spectrum of pore types and networks in mudrocks and a descriptive classification for matrix related mudrock pores matrix related pore networks in mudrocks are composed of nanometer to micrometer size pores in shale gas systems these pores along with natural fractures form the flow path permeability network that allows flow of gas from the mudrock to induced fractures during production a pore classification consisting of three major matrix related pore types is presented that can be used to quantify matrix related pores and relate them to pore networks two pore types are associated with the mineral matrix the third pore type is associated with organic matter om fracture pores are not controlled by individual matrix particles and are not part of this classification pores associated with mineral particles can be subdivided into interparticle interp pores that are found between particles and crystals and intraparticle intrap pores that are located within particles organic matter pores are intrap pores located within om interparticle mineral pores have a higher probability of being part of an effective pore network than intrap mineral pores because they are more likely to be interconnected although they are intrap om pores are also likely to be part of an interconnected network because of the interconnectivity of om particles in unlithifed near surface muds pores consist of interp and intrap pores and as the muds are buried they compact and lithify during the compaction process a large number of interp and intrap pores are destroyed especially in ductile grain rich muds compaction can decrease the pore volume up to 88 by several kilometers of burial at the onset of hydrocarbon thermal maturation om pores are created in kerogen at depth dissolution of chemically unstable particles can create additional moldic intrap pores

large scale intertidal polygonal features of the abu dhabi coastline this study provides the first quantitative description of modern giant polygons these large scale up to 166 m diameter sedimentological features are described here in detail from the intertidal zone of the arabian gulf near abu dhabi these features form by the displacive carbonate cementation of carbonate sand below a 3 to 5 cm thick cover of unconsolidated sediment the oxygen isotopic composition of cements is consistent with precipitation from evaporated sea water cementation proceeds via a poorly consolidated layer that grades downward into an 8 to 14 cm thick well cemented grainstone the margins of this expanding hardground form the overlapping borders of the polygons tepee structures at the borders of polygons are only occasionally preserved as supporting sediment is removed by strong tidal currents and high energy events such as storms that erode the unsupported tepees these observations have clear implications for the use of tepees in the interpretation of ancient polygons and their associated environments when preserved in the sedimentary record tepee structures are interpreted to indicate lower energy depositional environments than that observed in this study

sedimentological characteristics of the surficial sediments of the kuwaiti marine environment northern arabian gulf the textural characteristics carbonate content and the coarse fraction components of the recent bottom sediments of the marine environment off kuwait are described and the faunal sediment associations discussed the sediments were subdivided into seven textural classes namely sand silty sand muddy sand sandy silt sandy mud silt and mud most of the study area is covered with muddy sediments whereas sandy deposits are restricted to the rocky bottoms near the southern flat of kuwait bay the southern coast of kuwait and around the islands and bathymetric highs the textural classes carbonate contents and faunal types of the coarse fraction were used to construct a biolithofacies map of the marine bottom sediments off kuwait in which nine facies are identified the sedimentological characteristics of the recent marine bottom sediments off kuwait reflect the interaction between autochthonous calcareous fragments mostly of biogenic origin lime rock fragments derived from beachrocks and submerged reef flats and allochthonous terrigenous detritus transported to the area mainly by dust storms the kuwaiti offshore area is generally a low energy depositional environment with little sediment transport

detailed 3 d depositional architecture of late jurassic carbonate anhydrite cycles brightling mine weald basin uk abstract quantifying the geometries of evaporite deposits at a 13 c and 18 o isotope analysis the stratigraphic interval contains five facies in stratigraphic order these include supratidal porphyritic nodular evaporite shallow subtidal peloidal packstone with evaporite and two overlying rhythmic sequences of intertidal microbial laminite subtidal shale and subtidal laminar marl capped by nodular anhydrite the interpreted environment of deposition is a supratidal sabkha subject to periodic flooding in which intertidal tidal flat facies and subtidal shallow marine facies laterally passed into the evaporative sabkha the cycles are interpreted as meter scale shoaling upward sequences likely controlled by localized high frequency changes in relative sea level and or sabkha hydrology spatial patterns in the geometries of key stratigraphic surfaces reveal a subtle depression towards the central western region of the mine seam the variation in stratal geometries is interpreted as paleotopography and is a function of individual or composite processes related to dissolution eolian processes and coastal erosion these observations indicate a similar mode of deposition to the modern day sabkha of the persian gulf we conclude that the dynamic process of evaporite deposition led to subtle stratigraphic heterogeneities and changes in bed thicknesses but largely continuous lateral bedding at an interwell scale

carbonate evaporite sequences of the late jurassic southern and southwestern arabian gulf the carbonate evaporite sequences of the upper jurassic arab and overlying hith formations in the southern and southwestern arabian gulf form many supergiant and giant fields that produce from the arab formation and are excellent examples of a classic reservoir seal relationship the present day sabkha depositional setting that extends along most of the southern and southwestern coasts of the arabian gulf provides an analog to these upper jurassic sedimentary rocks in fact sabkha related diagenesis of original grain supported sediments in the arab and hith formations has resulted in five distinct lithofacies that characterize the reservoir seal relationship 1 oolitic peloidal grainstone 2 dolomitic grainstone 3 dolomitic mudstone 4 dolomitized grainstone an 5 massive anhydrite interparticle porosity in grainstones and dolomitic grainstones and intercrystalline porosity in dolomitized rocks provide the highest porosity in the study area these sediments accumulated in four types of depositional settings 1 supratidal sabkhas 2 intertidal mud flats and stromatolitic flats 3 shallow subtidal lagoons and 4 shallow open marine shelves the diagenetic history of the arab and hith formations in the southern and southwestern arabian gulf suggests that the anhydrite and much of the dolomitization are a result of penecontemporaneous sabkha diagenesis the character and timing of the paragenetic events are responsible for the excellent porosity of the arab formation and the lack of porosity in the massive anhydrites of the hith which together result in the prolific hydrocarbon sequences of these formations

a quantitative analysis of recent arid coastal sedimentary facies from the arabian gulf coastline of abu dhabi united arab emirates abstract this study presents the results of the first quantitative analysis of surface sediments along multiple transects of the arabian gulf shoreline of abu dhabi united arab emirates the natural coastline of this low angle carbonate ramp depositional system is being anthropogenically modified at an unprecedented rate as this system is much employed as a recent analogue for many ancient depositional sequences it is imperative that sedimentological characteristics of natural facies occurrences are accurately recorded for employment in future applications we establish distinct relationships between the geomorphic setting and sediment characteristics siliciclastic grains admixed to this system are naturally sourced from the pliocene ghayathi formation and from aeolian sediment influx during dust storms this natural source of siliciclastic detritus is being increasingly superseded by siliciclastic material derived from anthropogenic activities evaporite minerals are similarly being contributed from anthropogenic sources the occurrence of mud to silt grade sediments is primarily controlled by the presence of a sediment binding microbial mat that prevents the removal of fine material during high energy events similarly the presence of a halite crust in the upper tidal flats and supratidal zone prevents aeolian deflation this study did not establish any clear relationship between coastal geomorphic setting and the bioclastic components present in the sediments this finding has major implications for the application of bioclasts in fine tuning palaeoenvironmental interpretation of ancient carbonate ramp coastal systems

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

platform and off platform carbonates of the upper cambrian of western maryland u s a upper cambrian carbonates in western maryland are comprised of platform facies conococheague limestone west of south mountain and basin facies frederick limestone east of south mountain conocheague platform carbonates contain interbedded non cyclic and cyclic facies non cyclic facies consist of cross stratified grainstones thrombolitic bioherms and graded thin bedded dolostones these were deposited in shallow subtidal shelf lagoons cyclic facies are composed of repeated sequences of cross stratified grainstone ribbon rock wavy prism cracked laminite and planar laminated dolostone the cyclic facies are shallowing upward cycles produced by lateral progradation of tidal flats over shallow nearshore subtidal environments cyclic and non cyclic facies are interbedded in the conococheague in a layer cake fashion but no higher order cyclicity can be found the frederick limestone is dominated by monotonously thick sequences of graded thin bedded limestones interbedded with massive peloidal grainstones and beds of breccia up to 10 m thick in the lower frederick the breccias contain transported megaclasts of epiphyton girvanella boundstones the basal frederick was deposited in a slope to basinal setting east of a rimmed shelf an epiphyton girvanella marginal reef along the shelf edge was the source of the blocks in the breccias the upper frederick limestone formed on a carbonate ramp

sedimentation distribution and diagenesis of organic matter in a recent carbonate environment abu dhabi u a e abstract in the modern hypersaline carbonate lagoon and sabkha sedimentary environments of abu dhabi united arab emirates three types of organic matter originate respectively from microbial mat avicennia mangrove and halodule lagoonal seagrass the study of recent sedimentary processes and cross sections through the sabkha sediments lead to the definition of organo sedimentary facies based on geochemical and sedimentological criteria this permits the construction of an organo sedimentary sequence which expresses the holocene sedimentary record involving a transgressive and a regressive sequence the various organic facies occur in both sequences heterogeneity within the individual organic facies reflects several factors including sedimentation dynamics mineral matrix oxidation and reduction and selective organic and mineral diagenesis these parameters are discussed in terms of depositional environment and location within the organo sedimentary sequence changes in distribution quantity and preservation potential of the buried organic matter are discussed in terms of sea level changes and sedimentary accretion rates

quantification of carbonate ramp sedimentation and progradation rates for the late holocene abu dhabi shoreline abstract we utilize new radiocarbon dates and detailed sedimentological logging of the abu dhabi sabkha to produce the first well constrained internally consistent rates for late holocene carbonate ramp sediment accumulation and progradation for the southern shore of the persian gulf these data are applied to test the hypothesis that in low angle carbonate ramp systems ramp geometry is the primary control on sedimentation and progradation rates and therefore estimates acquired from other depositional environments cannot be applied to low angle carbonate ramp systems average calculated progradation rates of 0 75 m yr are higher than progradation rates proposed for other late holocene and recent carbonate settings a relationship that is explained by the lack of accommodation space in the low angle laterally extensive ramp system in the sedimentary record such relatively high progradation rates would produce laterally extensive lithologically uniform units with little or no evidence of progradational features and would appear to be largely contemporaneous across their extent the total average sediment accumulation rate of 0 029 cm yr is lower than those proposed from most other late holocene to recent shallow water carbonate depositional environments again a relationship interpreted to result from the limited accommodation space of low angle carbonate ramp systems calculated sediment accumulation rates show little variation over the past 1 400 years yet the calculated progradation rates exhibit a sharp decline from a maximum of 1 03 m yr before 677 946 cal bp to 0 70 m yr afterwards this is interpreted to reflect a rise in relative sea level or distal steepening of the ramp system applying the progradation rates proposed in this paper the lagoon system in the study area would be completely infilled in less than 4 000 years calculated sediment accumulation rates for syndepositional and early postdepositional interstitial displacive evaporite formation are higher than those for carbonate and microbial mat intervals continued precipitation of evaporite minerals during burial would result in a further increase in their relative contribution to the sediment pile conversely compaction particularly of microbial mat intervals will result in a decrease in apparent sediment accumulation rates for non evaporite intervals these processes need to be considered when modeling the basin evolution of mixed evaporite carbonate sequences in the stratigraphic record during calculation of sedimentation rates it is important to consider both a correction for compaction and a correction for evaporite formation

pore characteristics and influencing factors of different types of shales abstract shales in china mainly fall into three categories namely marine transitional and lacustrine shales various shales have different pore characteristics we studied the formation occurrence pore types and morphological characteristics of micropores mesopores and macropores in different types of shales through the approaches of gas adsorption and mercury injection our study found that the marine shale samples have larger specific surface area and pore volume providing a good hosting space for adsorption gas and free gas furthermore marine samples are dominated by ink bottle pores which are conducive to adsorption of shale gas continental and transitional pore types are mainly open pores characterized by good pores connectivity that is conducive to the migration of shale gas the main factors controlling the pore characteristics of the three types of shales were analyzed by investigating specific surface area pore volume organic content clay mineral content maturity and burial depth our study demonstrated that specific surface area and pore volume development have a good correlation with organic matter in the three types of shales types of organic matter can affect the development of organic pores the discrepancy in occurrence of organic matter leads to different correlations between the three types of shales and clay minerals on the other hand maturity impacts on pores of shales in two aspects organic matter and clay mineral transformation meanwhile compaction and dissolution of organic acid in hydrocarbon generation process are proved to be especially important to pore structure transformation

mineralogy and provenance of the clastic deposits of the modern intertidal environment of the northern arabian gulf abstract a detailed mineralogical investigation was carried out to determine the composition genesis and potential sources of the clastic deposits covering the modern intertidal environment of kuwait the study area can be broadly divided into northern and southern geomorphic provinces the intertidal zone of the northern province is characterized by wide mudflats covered by silicate dominated sediments with subordinate amounts of carbonates mostly of the low mg calcite and dolomite variety the southern province is marked by relatively steep sandy beaches fronted by narrow to moderately wide rocky intertidal flats partially covered by sand the southern sediments are dominated by aragonite and high mg calcite with less abundant quartz and feldspars erosion and abrasion of coastal deposits tertiary quaternary bedrock and coastal ridges fill material and beach rocks by waves and currents is believed to represent the most important source of the intertidal sediments especially the coarse fraction aeolian material transported as bedload from local sources and as suspended load from regional sources particularly the mesopotamian plain to the north is another important source contrary to common belief of all potential sources the euphrates tigris river system shatt al arab was found to have the least impact on the sedimentation regime of the modern intertidal environment of the northwestern arabian gulf its contribution is probably restricted to fine silt and clay fractions and even then only under flood conditions reworking of the ancient deltaic and estuarine deposits submerged in the northern arabian gulf is probably a more important contributor to the fine fraction of the study area than the shatt al arab discharge spatial variations in the abundance and distribution of the mineral constituents in the intertidal sediments indicate that the relative importance of the above sources varies from one area to another along the kuwaiti coast

deposition of a saline giant in the mississippian windsor group nova scotia and the nascent late paleozoic ice age abstract saline giants are vast marine evaporite deposits that currently have no modern analogues and remain one of the most enigmatic of chemical sedimentary rocks the mississippian windsor group ca 345 ma maritimes basin atlantic canada is a saline giant that consists of two evaporite rich sedimentary sequences that are subdivided into five subzones sequence 1 is composed almost entirely of thick halite belonging to subzone a osagean sequence 2 is in unconformable contact and comprised of stacked carbonate evaporite peritidal cycles of subzones b through e meramecian subzone b the focus of research herein documents the transition from wholly evaporitic to open marine conditions and thus preserves an exceptional window into the processes forming saline giants lithofacies stacking patterns in subzone b reveal that higher order fluctuations in relative sea level produced nine stacked parasequences interpreted to reflect high frequency glacioeustatic oscillations during the onset of the late paleozoic ice age each parasequence reflects progradation of intertidal and sabkha sediments over subtidal carbonate and evaporite deposits dissimilarities in cycle composition between sub basins imply the development of contrasting brine chemistries from differing recharge rates with the open ocean what the windsor group shows is that evaporite type is ostensibly linked to the amplitude and frequency of sea level rise and fall during deposition true saline giants like the basinwide evaporites of sequence 1 apparently require low amplitude long frequency changes in sea level to promote the development of stable brine pools that are only periodically recharged with seawater by contrast the high amplitude short frequency glacioeustatic variability in sea level that controlled the accumulation of peritidal evaporites in subzone b produce smaller subeconomic deposits with more complex facies relationships

cheniers and chenier plains a general introduction abstract cheniers and chenier plains have been studied in many coastal regions throughout the world an inventory of the investigations currently being carried out is presented in this and accompanying papers cheniers and chenier plains are azonal features their distribution ranges from tropical to the subarctic regions and they show a variety of features progradational shorelines where mud accretion is temporarily interrupted favour the development of these features in addition to the concept of otvos and price who define cheniers and chenier plains as being formed exclusively in relation to littoral progradational environments it is suggested here that chenier formation in deltaic progradational environments should also be included genetically two types of cheniers can be distinguished depending on the origin of the related sediments cheniers developing due to wave winnowing of the muddy sediments and the subsequent concentration of the coarser particles to form a longshore bar or ridge which is driven shoreward and cheniers built by littoral drift in both cases they can be recognised by their sedimentary structures when cheniers arrive onshore they will migrate further landward due to washover processes under extreme hydrodynamical conditions e g spring tides storm surges etc to summarise the information concerning the episodic development of chenier plains in order to produce a or a few universal model s appears to be very difficult owing to the numerous factors that influence their formation these include river mouth shifting sealevel changes climatic changes storm frequency mortality of shellfish and bay geometry owing to this sensitivity to environmental changes during their formation cheniers are considered to be very important geomorphological features they provide a relatively accurate record of sealevel and environmental changes which can be dated with high resolution

characterization of gas shale pore systems by porosimetry pycnometry surface area and field emission scanning electron microscopy transmission electron microscopy image analyses examples from the barnett woodford haynesville marcellus and doig units the nanometer scaled pore systems of gas shale reservoirs were investigated from the barnett marcellus woodford and haynesville gas shales in the united states and the doig formation of northeastern british columbia canada the purpose of this article is to provide awareness of the nature and variability in pore structures within gas shales and not to provide a representative evaluation on the previously mentioned north american reservoirs to understand the pore system of these rocks the total porosity pore size distribution surface area organic geochemistry mineralogy and image analyses by electron microscopy were performed total porosity from helium pycnometry ranges between 2 5 and 6 6 total organic carbon content ranges between 0 7 and 6 8 wt and vitrinite reflectance measured between 1 45 and 2 37 the gas shales in the united states are clay and quartz rich with the doig formation samples being quartz and carbonate rich and clay poor higher porosity samples have higher values because of a greater abundance of mesopores compared with lower porosity samples with decreasing total porosity micropore volumes relatively increase whereas the sum of mesopores and macropore volumes decrease focused ion beam milling field emission scanning electron microscopy and transmission electron microscopy provide high resolution 5 nm images of pore distribution and geometries image analysis provides a visual appreciation of pore systems in gas shale reservoirs but is not a statistically valid method to evaluate gas shale reservoirs macropores and mesopores are observed as either intergranular porosity or are confined to kerogen rich aggregates and show no preferred orientation or align parallel with the laminae of the shale networks of mesopores are observed to connect with the larger macropores within the kerogen rich aggregates

pore types in the barnett and woodford gas shales contribution to understanding gas storage and migration pathways in fine grained rocks the identification of organoporosity microscale and nanoscale pores within organic matter in shales its importance to storage and perhaps transfer of gas molecules through shales and methods for gathering three dimensional images of the pores such as by argon ion milling and or field emission scanning electron microscopy have all been well documented and discussed for unconventional gas shales however other types of pores exist within shales that can be important to storage and migration of gas and oil and other technologies are available for their identification and imaging the different pore types found in the barnett and woodford shales are described and classified in this article scanning electron microscopy revealed the presence of porous floccules in both the barnett and woodford shales which appear similar to laboratory produced floccules and to those in other ancient shales published experimental and observational studies indicate that floccules are hydraulically equivalent to coarser grains and are transported by traction processes current induced microsedimentary structures and textures within the barnett and woodford shales as well as the preserved floccules suggest such processes were active during transport and deposition pore spaces between the floccules are open and can provide storage space as well as permeability pathways for gas molecules through the shales pores are also found within organic matter that occurs both as discrete particles and as adsorbed coatings around clay grains in the shale they are referred to here as organopores porous fecal pellets are also common in the barnett shale preserved fossil fragments such as organic walled spores and inorganic sponge spicules have hollow central chambers which may remain partially or completely open even after burial intraparticle pores occur between grains of various minerals e g pyrite framboids microchannels within shale matrix which may be the bounding surfaces of scours or microsedimentary structures may also provide permeability pathways for hydrocarbon migration mircrofractures are also common and their initiation might be related to mineral crystal structure when present in sufficient quantity these pore types offer potential gas and oil molecule storage spaces and permeability pathways through the shales

comparison of sequences formed in marine sabkha subaerial and salina subaqueous settings modern and ancient marine evaporites occurring in modern subaqueous salina settings and subaerial sabkha settings are different subaqueous holocene evaporites occur as shoaling upward lacustrine sequences up to 10 m thick they are evaporite dominated and are composed primarily of bottom nucleated crystals that may be deposited as massive laminated or rippled units each coastal lake is dominated by laminated evaporites with subordinate carbonate sediments in plan view they show a well developed bull s eye pattern with a sulfate center and a carbonate rim in contrast subaerial sabkha evaporites occur as part of a laterally prograding shoaling upward peritidal sequence in which the supratidal unit is usually no more than 1 m thick sabkha sequences are matrix dominated not ev porite dominated with the bulk of the sulfate phase occurring as diagenetic nodules enteroliths or diapirlike structures these sulfates were formed during syndepositional diagenesis by replacement and displacement processes the various facies of the sequence tend to accumulate in belts parallel with the shoreline relative to the sea level or the brine level sabkhas tend to form over paleotopographic highs whereas salinas tend to occur in paleotopographic lows some of the characteristics that distinguish holocene subaerial and subaqueous evaporite sequences can be used to do the same for similar ancient facies even when gypsum has been converted to nodular anhydrite the distinction is important for it can be used by explorationists in the oil industry to define the paleotopography of the associated underlying porous and nonporous carbonates

morphology genesis and distribution of nanometer scale pores in siliceous mudstones of the mississippian barnett shale research on mudrock attributes has increased dramatically since shale gas systems have become commercial hydrocarbon production targets one of the most significant research questions now being asked focuses on the nature of the pore system in these mudrocks our work on siliceous mudstones from the mississippian barnett shale of the fort worth basin texas shows that the pores in these rocks are dominantly nanometer in scale nanopores we used scanning electron microscopy to characterize barnett pores from a number of cores and have imaged pores as small as 5 nm key to our success in imaging these nanopores is the use of ar ion beam milling this methodology provides flat surfaces that lack topography related to differential hardness and are fundamental for high magnification imaging nanopores are observed in three main modes of occurrence most pores are found in grains of organic matter as intraparticle pores many of these grains contain hundreds of pores intraparticle organic nanopores most commonly have irregular bubblelike elliptical cross sections and range between 5 and 750 nm with the median nanopore size for all grains being approximately 100 nm internal porosities of up to 20 2 have been measured for whole grains of organic matter based on point count data from scanning electron microscopy analysis these nanopores in the organic matter are the predominant pore type in the barnett mudstones and they are related to thermal maturation nanopores are also found in bedding parallel wispy organic rich laminae as intraparticle pores in organic grains and as interparticle pores between organic matter but this mode is not common although less abundant nanopores are also locally present in fine grained matrix areas unassociated with organic matter and as nano to microintercrystalline pores in pyrite framboids intraparticle organic nanopores and pyrite framboid intercrystalline pores contribute to gas storage in barnett mudstones we postulate that permeability pathways within the barnett mudstones are along bedding parallel layers of organic matter or a mesh network of organic matter flakes because this material contains the most pores

microstructural investigation of gas shales in two and three dimensions using nanometer scale resolution imaging the microstructure of gas shale samples from nine different formations has been investigated using a combination of focused ion beam fib milling and scanning electron microscopy sem backscattered electron bse images of fib cross sectioned shale surfaces show a complex microstructure with variations observed among the formations energy dispersive spectroscopy of the shale cross sections indicates that clay carbonate quartz pyrite and kerogen are the most prevalent components in the bse images areas of kerogen are observed interspersed with the inorganic grains pores are observed in both the kerogen and inorganic matrix with the size shape and number of pores varying among the shale samples by using fib milling and sem imaging sequentially and repetitively three dimensional 3 d data sets of sem images have been generated for each of the shale samples three dimensional volumes of the shales are reconstructed from these images by setting thresholds on the gray scale the kerogen and pore networks are segmented out and visualized in the reconstructed shale volumes estimates of kerogen and pore volume percentages of the reconstructed shale volumes have been made and range from 0 to 90 0 for the kerogen and 0 2 to 2 3 for pores estimates of pore size distributions suggest that although pores with radii of approximately 3 nm dominate in number they do not necessarily dominate in total volumetric contribution scanning electron microscopy images and 3 d reconstructions reinforce the facts that shales are quite different and that their microstructures are highly variable and complex