand as carriers of radionuclides, metalsand other contaminants in geologic systems. Because colloids exist in many forms,understanding the processes that determine their formation, speciation, atomic-level structure,and interfacial properties is necessary before their migration behavior can be modeled in naturalsystems. Advances in sampling technologies, characterization, and computational approacheswould enable acquisition of this information and lead to development of new conceptual modelsfor how colloids behave at a microscopic level. Innovation is needed in these approaches atlarger scales to enable the reliable prediction of the reactivity, fate and transport of colloidalparticles in aqueous environments. Novel sampling techniques must be implemented that allowcapture of representative colloids from natural environments without introducing artifacts.Colloids are difficult to characterize because of their size range and chemical complexity.Colloids may have ill-defined, irregular structures and variable chemical compositions.Examples of colloids include more or less thermodynamically well-defined polynuclearhydrolyzed metal species, organic macromolecules, and clays. The broad range of sizes,structures, compositions, and heterogeneous atomic positions make modeling colloids at themolecular level a particular challenge. Computational approaches require advances in treatingradionuclides, large nanoscale particles, and complex and heterogeneous species in solution andat interfaces. New reactive transport measurements at the pore, column and field scales will leadto new conceptual and mathematical models of colloid-associated contaminant transport inheterogeneous geologic environments. Scientific advancement on these fundamental issues willlead to lower uncertainty in predictive modeling of radionuclide transport, improvedperformance assessment of waste repositories, and improved engineered barriers aroundemplaced wastes.Coupled physical-chemical processes from the mineral surface to the pore scaleBreakthroughs in modeling of reactive transport processes relevant to chemical migration willoccur only by gaining fundamental understanding of coupled processes through a hierarchy ofscales.24 Basic Research Needs for Geosciences: Facilitating 21 st Century Energy Systems
PANEL REPORT: CHEMICAL MIGRATION PROCESSES IN GEOLOGIC MEDIABasic research is required to:• Develop robust multiscale, multiphase models that explicitly link mechanisms such astransport through thin films and complex reactions at mineral surfaces in differentgeochemical environments to the pore-scale and/or macroscale flow regimes• Interrogate operative submicron- to pore-scale reactive-transport processes in natural andsimulated systems through use of innovative experimental and analytical techniques for thepurpose of testing new conceptual and mathematical models.Many studies have documented orders of magnitude differences between mineral dissolutionrates measured in the laboratory and rates derived from natural weathering environments. Forexample, White and Brantley (2003) demonstrated a strong dependence of the dissolution ratesof common aluminosilicates (feldspars and biotite) on weathering “age.” Although the relativeroles of surface reactions and diffusion processes on overall reaction rates are topics of activedebate (e.g., Grambow 2006), it is clear that coupled processes influence multiple transportmechanisms and chemical reactions at grain surfaces and boundaries, and in fluid films, porethroats, and pores. Mineral reaction rates obtained from field observation and experiments applyonly to the systems for which they were measured, and for which the extent of process couplingon transport is usually unknown.In fine-grained and/or low permeability rocks (e.g., shales, bentonite, many igneous rocks), mostfluid is present in nanometer-scale fluid films and submicron-scale pores, resulting in bulkreaction and transport rates that are governed by local fluid-mineral surface environments.Transport of contaminants into these microenvironments is therefore a crucial first step leadingto immobilization on mineral surfaces or incorporation into minerals by precipitation or solidstatediffusion. Strong evidence for the role of such intergranular and intragranular processes onuranium immobilization as mineral precipitates has been documented (see sidebar on Uniquechemistry in intragranular microfractures and surface microstructures).Reactive-transport models are still in their infancy for multiphase fluids, yet multiphase systemsare ubiquitous in nature and prevalent in engineered systems designed for subsurface wastestorage. For example, documented effects of surface tension on thermodynamic properties ofaqueous species and the partial pressures of gases are not usually accounted for in macroscalemodels. In addition to processes encountered in single-phase systems, mass transfer betweenfluid phases can alter the composition of the fluids. For example, supercritical CO 2 injected intoa carbonate reservoir will displace water from the pore space, leaving brine films on mineralsurfaces. Dissolution of CO 2 into the brine films will alter their pH values and drive surfacereactions, such as carbonate dissolution and secondary mineral precipitation.The primary objective of this research direction is to demonstrate the critical role thatmicrostructural features and their associated geochemical environments play in basic coupledtransport processes. This will lead to new evaluation of the limitations of large-scale models andto development of innovative approaches for capturing effects of site-specific processes bycombining fundamental process-level models and site-specific data, and minimizingBasic Research Needs for Geosciences: Facilitating 21 st Century Energy Systems 25
Page 6 and 7: TABLE OF CONTENTSBasic Science Chal
Page 9 and 10: TABLE OF CONTENTSTechnology Impacts
Page 13 and 14: EXECUTIVE SUMMARYpurpose of linking
Page 15 and 16: INTRODUCTIONINTRODUCTIONWorldwide e
Page 17 and 18: INTRODUCTIONway into the rock forma
Page 19 and 20: PANEL REPORTSMULTIPHASE FLUID TRANS
Page 21: PANEL REPORT: MULTIPHASE FLUID TRAN
Page 24 and 25: PANEL REPORT: MULTIPHASE FLUID TRAN
Page 40 and 41: PANEL REPORT: CHEMICAL MIGRATION PR
Page 48 and 49: PANEL REPORT: SUBSURFACE CHARACTERI
Page 52: PANEL REPORT: SUBSURFACE CHARACTERI
Page 64 and 65: PANEL REPORT: MODELING AND SIMULATI
Page 80 and 81: 66 Basic Research Needs for Geoscie
Page 82 and 83: GRAND CHALLENGE: COMPUTATIONAL THER
Page 88 and 89:
GRAND CHALLENGE: COMPUTATIONAL THER
Page 90 and 91:
Page 92 and 93:
Page 94 and 95:
GRAND CHALLENGE:INTEGRATED CHARACTE
Page 96 and 97:
Page 98 and 99:
Page 100 and 101:
Page 102 and 103:
Page 104 and 105:
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
GRAND CHALLENGE: SIMULATION OF MULT
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
106 Basic Research Needs for Geosci
Page 122 and 123:
PRIORITY RESEARCH DIRECTION:MINERAL
Page 124 and 125:
Page 126 and 127:
Page 128 and 129:
PRIORITY RESEARCH DIRECTION:NANOPAR
Page 130 and 131:
Page 132 and 133:
Page 134 and 135:
Page 136 and 137:
PRIORITY RESEARCH DIRECTION:DYNAMIC
Page 138 and 139:
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
Page 146 and 147:
PRIORITY RESEARCH DIRECTION: TRANSP
Page 148 and 149:
Page 150 and 151:
Page 152 and 153:
Page 154 and 155:
PRIORITY RESEARCH DIRECTION:FLUID-I
Page 156 and 157:
Page 158 and 159:
Page 160 and 161:
PRIORITY RESEARCH DIRECTION:BIOGEOC
Page 162 and 163:
Page 164 and 165:
Page 166 and 167:
Page 168 and 169:
154 Basic Research Needs for Geosci
Page 170 and 171:
CROSSCUTTING ISSUE:THE MICROSOPIC B
Page 172 and 173:
CROSSCUTTING ISSUE:THE MICROSOPIC B
Page 174 and 175:
CROSSCUTTING ISSUE:HIGHLY REACTIVE
Page 176 and 177:
Page 178 and 179:
Page 180 and 181:
CROSSCUTTING ISSUE:THERMODYNAMICS O
Page 182 and 183:
CROSSCUTTING ISSUE:THERMODYNAMICS O
Page 184 and 185:
REFERENCESBenner, S.G., Hansel, C.M
Page 186 and 187:
REFERENCESChen, J., Hubbard, S., Pe
Page 188 and 189:
REFERENCESEnnis-King, J., Preston,
Page 190 and 191:
REFERENCESHolman, H.-Y., Perry, D.L
Page 192 and 193:
REFERENCESLi, L., and Tchelepi, H.A
Page 194 and 195:
REFERENCESNeal, A.L., Techkarnjanar
Page 196 and 197:
REFERENCESReeves, P.C., and Celia,
Page 198 and 199:
REFERENCESSteefel, C.I., DePaolo, D
Page 200 and 201:
REFERENCESZachara, J.M., Ainsworth,
Page 202 and 203:
AppendicesBasic Research Needs for
Page 204 and 205:
APPENDIX 1: TECHNICAL PERSPECTIVES
Page 206 and 207:
Page 208 and 209:
Page 210 and 211:
Page 212 and 213:
Page 214 and 215:
Page 216 and 217:
Page 218 and 219:
Page 220 and 221:
Page 222 and 223:
Page 224 and 225:
Page 226 and 227:
Page 228 and 229:
Page 230 and 231:
Page 232 and 233:
Page 234 and 235:
Page 236 and 237:
Page 238 and 239:
Page 240 and 241:
Page 242 and 243:
Page 244 and 245:
Page 246 and 247:
Page 248 and 249:
Page 250 and 251:
Page 252 and 253:
Page 254 and 255:
Page 256 and 257:
Page 258 and 259:
APPENDIX 2: WORKSHOP PROGRAMThursda
Page 260 and 261:
Basic Research Needs for Geoscience
Page 262 and 263:
Page 264 and 265:
Page 266 and 267:
Page 268 and 269:
Page 270 and 271:
Page 272 and 273:
Page 274 and 275:
Page 276 and 277:
Page 278 and 279:
Page 280 and 281:
Page 282 and 283:
Page 284 and 285:
Page 286:
APPENDIX 4: ACRONYMS AND ABBREVIATI
show all

Basic Research Needs for Geosciences - Energetics Meetings and ...

Create successful ePaper yourself

Delete template?

Save as template?