characterization of deep saline aquifers in the becancour area st lawrence lowlands quebec canada implications for co2 geological storage the present paper provides a case study of the assessment of the potential for co2 storage in the deep saline aquifers of the becancour region in southern quebec this assessment was based on a hydrogeological and petrophysical characterization using existing and newly acquired core and well log data from hydrocarbon exploration wells analyses of data obtained from different sources provide a good understanding of the reservoir hydrogeology and petrophysics profiles of formation pressure temperature density viscosity porosity permeability and net pay were established for lower paleozoic sedimentary aquifers lateral hydraulic continuity is dominant at the regional scale whereas vertical discontinuities are apparent for most physical and chemical properties the covey hill sandstone appears as the most suitable saline aquifer for co2 injection storage this unit is found at a depth of more than 1 km and has the following properties fluid pressures exceed 14 mpa temperature is above 35 c salinity is about 108 500 mg l matrix permeability is in the order of 3 10 16 m2 0 3 mdarcy with expected higher values of formation scale permeability due to the presence of natural fractures mean porosity is 6 net pay reaches 282 m available pore volume per surface area is 17 m3 m2 rock compressibility is 2 10 9 pa 1 and capillary displacement pressure of brine by co2 is about 0 4 mpa while the containment for co2 storage in the becancour saline aquifers can be ensured by appropriate reservoir characteristics the injectivity of co2 and the storage capacity could be limiting factors due to the overall low permeability of aquifers this characterization offers a solid basis for the subsequent development of a numerical hydrogeological model which will be used for co2 injection capacity estimation co2 injection scenarios and risk assessment

towards the reconstruction of the shallow plumbing system of the barombi mbo maar cameroon implications for diatreme growth processes of a polygenetic maar volcano abstract understanding the mechanisms involved in the formation of maars and their diatreme growth processes has been a subject of contention while there is no direct evidence of the presence of diatremes beneath most of the young maars their existence is inferred based on the amount and type of country rocks excavated at different depths and deposited as pyroclastic ejecta around their craters properly tracing fragmented country rocks in ejecta to interpret their depths of origin and thus the depths of phreatomagmatic explosions require good and detailed information on the substrate geology that is generally lacking at many maars as an alternative this paper explores the role of juvenile components in deposits of a maar for understanding the cratering and growth of diatremes during maar forming eruptions based on field investigations pyroclast distribution componentry and grain morphology examinations this study reports on the eruptive mechanisms that led to the formation of the barombi mbo maar bmm a polygenetic maar volcano in cameroon the bmm consists of three diatremes that formed during distinct eruptive events and coalesced to produce an amalgamated maar diatreme two end member types of eruption styles from the dry magmatic to the wet phreatomagmatic explosions governed the formation of the maar in total a minimum of 0 0658 km 3 of magma dense rock equivalent corrected was ejected based on calculation by applying interpolation techniques on digital elevation models obtained from srtm30m data corrected by rock textural data collected from the field the distribution of juvenile clasts throughout the stratigraphic sequence suggests a complex subsurface eruptive process which originated probably within the uppermost part of the diatreme from the distribution and morphology of juvenile clasts in the deposits it is inferred that cratering and country rock excavation during the growth of each of the small diatremes developed mainly from shallow level explosions sometimes with lateral and vertical variations in the position of the explosion loci a prospective juvenile based conceptual model is proposed for the formation of the bmm the model suggests that during maar forming eruptions explosions taking place at a deeper position might entrain extensive amount of lithics from the mostly lithic dominated upper crater infill to deposit juvenile poor 90 vol

electrical resistivity tomography revealing the internal structure of monogenetic volcanoes 1 eruptive activity of individual monogenetic volcanoes usually lasts a few days or weeks however their short lifetime does not always mean that their dynamics and structure are simple monogenetic cones construction is rarely witnessed from the beginning to the end and conditions for observing their internal structure are hardly reached we provide high resolution electrical resistivity sections 10 m electrode spacing of three monogenetic cones from northeastern spain comparing our results to geological observations to interpret their underground continuation the 100 m maximum depth of exploration provides information on almost the entire edifices highlighting the relationships between strombolian and hydromagmatic deposits in two multiphase edifices a main observation is a column of distinct resistivity centered on the puig d adri volcano which we interpret as the eruptive conduit this method can provide valuable information on the past volcanic dynamics of monogenetic volcanic fields which has real implications for the forecast of future activity

miocene phreatomagmatic volcanism at tihany pannonian basin hungary abstract a late miocene 7 56 ma maar volcanic complex tihany maar volcanic complex tmvc is preserved in the pannonian basin and is part of the bakony balaton highland volcanic field base surge and fallout deposits were formed around maars by phreatomagmatic explosions caused by interactions between water saturated sediments and alkali basalt magma carrying peridotite lherzolite xenoliths as well as pyroxene and olivine megacrysts subsequently nested maars functioned as a sediment trap where deposition built up gilbert type delta sequences at the onset of eruption magma began to interact with a moderate amount of groundwater in the water saturated sand as eruption continued phreatomagmatic blasts excavated downward into limestones providing access to abundant karst water and deeper to sandstones and schist both providing large amount of fracture filling water at the surface this wet eruption led to the emplacement of massive tuff breccias by fall surge mudflow and gravity flow deposition the nature of the tmvc maar eruptions and their deposits appears to depend on the hydrological condition of the karst and or fracture filling aquifer which varies seasonally with rainfall and spring runoff the west and east maar volcanoes of tmvc are interpreted to represent low water input from the karst and or fracture filling aquifer summer vent whereas the east maar is interpreted to have formed when abundant karst and or fracture filling water was available spring vent

diachronous tectonic collapse of the ordovician continental margin eastern canada comparison between the quebec reentrant and st lawrence promontory the upper ordovician trenton group of southern quebec represents the last taconian foreland basin carbonate unit in the quebec reentrant prior to final collapse of laurentia s continental margin and its burial under synorogenic flysch the trenton group either conformably or unconformably overlies the black river group and is in turn conformably overlain by the utica shales the tripartite trenton carbonate unit records progressive deepening 1 very shallow to shallow subtidal 2 shallow to deep carbonate ramp and 3 shallow to deep outer shelf regional facies distribution lithotectonic elements and thickness variations indicate that the trenton shelf was dissected by extensional faults delineating blocks subsiding at various rates this scenario compares favourably with taconian foreland basin development in the middle ordovician table head group at the st lawrence promontory newfoundland a similar stratigraphic succession and tectono sedimentary history occurring 10 15 ma earlier at the s

factors controlling the internal facies architecture of maar diatreme volcanoes most if not all kimberlite pipes show a multitude of facies types which imply that the pipes were emplaced under an episodic re occurrence of eruptive phases often with inter mittent phases of volcanic quiescence the majority of these facies can be related to either the fragmentation behaviour of the magma during emplacement or changing conditions dur ing sedimentation of volcaniclastic deposits as well as their alteration and compaction after deposition an additional factor controlling pipe facies architecture is the degree of mobility of the loci of explosions in the explosion chambers of the root zone or root zones at the base of the maar diatreme volcano in a growing pipe the root zone moves downward and with that movement the overlying diatreme enlarges both in size and diameter however during the life span of the volcano the explosion chamber can also move upward backintothelower diatreme where renewedexplosionsresult inthedestructionofolderdepositsandtheirstructures nextto vertical shifts of explosion chambers the loci of explosions can also move laterally along the feeder dyke or dyke swarm this mobility of explosion chambers results in a highly com plex facies architecture in which a pipe can be composed of several separate root zones that are overlain by an amalgam ated crosscutting diatreme and maar crater with several lobes pipe complexity is amplified by periodic changes of the fragmentation behaviour and explosivity of kimberlite mag ma recent mapping and logging results of canadian and african kimberlite pipes suggest that kimberlite magma frag mentation ranges from highly explosive with abundant entrained country rock fragments to weakly explosive spatter like production with scarce xenoliths on occasions spatter may even reconstitute and form a texturally coherent deposit on the crater floor in addition ascending kimberlite magma can pass the loci of earlier fragmentation events in the root zone and intrudes as coherent hypabyssal kimberlite dykes in high pipe levels or forms extrusive lava lakes or flows on the crater floor or the syneruptive land surface respectively this highly variable emplacement behaviour is typical for basaltic maar diatreme volcanoes and since similar deposits can also be found in kimberlites it can be concluded thatalsothevolcanologicalprocessesleadingtothesedeposits are similar to the ones observed in basaltic pipes

fracturing induced release of radiogenic 4he and 234u into groundwater during the last deglaciation an alternative source to crustal helium fluxes in periglacial aquifers external 4he sources have been invoked to explain 4he concentrations in groundwater greater than those expected from in situ u and th production in a fractured aquifer of ordovician age located in the st lawrence lowlands quebec canada 4he concentrations of up to 4 48 x 10 5 cm3 stp gh20 1 were measured such concentrations are ca 1000 times higher than would be expected from in situ production a concomitant increase in 4he concentration and 234u 238u activity ratio is shown suggesting a common release process in groundwater for 234u and 4he this process has tentatively been identified as glaciation induced rock fracturing following the laurentide ice sheet retreat the resulting increase in exposed grain surface facilitates 234u release by recoil and that of radiogenic 4he by diffusion using a model of helium diffusion from a spherical grain it is shown that rock fracturing facilitated the release of accumulated 4he at rates ranging from 4 2 x 10 10 cm3stp gh20 1 yr 1 to 1 06 x 10 8 cm3stp gh20 1 yr 1 these release rates are between 1 000 and 30 000 times higher than the local u and th steady state production rate of 3 5 1 4 x 10 13 cm3stp grock 1 yr 1 integration of 4he release rates over time yields a radiogenic 4he concentration of between 3 85 x 10 6 cm3stp gh20 1 and 7 12x 10 5 cm3stp gh20 1 in the range of concentrations measured in the st lawrence lowlands fractured aquifers results support the occurrence of a local radiogenic helium source to explain the excesses measured in groundwater without requiring a significant external he crustal flux

geochemical and geologic study of the volcano sedimentary sulfide orebody of la zarza province of huelva spain the la zarza orebody containing some 100 000 000 metric tons of ore is one of the three most important ones in the huelva province spain it overlies the second phase of acid volcanic activity within a volcanic sedimentary succession of visean age the stratigraphically lower part of the orebody consists of a finely bedded polymetallic ore overlain by a massive pyrite facies 90 of the orebody which is in turn covered by a more or less discontinuous resedimented pyritic capping the distribution of the metals within the orebody differs from the classical pattern in la zarza the pb zn contents are greater in the lower parts of the deposit than in the upper parts while cu is more or less independent of other metals and shows a typical basal concentration in a breccia type ore and stockwork restricted to a small area the foot and hanging walls are made up of acid epiclastic rocks and pelites and are practically without lavas however it is possible to recognize volcanic eruption centers some kilometers to the east of the mine below the sulfide orebody an intensively chloritized zone some hundred meters in diameter most probably represents a hydrothermally altered pipe overall the wall rocks are characterized by their enrichment in mg and impoverishment in na and si within the chloritized pipe an overall lowering of alkali values is accompanied by a strong increase in mg as analyzed by spectrometry and atomic absorption the distribution of trace elements in wall rocks and ore cu pb zn v co cr and mn tends to show the lack of consanguinity between ore and wall rocks on the one hand and the reasonably clear association between the ore and a late volcanic hydrothermalism on the other furthermore the high co ni ratios correspond to a hot sulfide deposition there is no distinct dispersion halo except for the presence of some disseminated sulfides around and very close to the ore the distribution of the elements and their correlations differ betweeen the ore and wall rocks although it lies on a volcanic sedimentary footwall the la zarza orebody is thus rooted in a hydrothermally altered pipe nevertheless the migration of magnesium and other metals is unconnected and there is evidence of a certain independence among the different metals above all in the case of copper

simulation of the hydraulic fracturing process of fractured rocks by the discrete element method this work presents a series of solid fluid coupled simulations of a natural fractured limestone sample the aim of this paper is to investigate the effects of the fluid injection on its mechanical behaviour on the particle scale a detailed study of the influence of the fluid flow on the microstructure of the virtual model including its internal stress state the fracture initialization and propagation and also the interactions between the existing fracturing networks and the new hydraulically induced fractures has been performed the results show that the change of the angle of the natural fracture alters the internal stress pattern of the model concluding that for fractures between 15 and 45 the stress regime below the fracture is always higher than the one related with the fractures between 45 and 90 furthermore the propagation of cracks has also been affected by the fracture angle where for fractures below 45 the cracks tend to propagate downwards and travelling mostly as a group of cracks in contrast for fractures above 45 easier upwards movement of the cracks and the formation of clusters that stray from the main volume of cracks are observed the overall fracture growth is in agreement with what conventional theory generally states where a hydraulic fracture is extended along the direction of the maximum compressive principal stress however the magnitude of this observation was restricted by the sample dimensions due to increased computational time for larger samples finally the relationship between the important cracking events abrupt increases of microcracks and the energy release within the model confirms the postulate that bond breakage causes further movement of particles and therefore increases the internal kinetic energy

screening and ranking of sedimentary basins for sequestration of co2 in geological media in response to climate change sedimentary basins are suitable to different degrees for co2 geological sequestration as a result of various intrinsic and extrinsic characteristics of which the geothermal regime is one of the most important warm basins are less favorable for co2 sequestration than cold basins because of reduced capacity in terms of co2 mass and because of higher co2 buoyancy which drives the upward co2 migration a set of 15 criteria with several classes each has been developed for the assessment and ranking of sedimentary basins in terms of their suitability for co2 sequestration using a parametric normalization procedure a basin s individual scores are summed to a total score using weights that express the relative importance of different criteria the total score is ranked to determine the most suitable basin or region thereof for the geological sequestration of co2 the method is extremely flexible in that it allows changes in the functions that express the importance of various classes for any given criterion and in the weights that express the relative importance of various criteria examples of application are given for canada s case and for the alberta basin in canada

present day stress analysis of the st lawrence lowlands sedimentary basin canada and implications for caprock integrity during co2 injection operations abstract a geomechanical analysis of the st lawrence lowlands sedimentary basin is important to reliably estimate the maximum sustainable fluid pressures for co 2 injection that will not reactivate pre existing faults in the caprock thereby inducing a breeched co 2 reservoir this requires the determination of prevailing stresses orientations and magnitudes fault and fractures geometries and rock strengths the average maximum horizontal stress orientation s hmax is estimated n59 e 20 in the st lawrence lowlands the stress orientations were obtained from stress induced wellbore breakouts inferred from four arm dipmeter caliper data in 17 wells these wellbore failure features are confined to paleozoic lithological units of the st lawrence platform succession and frontal thrusts of the quebec appalachians at depths from 250 m to 4 km our results are consistent with the regional ne sw s hmax stress orientation trend that is generally observed in eastern canada and the u s the stresses pressure gradients estimated for the st lawrence lowlands depths hmin 20 5 3 kpa m s v 25 6 kpa m s hmax 40 7 5 kpa m pore pressure p p 9 8 kpa m indicating a strike slip stress regime s hmin v hmax the high angle ne sw regional faults and fractures in the paleozoic sedimentary succession and the grenvillian basement are oblique to the s hmax stress orientations 10 to 36 and could be reactivated slip tendency 0 34 to 0 58 under the present day stress field if fluid pressures exceeded the critical threshold further refinement of regional geomechanical model is required to estimate the maximum sustainable injection pressure necessary for shear reactivation along the regional faults the regional pore pressure stress coupling ratio under assumed parameters is about 0 5 0 65 and may contribute to reduce the risk of shear reactivation of faults and fractures the maximum sustainable p p that would not cause opening of vertical tensile fractures during co 2 operations is about 18 5 20 mpa for the depth of 1 km

non isothermal modeling of co2 injection into saline aquifers at a low temperature to investigate the effects of temperature on the co2 storage in the deep saline aquifers we set up a 2 d non isothermal numerical model with simulating the co2 injection into the aquifers at a low temperature the evolution of the co2 plume and the temperature in the aquifer were studied and using temperature signal to monitor the arrival of co2 plume was also evaluated in addition the deviance of the isothermal model was analyzed the results show when the cold co2 is injected into the aquifers the aquifer can be divided into three zones in the direction away from the injection well during the injection period temperature drop zone temperature transition zone and temperature rise zone the temperature rise can reach approximately 1 c in the temperature rise zone during the injection period which should be enough for the temperature sensor to detect the arrival of the co2 plume however the value of the temperature rise reduces with distance from the injection well consequently we indicate that it is not suitable to monitor the long term migration of the co2 plume using temperature signal especially after the injection stops the initial formation temperature strongly affects the evolution of the co2 plume and the temperature distribution after the co2 injection not only the storage is safer but also using temperature signal to monitor co2 plume is more feasible in the cold aquifer the deviance of the isothermal model is small in the mass fraction of dissolved co2 and the arrival time of co2 plume throughout the simulation however the deviance of pressure buildup is great and increases with time up to 15 during the injection period the non isothermal model is necessary to accurately assess the pressure buildup around the injection well during the co2 injection period

experimental craters formed by single and multiple buried explosions and implications for volcanic craters with emphasis on maars 1 craters at many volcanoes including most maars are formed by multiple subsurface explosions experiments compared the crater formed by a single large buried explosion with craters formed by multiple explosions with the same cumulative energy explosive charges were detonated in pads composed of layered aggregates in three configurations 1 a single large charge buried near its optimal crater excavation depth 2 three charges each with 1 3 the energy of the first one buried at approximately the same depth with respect to the original pad surface 3 the same three charges buried successively deeper final crater size in the multiple explosion cases is not a good indicator of the energy of individual explosions however crater morphology and ejecta volume and distribution can be good indicators of explosion energy and depth these results directly impact the estimate of the energy released by past maar eruptions and future hazard assessments

grain size distribution of volcaniclastic rocks 1 a new technique based on functional stereology the power of explosive volcanic eruptions is reflected in the grain size distribution and dispersal of their pyroclastic deposits grain size also forms part of lithofacies characteristics that are necessary to determine transport and depositional mechanisms responsible for producing pyroclastic deposits however the common process of welding and rock lithification prevents quantification of grain size by traditional sieving methods for deposits in the rock record here we show that functional stereology can be used to obtain actual 3d volume fractions of clast populations from 2d cross sectional images tests made on artificially consolidated rocks demonstrate successful correlations with traditional sieving method we show that the true grain size distribution is finer grained than its representation on a random 2d section our method allows the original size of vesicular pumice clasts to be estimated from their compacted shapes we anticipate that the original grain size distribution of welded ignimbrites can also be characterized by this method our method using functional stereology can be universally applied to any type of consolidated weakly to non deformed clastic material regardless of grain size or age and therefore has a wide application in geology

3h 3he 14c and u th he groundwater ages in the st lawrence lowlands quebec eastern canada abstract this study attempts to place constraints on groundwater residence times using helium isotopes and 14c of a regional groundwater flow system the becancour river watershed located midway between montreal and quebec city quebec canada this densely populated region is one of the main targets for shale gas exploitation in eastern canada for this reason this watershed has been the focus of a detailed aquifer study to gain a better understanding of groundwater resources both in terms of availability and quality in the current study noble gases were sampled and analyzed in twenty eight wells from a quaternary granular aquifer and a regional bedrock aquifer of ordovician age tritium 3h and radiocarbon a14c activities were measured on selected wells helium isotopic ratios 3he 4he r normalized to that of the atmosphere ra 1 386 10 6 range from r ra 0 039 0 003 to 3 109 0 065 the helium isotopic signatures point to the presence of three water bodies 1 modern infiltration water with nearly atmospheric helium isotopic ratio and little post bomb tritium recharging the shallower granular aquifer 2 mid 50s tritium rich water slightly mineralized and 3 an older water component rich in terrigenic helium flowing in from the bedrock fractured aquifer uncorrected 14c ages range from 15 ka to modern 14c is affected by several dead carbon reservoirs related to carbonate dissolution cations exchange oxidation of organic matter and methanogenesis adjusted 14c ages calculated with netpath range from 7 ka to modern older 14c ages correspond to the end of the regional re organization of the hydrological system following deglaciation and isostatic rebound noble gas recharge paleotemperatures are 4 9 c colder than the present temperatures although no clear relation with ages has been found the relationship between the helium isotopic ratios and 14c ages suggests that the regional bedrock aquifer is affected by mixing between these three water sources calculated u th 4he ages can be partially explained by in situ production of 4he in the aquifer rock and the addition of a radiogenic helium source external to the aquifer calculated minimum helium fluxes of 1 0 10 8 to 1 8 10 7 cm3 stp cm 2 yr 1 are tens to hundreds of times lower than the average continental crust flux of 3 3 10 6 cm3 stp cm 2 yr 1 suggesting local sources possibly from production of radiogenic helium in the shale gas formations underlying the studied aquifers the occurrence of old groundwater in this aquifer system clearly limits the renewable resource and increases the risk of overexploitation in the case of increased use or in the case of pollution from different sources

effects of in situ conditions on relative permeability characteristics of co2 brine systems carbon dioxide capture and geological storage ccgs is an emerging technology that is increasingly being considered for reducing greenhouse gas emissions to the atmosphere deep saline aquifers provide a very large capacity for co2 storage and unlike hydrocarbon reservoirs and coal beds are immediately accessible and are found in all sedimentary basins proper understanding of the displacement character of co2 brine systems at in situ conditions is essential in ascertaining co2 injectivity migration and trapping in the pore space as a residual gas or supercritical fluid and in assessing the suitability and safety of prospective co2 storage sites because of lack of published data the authors conducted a program of measuring the relative permeability and other displacement characteristics of co2 brine systems for sandstone carbonate and shale formations in central alberta in western canada the tested formations are representative of the in situ characteristics of deep saline aquifers in compacted on shore north american sedimentary basins the results show that the capillary pressure interfacial tension relative permeability and other displacements characteristics of co2 brine systems depend on the in situ conditions of pressure temperature and water salinity and on the pore size distribution of the sedimentary rock this paper presents a synthesis and interpretation of the results

fossil brines preserved in the st lawrence lowlands quebec canada as revealed by their chemistry and noble gas isotopes abstract brines in cambrian sandstones and ordovician dolostones of the st lawrence lowlands at becancour quebec canada were sampled for analysis of all stable noble gases in order to trace their origin and migration path in addition to quantifying their residence time major ion chemistry indicates that the brines are of na ca cl type possibly derived from halite dissolution 87 sr 86 sr ratios and ca excess indicate prolonged interactions with silicate rocks of the proterozoic grenville basement or the cambrian potsdam sandstone the brines constrain a 2 3 contribution of mantle 3 he and large amounts of nucleogenic 21 ne and 38 ar and radiogenic 4 he and 40 ar 4 he 40 ar and 21 ne 40 ar ratios corrected for mass fractionation during incomplete brine degassing are identical to their production ratios in rocks the source of salinity halite dissolution plus the occurrence of large amounts of 40 ar in brines constrain the residence time of becancour brines as being older than the cretaceous evaporites in the st lawrence lowlands likely existed only during devonian silurian time brines might result from infiltration of devonian water leaching halite penetrating into or below the deeper cambrian ordovician aquifers during the devonian the basin reached temperatures higher than 250 c allowing for thermal maturation of local gas prone source rocks utica shales and possibly facilitating the release of radiogenic 40 ar into the brines the last thermal event that could have facilitated the liberation of 40 ar into fluids and contributed to mantle 3 he is the cretaceous monteregian hills magmatic episode for residence times younger than the cretaceous it is difficult to find an appropriate source of salinity and of nucleogenic radiogenic gases to the becancour brines

discussion on the paper of p moller et al geochemical proximity indicators of massive sulfide mineralization in the iberian pyrite belt and the east pontic metallotect

evaluating the geothermal heat pump potential from a thermostratigraphic assessment of rock samples in the st lawrence lowlands canada the installation cost and the performance of geothermal heat pump systems are influenced by the thermal state and properties of the subsurface the ground ability to transfer heat described by thermal conductivity is a dominant factor affecting the favorability of closed loop ground heat exchangers installed in vertical boreholes a study that aimed at evaluating the geothermal heat pump potential by mapping the thermal conductivity of rock sequences was therefore performed for the st lawrence lowlands sedimentary basin in canada thermal conductivity was measured in the laboratory on rock samples collected in outcrops and used to complete design calculations of a geothermal system with a single borehole results allowed the definition of thermostratigraphic units that can be linked to depositional environments basal quartz rich sandstones formed in a rift environment show a high geothermal potential overlying dolomites argillaceous limestones and shales deposited in a passive margin evolving to a foreland basin exhibit a transition toward the top from high to low geothermal potential upper turbidites and molasses have a moderate geothermal potential the thermal conductivity of the thermostratigraphic units is dominantly influenced by the mineralogy of the sedimentary rocks understanding their origin is a key to improve geothermal resource assessment and system design to anticipate new installations in the area

site characterization for co 2 geologic storage and vice versa the frio brine pilot texas usa as a case study careful site characterization is critical for successful geologic storage of carbon dioxide co2 because of the many physical and chemical processes impacting co2 movement and containment under field conditions traditional site characterization techniques such as geological mapping geophysical imaging well logging core analyses and hydraulic well testing provide the basis for judging whether or not a site is suitable for co2 storage however only through the injection and monitoring of co2 itself can the coupling between buoyancy flow geologic heterogeneity and history dependent multi phase flow effects be observed and quantified co2 injection and monitoring can therefore provide a valuable addition to the site characterization process additionally careful monitoring and verification of co2 plume development during the early stages of commercial operation should be performed to assess storage potential and demonstrate permanence the frio brine pilot a research project located in dayton texas usa is used as a case study to illustrate the concept of an iterative sequence in which traditional site characterization is used to prepare for co2 injection and then co2 injection itself is used to further site characterization efforts constrain geologic storage potential and validate understanding of geochemical and hydrological processes at the frio brine pilot in addition to traditional site characterization techniques co2 movement in the subsurface is monitored by sampling fluid at an observation well running co2 saturation sensitive well logs periodically in both injection and observation wells imaging with crosswell seismic in the plane between the injection and observation wells and obtaining vertical seismic profiles to monitor the co2 plume as it migrates beyond the immediate vicinity of the wells numerical modeling plays a central role in integrating geological geophysical and hydrological field observations

the effect of pre existing craters on the initial development of explosive volcanic eruptions an experimental investigation most volcanic eruptions occur in craters formed by previous activity the presence of a crater implies specific confinement geometries variably filled by loose fragmental deposits which are expected to exert a strong yet poorly studied control on the violent gas expansion that drives the eruption here we analyze patterns of ejection from buried explosions in analog experiments in order to investigate how the presence of a crater and changes in explosion depth and intensity may affect the formation of eruptive ejecta jets results show that scaled depth charge burial depth divided by the cubic root of charge energy controls the velocity and partly spread angle of eruptive jets independently of the presence of a pre existing crater conversely for a fixed scaled depth the presence of a pre existing crater limits the development of a laterally expanding annulus of the jet these results are directly applicable to interpretation of volcanic explosions key points analysis of ejection patterns from intra and extra crater buried explosions velocity and spread angle of ejecta jet are sensitive to explosion scaled depth radially expanding annulus of the jet is sensitive to pre existing crater

processes controlling 234u and 238u isotope fractionation and helium in the groundwater of the st lawrence lowlands quebec the potential role of natural rock fracturing abstract the goal of this study is to explain the origin of 234 u 238 u fractionation in groundwater from sedimentary aquifers of the st lawrence lowlands quebec canada and its relationship with 3 he 4 he ratios to gain insight regarding the evolution of groundwater in the region 234 u 238 u activity ratios or 234 u 238 u act were measured in 23 groundwater samples from shallow quaternary unconsolidated sediments and from the deeper fractured regional aquifer of the becancour river watershed the lowest 234 u 238 u act 1 14 0 01 was measured in ca hco 3 type freshwater from the quaternary shallower aquifer where bulk dissolution of the carbonate allows u to migrate into water with little 234 u 238 u isotopic fractionation the 234 u 238 u act increases to 6 07 0 14 in na hco 3 cl type groundwater preferential migration of 234 u into water by recoil is the underlying process responsible for this isotopic fractionation an inverse relationship between 234 u 238 u act and 3 he 4 he ratios has been observed this relationship reflects the mixing of newly recharged water with 234 u 238 u act close to the secular equilibrium and containing atmospheric tritiogenic helium and mildly mineralized older water 14 c ages of 6 6 kyrs with 234 u 238 u act of 6 07 and large amounts of radiogenic 4 he in excess of the steady state amount produced in situ the simultaneous fractionation of 234 u 238 u act and the addition of excess 4 he could be locally controlled by stress induced rock fracturing this process increases the surface area of the aquifer matrix exposed to pore water from which produced 4 he and 234 u can be released by recoil and diffusion this process would also facilitate the release of radiogenic helium at rates greater than those supported by steady state u th production in the rock consequently sources internal to the aquifers could cause the radiogenic 4 he excesses measured in groundwater

occurrence and resource evaluation of the subsurface high k brines in the pingluoba brine bearing structure in western sichuan basin in the western sichuan basin of china occurs an anticline in which high k brines are found in the carbonate rocks of the middle triassic leikoupo group the brine bearing formation is at depth ranging from 4 465 to 4 565 m and the brines are enriched in a fault zone in the anticline the pl4 well tapping the brine bearing formation flows brines having tds of 348 392 377 27 g l k contents of 48 95 53 267 g l and b contents of 4 994 g l the tds of the brines are close to those of the yellow sea water and the south china sea water when evaporated to the stage of epsomite precipitation the hydraulic head of the high k brines in the pl4 well tapping the brine bearing formation is calculated as high as 7 564 m and is 3 049 m above the land surface a 3d numerical model is used to simulate the flow of the brines under the condition of exploitation and prediction calculation of the exploitation of the pl4 well is also performed when the hydraulic head of the brines in the pl4 well is dropped to the land surface and to a depth of about 1 000 m below the land surface the exploitable brine resources of the well are estimated as approximately 1 1 106 and 3 8 106 m3 respectively

geochemical proximity indicators of massive sulphide mineralization in the iberian pyrite belt and the east pontic metallotect a comparative lithogeochemical study of mainly surface rocks of the iberian pyrite belt volcanic sedimentary sequence and the east pontic metallotect volcanic island arc system with few intercalations of marine sediments has been performed in order to find facies independent proximity indicators of massive sulphide mineralizations as sb tl and na seem to be the most promising indicator elements for primary hydrothermal exhalation and or alteration haloes the size of the alteration haloes largely depends on the permeability of the country rocks and is best defined by ratios such as as na sb na and tl na