noise based monitoring and imaging of aseismic transient deformation induced by the 2006 basel reservoir stimulation abstractwe have analyzed the time dependent properties of the ambient seismic wavefield between 0 1 and 8 hz to detect resolve monitor and image the deformation induced by the water injection associated with the stimulation of the 2006 deep heat mining project in the city of basel switzerland the application of passive methods allowed the detection of an aseismic transient of approximately 35 days duration that began with the onset of the reservoir stimulation peak deformation was reached some 15 days after the bleed off and after the induced seismicity ceased we resolved a significant increase in seismic velocities and a simultaneous decorrelation of the noise correlation coda waveforms the wavefield properties implied that the material response was monitored mainly in the sedimentary layer 2 5 km above the stimulated volume that was approximately 4 5 km deep we inverted the velocity change and decorrelation data to estimate the spatial distribution of the medium changes the resulting imag

sedimentary pyrite formation an update sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time the amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter dissolved sulfate and reactive detrital iron minerals organic matter appears to be the major control on pyrite formation in normal non euxinic terrigenous marine sediments where dissolved sulfate and iron minerals are abundant by contrast pyrite formation in non marine freshwater sediments is severely limited by low concentrations of sulfate and this characteristic can be used to distinguish ancient organic rich fresh water shales from marine shales under marine euxinic conditions sufficient h2s is produced that the dominant control on pyrite formation is the availability of reactive iron minerals calculations based on a sulfur isotope model indicate that over phanerozoic time the worldwide average organic carbon to pyrite sulfur ratio of sedimentary rocks has varied considerably high cs ratios during permo carboniferous time can be explained by a shift of major organic deposition from the oceans to the land which resulted in the formation of vast coal swamps at that time low cs ratios compared to today during the early paleozoic can be explained in terms of a greater abundance of euxinic basins combined with deposition of a more reactive type of organic matter in the remaining oxygenated portions of the ocean the latter could have been due to lower oceanic oxygen levels and or a lack of transportation of refractory terrestrial organic matter to the marine environment due to the absence of vascular land plants at that time

temporal changes of the crustal structure associated with the m6 1 earthquake on september 3 1998 and the volcanic activity of mount iwate japan we detected temporal changes of crustal structure by cross spectrum analyses of seismic waves excited by two artificial explosions that were carried out about one month before and two months after a m6 1 shallow earthquake phase spectrum analysis shows that seismic velocity of the upper crust around the focal area of the m6 1 earthquake and mount lwate decreased 0 3 1 0 during the three months since lager decreases of the seismic velocity were observed at the region close to the focal area and a volcanic pressure source we conclude that stress change in the upper crust is a most plausible candidate to cause the velocity changes among other candidates we further apply a coherence analysis to the observed seismic coda to locate regions where short wavelength heterogeneity temporally changed the result indicates a possibility of temporal changes of the heterogeneity beneath the volcano where a magmatic fluid intrusion is inferred

time resolved seismic tomography detects magma intrusions at mount etna the continuous volcanic and seismic activity at mount etna makes this volcano an important laboratory for seismological and geophysical studies we used repeated three dimensional tomography to detect variations in elastic parameters during different volcanic cycles before and during the october 2002 january 2003 flank eruption well defined anomalous low p to s wave velocity ratio volumes were revealed absent during the pre eruptive period the anomalies trace the intrusion of volatile rich 4 weight percent basaltic magma most of which rose up only a few months before the onset of eruption the observed time changes of velocity anomalies suggest that four dimensional tomography provides a basis for more efficient volcano monitoring and short and midterm eruption forecasting of explosive activity

reflectance of dispersed vitrinite in palaeozoic rocks with and without cleavage implications for burial and thermal history modeling in the devonian of rursee area northern rhenish massif germany abstract vitrinite reflectance is used as coalification parameter in coals and as maturity and palaeotemperature indicator in sedimentary rocks in high grade diagenetic rocks i e rocks at the boundary between diagenesis and metamorphism vitrinites become increasingly anisotropic therefore it has been suggested to study maximum minimum reflectance instead of mean reflectance for rocks which reached this stage in the present study vitrinite reflectance data from a folded sequence of the northern rhenish massif germany are combined with microtectonic study of thin sections in samples in which both bedding and cleavage are present we show that vitrinites in different microtectonic domains cleavage domains and microlithons show significant differences in both maximum vitrinite reflectance and vitrinite reflectance anisotropy this behaviour is due to a strong partitioning of deformation in cleavage domains as compared to microlithons so that vitrinite reflectance is controlled by the thermal and deformation history accordingly estimation of maximum palaeotemperatures during burial should be based on vitrinite reflectance measurements in microlithons unaffected by deformation after maximum burial based on this finding burial and temperature history of the rursee area in the eastern rhenish massif is reconstructed numerical simulations indicate a maximum burial at the siegen ems boundary of about 5000 m and a maximum burial temperature of about 220 c

high thermal maturity in the lower saxony basin intrusion or deep burial abstract the lower saxony basin lsb is situated at the southern rim of the northern permian basin the most important hydrocarbon bearing province in europe in its southern part areas of high thermal maturation up to 6 rr occur which were previously explained as being caused by magmatic intrusions of turonian to santonian age that affected carboniferous to lower cretaceous rocks in this area 2d numerical basin modelling was carried out in order to reconstruct the temperature histories along two parallel n s trending seismic sections along these sections new data about maturity distribution and temperature history were obtained by vitrinite reflectance measurements and apatite fission track analysis for the areas with highest maturity values low coalification gradients were established which agree well with earlier published data on wells further towards the west this new information does not support previous hypotheses on high heat flows from magmatic intrusions even if lateral heat transport is taken into account instead comparisons with a recently published map of the subsurface structure of the lsb indicate that maturity distribution may be closely related to major tectonic structures deep burial of individual structures of the lsb which are bordered by deep e w to ese wnw trending faults is further suggested by a rapidly increasing thicknesses of preserved cretaceous strata towards the south and b structural restoration of one of the seismic sections to achieve a fit between measured and calculated palaeo temperature and vitrinite reflectance data deep burial of carboniferous source rocks during cretaceous time has to be assumed due to an inversion phase in the early and middle upper cretaceous major amounts of sediment were removed and further uplift occurred in tertiary times in contrast the northern part of the lsb experienced maximum burial and temperatures during tertiary times

changes in shear wave splitting at anza near the time of the north palm springs earthquake changes in shear wave splitting are observed at knw before and after the m 6 north palm springs earthquake of july 8 1986 knw is a station of the anza seismic network monitoring the anza seismic gap on the san jacinto fault southern california the gradual increase in the delays between the split shear waves over 3 years at knw reported by peacock et al 1988 ended in june 1986 the further 2 years of observations analyzed here show that the behavior of the delays changed abruptly near the time of the north palm springs earthquake 33 km north of knw peacock et al demonstrated that the increase in delays could be simulated by increasing the aspect ratio of stress aligned fluid filled inclusions and speculated that this increase might be the result of a buildup of stress before an impending earthquake the new data appear to confirm this speculation but the temporal variations require a more complex interpretation although they still suggest that the changes in shear wave splitting are caused by earthquake induced stress changes to the fluid filled inclusions throughout the rockmass central to interpretation of temporal changes in shear wave splitting is the well established existence throughout at leastmore the uppermost 10 to 20 km of the crust of small fluid filled cracks microcracks and pores the existence of such inclusions introduces a compliant quality to otherwise stiff crustal rock the authors term these distributions of inclusions extensive dilatancy anisotropy or eda and the individual inclusions eda cracks because although they may include a wide range of shapes many of the seismic properties can be simulated by distributions of thin parallel cracks less

geochemical and geological characteristics of the es3l lacustrine shale in the bonan sag bohai bay basin china abstract although extensive studies have been conducted on unconventional shale oil resources in recent years little work has been performed on the resource potential of lacustrine shales the es3l lower sub member of the third member of the eocene shahejie formation shale of the bonan sag a set of thick lacustrine deposited sediments offers a good example for furthering the understanding of these rocks geochemical and mineralogical investigations were carried out on a large sample set from the 220 m thick sequence of well luo69 in total 200 core samples were analyzed for total organic carbon toc and rock eval pyrolysis and 421 core samples were analyzed for mineral compositions the es3l shales have a very high toc content with type i lacustrine oil prone kerogen in the early oil generation stage rock eval tmax suppression is evident in the lower part of the es3l member associated with a rise in pi production index with respect to fracability or brittleness the content of brittle minerals in the es3l shale is generally higher than that of marine shales in the usa with higher calcite mineral averaging 51 82 wt and lower clay content averaging 18 86 wt interparticle pores in minerals grains or clay aggregates intraparticle pores intercrystalline dolomite and pyrite framboid and four types of fractures tectonic fractures abnormal pressure fractures clay shrinkage fractures and inter laminar fractures are developed in the es3l shale organic matter pores are not present in the studied samples probably due to lower maturity tectonic fracture may play an important role in hydrocarbon migration and accumulation the results of this study suggest that the es3l shale in the bonan sag has very good shale oil potential especially in the lower section

evidence for widespread nonlinear strong ground motion in the mw 6 9 loma prieta earthquake we exploit 55 repeating microearthquake sequences on the san andreas fault just south of the rupture zone of the 1989 m w 6 9 loma prieta earthquake to search for time dependent properties of the earth s crust using moving window waveform cross correlation we identify clear and systematic delays as large as 20 msec for the direct s wave and exceeding 50 msec in the early s wave coda following the loma prieta mainshock others have also identified phase delays velocity reductions associated with damaging earthquakes and they have suggested a myriad of possible causal mechanisms here we present new evidence for a mechanism to produce velocity reductions correlated in time and space with an earthquake a strong correlation between the spatial patterns of s delays and the intensity of strong ground motion in the loma prieta earthquake suggests that physical damage the formation or growth of cracks during strong ground motion to the earth s shallow crust is responsible for the observed velocity reductions the strong spatial variability in s delays over short distances and the strong correlation of the magnitude of delays with surface geology indicate that the phase delays accumulate primarily near the receiver the effect is stronger at stations on young soft rocks than at stations on old hard rock disproportionately larger s coda delays than p coda delays suggest that the cracks formed by the strong shaking are fluid filled in the 10 years after loma prieta the initial increase in travel times reduces logarithmically with respect to time often back to the premainshock levels we attribute this behavior to the same slow dynamic healing observed in laboratory studies of the recovery of materials from transient nonlinear strain manuscript received 14 january 2004

toward supervolcano technology time lapse seismic tomography can provide detailed insights into magma movements in an active volcano and may help to predict volcanic hazards in the future

temporal changes of shallow seismic velocity around the karadere duzce branch of the north anatolian fault and strong ground motion we analyze temporal variations of seismic velocity along the karadere duzce branch of the north anatolian fault using seismograms generated by repeating earthquake clusters in the aftershock zones of the 1999 mw7 4 izmit and mw7 1 duzce earthquakes the analysis employs 36 sets of highly repeating earthquakes each containing 4 18 events the events in each cluster are relocated by detailed multi step analysis and are likely to rupture approximately the same fault patch at different times the decay rates of the repeating events in individual clusters are compatible with the omori s law for the decay rate of regional aftershocks a sliding window waveform cross correlation technique is used to measure travel time differences and evolving decorrelation in waveforms generated by each set of the repeating events we find clear step like delays in the direct s and early s coda waves sharp seismic velocity reduction immediately after the duzce main shock followed by gradual logarithmic type recoveries a gradual increase of seismic velocities is also observed before the duzce main shock probably reflecting post seismic recovery from the earlier izmit main shock the temporal behavior is similar at each station for clusters at various source locations indicating that the temporal changes of material properties occur in the top most portion of the crust the effects are most prominent at stations situated in the immediate vicinity of the recently ruptured fault zones and generally decrease with normal distance from the fault a strong correlation between the co seismic delays and intensities of the strong ground motion generated by the duzce main shock implies that the radiated seismic waves produced the velocity reductions in the shallow material

wavelet based time dependent travel time tomography method and its application in imaging the etna volcano in italy it has been a challenge to image velocity changes in real time by seismic travel time tomography if more seismic events are included in the tomographic system the inverted velocity models do not have necessary time resolution to resolve velocity changes but if fewer events are used for real time tomography the system is less stable and the inverted model may contain some artifacts and thus resolved velocity changes may not be real to mitigate these issues we propose a wavelet based time dependent double difference dd tomography method the new method combines the multiscale property of wavelet representation and the fast converging property of the simultaneous algebraic reconstruction technique to solve the velocity models at multiple scales for sequential time segments we first test the new method using synthetic data constructed using real event and station distribution for mount etna volcano in italy then we show its effectiveness to determine velocity changes for the 2001 and 2002 eruptions of mount etna volcano compared to standard dd tomography that uses seismic events from a longer time period wavelet based time dependent tomography better resolves velocity changes that may be caused by fracture closure and opening as well as fluid migration before and after volcano eruptions

rapid changes in magma storage beneath the klyuchevskoy group of volcanoes inferred from time dependent seismic tomography abstract we present the results of time dependent local earthquake tomography for the kluchevskoy group of volcanoes in kamchatka russia we consider the time period from 1999 to 2009 which covers several stages of activity of kluchevskoy and bezymianny volcanoes the results are supported by synthetic tests that recover a common 3d model based on data corresponding to different time windows throughout the period we observe a robust feature below 25 km depth with anomalously high v p v s values up to 2 2 we interpret this feature as a channel bringing deep mantle materials with high fluid and melt content to the bottom of the crust this mantle channel directly or indirectly determines the activity of all volcanoes of the kluchevskoy group in the crust we model complex structure that varies over time during the pre eruptive period we detected two levels of potential magma storage one in the middle crust at 10 12 km depth and one close to the surface just below kluchevskoy volcano in 2005 a year of powerful eruptions of kluchevskoy and besymiyanny volcanoes we observe a general increase in v p v s throughout the crust in the relaxation period following the eruption the v p v s values are generally low and no strong anomalous zones in the crust are observed we propose that very rapid variations in v p v s are most likely due to abrupt changes in the stress and deformation states which cause fracturing and the active transport of fluids these fluids drive more fracturing in a positive feedback system that ultimately leads to eruption we envision the magma reservoirs beneath the kluchevskoy group as sponge structured volumes that may quickly change the content of the molten phases as fluids pulse rapidly through the system

composition and pore characteristics of black shales from the ediacaran lantian formation in the yangtze block south china the ediacaran period was critical in the evolution of the biosphere and ocean in the history of the earth shales rich in organic matter om are well developed for this period in the yangtze block china and have recently been related to shale gas exploration in south china to date detailed characterisation of the ediacaran shales is not available the present work sets out a detailed investigation of the composition and pore characteristics of samples from a shallow drill core in the ediacaran lantian formation in the lower yangtze area and the effects of shale composition on the pore growth are discussed the 90 m thick lantian black shales are highly over mature equivalent vitrinite reflectance evro value approximately 4 0 with a total organic carbon toc content up to 12 they are dominated by quartz 33 72 generally with low clay or feldspar content bulk porosities of the shales range from 1 0 to 7 9 and are positively correlated with toc content high magnification scanning electron microscopy sem images support the crucial importance of om content on pore development generally pore volume shows excellent positive correlation with toc content for micropores good correlation for mesopores and relatively poor correlation for macropores two samples with mostly high toc content showed very low macropore volume and medium mesopore volume these results suggest a close relationship between om with relatively small pores and enhanced compaction effect on large pores in highly om enriched shales

a geometrical error in some computer programs based on the aki christofferson husebye ach method of teleseismic tomography some computer programs based on the aki christofferson husebye ach method of teleseismic tomography contain an error caused by identifying local grid directions with azimuths on the spherical earth this error which is most severe in high latitudes introduces systematic errors into computed ray paths and distorts inferred earth models it is best dealt with by explicitly correcting for the difference between true and grid directions methods for computing these directions are presented in this article and are likely to be useful in many other kinds of regional geophysical studies that use cartesian coordinates and flat earth approximations

organic geochemistry and petrography of lower cretaceous wealden black shales of the lower saxony basin the transition from lacustrine oil shales to gas shales abstract ninety seven wealden black shale samples from three wells in the lower saxony basin have been studied by organic geochemical and organic petrographical methods to determine their maturity organic facies and depositional environment the maturities of the three wells range from early mature ex a late to postmature ex c to overmature ex b as determined by vitrinite reflectance measurements diamondoid ratios and other geochemical maturity parameters ex c and ex b show distinct petrographic features related to oil generation and migration in particular the occurrence of dispersed solid bitumen replacing initial type i kerogen suggests a formerly active petroleum system structural and textural differences between early mature alginites and solid bitumen in postmature to overmature samples show an alteration of the pore system with increasing maturity a freshwater depositional environment is indicated by widespread occurrence of botryococcus algae and other small alginite particles predominating in the immature well these alginites are absent in the more mature gas shales of wells ex c and ex b geochemical evidence of algae and phytoplankton in general is provided by numerous biomarker parameters while the occurrence of carotane in some samples indicates events of increased salinity although no hypersaline conditions are inferred due to very low gammacerane indices increased amounts of vitrinite and inertinite in samples of ex b suggest locally significant terrigenous input of organic matter for some periods during wealden shale deposition high sulfur organic carbon ratios provide evidence for sulfate rich waters and partly anoxic bottom water conditions while the lower mature lacustrine source rocks generate paraffinic waxy oils gas and condensates are produced at post mature stages furthermore maturity distribution maps from 3d numerical petroleum systems modeling reveal substantial differences in respect to petroleum generation

mineralogy and geochemistry of mississippian and lower pennsylvanian black shales at the northern margin of the variscan mountain belt germany and belgium abstract exploration of unconventional gas resources from paleozoic formations in northwestern germany is just getting started large potential gas reservoirs are presumed to be present north of the rhenish massif where mississippian and pennsylvanian marine black shales occur this paper comprises geochemical and mineralogical data and other important aspects of potentially economic black shale formations of the carboniferous additionally the burial and thermal history was reconstructed using 1d modeling software schlumberger these 1d models were calibrated with vitrinite reflectance data from outcrops and shallow wells in general all paleozoic black shales are at present highly mature between about 1 5 and 3 vitrinite reflectance the shales of the uppermost mississippian upper alum shale chokier formation have high contents of organic carbon are tens of meters thick and can be regarded as potential gas shale targets most other mississippian and pennsylvanian black shales are relatively thin adjacent carbonates are often stained black and rich in solid bitumen indicating former oil impregnation of these reservoirs

sideritic ironstones as indicators of depositional environments in the weald basin early cretaceous se england the lower cretaceous wealden sideritic ironstones have a wide occurrence and great potential to aid the reconstruction of the depositional environments of the weald basin in se england however mineralogical and geochemical datasets on the ironstones are scarce in the literature geochemical and mineralogical data on the sideritic ironstones are presented from the wadhurst clay formation within the weald basin the mineralogy of the ironstones was examined using a panalytical x pert pro x ray diffractometer and panalytical s highscore plus software elemental composition of the ironstones was measured using a panalytical minipal2 ed xrf benchtop x ray spectrometer the examination of the mineralogy of the wealden ironstones confirms the presence of early diagenetic siderites the trace element assemblage shows that the sideritic ironstones are chemically pure pointing to a freshwater origin the sideritic ironstones reveal anoxic conditions and palaeo salinity in the basin more generally it is suggested that the composition of the host rocks has significant controls on the composition of sideritic ironstones in sedimentary basins this work reinforces the importance of the composition of sideritic ironstones as useful non traditional data for understanding the depositional settings of sedimentary basins especially when traditional datasets are not readily available or insufficient

evolution of the lower saxony basin abstract the lower saxony basin is a 300 km long and 65 km wide late jurassic and early cretaceous trough which parallels the northern margin of the rhenish massif this basin became inverted during the senonian and paleocene the lower saxony basin is the most important oil province of germany past production amounts to 200 10 6 t of oil 1 5 10 9 bbl the lower saxony basin is superimposed on the late carboniferous variscan foredeep basin and the frontal structures of the variscan fold belt during the permian to middle jurassic the area formed part of the northwest european basin differential subsidence of the lower saxony basin was initiated during the late jurassic and persisted till albian time this involved reactivation of permo carboniferous fracture systems by divergent wrenching a major aptian deep seated laccolith is evident in the western part of the lower saxony basin during the senonian and paleocene sinistral convergent wrenching induced uplift of the basin floor and folding of its sedimentary fill the margins of the inverted lower saxony basin are thrust over the adjacent stable platform areas the differential subsidence of the lower saxony basin can be related to a period of major crustal extension in the north sea rift basin inversion coincides with important orogenic events in the alpine system and is thought to have been induced by intra plate compressional stresses

application of diamondoids to distinguish source rock facies abstract diamondoid distributions in solvent extracts from marine siliciclastic shales marine carbonates and coals of a wide variety of maturities were determined by gc msd for this sample set published diamondoid maturity parameters did not change systematically throughout the oil window it was found that several novel diamondoid ratios were indicative of source it was possible to distinguish between terrigenous marine carbonate and marine siliciclastic facies the proposed dimethyl diamantane facies ratios are virtually unaffected by maturity while the ethyl adamantane ratio appears to be affected by maturity in the late gas window range

continuous active source seismic monitoring of co2 injection in abrine aquifer continuous crosswell seismic monitoring of a small scale co2injection was accomplished with the development of a noveltubing deployed piezoelectric borehole source this piezotube source wasdeployed on the co2 injection tubing near the top of the saline aquiferreservoir at 1657 m depth and allowed acquisition of crosswellrecordings at 15 minute intervals during the multiday injection thechange in traveltime recorded at various depths in a nearby observationwell allowed hour by hour monitoring of the growing co2 plume via theinduced seismic velocity change traveltime changes of 0 2 to 1 0 ms upto 8 percent were observed with no change seen at control sensorsplaced above the reservoir the traveltime measurements indicate that theco2 plume reached the top of the reservoir sand before reaching theobservation well where regular fluid sampling was occuring during theinjection thus providing information about the in situ buoyancy ofco2

thermal maturity source rock potential and kinetics of hydrocarbon generation in permian shales from the damodar valley basin eastern india abstract this study investigates the source rock characteristics of permian shales from the jharia sub basin of damodar valley in eastern india borehole shales from the raniganj barren measure and barakar formations were subjected to bulk and quantitative pyrolysis carbon isotope measurements mineral identification and organic petrography the results obtained were used to predict the abundance source and maturity of kerogen along with kinetic parameters for its thermal breakdown into simpler hydrocarbons the shales are characterized by a high toc 3 4 mature to post mature heterogeneous type ii iii kerogen raniganj and barren measure shales are in mature late oil generation stage rr raniganj 0 99 1 22 rr barren measure 1 1 1 41 vitrinite is the dominant maceral in these shales barakar shows a post mature kerogen in gas generation stage rr barakar 1 11 2 0 and consist mainly of inertinite and vitrinite the 13corg value of kerogen concentrate from barren measure shale indicates a lacustrine marine origin 24 6 30 84 vs vpdb and that of raniganj and barakar 22 72 25 03 vs vpdb show the organic provenance to be continental the 13c ratio of thermo labile hydrocarbons c1 c3 in barren measure suggests a thermogenic source discrete bulk kinetic parameters indicate that raniganj has lower activation energies e 42 62 kcal mol compared to barren measure and barakar e 44 68 kcal mol temperature for onset 10 middle 50 and end 90 of kerogen transformation is least for raniganj followed by barren measure and barakar mineral content is dominated by quartz 42 63 siderite 9 15 and clay 14 29 permian shales in particular the barren measure as inferred from the results of our study demonstrate excellent properties of a potential shale gas system

the posidonia shale of northern germany unconventional oil and gas potential from high resolution 3d numerical basin modelling of the cross junction between the eastern lower saxony basin pompeckj block and gifhorn trough

travel time monitoring with vibroseis abstract the general failure of searches for precursory seismic travel time variations associated with strike slip earthquakes in california has led to this investigation into the feasibility of using a controlled source seismic method to improve significantly the precision of travel time measurements and to investigate the nature of any detected travel time changes travel times have been measured over a period of several years at sites south of hollister california along the seismically active creeping zone of the san andreas fault using a single channel vibroseis system with real time on site data processing at a site near bear valley 7 km from the fault no variations in the travel time of a deep crustal reflection were observed that could be associated with local earthquakes however significant variations 0 5 to 2 5 msec of first arrival travel times observed near the cienega winery may have been associated with a series of nearby earthquakes and with a creep event major sources of measurement error have been identified in source variations and in rainfall induced variations in near surface properties the former limits the precision of the deep reflection measurements to about 0 05 per cent of the travel time and the first arrival measurements to about 0 1 per cent of the travel time the second effect is apparent as seasonal oscillations in travel time of as much as 15 to 20 msec and also in wavelet amplitude and waveform giving an implied travel time accuracy of about 0 2 per cent for the deep reflection measurements and about 1 per cent for first arrivals while these noise levels are disappointing they can be reduced significantly by improved field procedures ongoing experiments are testing such procedures

polyphase thermal evolution in the infra cambrian ara group south oman salt basin as deduced by maturity of solid reservoir bitumen petrographic and organic geochemical analyses on solid reservoir bitumen from the late precambrian to early cambrian ara group indicate polyphase thermal evolution in the south oman salt basin sosb the ara group constitutes a complex petroleum system in the deep subsurface 3 5 km of interior oman salt diapirs encase isolated partly highly overpressured carbonate bodies intra salt stringers which represent a predominantly self charging hydrocarbon system a large number of stringer cores show that reservoir quality is decreased by the presence of solid reservoir bitumen by using different microscopy techniques this solid reservoir bitumen has been identified within pores pore throats and microfractures of the carbonates solid bitumen reflectance measurements brr were converted to vitrinite reflectance vrr using a new improved calibration vitrinite reflectance geothermometry shows that maximum paleo temperatures have a highly heterogeneous distribution paleo temperatures of 380 c were obtained from coke like solid reservoir bitumen which most likely formed from thermal cracking of oil in our model this process is related to hydrothermal fluids deriving from deeper pre salt strata of the sosb which entered the intra salt carbonate stringers during times of basement tectonic activity via hydrofractures this caused the formation of high maturities pyrobitumens in close vicinity to the fractures and precipitation of migrabitumens with increasing distance to the ht source which is supported by the geochemical composition of the solid reservoir bitumens the influx of these fluids into the carbonate stringers is considered to represent a major contribution to their strong overpressures 2007 elsevier ltd all rights reserved

impact of laminae on pore structures of lacustrine shales in the southern songliao basin ne china abstract evaluating the influences of laminae on shale pore structures is vital to understand the enrichment mechanism of lacustrine shale gas this study investigates lacustrine shales from the lower cretaceous shahezi formation in the changling sag southern songliao basin ne china using mineralogical and geochemical analyses co2 n2 adsorption and high pressure mercury intrusion porosimetry mip to compare pore structure characteristics between laminated and massive shales and elucidate their main controlling factors our results show that laminae in lacustrine shales from the shahezi formation include those clay rich organic rich and silty ones and minor carbonate rich ones micropores in both laminated and massive shales show tri modal distributions with main peaks at 0 47 0 54 nm 0 57 0 63 nm and 0 80 0 85 nm respectively however the laminated shales exhibit great variations in micropore volumes among different samples mesopores within the laminated shales are smaller than those in the massive shales and their pore volumes pv are about 1 3 less than those of the massive shales this is due to that the laminated shales are rich in slit like pores whereas the massive shales have more plate like and ink bottle pores thermal maturity ro and total organic carbon toc contents are the essential factors controlling the development of micropores and mesopores in the laminated shales however they show weak effects on macropore development in this formation this may be related to that shales from the shahezi formation generally have low toc contents and type iii kerogen clay minerals and quartz both have weak relevance to pore development in this formation

new information on the thermal history of the southwestern lower saxony basin northern germany based on fission track analysis the southwestern part of the lower saxony basin lsb is characterized by gravity and magnetic anomalies and by an extremely high thermal maturity of organic matter this was for many years attributed to a late cretaceous intrusion but actually deep burial is being debated the complex thermal history of the area has been studied by fission track analysis zircon data provide evidence for widespread hydro thermal activity during the permian and upper jurassic lower cretaceous apatite ages indicate a major cooling event in the mid cretaceous 89 72 ma reflecting the time of inversion of the lsb during the cretaceous the cooling of the basin centre was rapid compared to the basin margins apatite fission track ages from borehole samples which are recently within the upper part of the apaz indicate a young heating of the sedimentary sequences until present

petrological and geochemical investigations of potential source rocks of the central congo basin democratic republic of congo paleozoic and mesozoic outcrop and core samples remina dekese and remina samba wells covering various stratigraphic intervals from the central congo basin were analyzed for total organic carbon corg total inorganic carbon cinorg and total sulfur content rock eval analysis and vitrinite reflectance ro measurements were performed on the basis of the corg content fifteen samples were chosen for molecular organic geochemistry nonaromatic hydrocarbons hcs were analyzed by gas chromatography gc flame ionization detection and gc mass spectrometry samples of the alolo shales from the aruwimi group lindi supergroup late neoproterozoic to early paleozoic are in general very poor in corg most samples 0 5 and contain a high amount of degraded organic matter om all samples of this group revealed a type iii to iv kerogen and cannot be considered as a potential source rock permian carboniferous sediments from the lukuga group dekese well and outcrop samples contain moderate contents of organic carbon 2 the tmax values heating temperature at which the top peak of s2 occurs indicate early mature om partly also a higher level of maturity because of ro 0 6 0 7 and production index values s1 s1 s2 0 2 all samples contain hydrogen poor type iii to iv kerogen with low hc generation potential only having a very minor gas generation potential the kinds of om as well as the biological markers indicate a terrestrial dominated depositional environment organic geochemical investigations on upper jurassic stanleyville group to lower cretaceous loia group samples from the samba well and outcrops in the northeastern part of the congo basin reveal moderate to high contents of organic carbon as much as 25 the kerogen has very high hydrogen index hi values reflecting type i kerogen of excellent quality in the stanleyville group as much as 900 mg hc g corg and type i to ii kerogen in the overlying loia group as much as 900 mg hc g corg outcrop samples from the stanleyville group have variable partly high corg contents and are also characterized by very high hi values as much as 900 mg hc g corg the samples studied are too immature for petroleum generation based on biomarker analysis an aquatic anoxic depositional environment can be assumed for the stanleyville group whereas a lacustrine deposition is likely for the samples of the loia group based on the geologic knowledge of the area deposition under lacustrine conditions is most likely also for the stanleyville group both the stanleyville and loia groups can be regarded as excellent petroleum source rocks and could be part of a petroleum system if sufficient burial and maturation have occurred the presence of resedimented vitrinite particles in the lukuga group of the dekese well with a slightly higher maturation rank than the autochthonous vitrinites suggests that 3000 4000 m 9840 13 120 ft of carboniferous to devonian sediment has been eroded from the eastern margin of the congo basin finally ro data were used to create one dimensional models for the dekese and samba wells giving an overview of the burial thermal and maturity histories of the area

petroleum source rocks of the tarfaya basin and adjacent areas morocco abstract this work characterizes the source rock potential of the tarfaya basin and enabled us to reconstruct its geochemical history outcrop samples covering different stratigraphic intervals plus the northwestern part of the zag tindouf basin bas draa area were analyzed for total organic carbon corg and total inorganic carbon contents and total sulfur content rock eval analysis and vitrinite reflectance measurements were performed on 56 samples chosen on the basis corg content a set of 45 samples were extracted and non aromatic hydrocarbons were analyzed by way of gas chromatography flame ionization detection gc fid and gc mass spectrometry gc ms non isothermal open system pyrolysis at different heating rates was applied to obtain kinetic parameters for modelling petroleum generation from four different source rocks high quality petroleum source rocks with high corg content and hydrogen index hi values were found for samples of eocene coniacian turonian and cenomanian age most samples were carbonate rich and organic sulfur values were high to moderate various maturity parameters indicated immature or possibly early mature organic matter based on organic geochemical and petrological data the organic matter is of marine aquatic origin cenomanian or a mixture of aquatic and terrigenous material eocene the early cretaceous interval did not contain high quality source rocks but indications of petroleum impregnation were found

monitoring a temporal change of seismic velocity in a volcano application to the 1992 eruption of mt merapi indonesia multiplets i e events with similar waveforms are selected from shallow earthquakes recorded on merapi volcano indonesia before the eruption of february 2nd 1992 two multiplet families are found with their sources close to the summit their seismograms are analyzed using the moving window cross spectrum technique which measures the precise time delay between seismic phases in the entire seismogram for both families of multiplets a gradual decrease in the arrival times of coda waves is observed as a function of the date prior to the eruption coda waves are becoming progressively faster up to 1 2 per cent as the time interval to the eruption shortens this observation is interpreted as the consequence of an increase in the seismic velocity inside the volcano the increase in velocity started in may 1991 and was observed until september 1991 4 months before the eruption this velocity increase may be related to an increase in pressure in the magma chamber or in the conduits and to the resulting closure of the surrounding cracks

diamondoid hydrocarbon ratios novel maturity indices for highly mature crude oils abstract diamondoid hydrocarbons have been identified in oil and source rock samples from the tarim yinggehai qiongdongnan and other chinese basins two diamondoid hydrocarbon ratios have been used as novel high maturity indices to evaluate the maturation and evolution of crude oils and condensates in these chinese basins the two ratios 1 ma 1 ma 2 ma mai methyl adamantane index and 4 md 1 md 3 md 4 md mdi methyl diamantane index were found to increase with increasing vitrinite reflectance the initial values for the ratios are ca 50 and 30 respectively diamondoid hydrocarbons are products of rearrangement of polycyclic hydrocarbons and their ratios are found to be affected by organic input to a minor extent based on this study crude oils from the tarim basin are generally believed to be very mature ro 1 1 the cambrian ordovician source beds are the major source rocks of crude oils and natural gases in this basin condensates from the tarim yinggehai and qiongdongnan basins have higher maturities equivalent to ro values of 1 6 2 0 gases and condensates from the yinggehai and qiongdongnan basins are generated mainly from tertiary source rocks below 4000 5000 m

origin properties and implications of solid bitumen in source rock reservoirs a review abstract this paper reviews the significance of solid bitumen with emphasis on source rock reservoirs we discuss difficulties and discrepancies with terminology especially those terms related to the origin of solid bitumen and its physical and chemical properties various definitions of solid bitumen have their own justifications and can be used provided there is clarity about which defining criteria are being considered difficulties in conforming to chemical solubility or origin related definitions lead us to suggest adapting the reflectance of solid hydrocarbon as a practical choice for placing the boundary between solid bitumen and pyrobitumen and 1 50 is proposed as the boundary value it has to be noted that this boundary may be shifted down to 1 3 for sulfur rich kerogen recently much progress has been made by combining imaging and physical adsorption techniques in porosity studies and so the porosity of solid bitumen is given special emphasis comparing pore characteristics obtained from sem versus those generated by gas adsorption mercury intrusion or neutron scattering techniques indicates that the sem pore inventory fails to account for the smallest pores we review the implications of the abundance of solid bitumen on reservoir quality porosity permeability and producibility based on examples of selected sequences one of the difficulties in predicting the influence of solid bitumen bearing horizons on reservoir quality arises from the problems with detecting organic phases using various logging techniques the use of specialized techniques such as nmr logging that allows two dimensional t1 and t2 measurements should be expanded and other potential techniques need to be further researched and tested certain aspects of the properties of solid bitumen that are not as well understood such as its hydrocarbon generation potential or its role in hydrocarbon migration are also discussed with the aim of identifying further research that could lead to a better understanding of the role that solid bitumen plays in unconventional reservoirs

seismic image of a co2 reservoir beneath a seismically active volcano mammoth mountain is a seismically active volcano 200 000 to 50 000 years old situated on the southwestern rim of long valley caldera california since 1989 it has shown evidence of unrest in the form of earthquake swarms hill et al 1990 volcanic long period earthquakes pitt hill 1994 increased output of magmatic 3he sorey et al 1993 and the emission of about 500 tonnes day 1 of co2 farrar et al 1995 hill 1996 m sorey personal communication 1997 which has killed trees and poses a threat to human safety local earthquake tomography shows that in mid 1989 areas of subsequent tree kill were underlain by extensive regions where the ratio of the compressional and shear elastic wave speeds vp vs was about 9 per cent lower than in the surrounding rocks theory mavko mukerji 1995 experiment ito devilbiss nur 1979 and experience at other geothermal volcanic areas julian et al 1996 and at petroleum reservoirs harris et al 1996 indicate that vp vs is sensitive to pore fluid compressibility through its effect on vp the observed vp vs anomaly is probably caused directly by co2 and seismic vp vs tomography is thus a promising tool for monitoring gas concentration and movement in volcanoes which may in turn be related to volcanic activity

organic matter maturation under the influence of a deep intrusive heat source a natural experiment for quantitation of hydrocarbon generation and expulsion from a petroleum source rock toarcian shale northern germany four shallow boreholes were drilled in the hils syncline northern germany in order to determine quantitatively the amount of hydrocarbons generated and expelled during maturation of a typical kerogen type ii bearing source rock the holes penetrated the carbonceous lias shales posidonia shale lower toarcian and part of the adjacent dogger and lias mudstones the maturity of the organic matter in the cores recovered ranges from immature 0 48 r0 to overmature 1 45 r0 due to location of the hils syncline in the vicinity of the vlotho massif which is deep seated intrusive body facies variations of the lias within the short geographical distances in the study area are negligible organic matter mass balance calculations were based on detailed organic geochemical analyses of residual material in the lias shales kerogen bitumen etc and on the evidence of a uniform initial composition of these sediments in the study area dead carbon determinations supported this latter criterion but were not used as a parameter in the calculations about 50 of the initial kerogen was transformed into oil gas and inorganic compounds during the vitrinite reflectance increase from 0 48 to 0 88 ro and only marginally more during the maturity increase from 0 88 to 1 45 ro only a small portion of the generated material remained in the source rock even at a relatively early stage of generation 0 68 ro expulsion efficiency of oil plus gas reached a value of 86 at the end of the main generation stage 0 88 ro

depositional environment and thermal maturity of the coal bearing longtan shale in southwest guizhou china implications for shale gas resource potential abstract significant knowledge has been assembled on the marine longmaxi shale in the sichuan basin over the past ten years however the distribution of shale gas resources on the periphery of the sichuan basin and in other source rock formations are still not sufficiently understood to improve our understanding on the depositional environment and thermal maturity and their relevance to the source rock quality and shale gas potential of the thick coal bearing longtan shale 36 organic rich shale samples were selected from a single borehole located in the southwestern guizhou province for geochemical and petrographic analysis total organic carbon toc contents are high with 7 7 wt on average reaching partly up to 28 21 wt while carbonate contents are low vitrinite reflectance vrr values and rock eval tmax temperatures range from 1 48 to 1 84 and 482 to 583 c respectively indicating a high thermal maturity which is in accordance with aromatic molecular parameters the remaining present day hydrocarbon generation potential rock eval s2 is rather low due to the high maturity microscopic investigations further show that the organic matter in the rocks is mainly composed of higher land plant particles present as large and poorly rounded vitrinite and inertinite particles indicating a rather short transport distance toc vs total sulfur ts relationships as well as specific hydrocarbon ratios e g pristane phytane and framboidal pyrite size distributions indicate a variable either marine or freshwater environment for the shales in the coal bearing sequence and suggest that original kerogen was either type iii or type ii iii bottom water during deposition was probably oxygen depleted but not anoxic high sedimentation rates can be assumed for the now 700 m thick compacted sequence favorable for the preservation of organic matter overall the present results are in accordance with previous studies of the longtan shale which initially had a high hydrocarbon mainly gas generation potential furthermore the thickness of the formation is much larger in the here studied southwestern part of the guizhou province than in the previously studied northern parts

coseismic and postseismic velocity changes measured by repeating earthquakes 1 repeating earthquakes that rupture approximately the same fault patch and have nearly identical waveforms are a useful tool for measuring temporal changes in wave propagation in the earth s crust since source and path effects are common to all earthquakes in a repeating earthquake sequence multiplet differences in their waveforms can be attributed to changes in the characteristics of the medium we have identified over 20 multiplets containing between 5 and 40 repeating events in the aftershock zones of the 1989 loma prieta and 1984 morgan hill california earthquakes postmain shock events reveal delays of phases in the early s wave coda of as much as 0 2 s relative to premain shock events the delay amounts to a path averaged coseismic velocity decrease of about 1 5 for p waves and 3 5 for s waves since most of the multiplets are aftershocks and follow omori s law we have excellent temporal sampling in the immediate postmain shock period we find that the amplitude of the velocity decrease decays logarithmically in time following the main shock in some cases it returns to the premain shock values while in others it does not similar results are obtained for the morgan hill main shock because the fractional change in s wave velocity is greater than the fractional change in p wave velocity it suggests that the opening or connection of fluid filled fractures is the underlying cause the magnitude of the velocity change implies that low effective pressures are present in the source region of the velocity change our results suggest that the changes are predominantly near the stations and shallow but we cannot exclude the possibility that changes occur at greater depth as well if the variations are shallow we may be detecting the lingering effects of nonlinearity during main shock strong ground motion if the variations are deep it suggests that pore pressures at seismogenic depths are high which would likely play a key role in the earthquake process

seismic wave velocity changes and stress build up in the crust of the kanto tokai region we show there are large temporal p wave velocity changes in the crust of the kanto tokai region in japan from repeated observations of explosions we find that the variation is the response of the crustal rocks to two components of stress change the tidal stress and the secular stress accumulation the inferred annual rate of fractional velocity change year caused by the stress accumulation in the upper crust is of the order of 10 3 year the results indicate that the build up of stress in the crust can be monitored by precise observations of seismic wave velocities

molecular structure and origin of solid bitumen from northern sichuan basin abstract four natural solid bitumen samples were collected from the guangyuan area northwest sichuan basin southwest china to characterize their structure samples were ground to power 120 mesh purified by znbr2 solution to remove mineral and soluble impurities and analyzed using rock eval pyrolysis elemental analysis raman spectroscopy solid bitumen reflectance and solid state 13c nuclear magnetic resonance to determine the maturity degree of samples and obtain structural information results showed that guangyuan solid bitumen samples are in low maturity and three solid bitumen maturity detection methods are compared in this research with respect to the solid bitumen molecular structure less than 10 carbon atoms were determined in aliphatic chains and the solid bitumen aromatic clusters ranged from two to four rings which indicates that the solid bitumen comprises complex geological organic matter such as kerogen four molecular models were established in this research to reflect the basic molecular configuration of natural solid bitumen samples were classified into two types based on the structural information and models and the results imply that the solid bitumen samples may have been derived via different evolutionary processes this phenomenon indicates that structural studies could play an important role in the research of oxidation and carbon isotope changes in solid bitumen in summary this investigation provides an understanding of the evolutionary stages of guangyuan bitumen establishes associated molecular structure models and researches the role of structural information in bitumen source studies as the focus of this study the four molecular models were used to restore the structural characteristics of natural solid bitumen as possible and this study tried to find out the relationship between the solid bitumen structure information and it geology evolution as the carbon isotope may not accurately determine the source of solid bitumen because of oxidation molecular information could be used to research the solid bitumen source and associated evolution

the biogenic methane potential of european gas shale analogues results from incubation experiments and thermodynamic modelling abstract core samples from the lower jurassic posidonia shale lower toarcian wealden black shales both from the lower saxony basin northern germany and from the cambrian ordovician alum shale southern sweden have been investigated for their biogenic gas potential in incubation experiments the sample set represents all stages of thermal maturity from immature to overmature methane and to a higher degree carbon dioxide are generated from all samples by added microorganisms in general overmature samples rr 1 5 show lowest gas generation rates the highest generation rates for produced methane up to 89 mol g 1 day 1 and carbon dioxide 139 mol g 1 day 1 were detected in immature alum shale samples when different hydrocarbon degrading inocula where added whereas the lowest methane production rates were detected in wealden sediments the lightest 13c values for produced methane and carbon dioxide have been detected in posidonia shale samples of oil window maturity such samples are some of the most sensitive for gas generation and exhibit the strongest decreases of hydrogen indices after incubation hydrogeochemical modelling of methane generation fate and behaviour showed that methane formed during the early diagenesis got lost from posidonia shale the mainly investigated shale in this study as the mature posidonia shale is according to the incubation experiments still sensitive for gas generation a production scenario of generically generated methane due to oil degradation is simulated the basic conditions resemble the conditions in the antrim shale in the michigan basin gas production due to dewatering and pressure decrease results in an increase of the gas volumes coupled to a progressive enrichment of carbon dioxide in the produced gas moreover calcite scaling may be the consequence during progressive production similar to the antrim shale in the michigan basin such calcite precipitation has been demonstrated to predominantly occur in natural samples at oil window maturity

petroleum isotopic and biomarker composition related to source rock organic matter and depositional environment abstract a multivariate approach has been developed that separates oils derived from organic matter in nonmarine shales marine shales and marine carbonates some or all of the following analyses were completed on 43 oils from known source rocks 1 c30 sterane and monoaromatic steroid biomarker ratios and 2 stable carbon and hydrogen isotope compositions of whole oil saturates and aromatics three group discriminant analysis of the 28 oils whereall biomarker and isotopic data are available results in no misclassifications at a significance level of 99 using only carbon and hydroogen isotopic data for whole oils saturates and aromatics results in correct classifications of 82 for oils derived from marine shale organic matter and 100 for oils from the other two sources triangular plots probabilities can be used to distinguish oils derived from the three source rock organic matter end members several publications describe classifications of marine vs nonmarine oils using stable carbon isotope ratios of the whole oil or the saturate and aromatic fractions our results confirm that these methods do not completely differentiate oils by source

sedimentary basin evolution gravity flows volcanism and their impacts on the formation of the lower cretaceous oil shales in the chaoyang basin northeastern china abstract no detailed research has been carried out on the oil shales that are interbedded with gravity flow deposits and volcaniclastic rocks in the third member of the jiufotang formation in order to study the impact of basin evolution gravity flows and volcanism on oil shale formation petrology sedimentology sequence stratigraphy organic geochemistry and elemental geochemistry were used to characterise the oil shales extensional tectonic subsidence is suggested as the controlling factor for basin evolution the predominant maceral in the oil shales is sapropelinite suggesting organic matter was derived from mainly aquatic organism especially algae element indices u cu mo zn sr ba th g g zr g g and the chemical index of alteration cia show that the water conditions during deposition of the oil shales were anoxic and brackish with little terrigenous detrital input and a cold and dry palaeoclimate gravity flows were accompanied by the input of terrestrial detritus and a degree of oxygenation of the bottom waters reducing oil shale formation volcanic eruptions ejected intermediate acidic ashes not only leading to climate cooling but also either enhancing algal blooms by a fertilisation effect due to minor volcanic ash input or inhibiting algal blooms by a poisoning effect due to major volcanic ash input there is synchronicity between the occurrence of rifting gravity flows volcanism and earthquakes the best periods for oil shale formation were during intermissions between tectonic movement when there were few gravity flows volcanic eruptions or earthquakes high bioproductivity and lake expansion along with an anoxic environment were the main controlling factors for high quality oil shale formation there is a series of oil shale bearing rift basins formed in northeastern china that share a similar geological setting so this research provides a useful example for future resource exploration of coeval oil shales in northeastern china

geochemical evolution of organic rich shales with increasing maturity a stxm and tem study of the posidonia shale lower toarcian northern germany hydrocarbon generation and retention processes occurring within gas shales as a response to increases in thermal maturation are still poorly constrained while efforts have been directed at unravelling the resource potential composition and textures of these economically important unconventional systems their spatial variability in chemistry and structure is still poorly documented at the sub micrometer scale here we have characterized samples of the lower toarcian posidonia shale samples from northern germany at varying stages of thermal maturation using a combination of compositional organic geochemistry and spectromicroscopy techniques including synchrotron based scanning transmission x ray microscopy stxm we document geochemical and mineralogical heterogeneities down to the nanometer scale within the investigated samples as a function of their level of thermal maturity in particular authigenic albite crystals containing nanometric halite inclusions have been documented within the investigated mature and overmature samples the presence of such tracers of palaeobrine carbonate interactions supports a maturation scenario for the lower toarcian posidonia shale intimately related to ascending brine fluids rather than a maturation scenario solely resulting from high heat flows in addition various types of asphaltene and nso rich bitumen have been detected within the same samples very likely genetically derived from thermally degraded organic precursors furthermore the formation of nanoporous pyrobitumen has been inferred for samples of gas window maturity likely resulting from the formation of gaseous hydrocarbons by providing in situ insights into the fate of bitumen and pyrobitumen as a response to the thermal evolution of the macromolecular structure of kerogen the results reported here constitute an important step towards better constraining hydrocarbon generation processes during natural shale gas maturation

total shale oil inventory from an extended rock eval approach on non extracted and extracted source rocks from germany abstract rock eval pyrolysis data are used for assessments of the quality and maturity of potential hydrocarbon source rock but is also often applied among shale oil studies to estimate the so called total oil for oil in place oip calculations however for these approaches rock eval may underestimate total oil due to a carryover effect a bias which is particularly crucial for shale oil investigations in this study we examined the total oil of marine to lacustrine source rocks from german shale oil formations using data from rock eval combined with solvent extraction each source rock was analysed by rock eval both non extracted and extracted to obtain values for total oil s1whole rock s1extracted rock s2whole rock s2extracted rock comparison of these two data sets revealed that for the individual formations in average 17 23 of the s2 fraction is extractable herein termed s2 oil this s2 oil increases the total oil amount compared to the conventional free oil s1 by average factors of 2 2 3 6 for selected source rocks the molecular composition of the s2 oil was obtained by a specific approach rock eval analysis was terminated after s1 detection at 301 c samples were retrieved solvent extracted and analysed by gas chromatography depending on the type of organic matter and maturity the s2 oil contains significant amounts of higher boiling hydrocarbons such as n alkanes but also contributes to the unresolved complex mixture it is to date unclear how much of this s2 oil should be finally considered as technically mobilized shale oil

late cretaceous late turonian coniacian and santonian petroleum source rocks as part of an oae tarfaya basin morocco abstract late turonian coniacian and santonian source rock samples from a recently drilled well tafaya sondage no 2 2010 in the tarfaya basin were analyzed for quantity quality maturity and depositional environment of the organic matter om to our knowledge such a thick sequence of organic matter rich turonian to santonian source rocks was investigated in that great detail for the first time organic geochemical and organic petrological investigations were carried out on a large sample set from the 200 m thick sequence in total 195 core samples were analyzed for total organic carbon corg total inorganic carbon contents and total sulfur ts contents rock eval pyrolysis and vitrinite reflectance measurements were performed on 28 samples chosen on the basis of their corg content non aromatic hydrocarbons were analyzed on selected samples by way of gas chromatography flame ionization detection gc fid and gc mass spectrometry gc ms the organic matter rich carbonates revealed a high source rock potential representing type i kerogen and a good preservation of the organic matter which is mainly of marine phytoplankton origin hi values are high 400 900 mg g corg and in a similar range as those described for more recent upwelling sediments along the continental slope of north africa ts corg ratios as well as pristane over phytane ratios indicate variable oxygen content during sediment deposition all samples are clearly immature with respect to petroleum generation which is supported by maturity parameters such as vitrinite reflectance 0 3 0 4 tmax values 401 423 c production indices s1 s1 s2 0 1 as well as maturity parameters based on ratios of specific steranes and hopanes

depth extent of damage zones around the central calaveras fault from waveform analysis of repeating earthquakes summary we systematically investigate spatial variations of temporal changes and depth extent of damage zones along the calaveras fault that ruptured during the 1984 morgan hill earthquake by the waveform analysis of 333 sets of repeating earthquakes we use a sliding window waveform cross correlation technique to measure traveltime changes in waveforms generated by each repeating cluster we find clear traveltime delays in the s and early s coda waves for events immediately after the morgan hill main shock the amplitudes of the time delays decrease logarithmically with time since the main shock indicating a time dependent recovery healing process following the abrupt coseismic temporal changes the largest temporal changes are observed at station cco that is the closest to the rupture zone of the morgan hill main shock the time delays at this station are larger for clusters in the top 6 km and decrease systematically at larger depth in comparison the time delays observed at other five stations are much smaller and do not show clear relationship with hypocentral depth we suggest that the temporal changes at these five stations mostly occur in the top few hundred metres of the near surface layers while the temporal changes at station cco are likely associated with the damage zone around the calaveras fault that is well developed in the top few kilometres of the upper crust our results are consistent with the inference of a widespread damage and non linearity in the near surface layers associated with strong ground motions of nearby large earthquakes and localized damages and flower type structures around active faults based on previous studies of fault zone structures and recent 3 d numerical simulations

tectonic control on hydrocarbon generation in the northwestern neuquen basin argentina the petroleum systems of the malargue fold thrust belt in the northwestern neuquen basin argentina comprise multiple reservoir and seal rocks and three major source rocks of the lower jurassic los molles formation fm the lower tithonian to lower valanginian vaca muerta fm and the lower hauterivian to lower barremian agrio fm the thermal history of the mesozoic source rocks has been reconstructed using one dimensional and two dimensional modeling the most important factors that affected the source rock maturation are the timing of maximum late cretaceous to paleogene burial and the heat flow during back arc extension we postulate that synclines have been buried over longer periods and source rock maturation ceased earlier in anticlines accordingly hydrocarbon generation from the vaca muerta fm and agrio fm has started during the campanian despite late stage magmatic activity causing local thermal perturbations the models suggest that the thermal field has been dominated by conductive heat transport and that heat flow has been a response to the evolution from back arc extension to orogenic shortening high heat flows of 85 mw m2 during back arc extension between the latest cretaceous and paleogene have been modeled two main source pods supply hydrocarbons until the present they are related to structurally deep footwall positions of thrust faults active since the late cretaceous and to deep frontal synclines having formed through late stage thick skinned tectonics since the neogene modeling of hydrocarbon fluid type is consistent with existing oil fields exhibiting light and medium oils with api between 22 api and 39 api charged from early to peak mature source rocks

microscopic and sedimentologic evidence for the generation and migration of hydrocarbons in toarcian source rocks of different maturities abstract this study is part of a comprehensive research program on the generation and migration of petroleum from the organic rich posidonia shale lower toarcian jurassic of the hils syncline northern germany four cores of the complete posidonia shale with varying amounts of underlying pliensbachian and overlying aalenian mudstones provided the sample base depending upon their distance from a presumed subjacent heat source the vlotho massif the cores display progressive levels of increasing thermal maturation with r 0 values 0 48 0 68 0 88 and 1 45 which span the limits of the oil generation window primary stratigraphic lithologic and petrographic attributes of the four sections are all very similar each includes a lower marlstone member about 5 m thick overlain by 11 31 m of calcareous clay shale clay minerals calcite pyrite kerogen and quartz are the principal constituents thus there is no evidence that depositional conditions of the posidonia shale varied significantly over the sampled area the omnipresence of framboidal pyrite clearly formed from the activity of sulphate reducing bacteria at or near the depositional interface is strong evidence that uniform reducing anoxic conditions were persistent at all localities this conclusion supports the assumption that initially each section was identical in overall properties and that significant differences observed in geochemistry organic macerals and other properties are directly related to the variable levels of thermal maturation kerogen from the least mature section r o 0 48 is type ii and composed of alginite a alginite b liptodetrinite bituminite and some terrestrial sporinite vitrinite and inertinite macerals with increasing maturation the alginite macerals exhibit a progressive change in morphology and fluorescence properties alginite of the least mature section displays a strong green fluorescence at 0 68 r o alginite macerals exhibit yellow orange fluorescence and are structurally well preserved although geochemical data indicate generation and loss of large amounts of oil at 0 88 r o hydrocarbon generation is almost complete and few primary alginites remain they have been transformed into secondary liptinites designated as metaalginite which have similar fluorescence colours at the highest maturation level 1 45 r o metaalginites are only weakly fluorescent with a shift toward red colours calcite and or bitumen filled bedding plane micro and macrofractures occur exclusively in the organic rich posidonia shale at maturity levels of 0 68 r o and above such features are totally absent in the immature posidonia section and in the adjacent organic poor mudstones this observation indicates that the fractures developed in direct response to overpressuring i e pore pressure exceeding lithologic load related to oil and gas generation in the source rock the fractures undoubtedly provided important expulsion conduits for generated products

from shale oil to biogenic shale gas retracing organic inorganic interactions in the alum shale furongian lower ordovician in southern sweden methane rich gas occurs in the total organic carbon rich alum shale furongian to lower ordovician in southern sweden the lower part of the thermally immature alum shale was impregnated by bitumen locally generated by heating from magmatic intrusions from the carboniferous to the permian organic geochemical data indicate that the migrated bitumen is slightly degraded in the upper alum shale where methane is the main hydrocarbon in thermovaporization experiments centimeter size calcite crystals occur that contain fluid inclusions filled with oil gas or water the alum shale is thus considered a mixed shale oil biogenic shale gas play the presented working hypothesis to explain the biogenic methane occurrence considers that water soluble bitumen components of the alum shale were converted to methane a hydrogeochemical modeling approach allows the quantitative retracing of inorganic reactions triggered by oil degradation the modeling results reproduce the present day gas and mineralogical composition the conceptual model applied to explain the methane occurrence in the alum shale in southern sweden resembles the formation of biogenic methane in the antrim shale michigan basin united states in both models melting water after the pleistocene glaciation and modern meteoric water may have diluted the contents of total dissolved solids tds in basinal brines such pore waters with low tds contents create a subsurface aqueous environment favorable for microbes that have the potential to form biogenic methane today biogenic methane production rates with shale as the substrate using different hydrocarbon degrading microbial enrichment cultures in incubation experiments range from 10 to 620 nmol per gram and per day

stable carbon isotope ratios of ch4 rich gas inclusions in shale hosted fracture fill mineralization a tool for tracing hydrocarbon generation and migration in shale plays for oil and gas abstract fluid inclusion gases in minerals from shale hosted fracture fill mineralization have been analyzed for stable carbon isotopic ratios of ch 4 using a crushing device interfaced to an isotope ratio mass spectrometer irms the samples of paleozoic strata under study originate from outcrops and wells in the rhenish massif and campine basin harz mountains and the upper slope of the southern permian basin fracture fill mineralization hosted by mesozoic strata was sampled from drill cores in the lower saxony basin some studied sites are candidates for shale gas exploration in germany samples of mesozoic strata are characterized by abundant calcite filled horizontal fractures which preferentially occur in toc rich sections of the drilled sediments only rarely are vertical fractures filled with carbonates and or quartz in drill cores from mesozoic strata but in paleozoic shale they occur frequently the 13 c ch 4 values of fluid inclusions in calcite from horizontal fractures hosted by mesozoic strata suggest that gaseous hydrocarbons were generated during the oil early gas window and that the formation of horizontal fractures seems to be related to hydraulic expulsion fracturing the calculated maturity of the source rocks at the time of gas generation lies below the maturity derived from measured vitrinite reflectance thus the formation of horizontal fractures and trapping of gas that was generated in the oil and or early gas window obviously occurred prior to maximal burial rapidly increasing vitrinite reflectance data seen locally can be explained by hydrothermal alteration as indicated by increasing 13 c ch 4 co 2 values in fluid inclusions the formation of vertical fractures in studied mesozoic sediments is related to stages of post burial inversion gas rich inclusions in fracture filling minerals recorded the migration of gas that had probably been generated instantaneously rather than cumulatively from high to overmature source rocks since no evidence is given for the presence of early generated gas in studied paleozoic shale it appears likely that major gas loss from shales occurred due to deformation and uplift of these sediments in response to the variscan orogeny

macrocyclic alkanes a new class of biomarker a new class of cyclic hydrocarbon biomarker macrocyclic alkanes and their methylated analogues have for the first time been unambiguously identified in a botryococcus braunii rich sediment torbanite the compounds consisting of a homologous series of macrocyclic alkanes ranging from c15 to c34 and their methylated derivatives ranging from c17 to c26 were identified by using authentic standards and gc ms techniques

temporal change in site response caused by earthquake strong motion as revealed from coda spectral ratio measurement 1 the spectral ratios of coda waves of local earthquakes have been often used as measures of relative amplification factors of different sites applying this method to coda waves registered by seismometers installed on the surface and at the bottom of a borehole we succeeded in stably measuring the temporal change in site response associated with the occurrence of a large earthquake strong motion a remarkable drop of coda spectral ratio and a shift of the peak frequency were observed during strong shake at two sites by the 2000 western tottori earthquake and at a site by the 2003 tokachi oki earthquake in japan the reduction of the peak frequency reached 30 70 at all the sites after that the peak frequency logarithmically recovered to the value before the strong motions for a few years at two sites whereas the other one quickly recovered in a few tens of minutes

metagenetic methane generation in gas shales i screening protocols using immature samples abstract the gas generative potential of organic matter is one key parameter for the calculation of total gas in place gip when evaluating thermogenic shale gas plays having first demonstrated that late gas forming structures are present in coals of anthracite rank 2 r0 we go on to examine other rocks at the immature stage of maturity and report on how to recognise which might generate significant amounts of late dry gas at geologic temperatures well in excess of 200 c in the zone of metagenesis r0 2 0 i e subsequent to primary and secondary gas generation by thermal cracking of kerogen or retained oil such a distinction could clearly be of major value when assessing risks and pinning down sweet spots a large selection 51 samples of source rocks i e shales and coals stemming from different depositional environments and containing various types of organic matter which contribute to the formation of petroleum in putative gas shales were investigated using open and closed system pyrolysis methods for the characterisation of kerogen type molecular structure and late gas generative behaviour a novel rapid closed system pyrolysis method which consists of heating crushed whole rock samples in mssv tubes from 200 c to 2 different end temperatures 560 c 700 c at 2 c min provides the basis for a newly proposed approach to discriminate between source rocks with low high or intermediate late gas potential it is noteworthy that late gas potential goes largely unnoticed when only open system pyrolysis screening methods are used high late gas potentials seem to be mainly associated with heterogeneous admixtures or structures in terrestrially influenced in some cases marine type iii and type ii iii coals and shales aromatic and or phenolic signatures are therefore indicative of the possible presence of elevated late gas potential at high maturities high temperature methane was calculated to potentially contribute an additional 10 40 mg g toc which would equal up to 30 of the total initial primary petroleum potential in many cases low late gas potentials are associated with homogeneous paraffinic organic matter of aquatic lacustrine and marine origin source rocks exhibiting intermediate late gas potentials might generate up to 20 mg g toc late dry gas and seem to be associated with heterogeneous marine source rocks containing algal or bacterial derived precursor structures of high aromaticity or with aquatic organic matter containing only minor amounts of aromatic phenolic higher land plant material

upper crustal structure seismicity and pore pressure variations in an extensional seismic belt through 3 d and 4 d vp and vp vs models the example of the val d agri area southern italy 1 we use local earthquake tomography and background seismicity to investigate static and transient features of the crustal velocity structure in the val d agri southern apennines italy one of the regions in central mediterranean with the highest seismogenic potential the upper crust is dominated by two broad high velocity anticlines of the buried apulia carbonate platform ramping on two parallel high angle thrusts interpreted as preexisting inverted normal faults the deep core of the anticlines consists of very high vp up to 6 9 km s and low vp vs rocks suggesting the involvement of the apulian crystalline basement in the apennine belt these results provide valuable constraints on the apennine belt tectonic evolution supporting a thick skinned interpretation for the pliocene terminal phase of the compressional tectonics the geometry of the val d agri quaternary basin is controlled by these inherited compressive features whereas the presently active extensional tectonics barely reworked the structure we find inconsistency between the structure of the apulia carbonate platform and the location and geometry of the quaternary normal faults mapped at the surface this suggests either the immaturity of the normal faults or their secondary role in accommodating the extension we observe spatiotemporal 4 d changes of vp and vp vs models defining transient variations of pore fluid pressure in the upper crust a strong change in the vp vs ratio heralds a raise in the seismicity rate that can be related to large water level changes in a nearby artificial lake this evidence is consistent with a mechanism of reservoir induced seismicity by fluid pressure increase and pore pressure diffusion the 4 d velocity variations are confined in the shallow portion of the upper crust 3 6 km depth where fluids are stored in a highly fractured medium pore pressure fluctuations can affect the strength of fault segments favoring seismicity rate changes along the active faults and possibly promoting large future earthquakes

seismic tomography at popocatepetl volcano mexico abstract we performed the first 3d seismic tomography of the popocatepetl volcano mexico from the inversion of the p wave arrival times of nearly 1500 earthquakes recorded by up to 11 seismic stations of the permanent cenapred ssn network we used the bayesian tomographic algorithm developed by monteiller et al 2005 to perform this p wave travel time tomography and carefully choose optimal regularization hyper parameters sensitivity tests show that the inversion is correctly constrained under the volcano from 1 to 4 km depth b s l at these depths the optimal tomographic model mainly shows low velocity volumes surrounded by higher velocity volumes lateral heterogeneity is strong the variation of the p wave velocity may reach up to 20 of the average value at a given depth low velocity volumes correlate well with results from former geological and geophysical studies

time dependent seismic tomography summary of methods for measuring temporal changes in seismic wave speeds in the earth seismic tomography is among those that offer the highest spatial resolution 3 d tomographic methods are commonly applied in this context by inverting seismic wave arrival time data sets from different epochs independently and assuming that differences in the derived structures represent real temporal variations this assumption is dangerous because the results of independent inversions would differ even if the structure in the earth did not change due to observational errors and differences in the seismic ray distributions the latter effect may be especially severe when data sets include earthquake swarms or aftershock sequences and may produce the appearance of correlation between structural changes and seismicity when the wave speeds are actually temporally invariant a better approach which makes it possible to assess what changes are truly required by the data is to invert multiple data sets simultaneously minimizing the difference between models for different epochs as well as the rms arrival time residuals this problem leads in the case of two epochs to a system of normal equations whose order is twice as great as for a single epoch the direct solution of this system would require twice as much memory and four times as much computational effort as would independent inversions we present an algorithm tomo4d that takes advantage of the structure and sparseness of the system to obtain the solution with essentially no more effort than independent inversions require

analysis of frost heave mechanisms in a high speed railway embankment the harbin dalian high speed railway in northeastern china has a significant portion of track foundation built on seasonally frozen ground wide spread frost heave was observed during the first win

statistical parameters of seismicity induced by the impoundment of the three gorges reservoir central china abstract induced seismicity has been observed in the three gorges reservoir tgr area central china since its impoundment in may 2003 data from a local seismic network in the tgr area and a temporal network allow us to obtain a detailed picture of the spatio temporal distribution of earthquakes in the badong area in which earthquakes are clustered statistical parameters namely the seismic b value spatial correlation length and fractal dimension of the hypocentre distribution as an integrated set are investigated and taken as indicators to divide the seismicity in the study area into typical stages epidemic type aftershock sequence modelling which is useful for extracting possible fluid signals from earthquake occurrences is applied to the data set the temporal variations in the parameters indicate a long term increasing and diffusing stress until the present thus much more attention should be given to seismic activity in the tgr area the largest earthquake m5 1 which was followed by aftershocks a large fraction of which were omori type primarily resulted from a triggered fault movement in the m4 3 earthquake sequence both omori type seismic triggering and reservoir triggering are statistically important after the omori type aftershocks which accounted for a small fraction

different behaviours of the seismic velocity field at soultz sous forets revealed by 4 d seismic tomography case study of gpk3 and gpk2 injection tests the geothermal power plant of soultz sous for ets in northeastern france consists of three boreholes gpk2 gpk3 gpk4 reaching a depth of about 5 km all the wells were stimulated through hydraulic injections in this study we present the results of a time dependent 4 d seismic tomography obtained with the p wave arrival times of seismic events recorded in 2003 during the stimulation of the gpk3 well the method combines double difference tomography with the weighted average model post processing that corrects for parameter dependence effects in light of additional processing of the continuous seismic records of 23 surface stations some 4728 precisely located events were selected and separated into 13 subsets to examine periods defined with respect to the injection scheme particular attention is given to changes in injected flow rates periods of stationary injection conditions periods of dual stimulation with the gpk2 well and post injection periods results confirm that significant structures crossing the well have controlled the evolution of the seismicity and have played a fundamental role in the distribution and amplitude of the seismic anomalies furthermore the evolution of the seismic velocity field together with the representation of the relocated seismicity have been compared with the results of the 4 d tomography of the gpk2 well which is located at only 600m from the stimulated well

fractured shale gas systems the first commercial united states natural gas production 1821 came from an organic rich devonian shale in the appalachian basin understanding the geological and geochemical nature of organic shale formations and improving their gas producibility have subsequently been the challenge of millions of dollars worth of research since the 1970s shale gas systems essentially are continuous type biogenic predominant thermogenic or combined biogenic thermogenic gas accumulations characterized by widespread gas saturation subtle trapping mechanisms seals of variable lithology and relatively short hydrocarbon migration distances shale gas may be stored as free gas in natural fractures and intergranular porosity as gas sorbed onto kerogen and clay particle surfaces or as gas dissolved in kerogen and bitumen five united states shale formations that presently produce gas commercially exhibit an unexpectedly wide variation in the values of five key parameters thermal maturity expressed as vitrinite reflectance sorbed gas fraction reservoir thickness total organic carbon content and volume of gas in place the degree of natural fracture development in an otherwise low matrix permeability shale reservoir is a controlling factor in gas producibility to date unstimulated commercial production has been achievable in only a small proportion of shale wells those that intercept natural fracture networks in most other cases a successful shale gas well requires hydraulic stimulation together the devonian antrim shale of the michigan basin and devonian ohio shale of the appalachian basin accounted for about 84 of the total 380 bcf of shale gas produced in 1999 however annual gas production is steadily increasing from three other major organic shale formations that subsequently have been explored and developed the devonian new albany shale in the illinois basin the mississippian barnett shale in the fort worth basin and the cretaceous lewis shale in the san juan basin in the basins for which estimates have been made shale gas resources are substantial with in place volumes of 497 783 tcf the estimated technically recoverable resource exclusive of the lewis shale ranges from 31 to 76 tcf in both cases the ohio shale accounts for the largest share

reservoir depletion at the geysers geothermal area california shown by four dimensional seismic tomography intensive geothermal exploitation at the geysers geothermal area california induces myriads of small magnitude earthquakes that are monitored by a dense permanent local seismometer network using this network tomographic inversions were performed for the three dimensional vp and vp vs structure of the reservoir for april 1991 february 1993 december 1994 october 1996 and august 1998 the extensive low vp vs anomaly that occupies the reservoir grew in strength from a maximum of 9 to a maximum of 13 4 during the 7 year study period this is attributed to depletion of pore liquid water in the reservoir and replacement with steam this decreases vp by increasing compressibility and increases vs because of reduction in pore pressure and the drying of argillaceous minerals e g illite which increase the shear modulus these effects serendipitously combine to lower vp vs resulting in a strong overall effect that provides a convenient tool for monitoring reservoir depletion variations in the vp and vs fields indicate that water depletion is the dominant process in the central part of the exploited reservoir and pressure reduction and mineral drying in the northwest and southeast parts of the reservoir the rate at which the vp vs anomaly grew in strength in the period 1991 1998 suggests most of the original anomaly was caused by exploitation continuous monitoring of vp vs and vp vs is an effective geothermal reservoir depletion monitoring tool and can potentially provide information about depletion in parts of the reservoir that have not been drilled

geochemical and petrophysical source rock characterization of the vaca muerta formation argentina implications for unconventional petroleum resource estimations abstract the vaca muerta formation is currently regarded as the most prolific source rock interval for unconventional petroleum exploration in argentina in this study we integrate recent ct scanner nuclear magnetic resonance nmr t1 t2 and rock eval shale play analytical techniques combined with classical geochemical petrological and petrophysical methods to characterize vaca muerta source rocks along a vertical profile the proposed analytical workflow was tested here on 4 samples derived from one core the lje 1010 borehole drilled in the lowermost jurassic vaca muerta member neuquen basin argentina to evaluate the unconventional hydrocarbon potential and pore network attributes first entire rock samples were analyzed by dual energy ct scanner to evaluate possible heterogeneities this also helped in the selection of representative samples then the organic matter properties were investigated by open system pyrolysis techniques organic petrography and biomarker analyses as a function of the core depth a comparative approach between open system pyrolysis methods e g rock eval basic bulk rock shale play methods vs source rock analyzer is also illustrated in this work finally petrophysical characteristics and pore network attributes in shale were estimated by gas permeability steady state method corrected for klinkenberg effect porosity and nmr methods the investigated samples have oil window maturity and are characterized by a network of solid bitumen based on new rock eval shale play data the potentially producible oil present in the rock samples was estimated using the modified oil saturation index osi sh0 sh1 peaks 100 toc results indicate that the oil crossover effect and potential productive oils occur within intervals showing higher toc values 3 to 8 wt we also illustrated here that for unconventional shale play perspectives rock eval shale play parameters sh0 sh1 allow to obtain both a better quantification of free and retained hydrocarbons in source reservoir rock samples and correct original oil in place ooip estimations in early exploration campaign for shale oil and shale gas assessment for vaca muerta rock samples ooip estimations range from 60 to 160 bbl oil acre ft approximately we also demonstrated that the solid bitumen oil and organic matter are clearly distinguished in the studied samples using advanced nmr t1 t2 maps obtained at different temperatures the solid bitumen was clearly evidenced as a peak with t1 t2 ratio 14 on nmr t1 t2 maps concerning the matrix bulk rock permeability the obtained results showed that the most deep sample is characterized by a permeability of about 140 nanodarcy nd whereas the shallower sample containing also higher amounts of organic matter is more permeable 213 nd indicating that toc values play a main control on vaca muerta poromechanical characteristics the maximum total porosity values range between 6 5 and 21 8 and were calculated in this work integrating nmr and helium porosity values finally global interpretations of these obtained results suggest that the vaca muerta formation could be considered as a prolific shale play interval for unconventional petroleum exploration in the near future

climate driven paleolimnological change controls lacustrine mudstone depositional process and organic matter accumulation constraints from lithofacies and geochemical studies in the zhanhua depression eastern china abstract the influence of paleoclimate on the depositional process of lacustrine mudstone and organic matter accumulation is important to both paleoclimate reconstruction and hydrocarbon exploration here we study the lower third member es3l of the eocene shahejie formation in the zhanhua depression bohai bay basin eastern china in order to understand how paleoclimate influenced depositional processes and organic matter accumulation of lacustrine organic rich mudstone by combining detailed core descriptions and microscopic observations and high resolution mineralogical and geochemical analyses we identified two major lithofacies including massive calcareous mudstone and laminated calcareous mudstone from the luo 69 drilling core the sedimentologic observations and changes of geochemical proxies including detritus index ln al2o3 na2o b ga and v v ni suggest that the massive calcareous mudstone was deposited in a small shallow salt lake that was dysoxic anoxic and the paleoclimate in the lake catchment was cool and arid and the laminated calcareous mudstone was deposited in a large and deep stratified lake which has anoxic highly saline bottom and oxic less saline surface water and the lake catchment was more humid and warm the dominant lithofacies changed from laminated calcareous mudstone to massive calcareous mudstone in the studied core suggesting that the lake became shallower and smaller when the paleoclimate became cooler and drier through time such a climate trend may be a response to global cooling during the middle eocene the average total organic content toc in both lacustrine highstand and lowstand are comparable even though the lake water chemistry and amount of terrigenous input are different we infer that the accumulation of organic matter within the lacustrine highstand was controlled by the combination of primary productivity carbonate production and preservation in anoxic bottom water while accumulation within lacustrine lowstand was only controlled by primary productivity

predicted bulk composition of petroleum generated by lower cretaceous wealden black shales lower saxony basin germany the berriasian wealden shale provides the favourable situation of possessing immature to overmature source rock intervals due to differential subsidence within the lower saxony basin hydrocarbon generation kinet ics and petroleum physical properties have been investi gated on four immature wealden shale samples situated in different depth intervals and following the phaseki netics approach of di primio and horsfield aapg bull 90 7 1031 1058 2006 kinetic parameters and phase prediction were applied to a thermally calibrated 1d model of the geodynamic evolution at the location of an overmature well the immature source rocks of all depth intervals comprise kerogen type i being derived from the lacustrine algae botryococcus braunii bulk kinetics of the lower three depth intervals sample 2 4 can be described by one single activation energy ea typical for homogene ous lacustrine organic matter om whereas sample 1 from the uppermost interval shows a slightly broader ea distribution which hints to a more heterogeneous less sta ble om but still of lacustrine origin predicted physical

petroleum generation and migration in the styrian basin pannonian basin system austria an integrated geochemical and numerical modelling study abstract source rock analysis and numerical modelling techniques have been applied to evaluate the hydrocarbon potential of the styrian basin oil and gas prone sediments occur in the lower miocene section ottnangian and karpatian levels kinetic parameters indicate that hydrocarbons are generated at higher temperatures and within a narrower temperature interval from ottnangian sediments than from karpatian sediments the thermal history of the basin is governed by miocene magmatic activity due to subduction along the carpathian front heat flow during magmatic activity in close vicinity to the volcanic centres was about 300 mw m2 decreasing to about 120 mw m2 at a distance of a few kilometres after the magmatic activity the heat flow decreased and has remained at 60 85 mw m2 since the end of the middle miocene the increased heat flow resulted in an early miocene karpatian to early badenian petroleum generation phase near the volcanoes because no traps were formed at that time the generated hydrocarbons may have been lost thus the early magmatic episode had a negative impact on the hydrocarbon potential from a timing aspect at some distance from the volcanoes generation continued up to the end of the middle miocene early sarmatian hydrocarbons generated during and since the middle badenian have had a good chance of becoming trapped and forming accumulations only small amounts of oil formed after the middle miocene the numerical modelling of petroleum migration provides important information on its timing and pathways and predicts correctly the only drilled hydrocarbon occurrence in the styrian basin the calculated gas to oil ratio is 0 5 the integration of all these data helps to define areas with high petroleum potential

the impact of the 24 march 2011 myanmar earthquake ms 7 2 on seismic structure of the yunnan region abstract the temporal and spatial variations of the velocity structure 60 days before and after the march 24 2011 myanmar m7 2 earthquake in the yunnan region are studied by using the ambient noise cross correlation method with the continuous seismic waveform records in addition the response ratio of strain energy release is obtained using moderate and small earthquakes and the coulomb stress changes along different faults are calculated using the source parameters of the myanmar earthquake there are three regions where the velocities increased the area from the zemuhe xiaojiang fault zone to the yuanmou lvzhi fault zone the southern segment of the honghe fault zone and the area from the nantinghe fault zone northward extending to the dayingjiang fault zone the seismic activity and the coulomb stress of these regions are also enhanced by contrast there are several regions where velocities decreased such as the area from the nantinghe fault zone southward extending to the simao region the seismic activity and the coulomb stress of these regions are decreased as well the consistency of the variation indicates some relationship between the variation and the myanmar earthquake