mapping surface mineralogy using imaging spectrometry abstract imaging spectrometry simultaneous measurement of spectra and images in up to hundreds of spectral channels or bands is a proven technology for identifying and mapping minerals based on their reflectance or emissivity signatures also known as hyperspectral imaging or hsi extraction of key spectral signatures from these data allows direct identification of iron minerals such as hematite goethite and jarosite in the visible near infrared vnir clays carbonates micas sulfates and other minerals in the short wave infrared swir and silicates and carbonates in the long wave infrared lwir the unique capability of imaging spectrometry to produce detailed maps of the spatial distribution of specific minerals mineral assemblages and mineral variability on the surface of earth makes it an ideal tool for enhanced geomorphic mapping case histories illustrate the use of hsi for characterizing and mapping active and relict geothermal hydrothermal systems and determining relations between mineralogy and derived landforms imaging spectrometry used in conjunction with complimentary datasets such as insar interferometric synthetic aperture radar light detection and ranging lidar or stereo photogrammetric derived digital elevation models dems provides a unique means of visualizing the spatial distribution and association of mineralogy with topography thus contributing to the understanding of the relations between geology and landscape and to improved interpretation of surface geologic processes

continuous porosity characterization metric scale intervals in heterogeneous sedimentary rocks using medical ct scanner abstract although computed tomography ct scanning has been regularly applied to core analyses in petroleum geology there is still a need to improve our ways to document porosity and porosity distribution in the entire pore scale spectrum from the tens of nanometer to the meter scale porosity imaging is particularly crucial for complex and heterogeneous rocks such as hydrothermally altered and fractured carbonates the present work proposes an improved method using medical ct to reliably estimate reservoir porosity an in house core flooding setup allowed to analyse several individual core samples scanned simultaneously dry and saturated as well as continuous core sections up to 1 5 m long without any prior knowledge of samples three dimensional alignment and subtraction of the two data sets dry and saturated states results in the generation of 3d porosity matrices the methodology tested on a large set of reference core material shows a strong correlation between conventional gas porosimetry techniques and porosity from ct scan the added value of the porosity measurements by ct scan is first of all the generation of 3d images of pore network allowing to assess spatial attributes of macropores their distribution and connectivity secondly the ct scan method also provides continuous porosity profile at the millimetric scale both developments are crucial for the understanding of reservoir rock properties

the expulsinator versus conventional pyrolysis the differences of oil gas generation and expulsion simulation under near natural conditions abstract the expulsinator provides a new technique to simulate generation and expulsion of hydrocarbons under near natural conditions this is realized by application of lithostatic pressure onto an intact source rock disc with undisturbed mineral matrix and kerogen network and by hydrous pyrolysis conducted in open flow through mode conventional pyrolysis methodologies serve well in generation kinetics assessment but are only of limited use for investigation of primary migration and expulsion due to destructive sample preparation inappropriate pressure regimes and pyrolysis in closed mode and or in the absence of water however comparison of results generated with conventional pyrolysis with expulsinator experiments is important to assess the performance of the generation and expulsion simulation carried out with the expulsinator thus the generation and expulsion behaviour of this new methodology has been compared with established pyrolysis methodologies like hypy and closed small vessel pyrolysis csvp and has been assessed by rock eval pyrolysis expulsinator experiments released higher amounts of bitumen than csvp this has been attributed to increased cross linking reactions of bitumen in case of the classic pyrolysis favouring formation of pyrobitumen differences in yields and composition of n alkanes were controlled not by generation kinetics exclusively but also by expulsion effects in particular delayed expulsion caused by geochromatography expulsinator conversion rates of toc exceeded 81 whereas those of hydrous csvp remained at 65 higher expulsinator toc conversion was accompanied by lower gas generation compared to csvp this is attributed to the open setup of the expulsion experiment which by rapid removal of products generated prevents their secondary alteration particularly polymerization to pyrobitumen and oil to gas cracking at higher temperatures hypy of expulsinator pyrolysis residues verified a low generation potential remaining after the expulsion experiment the expulsinator device delivers oil and gas generation data which can be applied in numerical modelling exercises

multiscale modeling of shale samples based on low and high resolution images abstract accurate modeling of shale samples is very crucial for evaluating and predicting the physical properties however obtaining large scale and high resolution images of shales using a single imaging tool such as x ray computed tomography or scanning electron microscopy machine might not be plausible as there is always a trade off between the resolution and field of view on the other hand relying on small scale images may jeopardize the accuracy of porous media modeling one solution scheme for addressing these issues is to fuse the spatial information from the multiscale and multiresolution images into a multiscale high resolution image as such a novel multiscale modeling algorithm based on template matching for complex rocks is proposed in this study this algorithm can fuse multiscale and multiresolution structural patterns from the images with different scales resolution and phases into one single image the accuracy of the presented algorithm is tested using two heterogeneous shale samples and the results are compared with the actual large and high resolution images we found that the algorithm can generate an accurate image after comparing the geometrical properties of pore systems correlation functions and image similarity indicators of the generated image and reference image

predicting flow properties in diagenetically altered media with multi scale process based modeling a wilcox formation case study abstract two approaches to capture the complex texture of wilcox sandstone samples in a pore scale model are employed a process based method and an image based method in the process based method petrographic analyses from transmitted light microscopy are used to infer the diagenetic history of the rock key steps in the diagenesis are quantitatively followed using a multi scale pore network modeling method to reconstruct the porous medium at different times in its history including the final state further information about pore sizes is gathered from scanning electron microscopy and nitrogen adsorption hysteresis measurements the ability to incorporate texture information of each diagenetic stage of a tight gas sandstone into a predictive multi scale pore network model is a novel aspect of this work in the image based method a micro ct image of the sample is acquired and a pore network model is extracted based on skeletonizing the resolvable pore space and mapping clusters of micropores to the unresolved porous areas the paragenesis of the formation was not captured using the image based method since sufficient details of its history could not be extracted the process based and image based methods produce comparable drainage capillary pressure curves while the drainage relative permeability curves in both methods display permeability jail effect they considerably differ from each other quantitatively the process based method produced a higher porosity and permeability compared to the image based method which is potentially due to the lower degree of its disorder high uncertainties in the petrophysical properties of tight gas sandstones is a costly challenge in their reservoir development our work provides insights into the effect of pore texture from different scales on rock fluid properties furthermore the methods demonstrated in this work can be pursued to extrapolate tight gas sandstone petrophysical properties between wells and throughout paragenetic sequences

phenomenological understanding of poroelasticity via the micromechanics of a simple digital rock modelmicromechanics basis of poroelasticity

modelling the impact of depositional and diagenetic processes on reservoir properties of the crystal shrub limestones in the pre salt barra velha formation santos basin brazil abstract the cretaceous barra velha formation pre salt of the santos basin brazil includes lacustrine crystal shrub limestones which represent important hydrocarbon reservoirs neither single nor multi phase flow behaviour of these unusual fabrics has been modelled to date here we quantify the impact of depositional and diagenetic processes on selected reservoir properties of the crystal shrub limestones using highly flexible 3d synthetic pore scale models that can explore parameter space rather than producing models validated to actual reservoir properties this seeks to establish trends and identify emergent clustering behaviour shrubby aggregates nucleate from a surface to form upward and outward growing branching fascicular optical calcite crystal fans that are diverse in size and form the model allows exploration of the impact of primary growth parameters number of bifurcations or branching shrub height angle of cone or fan inflation as well as subsequent inter shrub cementation and dissolution on resultant porosity permeability and multiphase flow simulations show that depositional parameters as well as two major diagenetic processes cementation and dissolution control porosity and permeability in some cases these trends diverge considerably from widely referenced kozeny carman kc porosity permeability relationships the angle of shrub inflation produces data clusters that traverse kc bands by contrast the number of bifurcations and the degree of dissolution follows kc trends so providing guidance for potential rock type subdivision of similar lithologies on this basis we propose that the crystal shrub limestones in the barra velha formation can be subdivided into three broad petrophysical reservoir rock types based on the degree of shrubby aggregate bifurcation and extent of dissolution the trends explored here can be used to link conceptual and process based geological models to data so enabling more accurate prediction and upscaling of heterogeneous reservoir properties and their reservoir scale distribution

primary migration by diffusion through kerogen i model experiments with organic coated rocks abstract laboratory experiments were performed to assess diffusion through kerogen as a mechanism of hydrocarbon transport through fine grained rocks such transport can be important in primary migration within source rocks and in leakage through seals to test the concept of diffusion through organic matter networks model experiments were performed in which hydrocarbon diffusion was measured through austin chalk cores that had been coated with a monolayer of fatty acids hydrocarbon fluxes through the coated cores were compared to hydrocarbon fluxes through uncoated austin chalk cores results showed that the organic coating enhanced transport through the core by a hundredfold over diffusion through its water filled pore space alone

the effect of oil expulsion or retention on further thermal degradation of kerogen at the high maturity stage a pyrolysis study of type ii kerogen from pingliang shale china high maturity oil and gas are usually generated after primary oil expulsion from source rocks especially from oil prone type i ii kerogen however the detailed impacts of oil expulsion or retention in source rock on further thermal degradation of kerogen at the high maturity stage remain unknown in the present study we collected an ordovician pingliang shale sample containing type ii kerogen the kerogens which had previously generated and expelled oil and those which had not were prepared and pyrolyzed in a closed system to observe oil expulsion or oil retention effects on later oil and gas generation from kerogen the results show that oil expulsion and retention strongly impacts on further oil and gas generation in terms of both the amount and composition in the high maturity stage gas production will be reduced by 50 when the expulsion coefficient reaches 58 and gas from oil expelled kerogen less oil retained is much drier than that from fresh kerogen the oil expulsion also causes n alkanes and gas compounds to have heavier carbon isotopic compositions at high maturity stages the enrichment of 13c in n alkanes and gas hydrocarbons are 1 and 4 6 respectively compared to fresh kerogen oil expulsion may act as open system opposite to the oil retention that influences the data pattern in crossplots of 13c2 13c3 versus c2 c3 13c2 13c3 versus 13c1 and 13c1 13c2 versus ln c1 c2 which are widely used for identification of gas from kerogen cracking or oil cracking these results suggest that the reserve estimation and gas source correlation in deep burial basins should consider the proportion of oil retention to oil expulsion the source rocks have experienced

unconventional shale gas systems the mississippian barnett shale of north central texas as one model for thermogenic shale gas assessment shale gas resource plays can be distinguished by gas type and system characteristics the newark east gas field located in the fort worth basin texas is defined by thermogenic gas production from low porosity and low permeability barnett shale the barnett shale gas system a self contained source reservoir system has generated large amounts of gas in the key productive areas because of various characteristics and processes including 1 excellent original organic richness and generation potential 2 primary and secondary cracking of kerogen and retained oil respectively 3 retention of oil for cracking to gas by adsorption 4 porosity resulting from organic matter decomposition and 5 brittle mineralogical composition the calculated total gas in place gip based on estimated ultimate recovery that is based on production profiles and operator estimates is about 204 bcf section 5 78 10 9 m 3 1 73 10 4 m 3 we estimate that the barnett shale has a total generation potential of about 609 bbl of oil equivalent ac ft or the equivalent of 3657 mcf ac ft 84 0 m 3 m 3 assuming a thickness of 350 ft 107 m and only sufficient hydrogen for partial cracking of retained oil to gas a total generation potential of 820 bcf section is estimated of this potential approximately 60 was expelled and the balance was retained for secondary cracking of oil to gas if sufficient thermal maturity was reached gas storage capacity of the barnett shale at typical reservoir pressure volume and temperature conditions and 6 porosity shows a maximum storage capacity of 540 mcf ac ft or 159 scf ton

multiscale pore network representation of heterogeneous carbonate rocks a multi scale network integration approach introduced by jiang et al 2013 is used to generate a representative pore network for a carbonate rock with a pore size distribution across several orders of magnitude we predict the macroscopic flow parameters of the rock utilising i 3d images captured by x ray computed micro tomography and ii pore network flow simulations to capture the multi scale pore size distribution of the rock we imaged four different rock samples at different resolutions and integrated the data to produce a pore network model that combines information at several length scales that cannot be recovered from a single tomographic image a workflow for selection of the number and length scale of the required input networks for the network integration process as well as fine tuning the model parameters is presented mercury injection capillary pressure data were used to evaluate independently the multi scale networks we explore single scale two scale and three scale network models and discuss their representativeness by comparing simulated capillary pressure versus saturation curves with laboratory measurements we demonstrate that for carbonate rocks with wide pore size distributions it may be required to integrate networks extracted from two or three discrete tomographic data sets in order to simulate macroscopic flow parameters this article is protected by copyright all rights reserved

resolution effect on image based conventional and tight sandstone pore space reconstructions origins and strategies abstract a suitable choice of spatial resolution is essential to the three dimensional 3d image based reconstruction of rock pore space a too low spatial resolution may result in the omission of sub resolution porosity while too high spatial resolution may lead to a field of view smaller than the representative volume in this work the 3d pore spaces of conventional and tight sandstone specimens are reconstructed by x ray computed tomography with spatial resolutions of 2 m 5 m 10 m and 20 m and equal image voxel quantities 600 600 600 to study the influence of spatial resolution on the reconstruction quality petrophysical properties such as porosities permeabilities and pore throat structure parameters are calculated from the 3d images and measured by helium porosity klinkenberg corrected permeability and mercury intrusion capillary pressure porosimetry for comparison high resolution images are sampled from different positions in the specimens to evaluate the core scale heterogeneities rock textures and pore throat structures of the specimens are analyzed through casting thin sections and micp to find out the origin of the resolution effect the results show that 3d images with any single spatial resolution have limited detectivities to recover the full pore and throat distribution of sandstone specimens which is the root cause of the resolution effect the contributions of different pore genetic types with various pore sizes to petrophysical properties vary with simulation targets and methods for conventional sandstone specimens with only one dominate pore genetic type the appropriate spatial resolution can be chosen by calibrating the simulated petrophysical properties to actual measurements for tight sandstone specimens with several pore genetic types the contents and contributions to the petrophysical properties should be investigated before pore space reconstructions

simulating secondary waterflooding in heterogeneous rocks with variable wettability using an image based multiscale pore network model the two phase flow properties of natural rocks depend strongly on their pore structure and wettability both of which are often heterogeneous throughout the rock to better understand and predict these properties image based models are being developed resulting simulations are however problematic in several important classes of rocks with broad pore size distributions we present a new multi scale pore network model to simulate secondary waterflooding in these rocks which may undergo wettability alteration after primary drainage this novel approach permits to include the effect of microporosity on the imbibition sequence without the need to describe each individual micropore instead we show that fluid transport through unresolved pores can be taken into account in an upscaled fashion by the inclusion of symbolic links between macropores resulting in strongly decreased computational demands rules to describe the behaviour of these links in the quasi static invasion sequence are derived from percolation theory the model is validated by comparison to a fully detailed network representation which takes each separate micropore into account strongly and weakly water and oil wet simulations show good results as do mixed wettability scenarios with different pore scale wettability distributions we also show simulations on a network extracted from a micro ct scan of estaillades limestone which yields good agreement with water wet and mixed wet experimental results this article is protected by copyright all rights reserved

a new technique for recognition of geological and geomorphological patterns in digital terrain models abstract we have developed a technique that recognizes monoclinal sedimentary strata showing strike ridge geomorphology and fluvial deposits from digital terrain models dtms this technique is efficient and reliable and may be expanded to analysis of other landforms techniques for rapid geomorphic analysis of dtms are becoming increasingly useful since digital stereoscopic spot data will soon be available worldwide our technique recognizes geomorphic elements in two steps first elementary objects including crests thalwegs and various slope types are classified from slope changes along n s e w nw se and ne sw profiles through pixels in the dtm image second grammatical pattern recognition is used to identify and map geomorphic forms from the succession of elementary objects

surface texture analysis of a high resolution dtm interpreting an alpine basin abstract this study focuses on a geomorphometric analysis of a small headwater basin of the dolomites eastern italian alps the analysis of the fine scale surface morphology was performed on a high resolution digital elevation model cell size 2 m derived from an airborne lidar survey the topography was synthesized by a set of spatial statistical indexes representing a signature of the local surface morphology and the relationships between the geomorphometric indexes and morphological features were evaluated the studied basin was then segmented by means of a fuzzy k means classification algorithm into different spatial subdomains characterized by specific local geomorphic signatures this method allows us to objectively choose the optimal combination of the number of classes and degree of fuzziness characterizing the studied basin accordingly the analysis can be adopted to the characteristics of the studied area improving the interpretation of surface morphology and offering a valuable tool for comparative analysis between different geomorphological contexts the results of the classification were compared with the actual surface morphology based on high resolution orthophotos aerial photos and field surveys

pore scale modeling of carbonates abstract carbonate rocks display complex pore textures with heterogeneities that extend over several length scales identifying and capturing the significant pore space properties in a computationally tractable model is therefore nontrivial pore scale models bridge predictions of transport properties from sub pore to core scale and attempts have been made to render such methods cost effective this chapter reviews several methods for fabricating pore scale models of carbonate rocks and discusses approaches to simulating their fluid flow and solute transport properties the advantages and limitations of each method in reducing the reservoir development uncertainties are explained we argue that pore scale models can play an important role in predicting the petrophysical properties of carbonate rocks even more importantly they provide sensitivity analyses of pore scale features on macroscopic transport observations and offer explanations for anomalous flow behaviors

primary migration by diffusion through kerogen ii hydrocarbon diffusivities in kerogen abstract laboratory experiments were performed to assess diffusion through kerogen as a mechanism of liquid hydrocarbon transport through fine grained rocks such transport can be important in primary migration within source rocks and in leakage through seals previous work with organic coated model cores has shown that hydrocarbon diffusion through organic matter networks can be substantially greater than hydrocarbon diffusion through aqueous pore space in the present work natural kerogen networks were evaluated experiments with five natural source rocks showed that kerogen increased the experimental hydrocarbon flux over the calculated hydrocarbon flux through pore water in only one of these source rocks the richest 2 2 toc carbonate sample effective diffusivities through kerogen were calculated for the two experimental hydrocarbons through this sample the results were extended with the wilke chang correlation to yield diffusivities of several other hydrocarbons through similar source rocks

geochemical characterization of free versus asphaltene sorbed hydrocarbons in crude oils implications for migration related compositional fractionations based on the existing petroleum migration models that focus on the role of organic sorption a laboratory study has been performed to simulate the migration effects on the various fractions of oil in this study one free oil fraction defined as bitumen 1 existing outside of or loosely attached to asphaltene and three to four absorbed oil fractions defined as bitumens 2 3 4 and 5 more strongly attached to asphaltene macromolecules that were obtained from three oil samples collected from the bohai bay basin east china were analyzed in detail based on the laboratory partition of oil components between the solvent phase oil and the asphaltene phase petroleum migrationrelated effect on saturate fraction was re evaluated our observation indicates that the compositional variation from bitumen 1 to bitumen 4 or 5 includes the following 1 the resin content increases while the saturate content and saturates aromatics ratio decrease 2 the relative abundance of short chain n alkanes decreases while that of the long chain n alkanes increases 3 pr nc17 ph nc18 and pr ph ratios stay virtually unchanged while the relative abundances of terpanes to n alkanes and steranes to n alkanes decrease 4 the ratios of c21 c21 c29 steranes and c23 c23 c30 terpanes in the free oil fraction are similar to or even lower than those in the whole absorbed fraction suggesting relatively stronger affinities of these smaller terpane and sterane molecules to asphaltenes in contrast to the relatively larger ones and 5 the isomerization parameters of c27 and c29 steranes are slightly higher in the free fraction than in the whole absorbed oil fraction large variations were observed in the distributions of steranes among the four bitumen fractions of the x52 oil and were considered to be related to the heterogeneity of the source rocks in addition to the partition of these compounds between the asphaltene phase and the solvent phase q 2002 elsevier science ltd all rights reserved

investigating the relative permeability behavior of microporosity rich carbonates and tight sandstones with multiscale pore network models the relative permeability behavior of rocks with wide ranges of pore sizes is in many cases still poorly understood and is difficult to model at the pore scale in this work we investigate the capillary pressure and relative permeability behavior of three outcrop carbonates and two tight reservoir sandstones with wide multi modal pore size distributions to examine how the drainage and imbibition properties of these complex rock types are influenced by the connectivity of macropores to each other and to zones with unresolved small scale porosity we apply a previously presented micro computed tomography based multi scale pore network model bultreys et al 2015b 2016b to these samples the sensitivity to the properties of the small scale porosity is studied by performing simulations with different artificial sphere packing based networks as a proxy for these pores finally the mixed wet water flooding behavior of the samples is investigated assuming different wettability distributions for the micro and macroporosity while this work is not an attempt to perform predictive modeling it seeks to qualitatively explain the behavior of the investigated samples and illustrates some of the most recent developments in multi scale pore network modeling

effect of maturity and petroleum expulsion on pyrrolic nitrogen compound yields and distributions in duvernay formation petroleum source rocks in central alberta canada abstract a quantitative study of pyrrolic nitrogen compounds was conducted on a series of marine carbonate petroleum source rock extracts taken from the upper devonian duvernay formation in the central alberta portion of the western canada sedimentary basin with increasing thermal maturity concentrations of various pyrrolic nitrogen compounds in the rock extracts increase drastically together with significant compositional variations related to alkyl substitution position the study provides circumstantial evidence for adsorptive interactions operating between organic nitrogen compounds and solid organic mineral phases in subsurface sedimentary rocks during petroleum generation and expulsion the absolute concentrations and relative distributions of pyrrolic nitrogen compounds in the extracts of different maturity ranges provide background information for the calibration of such data in migrated petroleums as an independent measurement of secondary oil migration range of duvernaysourced oils in the basin

primary migration behaviour of hydrocarbons from laboratory experiments to geological situations through fluid flow models abstract primary migration is a complex process involving coupled fluid generation and mass transfer in low permeable rocks joint experimental and modelling work have been performed in order to better understand this problem eventually experimental results have been modelled and extrapolated to geological conditions maturation and expulsion experiments have been carried out with water saturated immature type ii source rocks from the paris basin with sample weights up to 3 kg temperatures were stepwise increased from 20 c to 285 330 or 380 c at constant hydrostatic pressures of respectively 17 or 55 mpa during up to 5000 h during the experiments generated fluids expelled out of the heating cell and were sampled prior to a complete analysis mass balances were checked on hydrocarbon gases liquid hydrocarbons co 2 and water meanwhile closed system pyrolysis experiments were performed on isolated kerogen extracted from the same source rocks they allowed us to derive a compositional kinetic cracking reaction network it was then possible to tackle the expulsion of fluids out of the source rock the kinetic scheme provides a guideline to understand the generation of fluids from kerogen the expulsion experiments provide an insight into the expulsion mechanisms no axial stress has been applied to the samples in the experiments therefore the influence of rock compaction due to effective stress was not studied in these experiments a numerical model of expulsion has been set up based on volume and mass balance conservation equations in the source rock the volume is assumed to vary as solid kerogen transforms to liquid products and solid residue the mass of each compound is kept in balance as it is created or destroyed through primary and secondary cracking and expelled through multiphase fluid flow therefore depending on pressure temperature and composition fluids in the source rock are split into several phases following a thermodynamical equation of state all mobile phases flow according to darcy s law experiments were modelled the best fit being achieved with the following conditions all fluids including water co 2 and hydrocarbons are allowed to form a multiphase mixture the heavy compounds resins and asphaltenes are in a single very viscous phase and are less easily expelled as most of them are cracked inside the source rock extrapolations to geological pressure and temperature conditions were performed afterwards in order to check the phase behaviour and the expulsion efficiency

a forward analysis on the applicability of tracer breakthrough profiles in revealing the pore structure of tight gas sandstone and carbonate rocks we explore tracer breakthrough profiles tbp as a macroscopic property to infer the pore space topology of tight gas sandstone and carbonate rocks at the core scale the following features were modeled via three dimensional multiscale networks microporosity within dissolved grains and pore filling clay cementation in the absence and presence of microporosity each classified into uniform pore preferred and throat preferred modes layering vug and microcrack inclusion a priori knowledge of the extent and location of each process was assumed to be known with the exception of an equal importance of macropores and pore filling micropores tbps show little sensitivity to the fraction of micropores present in general significant sensitivity of the tbps was observed for uniform and throat preferred cementation layering parallel to the fluid flow direction had a considerable impact on tbps whereas layering perpendicular to flow did not microcrack orientations seemed of minor importance in affecting tbps

primary migration by diffusion through kerogen iii calculation of geologic fluxes abstract geologic flux calculations were performed to assess diffusion through kerogen as a mechanism of liquid hydrocarbon transport through fine grained rocks such transport can be important in primary migration within source rocks and in leakage through seals from previous experimental measurements of hydrocarbon diffusivities through kerogen a geologic hydrocarbon flux was estimated for rocks similar to the experimental sample diffusion driven by the hydrostatic pressure gradient through its influence on chemical potential gave an estimated bitumen flux of 2 5 bbl acre ma 98 m 3 km 2 ma this was compared to fluxes required to source oil accumulations in four basins and it indicated that diffusion through kerogen could account for small to moderate accumulations

representation of multiscale heterogeneity via multiscale pore networks 1 developing a better understanding of single multiphase flow through reservoir rocks largely relies on characterizing and modeling the pore system for simple homogeneous rock materials a complete description of the real pore structure can be obtained from the pore network extracted from a rock image at a single resolution and then an accurate prediction of fluid flow properties can be achieved by using network model however for complex rocks e g carbonates heterogeneous sandstones deformed rocks a comprehensive description of the real pore structure may involve several decades of length scales e g from submicron to centimeters which cannot be captured by a single resolution image due to the restriction of image size and resolution hence the reconstruction of a single 3 d multiple scale model of a porous medium is an important step in quantitatively characterizing such heterogeneous rocks and predicting their multiphase flow properties in this paper we present a novel methodology for the numerical construction of the multiscale pore structure of a complex rock from a number of ct images models of a carbonate sample at several length scales the success of this reconstruction relies heavily on image segmentation pore network extraction and stochastic network generation which are provided by our existing software system referred to as pore analysis tools pat specifically the statistical description of pore networks of 3 d rock images at multiple resolutions makes it possible for us to a construct an arbitrary sized network which is equivalent in a specified domain and b integrate multiple networks of different sizes into a single network incorporating all scales using multiscale networks of carbonate rocks generated in this manner two phase network modeling results are presented to show how the resulting flow properties are dependent on inclusion of information from multiple scales these outcomes reinforce the importance of capturing both geometry and topology in the hierarchical pore structure for such complex pore systems the example presented reveals that isolated large scale e g macro pores are mainly connected by small scale e g micro pores which in turn determines the combined effective petrophysical properties capillary pressure absolute and relative permeability it is also demonstrated that multi three scale networks reveal the effects of the interacting multiscale pore systems e g micropores macropores and vugs on bulk flow properties in terms of two phase flow properties

petroleum retention in the mandal formation central graben norway abstract upper jurassic organic matter rich marine shales of the mandal formation have charged major petroleum accumulations in the north sea central graben including the giant ekofisk field which straddles the graben axis recent exploration of marginal basin positions such as the mandal high area or the sogne basin has been less successful raising the question as to whether charging is an issue possibly related to high thermal stability of the source organic matter or delayed expulsion from source to carrier the mandal formation is in part a very prolific source rock containing mainly type ii organic matter with

dispersion index of topographic surfaces abstract the dispersion index d of topography is introduced this index is a geomorphic parameter which characterizes each point of topography with respect to the stability instability of the steepest descent path sdp originating from it the procedure for calculating d is based on the assessment of sdp variations as the initial topography is also varied within a given elevation h while a length scale l defines the maximum extent of the sdp as a result d can be derived for different ranges h and different bandwidths l since at each point the gravitational force would direct a surface flow along the sdp d appears to have a strong influence on the behavior of gravity driven mass flows influencing local topographic widening spreading or channelization considering mount etna italy as a test case we present maps of d for h 3 m and l 1 2 4 and 8 km demonstrating also the relationship between the range h 3 m and etnean lava flows focusing on the 2001 lava flow we show that the presented maps of d besides being a tool for viewing morphologies have interesting applications for hazard assessment related to lava flows

simple kinetic models of petroleum formation part iii modelling an open system abstract the movement of petroleum from organic rich source beds to potential carrier beds is the net result of two processes expulsion the release of generated petroleum from kerogen within the source bed and primary migration flow of a petroleum phase through the inorganic void networks of the source bed and all other intervening fine grained rocks expulsion is by far the more important process within the source bed orgas a simple zero dimensional model of the source rock as an open system explicitly models expulsion concurrent with oil and gas generation and oi lgas cracking as a storage threshold problem oil and gas are retained adsorbed absorbed within kerogen until their concentrations exceed the respective sorptive capacity of the residual organic carbon 0 1 and 0 02 g g ck 1 the initial hydrogen index hl 0 controls the important balance between potential sorbate petroleum and sorbant residual carbon using simple geochemical measurements the initial organic carbon is divided into initial oil inert kerogen and oil and gas generative reactive kerogen components reactive kerogens are assigned to one of five global kinetic organofacies with pre determined kinetic parameter sets governing separately rates of oil and gas generation kinetic parameters governing the rates of oil cracking within the source rock are predicted from hl 0 the two most important determinants of source rock behaviour are organofacies and hl 0 at a reference constant heating rate of 2 c ma 1 the projected oil expulsion threshold for typical organofacies members increases in the order a de 100 110 120 135 c f typically expels no oil an order of magnitude increase decrease in heating rate increases decreases these thresholds by ca 15 c typical cumulative gas mass fractions in their ultimate expulsion products are a f 0 25 0 3 0 25 0 65 and 1 0 g g 1 a value of 200 mg hc g c 1 is an approximate minimum hl 0 prerequisite for oil expulsion irrespective of absolute petroleum potential p 0 as a family coals vary dramatically in their expulsion behaviour as their hl 0 ranges both above and velow this value primary migration is efficient for expulsive source rocks movement within the source bed is limited only at low p 0 a source rocks total genetic potential p 0 thickness becomes important during migration outside the source bed it potentially restricts the primary migration distance and the excess of petroleum available for secondary migration and entrapment we evaluate primary migration approximately using a small migration loss factor no more than about 10 saturation of porosity or 1 mg g 1 coupled with an understanding of fluid potential gradients which determine migration direction within the stratigraphic architecture ultimately kerogen degradation and oil to gas cracking in the source rock are the rate limiting processes in petroleum accumulation

supervised landform classification of northeast honshu from dem derived thematic maps this paper proposes a quantitative method to classify landforms using four morphometric parameters from dem derived thematic raster maps of slope and topographic openness because the different surficial processes and stages in the evolution of slopes create landscapes with different shapes these parameters may lead to a genetic interpretation of topography the raster maps of slope and topographic openness were constructed for northeast honshu japan from 50 m dems the mean and standard deviation of morphometric parameters within a 3050m by 3050m moving window on the raster maps were calculated the results for some training areas show that constructional depositional and erosional landforms with different relief have different morphometric characteristics a supervised landform classification for northeast honshu using the knowledge from the training areas revealed a ladder geomorphological structure composed of high mountains ranges and volcanoes the close relationship between the ladder geomorphological structure and volcano distribution indicates that the structure reflects the magmatic plumbing system from the upper mantle to the crust of the northeast honshu arc

digital core analysis improved connectivity and permeability characterization of thin sandstone layers in heterolithic rocks abstract heterolithic thin beds reservoirs contain significant amounts of hydrocarbons we characterized the reservoir properties sandstone connectivity continuity and permeability of sandstone layers in heterolithic rocks using three dimensional imaging and analysis of heterolithic core plugs and mini plugs the high resolution three dimensional models of the samples are smaller than a typical reservoir model grid block and similar the millimetre to centimetre beddings in heterolithic rocks we find that the key to reservoir quality in heterolithic rocks is the connectivity and continuity of thin reservoir sandstone layers also we show that these well connected and continuous thin sandstone layers have higher effective permeabilities that are comparable to a reference reservoir sandstone these results can provide further information as to why some low resistivity heterolithic intervals with low net to gross values of the sandstone produced a significant amount of hydrocarbon despite lower production forecast based on well logs and core plug data determining the connectivity and continuity of thin sandstone layers is difficult due to limitations of well logs and core plug analysis that do not resolve and capture the connectivity of thin beddings we show that 3 d image visualization is effective in characterizing the connectivity and continuity of thin sandstone layers in heterolithic rocks also our digital core analysis method computed permeability of thin sandstone layers in 3 d models of mini plugs representing thin sandstone layers in heterolithic core plugs our results represent information and reservoir properties at the millimetre to centimetre scale that are similar to the thickness of thin sandstone beddings in heterolithic rocks

practical kinetic modeling of petroleum generation and expulsion abstract models for petroleum generation used by the industry are often limited by a sub optimal laboratory pyrolysis methods for studying hydrocarbon generation b over simple models of petroleum generation c inappropriate mathematical methods to derive kinetic parameters by fitting laboratory data d primitive models of primary migration expulsion and its coupling with petroleum generation and e insufficient use of subsurface data to constrain the models problems a b and c lead to forced compensation effects between the activation energies and frequency factors of reaction kinetics that are wholly artificial and which yield poor extrapolations to geological conditions simple switch or adsorption models of expulsion are insufficient to describe the residence time of species in source rocks yet the residence time controls the thermal stresses to which the species are subjected for cracking to lighter species the shellgenex model for petroleum generation and expulsion has been developed since 1988 in this multi species model the rate limiting step of primary migration is treated as the slow diffusion of the petroleum through the kerogen itself other key aspects of the model are the reaction and transport behaviour of the heavy compounds the role of free radicals in the cracking kinetics of hydrocarbon species in the model and the evolving free volume of the kerogen the last of these has a particularly strong effect on the primary migration of the generated petroleum molecules some implications of this model are that a compositions of expelled petroleum vary more strongly than the standard parallel reaction model suggests and b expulsion is not immediately extinguished by waning temperatures and pressures but continues with decreasing gor of the expelled petroleum and increasing density of the expelled oil

characterization of volcanic geomorphology and geology by slope and topographic openness abstract we used a digital elevation model dem of iwate volcano japan to calculate slope and topographic openness for every geological unit in that area further we conducted principal component analysis pca and stepwise discriminant analysis sda to evaluate statistical differences in the morphometric parameters of the geological units we categorized the geological units according to their ages and their formation processes the categorization based on formation processes was as follows lava flow lava central cone stratocone air fall deposit pyroclastic flow deposit volcanic fan deposit and debris avalanche deposit pca allowed us to select geological units suitable for analysis while sda was used to select some morphometric parameters which could explain the differences in the formation processes and ages of the geological units we found that the formation processes correspond well to mean slope and that the geological ages that control the degree of surface dissection correspond well to the standard deviations of slope and negative topographic openness

multi scale x ray tomography analysis of carbonate porosity the porosity from values of 1 up to more than 50 with a mean value of 36 5 and permeability from very low values to 20 4 d with a mean value around 800 md of 38 plugs with a diameter 40 mm have been measured these plugs were taken approximately every 1 5 m along a 100 m long core sampling a series of reefal carbonate platform lithofacies a non unique relationship between porosity and permeability is obtained in addition the porosity was measured from processing x ray micro tomography images with resolutions ranging from 0 42 to 190 0 m and sampling volumes ranging from less than 1 m3 to few cm3 depending on the structure of the pore network the computed porosity is in some cases controlled by the x ray image resolution and the sampled volume while high resolution is required to image micro porous material large samples with lower resolution images are necessary for identifying distributed vugs and millimetre scale structures this study shows that multi resolution x ray micro tomography is an effective tool for characterizing the multi scale pore structure of carbonate rocks and understanding how it may control key petrophysical parameters such as porosity and permeability

discrimination of fluvial eolian and neotectonic features in a low hilly landscape a dem based morphotectonic analysis in the central pannonian basin hungary abstract the godoll hills a low relief terrain within the central pannonian basin in hungary is characterised by moderate tectonic deformation rates although typical tectonic landforms are not clearly recognisable in the study area this paper succeeded in discriminating between tectonically controlled landforms and features shaped by fluvial erosion or deflation with no tectonic control dem based morphometric parameters including elevation slope and surface roughness enabled the delineation of two nw se trending spearhead shaped ridges separated by a wide rectilinear valley of the same strike although directional statistics suggested possible tectonic control of nw se striking landforms precise morphometry completed with an analysis of subsurface structures rejected their tectonic preformation deflation plays a significant role in shaping the area and the presence of two large scale yardangs separated by a wind channel is proposed in temperate continental areas of europe no deflational landforms of such scale have been described so far suggesting that pleistocene wind power in periglacial areas was more significant than it was previously thought characteristic drainage patterns and longitudinal valley profiles enabled the recognition of areas probably affected by neotectonic deformation a good agreement was observed between locations of quaternary warping predicted by the morphometric study and subsurface structures revealed by the tectonic analysis zones of surface uplift and subsidence corresponded to anticlinal and synclinal hinges of fault related folds in low relief and slowly deforming areas where exogenous forces may override tectonic deformation only the integrated application of morphometric and subsurface structural indications could assure correct interpretation of the origin of various landforms while a morphometric study alone could have led to misinterpretation of some morphometric indices apparently suggesting tectonic preformation on the other hand the described morphological expression of subsurface structures could verify quaternary age of the deformation