the effect of carbonate cementation on permeability heterogeneity in fluvial aquifers an outcrop analog study abstract spatial variations in permeability have been widely recognized as a dominant control on solute transport and petroleum migration outcrop studies are one means of improving our understanding of the nature of permeability heterogeneity and the underlying geologic controls to date these studies have either neglected the importance of cementation or investigated only the modern cemented permeability without explicitly considering how cementation has affected permeability two outcrops of channel sand deposits in the plio pleistocene sierra ladrones formation new mexico are investigated to quantify 1 the effect of cementation on permeability at a given location and 2 the patterns of cementation and their impact on permeability heterogeneity we analyzed approximately 400 spatially located samples 10 cm 3 each from the two outcrops cementation is typically weak to moderate filling less than 60 of the original pore space permeability and cement content are bimodally distributed and negatively correlated permeability reduction is investigated by measuring modern permeability minus cement permeability minus cement porosity and volumetric cement content permeability is reduced locally by up to three orders of magnitude by combining models of permeability for uncemented sediments and cemented sediments we derive a model of cemented permeability k c that depends primarily on three factors uncemented permeability k u original porosity and cement fraction our results suggest that accounting for porosity reduction only may result in an overestimation of k c conversely accounting for porosity reduction increased specific surface area and increased tortuosity appears to result in an underestimation of k c accounting for porosity reduction and increased specific surface area provide the best estimate of k c cementation is highly variable spatially and is poorly correlated with lithofacies variogram analysis of cementation and permeability indicates that the spatial distribution of cementation is the dominant control on the permeability correlation structure the spatially variable cementation also results in an order of magnitude increase in the variance of log permeability applying stochastic models of effective flow and transport properties to the results of this study suggest that cementation has a relatively small effect on effective permeability but can potentially increase dispersivity by two orders of magnitude

structure of the crust and upper mantle beneath the great valley and allegheny plateau of eastern pennsylvania 2 gravity modeling and migration of wide angle reflection data linear inversion of p composites for three different profiles suggests that the lower crust beneath eastern pennsylvania consists of material with high averaged p wave velocities 6 8 7 5 km s compared with 6 4 7 1 km s for most crustal models derived for surrounding areas within the appalachians and the grenville province of the canadian shield interpretations of these velocities in terms of rock type are limited by the low resolving power of the data and by the nonuniqueness in inferring rock type from p wave velocity alone the high averaged p wave velocities could be associated with substantial volumes of mafic rock perhaps emplaced by underplating or with high grade metamorphic assemblages of intermediate composition and sedimentary origin similar to those found in the ivrea zone in northern italy because of the sparseness of the s wave data averaged shear wave velocities are not well enough resolved over most depth ranges to distinguish among the different compositional models computations of gravity anomalies for two dimensional models using various linear velocity density relations however suggest that at least part of the crust beneath the scranton gravity high is mafic moreover if the entire basement section beneath this anomaly consists of mafic material then the gravity studies indicate that the lower crust beneath the great valley must be mafic as well migrated shot gathers show a concentration of reflectors at depths between 35 and 45 km a result that is controlled in part by the limited range of offsets used but that is also consistent with recent observations of a highly reflective lower crust reflections that are migrated to depths within the uppermost mantle could be multiples or primary reflections from upper mantle layering although the data are rather sparse the interpretation of these later arrivals as primary reflections is supported by their small ray parameters which suggests that they are not converted phases and by their large relative amplitudes which suggests that they are not multiples layering within the upper mantle could be in the form of alternating high and low velocity zones perhaps related to emplacement of eclogites or garnet granulites in the uppermost mantle during the process of underplating

inferring spatial correlation of hydraulic conductivity from sediment cores and outcrops spatial variation of hydraulic conductivity is often assumed to follow patterns of sediment texture this study examines whether sediment texture observed in cores and outcrops can be used to infer spatial correlation of hydraulic conductivity the measures of spatial correlation that we consider correlation length and hurst coefficient are commonly used for interpolating conductivity at unmeasured locations and making stochastic estimates of dispersivity results indicate that when comparing hydraulic conductivity values derived from sediment texture to those measured by pumping tests horizontal correlation lengths are approximately the same but vertical correlation does not correspond well the results also suggest that sediment information may be useful for setting spatial limits to scaling behavior that is assumed with fractal interpretation of hydraulic conductivity variability

dilution enhancement in hierarchical and multiscale heterogeneous sediments abstract we quantify the dilution of solute clouds in geological formations displaying hierarchical and multiscale sedimentary architecture through the use of a lagrangian framework this allows for a fundamental understanding of how dilution arises from the hierarchical architecture of sedimentary facies and enables for a quantitative decomposition of dilution into facies related contributions at different scales within the hierarchy the new developed semi analytical solution that quantify the dilution index is based on hierarchical expressions of the spatial covariance of the log conductivity the spatial correlation structure in the covariance expression is defined by the probability of transitioning within and across facies types of different scales which are parameterized by independent and physically quantifiable attributes of sediments including geostatistical properties of the conductivity field and the proportions and lengths of facies types we illustrate the applicability of the model in the well documented tracer test at the borden research site canada we show how different scales of sedimentary architecture contribute to the dilution enhancement of the solute cloud at borden aquifer by quantitatively decomposing the dilution index into facies related contributions we gain fundamental insights on the key factors controlling the time dependent rate of dilution the results also illustrate that the probability of transitioning from one facies to another i e cross transitions at different scales defines the temporal scaling for enhanced dilution additionally we perform sensitivity analyses to investigate the effects of mean difference in conductivity volume proportion the statistical anisotropy ratio and the scale of heterogeneity on the overall solute dilution

environments of formation and controls on spatial distribution of calcite cementation in plio pleistocene fluvial deposits new mexico u s a abstract the sierra ladrones formation is the uppermost syn rift sedimentary unit of the rio grande rift in central new mexico in the vicinity of the study site it was deposited in a variety of fluvial subenvironments portions of the formation are strongly cemented by calcite forming resistant ledges in otherwise poorly consolidated sediment the calcite exhibits a wide range of macroscopic and microscopic textures and structures which formed in different hydrologic environments including vadose nonpedogenic vadose pedogenic and phreatic phreatic cements are characterized by sparite with uniform disseminated isopachous poikilotopic and drusy textures vadose nonpedogenic by micrite with meniscus textures and vadose pedogenic by textures similar to those in the vadose nonpedogenic environment plus macroscopic features such as root structures destruction of primary sedimentary textures and a red hue many of the cements are of mixed vadose phreatic origin with vadose micrite formation preceding phreatic sparite the calcite is near end member in composition with only minor substitution of trace elements sr mg mn and fe for ca in the calcite structure vadose micrite cements generally have a higher trace element content than phreatic sparite perhaps as a result of more rapid precipitation in the vadose zone carbon isotope values range from 4 7 to 3 5 pdb and 18o values range from 10 3 to 7 2 pdb cements that are dominantly vadose have a wider range of 13c values and are more 13c depleted overall than phreatic cements oxygen values are similar for both vadose and phreatic cements at large scales i e several meters to decameters vertical dimension calcite is present preferentially in coarse grained sediments that had high pre cementation saturated permeabilities relative to uncemented finer grained strata at smaller scales i e several meters or less vertical dimension however there is no clear relationship between degree of cementation and pre cementation permeability at these scales calcite cement is present preferentially in areas that contain early vadose calcite this suggests that at large scales cementation was controlled by pre cementation permeability perhaps due to a greater flux of ca2 and or hco3 in permeable horizons whereas at smaller scales within high permeability units the distribution of cementation was controlled by other factors such as the presence of nucleating material

hydrofacies distribution and correlation in the miami valley aquifer system this study combines geostatistical analyses with geologic interpretations to further the quantitative understanding of physical heterogeneity within glaciofluvial aquifers the stochastic simulation of aquifers requires quantitative measures of heterogeneity including both cumulative distribution and spatial correlation functions the heterogeneity in glaciofluvial aquifers is typified by low permeability facies e g till or lacustrine clay juxtaposed with high permeability facies e g sand and gravel outwash the miami valley aquifer system was examined at multiple sites for the spatial distribution and correlation of these two hydrofacies binary indicator geostatistics were used to quantitatively determine at each site the relative volume of each hydrofacies their spatial distribution the major principal direction of their spatial correlation the minor principal direction and the correlation range in these directions the percent by volume of the system that is aquitard material decreases down the valley from 31 to 12 each site has an elevation zone with more aquitard material relative to other elevations at that site the percent aquitard material in these zones decreases down the valley from 45 to 22 the maximum principal direction of spatial correlation in the aquitard zones generally is ne sw subparallel to the trend of the bedrock valley with a range of the order of 0 75 km and minimum maximum anisotropy ratio of 0 4 the locations exceeding 0 5 probability of aquitard occurrence generally occur on the valley margins thus among the sites investigated there is a trend down the valley in the ratio of aquitard volume to aquifer volume and the spatial correlation and distribution of aquitard material are similar within the aquitard zones furthermore these findings are consistent with aspects of the subglacial and proglacial depositional environments responsible for the facies assemblage and thus are likely to be applicable to other parts of the aquifer system and other aquifer systems where similar geologic processes are inferred to have existed

a new method for analysis of variance of the hydraulic and reactive attributes of aquifers as linked to hierarchical and multiscaled sedimentary architecture this technical note presents a useful methodology for studying how the variance of hydraulic and or reactive attributes of an aquifer are linked to the multiscaled and hierarchical sedimentary architecture of the aquifer a new recursive equation is derived which quantitatively describes how the variance is related to sedimentary facies defined at all scales across an entire stratal hierarchy as compared to prior published equations that emphasize differences in means among facies populations within a hierarchical level it emphasizes differences across levels because of the hierarchical relationships among the terms of the equation we find it to be useful for conducting a holistic analysis of the relative contributions to the variance arising from all facies types defined across all scales the methodology is demonstrated using appropriate field data and is shown to be useful in defining parsimonious classification systems

sedimentology and hydrogeology of two braided stream deposits abstract two approaches were used to quantify the spatial distribution of hydrofacies in braided stream deposits one approach involved mapping a 50 by 60 by 3 3 m section of a proximal braided stream deposit in a second study we generated a 400 by 400 by 2 6 m section of a medial braided stream deposit using a computer model in both cases we produced three dimensional images showing connected hydrofacies with high permeabilities that form preferential flow paths this information was input to a groundwater flow model and flow paths were analyzed by following the transport of imaginary particles in both systems particles that were uniformly distributed at the up gradient end of the model clustered along preferential flow paths during transport showing that connection among high permeability facies is a critical factor in hydrogeological investigations involving assessment of contaminant movement and remediation

what have we learned from deterministic geostatistics at highly resolved field sites as relevant to mass transport processes in sedimentary aquifers summary in the method of deterministic geostatistics sensu isaaks and srivastava 1988 highly resolved data sets are used to compute sample spatial bivariate statistics within a deterministic framework the general goal is to observe what real highly resolved sample spatial bivariate correlation looks like when it is well quantified in naturally occurring sedimentary aquifers furthermore it is to understand how this correlation structure i e shape and correlation range is related to independent and physically quantifiable attributes of the sedimentary architecture the approach has evolved among work by rubin 1995 2003 barrash and clemo 2002 ritzi et al 2004 2007 2013 dai et al 2005 and ramanathan et al 2010 in this evolution equations for sample statistics have been developed which allow tracking the facies types at the heads and tails of lag vectors the goal is to observe and thereby understand how aspects of the sedimentary architecture affect the well supported sample statistics the approach has been used to study heterogeneity at a number of sites representing a variety of depositional environments with highly resolved data sets what have we learned we offer and support an opinion that the single most important insight derived from these studies is that the structure of spatial bivariate correlation is essentially the cross transition probability structure determined by the sedimentary architecture more than one scale of hierarchical sedimentary architecture has been represented in these studies and a hierarchy of cross transition probability structures was found to define the correlation structure in all cases this insight allows decomposing contributions from different scales of the sedimentary architecture and has led to a more fundamental understanding of mass transport processes including mechanical dispersion of solutes within aquifers and the time dependent retardation of reactive solutes these processes can now be described in terms of quantifiable physical attributes of the sedimentary architecture in addition to discussing the benefits to basic scientific understanding we also discuss some of the practical benefits derived from this insight

sedimentology and fractal based analysis of permeability data john henry member straight cliffs formation upper cretaceous utah u s a interpretation of depositional environments combined with field measurement of permeability for a portion of the upper cretaceous straight cliffs formation near escalante utah provides new results for understanding and modeling facies dependent perme ability variations offshore transition lower shoreface upper shore face and foreshore environments are interpreted for part of the john henry member on the basis of outcrop investigation using a newly designed drillhole minipermeameter probe permeability was measured for two of the facies within this unit lower shoreface bioturbated sand stone and upper shoreface cross bedded sandstone approximately 500 permeability measurements at a sample spacing of 15 cm were made along four vertical profiles and three horizontal transects o na6m 3 21 m outcrop permeability ranges from 41 to 1 675 millidarcies md in the bio turbated sandstone facies which is massive bedded moderately to well sorted and very fine to fine grained in contrast permeability ranges from 336 to 5 531 md in the moderately to moderately well sorted fine to medium grained cross bedded sandstone facies a high degree of variability in permeability of the cross bedded facies is caused by small scale variations in grain size and structure related to depositional processes the geometric mean permeability in the bio turbated sandstone is 253 md compared with 1 395 md in the cross bedded facies while the facies dependent differences in permeability k are ap parent and related to depositional and biological processes fractal based statistical analysis of the horizontal ln k increments yields near ly identical results for the bioturbated facies and the cross bedded fa cies possibly suggesting an underlying statistical commonality in the formation of both facies increment distributions from both facies ap pear similar with peaking around the mean ln k increments from the smaller vertical data set appear similar also but with a variance approximately 3 7 times larger than the horizontal value variance scaling analyses of horizontal and vertical data both yield a hurst co efficient near 0 26 which is characteristic of negative spatial correla tion of the increments the methodology developed herein offers a po tential high resolution alternative to existing methods for understand ing and characterizing subsurface properties

architecture of the sierra ladrones formation central new mexico depositional controls on the permeability correlation structure statistical models of hydrogeological heterogeneity are often used in aquifer and reservoir characterization the number of data required to estimate objectively the spatial correlation structure of permeability however is often prohibitive the objective of this study was to develop a better understanding of how information about depositional processes can be used to characterize hydrogeological heterogeneity an outcrop of the fluvial interfluvial sierra ladrones formation of new mexico was studied for this purpose on the basis of previous studies of paleogeography and our own field observations deposits of the sierra ladrones formation are interpreted as marginal ancestral rio grande flood plain and tributary deposits architectural elements were mapped over a 0 16 km sup 2 peninsular outcrop of pliocene pleistocene deposits of the central albuquerque basin geostatistical analysis of the architectural element map data indicates non orthogonal anisotropy in the horizontal direction the orientations of the strongest n30 degree w and weakest n90 degree e correlation correspond to the orientation of the tributary system and the ancestral rio grande flood plain respectively in the vertical direction the correlation structure exhibits exponential behavior corresponding to the average element thicknesses the results demonstrate that information about depositional environment can be used to help to quantify statistically subsurface heterogeneity 28 refs 9 figs 1 tab

spatial variability in river sediments and its link with river channel geometry 1 this study explores the link between spatial variability within fluvial sedimentary strata and river channel geometry this link is then used to determine the macrodispersion coefficients for solute transport in groundwater flow in river deposits in doing that we combine concepts from sedimentology geostatistics and the stochastic lagrangian theory of subsurface transport it is proposed to analyze the spatial variability of river sediments in terms of transition probabilities the transition probabilities can be determined from the averages and variances of the lengths of stratasets and their volumetric fractions using concepts developed by carle and fogg 1996 and ritzi 2000 strataset length scales are shown to correlate well with the geometry of the river channel and its bed forms and can be determined indirectly from aerial photogrammetry and more directly through surface ground penetrating radar surveys stratal dimensions can also be related using lagrangian transport analysis to macrodispersivity of subsurface transport this allows relationships between the geometry of river channels and subsurface transport parameters of associated fluvial deposits for demonstration the longitudinal macrodispersivity in a compound bar deposit in the gravelly braided sagavanirktok river was investigated

measurement of anisotropic hydraulic conductivity in unconsolidated sands a case study from a shoreface deposit oyster virginia in this study an integrated field and laboratory method which can be used to evaluate the magnitude and distribution of anisotropic hydraulic conductivity at the scale of bedding structures in unconsolidated sediment is demonstrated undisturbed sediment cores 10 16 cm in diameter and 18 25 cm long are obtained using a split barrel core sampler two undisturbed 5 72 cm diameter 7 90 cm long subcores oriented parallel and perpendicular to the primary bedding structures are then obtained from each field core the hydraulic conductivities of the subcores are then measured with a constant head permeameter the sampling and experimental procedures are designed to minimize potential sources of error sixty four 10 16 cm cores were sampled in a coastal sand outcrop located 300 m from a subsurface injection experiment near oyster virginia four distinct lithologies were sampled in horizontal transects with a spacing of 0 5 m between core locations in addition iron oxide bands which were prevalent throughout the exposure were sampled from both ends of the outcrop the average hydraulic conductivity values are consistent with the observable geologic features grain size sorting and iron oxide banding hydraulic conductivity is greater in the parallel oriented subcore for 90 of the core pairs and mean hydraulic conductivity ratios of parallel to perpendicular oriented subcores k k for the different lithologies ranged from 1 33 to 1 57 the major control on the anisotropy in this sediment is interpreted to be preferential grain orientations resulting from depositional processes with additional influences from the prominence of the bedding structures and secondary features such as hydrous iron oxide banding

geostatistical models of secondary oil migration within heterogeneous carrier beds a theoretical example this paper critically evaluates the utility of two different geostatistical methods in tracing long distance oil migration through sedimentary basins geostatistical models of petroleum migration based on kriging and the conditional simulation method are assessed by comparing them to known oil migration rates and directions through a numerical carrier bed in this example the numerical carrier bed which serves as ground truth in the study incorporates a synthetic permeability field generated using the method of turning bands different representations of lateral permeability heterogeneity of the carrier bed are incorporated into a quasi three dimensional model of secondary oil migration the geometric configuration of the carrier bed is intended to represent migrat on conditions within the center of a saucer shaped intracratonic sag basin in all of the numerical experiments oil is sourced in the lowest 10 of a saucer shaped carrier bed and migrates 10 14 km outward in a radial fashion by buoyancy the effects of vertical permeability variations on secondary oil migration were not considered in the study two sets of numerical experiments are presented in this study in the first set computed oil migration patterns and rates through the numerical carrier bed are compared to kriged and optimal estimations based on a suite of 50 conditional simulations to determine the utility of each geostatistical approach the geostatistical models also are compared to a much simpler oil migration simulation using a homogeneous carrier bed an assumption typically made in cross sectional models of oil migration the permeability realizations generated by kriging and the conditional simulation method were constructed using 50 randomly placed sampling points a second set of numerical experiments was made to determine how data sample size 20 35 50 100 and 250 randomly selected points influences p edicted oil migration patterns using kriged permeability fields oil migration patterns through the synthetic carrier bed were quantitatively compared to geostatistical representations of oil transport by computing the degree of correlation r2 of oil lens thickness at 5 10 and 15 m y after the onset of migration quantitative results indicate that both kriging and the conditional simulation method produced realistic representations of spatial oil lens patterns and first arrival times both kriging and the conditional simulation method produced results far more realistic than the simulation with a homogeneous carrier bed after 15 m y the spatial correlations r2 between the known oil lens patterns and that of the kriged and ensemble average of the 50 conditional simulations were 0 67 and 0 74 respectively although the conditional simulation method produced the best results it did so at a significant computational expense computed oil migration patterns based on different kriged permeability maps that incorporated varying amounts of control data points did not improve signif cantly when more than 100 randomly placed wells were used the study provides compelling evidence that secondary oil migration is an inherently three dimensional process for well studied basins geostatistical representations of long range oil migration could be of value in ongoing exploration strategies end page 1679

visual attributes of a rock and their relationship to permeability a comparison of digital image and minipermeameter data 1 what is the relationship between the visual attributes of a rock sample and its permeability and how might such information be used in aquifer reservoir characterization we investigated these questions by way of three meter scale blocks of rock two sandstones and one volcanic tuff each rock exhibits visual and permeability patterns that differ in geometry intensity and scale using a gas minipermeameter hundreds to thousands of permeability values were collected on grids at centimeter scale resolution from each block face and compared to the digital visual image of the same face we found no significant direct correlation between the permeability measurements and any objective textural measure drawn from the corresponding digital images despite the obvious resemblance of the permeability maps and visual images hypothesizing that the human eye relies on spatial correlation to synthesize information we calculated and compared semivariograms for both the maps and the images semivariogram shape anisotropy ratio and principal axes orientation were consistent for the maps and images of each rock but different between rocks to explore this similarity further we compared discrete features appearing in map image pairs using a difference of gaussian edge filter to segment i e delineate the spatial features the filter consistently colocated visually sharp features such as sedimentological bounding surfaces in both the map and the image additionally cumulative distribution functions characterizing the size shape and orientation of the segmented features were statistically indistinguishable between a permeability map and its corresponding visual image but statistically different between rocks these results suggest that it may not always be possible to use visual images photographs or scans of outcrops to directly map permeability even with a training set of punctual permeability data in particular defining such relations may be difficult where the scales of analysis and or intensity of heterogeneity are limited e g within a given facies as is the case here where direct mapping is not possible these results suggest that visual images can still be used to delineate spatial permeability patterns especially to locate boundaries where sharp permeability contrasts occur other surrogate measurements of permeability in particular the various geophysical methods may exhibit similar behavior

characterizing the heterogeneity and correlation of perchloroethene sorption and hydraulic conductivity using a facies based approach a facies based approach was used to delineate both geochemical and physical aquifer property heterogeneity specifically the parameters considered were the sorption coefficient kd for a model organic contaminant and hydraulic conductivity k inferred from the particle size distribution subfacies sized samples were analyzed for both tetrachloroethene kd and k in a vertical core of the borden aquifer both parameters were correlated with the six sedimentary facies identified within the vertical core as a consequence of their relations to sedimentary facies significant positive correlations between ln k and ln kd which were different from the core scale correlation and different from each other were identified for some facies fades specific correlations generally resulted in improved statistics i e higher correlation coefficients and reduced confidence intervals compared to the core scale correlation the results suggest that a facies based approach can be useful in characterizing the heterogeneity of the transport properties of sedimentary aquifers

use of sedimentological information for geometric simulation of natural porous media structure a geometric simulation method was used to develop a three dimensional highly detailed synthetic representation of point bar sediments in the wabash river system geometric simulation methods in comparison to well known second order stochastic methods offer the advantage of being more closely related to depositional processes which are often similarly conceptualized i e described in terms of shapes of discrete bed forms trends in grain size and spatial relationships of defined geologic facies multiple scales of geometric variation were defined within a sedimentologically prescribed framework and shapes of discrete geometric elements were established at each scale the selected shapes were based on published field studies including sedimentological bed form studies and trench studies in active point bar sediments the parameterization of the shapes allowed for random variability of the shape descriptors discrete shapes were then generated and assimilated by computer hydraulic conductivity values were assigned to the discrete elements based on reports of observed variations in grain size and field measurements of hydraulic conductivity the synthetic model referred to as a numerical aquifer is being used as the basis for extensive numerical experimentation to study the relationship between natural spatial structure and subsurface flow and transport

offset of latest pleistocene shoreface reveals slip rate on the hosgri strike slip fault offshore central california abstract the hosgri fault is the southern part of the regional hosgri san gregorio dextral strike slip fault system which extends primarily in the offshore for about 400 km in central california between morro bay and san simeon high resolution multibeam bathymetry reveals that the eastern strand of the hosgri fault is crossed by an 265 m wide slope interpreted as the shoreface of a latest pleistocene sand spit this sand spit crossed an embayment and connected a western fault bounded bedrock peninsula and an eastern bedrock highland a paleogeography resembling modern coastal geomorphology along the san andreas fault detailed analysis of the relict shoreface with slope profiles and slope maps indicates a lateral slip rate of 2 6 0 9 mm yr considered a minimum rate for the hosgri given the presence of an active western strand this slip rate indicates that the hosgri system takes up the largest share of the strike slip fault budget and is the most active strike slip fault west of the san andreas fault in central california this result further demonstrates the value and potential of high resolution bathymetry in characterization of active offshore faults online material 1 high resolution bathymetric data for the cross hosgri slope and 2 metadata that describes data collection processing and formatting

architectural element analysis applied to glacial deposits internal geometry of a late pleistocene till sheet ontario canada deposits left by continental ice sheets are characterized by sedimentological complexity and stratigraphic heterogeneity but stratigraphic descriptions of such deposits and resulting first generation facies models are still based primarily on one or two dimensional borehole or outcrop data reconstruction of depositional environments hydrogeological investigations of pleistocene glacial deposits and hydrocarbon exploration in pre pleistocene glaciated basin fills require a more detailed understanding of the form and heterogeneity of lithofacies sequences in three dimensions architectural element analysis is used widely by sedimentologists for categorizing internal stratigraphic heterogeneity in sandstones particularly those of fluvial origin this paper demonstrates the first application of architectural element analysis to glacial deposits such as tills outcrop borehole and a broad range of subsurface geophysical data were collected from a thick 60 m till sheet present across an 80 km 2 study area near toronto canada the till sheet is not homogeneous but is composed of three distinct architectural elements and associated lithofacies viz diamict elements interbeds of subglaciofluvial sediments and glaciotectonically deformed zones application of architectural element analysis to these subglacial strata provides insights into the origin of drumlin bedforms and subglacial processes below the laurentide ice sheet and creates a framework for understanding ground water and contaminant movement in underlying aquifers

characterization of alluvial hydrostratigraphy with indicator semivariograms current trends in hydrogeology seek to enlist sedimentary concepts in the interpretation of permeability structures however depositional models tend to account insufficiently for heterogeneities caused by complex controls on sediment preservation conversely geostatistical methods empirically describe both random and structured attributes this paper presents comparative indicator semivariograms for proximal medial and distal alluvial fan settings in santa clara valley california hydrostratigraphic structures revealed by a binary textural indicator are consistent within each setting yet differ from one setting to another in the bedrock bounded proximal setting buried channel deposits exhibit a small nugget effect and a zonal anisotropy with correlation ranges up to 900 m in the distal setting deposits display relatively weak hydrostratigraphic correlation with a relative nugget effect of 50 and a correlation range of 80 m in the medial setting the correlation range is similar to the proximal area but with a large nugget effect similar to the distal area

relating small scale sedimentary structures and permeability in a cross bedded aquifer summary the objective of this study is to investigate the relation between small scale sedimentary structures and permeability in the brussels sands formation an early middle eocene shallow marine sand deposit in central belgium that constitutes a major groundwater source in the region a field campaign was carried out consisting of field observations of the sedimentary structures and in situ measurements of air permeability the sedimentary structures were interpreted sketched digitally photographed and measured in a representative outcrop additionally a total of 2750 cm scale air permeability measurements were carried out in situ analysis of the spatial distribution of sedimentary structures and permeability shows that clay rich sedimentary features such as bottomsets and distinct mud drapes exhibit a different statistical and geostatistical permeability distribution compared to the other lithofacies in the cross bedded sands spatial analysis of the air permeability data shows that permeability anisotropy in the cross bedded lithofacies is dominated by the foreset lamination orientation these results show that small scale sedimentary heterogeneity strongly influences the local spatial distribution of the hydraulic properties and results in permeability heterogeneity and stratification that would produce anisotropy in upscaled permeability values

late quaternary sequence stratigraphy as a tool for groundwater exploration lessons from the po river basin northern italy sequence stratigraphy typically used for hydrocarbon exploration in ancient strata can be applied to late quaternary successions to decipher complex spatial relations among their aquifers late pleistocene holocene strata of the po basin were investigated using a sequence stratigraphic approach to produce a high resolution model for guiding groundwater exploitation because facies tend to be diachronous across depositional basins facies analysis was done within the conformable intervals of strata revealed by sequence stratigraphy to accurately interpret and map coeval lateral facies relations volumetric assessments sand distribution mapping hydraulic characterization of facies and spatial variations of hydraulic parameters revealed two aquifer systems the lowstand systems tract lst and the highstand systems tract hst vertically separated by an aquitard the transgressive systems tract tst the lst aquifer consists of amalgamated fluvial sands average transmissivity 3 5 e 3 m2 s 37 7 e 3 ft2 s with considerable width 25 km 16 mi preferentially elongated downstream the widespread tst aquitard is dominated volumetrically 57 by low permeability estuarine deposits the hst aquifer average transmissivity 5 4 e 5 m2 s 58 1 e 5 ft2 s is 5 10 km 3 6 mi wide elongated parallel to the modern shoreline sequence stratigraphic analysis at the parasequence scale revealed an almost unprecedented level of detailed insight into aquifer or aquiclude dimensions and the complex distribution of hydraulic parameters in the subsurface showing that similar facies have different permeabilities depending on systems tract in contrast lithostratigraphic mapping obscures subsurface connectivity and directional trends and has minimal predictive power away from control these insights should be useful for guiding correlation and mapping of the deep subsurface and for hydrocarbon reservoir modelers

hierarchical geostatistics and multifacies systems boise hydrogeophysical research site boise idaho 1 the geostatistical structure of a heterogeneous coarse fluvial aquifer is investigated with porosity data derived from neutron logs at a research well field boise hydrogeophysical research site or bhrs that was designed in part to support three dimensional geostatistical analysis of hydrologic and geophysical parameters recognizing that the coarse fluvial deposits include subdivisions units between bounding surfaces we adopt a hierarchical approach and examine the porosity geostatistics of the aquifer at three scales at the bhrs the saturated fluvial deposits as a whole maximum interwell spacing 80 m thickness 16 18 m are at hierarchical level 1 five subhorizontal units within these deposits four cobble dominated units and a channel sand can be traced across the central area of the bhrs and are at hierarchical level 2 and subunits patches or lenses in one of the level 2 units unit 4 are at hierarchical level 3 we use variography and porosity statistics to recognize nonstationarity at hierarchical level 1 and in one of the level 2 units unit 4 where the means and variances of porosity differences as a function of lag are not constant between distinct units and subunits respectively the geostatistical structure at level 1 is modeled with different horizontal and vertical structures that have different sills vertical sill greater than horizontal sill the difference in sills can be explained quantitatively by the summing of weighted sills from all individual units and combined units i e a given pair of different units where the weights are the proportions of data pairs contributing to the sills at each lag from the individual and combined units extension of this analysis leads to a weighted multistructure form of the variogram function whereby a global experimental variogram in a hierarchical system can be decomposed quantitatively into weighted component individual and combined unit or facies structures for any number of units or hierarchical levels such decomposition of the global horizontal variogram from the bhrs indicates that short range periodicity in that structure is due to both 1 combined unit structures associated with patches or lenses at hierarchical level 3 in unit 4 and 2 variations in thickness of unit 2 for hierarchical multifacies systems structure models fit to global horizontal and vertical experimental variograms may not be useful for subsequent stochastic modeling if the system on which the structure models are based is nonstationary

comparing statistical models of physical heterogeneity in buried valley aquifers the hypothesis that physical heterogeneity has similarities in separate aquifers created by similar depositional environments is tested by comparing statistical characteristics of facies assemblages the comparisons are made for a number of data rich sites in two buried valley aquifers in the north american midcontinent the white river aquifer in indiana and the miami valley aquifer in ohio these were proglacial valleys that directed drainage away from quaternary ice margins and were filled with glaciofluvial sediments predominantly sand and gravel s lithofacies with interbedded mud and diamicton m lithofacies at scales encompassing assemblages of both lithofacies m and s permeability is strongly bimodal we find that it is useful to compare statistics that characterize the proportions geometry and spatial distribution of each facies the results give rise to a general model for heterogeneity in valley fill sediments along the proglacial sluiceway in both aquifers the proportion of facies m is 15 the mean thickness of facies m is 3 5 m and of the order of 10 m for facies s the coefficient of variation in thickness for either facies is of the order of 1 with thickness ranging over orders of magnitude correspondingly the vertical autotransition probabilities are exponential and they are relatively symmetric with effective range of the order of 10 m the lateral facies lengths are indicated to vary over orders of magnitude and to be multimodally distributed with mean lengths of the order of 102 m effective range in correlation structure of the order of 103 m and lateral anisotropy ratio 2 there is some variation in how the facies m are vertically embedded within the facies s the white river aquifer and areas in the miami aquifer have facies proportions relatively stationary with elevation in other areas of the miami there are near horizontal zones having relatively higher or lower proportions however such variations on the general model give rise to similar statistics for mass transport within the context of a relevant remediation problem and thus would lead to a similar conclusion or decision thus one general model is applicable to both aquifers in this context in a broader sense we have illustrated a method by which other examples developed from data rich sites can be compared

improving permeability semivariograms with transition probability models of hierarchical sedimentary architecture derived from outcrop analog studies received 21 july 2004 revised 22 february 2005 accepted 23 march 2005 published 30 july 2005 1 as analogs for aquifers outcrops of sedimentary deposits allow sedimentary units to be mapped permeability to be measured with high resolution and sedimentary architecture to be related to the univariate and spatial bivariate statistics of permeability sedimentary deposits typically can be organized into hierarchies of unit types and associated permeability modes the types of units and the number of hierarchical levels defined on an outcrop might vary depending upon the focus of the study regardless of how the outcrop sediments are subdivided a composite bivariate statistic like the permeability semivariogram is a linear summation of the autosemivariograms and cross semivariograms for the unit types defined weighted by the proportions and transition probabilities associated with the unit types the composite sample semivariogram will not be representative unless data locations adequately define these transition probabilities data reflecting the stratal architecture can often be much more numerous than permeability measurements these lithologic data can be used to better define transition probabilities and thus improve the estimates of the composite permeability semivariogram in doing so bias created from the incomplete exposure of units can be reduced by a bayesian approach for estimating unit proportions and mean lengths we illustrate this

field example of data fusion in site characterization application of data fusion to characterization of the fountain and lyons formations at a field site incorporates geologic knowledge geophysical log data cross hole seismic tomography hydraulic test data and observations of head to reduce uncertainty associated with subsurface interpretation these formations consist of channel and overbank deposits that have undergone variable diagenesis resulting in more hydrofacies than would have been encountered in the original unaltered deposits the disparate types of available data are integrated to yield a coherent hydrofacies classification through use of discriminant analysis and soft data techniques this data fusion improves definition of the complex hydrofacies and increases knowledge of their spatial correlation two hundred multiple indicator conditional stochastic simulations of the site are generated 100 with only hard data and 100 with both hard and soft data forward groundwater flow modeling using estimates of hydraulic conductivity from field testing yields smaller head residuals for realizations which include soft data inverse modeling is used to eliminate hydrofacies realizations that do not honor hydraulic data and to estimate hydrofacies hydraulic conductivity ranges for the hard and hard soft data ensembles inverse parameter estimation substantially decreases head residuals for both ensembles standard deviations of hydraulic conductivities estimated through inverse modeling are smaller when both hard and soft data are used to generate the simulations even though head residuals are similar within the two ensembles when these estimated hydraulic conductivities are used

probe permeametry an overview and bibliography applications of probe permeameters in both laboratory and outcrop studies of permeability heterogeneity are common we present an overview of the current status of probe permeameter data acquisition analysis and application the multidisciplinary nature of probe permeameter studies has led to their publication in diverse scientific journals we present a bibliography that includes literature covering both the technology and the application of probe permeametry

spatial correlation structure estimation using geophysical and hydrogeological data the large spatial variability of hydraulic properties in natural geologic systems over a wide range of scales and the difficulty of collecting representative and sufficient hydraulic property measurements using conventional sampling techniques render estimation of spatial correlation parameters difficult further compounding the estimation problem is the observation that the integral scale estimate is a function of the measurement support scale to mitigate these problems we investigate the use of tomographic geophysical data in combination with hydrogeological data in the spatial correlation estimation procedure two synthetic case studies were investigated where the scale of the geophysical measurements were varied relative to the scale of the hydrogeological properties the spatial correlation structure parameter estimation procedure was performed in the spectral domain where analysis of data having different support scales and spatial sampling windows was facilitated comparison of the spatial correlation structure parameters estimated from measured data with those of the synthetic aquifers revealed which type of data tomographic hydrogeological or a combination of both was most effective for recovering spatial correlation statistics under different sampling heterogeneity conditions these synthetic case studies suggest that collection of a few tomographic profiles and interpretation of these profiles together with limited well bore data can yield correlation structure information that is otherwise obtainable only from extensive hydrological sampling

oriented carbonate concretions in a paleoaquifer insights into geologic controls on fluid flow oriented carbonate concretions appear to provide a powerful new tool in the evaluation of flow through heterogeneous aquifers calcite cement forms elongate bodies of indurated rock that have distinct and mappable spatial orientations we have mapped 200 of these concretion orientations as well as the hydrogeologic characteristics of the host sediments in outcrops of the pliocene pleistocene sierra ladrones formation in central new mexico the average azimuthal concretion orientations is 150 which is consistent with the southeasterly groundwater flow suggested by past and present basin geometry using a first order approximation the dimensionless transverse velocity is estimated from the orientation data the spatial correlation structure of the dimensionless transverse velocity is distinctly different in the two units investigated however both are consistent with existing stochastic models the differences between the units and the similarities with theoretical models suggest that concretion orientations can be used to study how fluids flow through heterogeneous systems over scales ranging from centimeters to tens of kilometers

relating lithofacies to hydrofacies outcrop based hydrogeological characterisation of quaternary gravel deposits abstract a considerable part of today s drinking water supplies in europe and north america rely on clean groundwater from gravelly valley aquifers of quaternary age the sedimentary architecture the distribution of lithofacies and of architectural elements in such heterogeneous deposits are of fundamental importance for the analysis of groundwater flow and contaminant transport as the aquifers are not directly accessible for observation representative outcrop analogues were used to study the sedimentology on a local scale conventional sedimentological classification schemes were adapted for the purpose of hydrogeological evaluations measurements of hydraulic properties were then used to define a set of 5 hydrofacies from 23 possible sediment lithofacies a digital photographic mapping procedure was developed to allow fast data acquisition in the field the sedimentologically interpreted outcrops were stored in a gis style database and thus allow the output for further sedimentological or hydrogeological analysis