dating reservoir filling a case history from the north sea abstract secondary petroleum inclusions in reservoir sandstones in the froy field and the rind discovery are used in combination with burial history modelling reservoir oils and core extracts to shed light on how and when these structures received their hydrocarbon charges analysis of normal alkane and biomarker distributions in these three data sets fluid inclusions core extracts and drill stem tests dsts provide information on the changes in organic facies and maturity of petroleum in the various reservoir strata over time the geochemistry of core extracts and dst oils in rind and froy reveal that the maturity of the rind petroleum system is higher and also of slightly less anoxic facies compared to the oil present in the froy system biodegraded oil is found today in a small sub compartment of the froy field using the burial history of the froy and the assumption that biodegradation effectively comes to a halt at 70 80 c we tentatively conclude that the filling of this sub compartment and the biodegradation of the oil must have occurred earlier than 30 40 m y b p and before oil from the upper jurassic draupne shales more recently homogeneously filled the main froy structure at 30 40 m y b p the froy structure was at a depth of 1 5 2 km compared to the present depth of 3 5 4 km and it is more than likely that neither the heather nor the draupne formations were mature in the paleo drainage area of the field at this time still the stratigraphically deeper dunlin formation could have been mature and the geochemical signatures of the now biodegraded oil correlates with known signatures from the dunlin formation in this region in the rind discovery no fluorescent petroleum inclusions are observed in k feldspar overgrowths however the number of inclusions in quartz and plagioclase is larger than that observed in the shallower froy field from the mean homogenization temperatures of the petroleum inclusions which are close to the present reservoir temperature filling of the froy field and main rind structure is suggested to have been a recent event a presently dry compartment penetrated by well 25 2 15r2 in the rind discovery contains high residual oil saturations indicating loss of oil from this structure either by direct cap rock leakage or displacement of oil by gas and subsequent cap rock leakage numerous petroleum and coexisting water inclusions were found in the presently dry overpressured structure and it is clear from measurements of homogenization temperatures that the water and the petroleum inclusions are not both saturated with respect to gas due to the lower solubility of hydrocarbon gas in water compared to in oil it is more likely that water inclusions are closer to saturation than are the petroleum inclusions using the difference in homogenization temperatures in these two systems and the burial history we tentatively suggest that the cap rock leakage occurred later than 10 m y b p such information on time for reservoir filling and seal failure when used to calibrate basin modelling should facilitate better models for understanding movement of hydrocarbon fluids in basins

inter and intrafield hydrocarbon compositional variations in the ula and the gyda fields central graben north sea implication for understanding the controls on hydrocarbon distribution within and between these fields abstract a suite of 34 oil samples from the ula and 30 from the gyda oil fields lying in the central graben of the norwegian continental shelf was analyzed using thin layer chromatography with flame ionization detection tlc fid capillary gas chromatography with flame ionization detection gc fid and gas chromatography mass spectrometry gc ms the results obtained were used to calculate several source and maturity based parameters these parameters suggest that within the ula field oils produced more recently have greater compositional homogeneity than those produced earlier this has been attributed to a recent change in the crestal fault behavior this change in fault behavior is probably production related the gyda field oils are compositionally more homogeneous however oils from the gyda south culmination are compositionally different this difference shows up in both maturity and source related parameters

contemporary changes in sediment yield in an alpine mountain basin due to afforestation the upper drome in france abstract the baurieres plain within the upper drome river basin was used to reconstruct recent changes in sediment supply in relation to changes in land use within an alpine catchment a considerable body of archival information is available furthermore the plain acts as a natural sediment trap and the reach basin interaction has not been disrupted by human activity based on archival data channel geometry measurements dendrogeomorphological and radionuclide analysis cs137 and unsupported pb210 the trends in channel change and sediment supply over the past two centuries are assessed and their causes are interpreted dendrogeomorphology and radionuclide profiles show that the floodplain is characterised by a decrease in sedimentation rate in the 1960s the ex pb210 profiles also suggest a spatial modification of the relative contribution in sediment supply of the catchment bedload yields are estimated to be at least 26 m3 km 2 year 1 between 1928 and 1996 based on an estimate of storage over a channel length of 11 5 km archival data concerning bedload removal from traps yields an estimate of 25 6 m3 km 2 year 1 between 1993 and 2001 these two values are very comparable suggesting no major modification in bedload transport within the reach during the 20th century if the bedload supply has not strongly decreased in the studied reach during this period the bedload sources have changed the volume of sediment stored in the beaurieres area between 1928 and 1996 corresponds to at least 40 of the sediment delivered by channel degradation from an upstream alluvial reach both changes in floodplain sedimentation as well as changes in bedload and suspended contributions from catchment sources are interpreted as responses to land use but also flow regime hillslope sediment production strongly decreased due to planned hillslope afforestation and torrent regulation at the end of the 19th century and spontaneous hillslope afforestation resulting from grazing decline mainly in the two decades following world war ii the observed change in suspended sediment supply which occurred around 1960 1965 has a clear synchronicity with spontaneous catchment afforestation following world war ii after this period a decrease in sediment supply a change in source but also a decrease in peak flow were observed changes in run off are complex and cannot be caused with only land use change flood hydrographs underwent peak decreases and duration increases through the 20th century because of increase in water retention capacity of the forested catchment in addition flood seasonality has changed with september and october flood events being much less frequent in the last part of the 20th century

hydrocarbon composition of authigenic inclusions application to elucidation of petroleum reservoir filling history abstract geochemical analysis of petroleum inclusions trapped in authigenic feldspar and quartz in the ula formation in the north sea ula oil field revealed a petroleum of markedly different composition than the oil presently in the reservoir using microthermometry and the burial history as a dating tools it is concluded that the petroleum in the k feldspar inclusions was present in the more porous and permeable parts of the ula formation as early as 45 75 my bp when the field was at a depth of about 1 0 1 5 km as compared with the current depth of 3 4 km this early petroleum which was trapped as inclusions in authigenic k feldspar shows a distinctly different distribution of tricyclic terpanes and pentacyclic triterpanes from that of the current petroleum charge in the ula formation which was derived from the mandal formation source rock in late neogene time molecular parameters show that the oil in the k feldspar inclusions is significantly less mature than the crude oil in the present reservoir the approximate 90 c temperature increase occurring after entrapment of the early petroleum in kfeldspar the field is currently at 143 c appears not to have reset the low maturity signature of the oil in the k feldspar inclusions this could suggest that the temperature in the inclusions is too low for isomerization selective thermal degradation to occur lack of catalysts or that there are other controls on the ratio of some of these parameters still parameters like the ratio of c21 to c28 triaromatic steroids and those based on dimethyl and trimethyl naphthalenes are comparatively similar in both the inclusions and in the reservoir crude the oil inclusions in authigenic quartz and albite formed from about 10 my bp burial depth 2 5 km until the present burial depth 3 4 km are interpreted as representing a palaeo petroleum charge having a composition intermediate between the oil found in k feldspar inclusions and the oil charge in the present reservoir our data suggest strongly that the petroleum trapped in the inclusions in quartz and plagioclase represents progressive dilution of the early reservoired oil now found only in k feldspar inclusions with oil from the mandal formation analysis of solution gas in these inclusions suggests that the first petroleum associated gas to arrive at the trap from the progressively maturing mandal formation had a much wetter composition than the current reservoir solution gas to explain the present comparatively drier and isotopically lighter reservoir solution gas composition the inference is made that there has been a recent during formation of k feldspar inclusions 45 75 my bp maturation of the upper jurassic mandal formation the main source rock in this region was limited possibly to the graben axis this suggests that the petroleum found in the k feldspar inclusions was most likely derived from a deeper post caledonian palaeozoic formation

molecular memory effects recording the accumulation history of petroleum reservoirs a case study of the heidrun field offshore norway abstract the immobile portion of the oil occupying the pore space of reservoir sandstones which is mostly represented by visible impregnations is shown by the present study to contain geochemical signals that record their filling history the clue to unravelling these signals is sequential extraction of such impregnations of residual oil by a high pressure solvent flow through cell in which the solvent percolates through the intact and primary pore system of the rock sample gas chromatography mass spectroscopy gc ms analysis of residual oils extracted from samples of certain reservoir sandstones within the heidrun field offshore norway reveal significant contrasts in the chemical maturity of the first and the last fractions recovered as high as 0 69 versus 0 50 for the mpi 1 ratio corresponding to 0 79 versus 0 67 rc the hypothesis is proposed that by using this extraction technique oil impregnations from different portions of the pore system i e from large versus small pores are obtained separately this interpretation is especially supported by the regular occurrence of reservoir sandstones in which the residual oil exhibits maturity contrasts between those fractions extracted from large and small pores of the same rock within the heidrun field the distribution of reservoir sandstones with such maturity contrasts is strictly controlled by their position in the oil column and the location of their fault compartment these contrasts are interpreted to reflect the maturity levels of end members of the petroleum charges which have filled this trap during an extended period of geological time reservoir sandstone samples containing such end member charges are limited to the uppermost portion of the oil column lower in the oil column the pore system of all reservoirs contains oil impregnations of a uniform maturity level regardless of their pore size origin this distribution is believed to indicate an early stage of the accumulation history of the heidrun field characterised by the formation of a palaeo oil water contact well above the present one moreover the four fault compartments studied each controlled by bordering faults with different sealing capacities were not filled during the same stages of the accumulation history in summary the present study has shown that oil impregnations depending on their location within the pore system of individual reservoir sandstones can retain molecular memory effects which in turn allow the accumulation history of petroleum fields to be reconstructed

quantitative spore colour measurement using colour image analysis abstract the colour changes that spores exhibit with increasing depth of burial are used as a thermal maturity indicator for evaluating hydrocarbon source rocks spore colour is determined visually leading to an intrinsic difficulty of unequivocally assessing and recording their colour quantitative scales using photometers are available but are not widely applied colour image analysis cia is presented here as an alternative method for the quantification of spore colour through the use of image analysis software common in many laboratories using the rgb red green blue colour format the colour of spores was determined the material included a set of artificially heated lycopodium spores and geological samples from a range of ages and geographical areas covering the entire maturity range these data were then compared to samples from a well section of carboniferous age which were fully mature to post mature with increasing maturity the colour changes in spores and pollen define a consistent and reproducible trend on the red vs green pixel intensity graph significantly all samples suites experimental and natural exhibit the same behaviour previous research milton 1993 ph d thesis gutjahr 1966 leidse geologische medelingen 38 1 30 show a strong morphological control on colour based on differences in wall thickness and original chemistry however if spores and pollen are chosen carefully i e avoiding taxon with cracks folds apertures and ornamentation as well as those with exceptionally thin bag type or thick exines a good sample average can be made by measurement of 40 50 similar spore pollen types specific points on the red vs green colour graph coincide with significant chemical transformations and these coincide with the thermal cracking of the spore wall spore oil window

the petroleum characteristics and filling history of the froy field and the rind discovery norwegian north sea abstract the brent group reservoirs of the froy field and the rind discovery norwegian north sea show complex distributions of petroleum and aqueous fluids multiple fluid contacts are present in the rind discovery and the fields show various extent of compartmentalisation due to faulting geochemistry data of core extracts indicate that the two fields have different petroleum sources bhullar karlsen holm backer owe tran 1998 late diagenetic modifications of the reservoir quality consist of quartz cementation followed by carbonate and kaolinite cementation and dissolution of k feldspar fluid inclusion results indicate that filling of the reservoirs occurred after the main phase of quartz cementation at pressure temperature conditions close to the present differences in fluid properties between fault compartments in both fields have been identified fluid inclusion data have proved especially valuable for evaluation of the sealing capacity of faults through time and given evidence for the fault lineament north of both fields to be a time integrated pressure seal except for a lower gas condensate zone in the 25 2 13 compartment of rind the present reservoir fluids are volatile oils close to gas saturation the previous presence of an oil in the lower reservoir zone of 25 2 13 has also been demonstrated the fluid inclusion data indicate that the condensate in 25 2 13 represents a second episode of migration filling rather than phase separation

pressure temperature time composition p t t x constraints of multiple petroleum charges in the hild field norwegian north sea abstract the brent reservoirs of the hild field situated at 3 8 4 3 km depth in the northern north sea show evidence of multiple episodes of diagenetic events fracturing and petroleum charging data from fluid inclusions and drill stem test samples characterise the petroleum filling history of the hild field two main types of petroleum inclusions occur type 1 inclusions which occur in two of the fault compartments of the field show a heavier composition than the present reservoir fluids from a comparison of fluid inclusion analyses and burial history onset of reservoir filling is most likely represented by type 1 inclusions and took place at 125 130 c in well 30 7 8r this temperature corresponds to a burial depth of 3 5 3 7 km which occurred 35 32 ma ago type 2 inclusions occur in all wells and are compositionally similar to the reservoir fluids suggesting recent trapping considerable differences in homogenisation temperature and phase behaviour of type 2 inclusions between the three wells of the hild field indicate the compartmentalised nature of the reservoir pvt modelling of fluid properties and trapping conditions was based on microthermometry gc data for type 1 inclusions and present day fluid compositional data for type 2 inclusions the results show generally good agreement between estimated pressure for type 2 inclusions and present day reservoir conditions and an increase in overpressure between trapping of types 1 and 2 inclusions we suggest that quartz cementation may continue after onset of reservoir filling and may exert major control on the pressure evolution in deep reservoirs

geochemical comparison of fluid inclusion and present day oil accumulations in the papuan foreland evidence for previously unrecognised petroleum source rocks abstract petroleum production in papua new guinea is limited to the papuan fold belt present day oil accumulations in fields such as iagifu hedinia and gobe are thought to be mainly derived from clay rich jurassic marine source rocks containing terrestrially derived organic matter that were deposited under oxic conditions in this study other generative source rocks in the papuan foreland are indicated using fluid inclusion fi oil data from three wildcat wells koko 1 bujon 1 and kimu 1 which were drilled on the bosavi arch detailed organic geochemistry of these fi oils and associated free oils or oil stains suggests that none of these were generated from the aforementioned jurassic source rocks instead at least three different generative source rocks are indicated firstly a marine probably late cretaceous or younger source rock deposited under reducing conditions is indicated by the bujon 1 fi oil this source rock had a moderate contribution from higher plant organic matter including oleanane and or lupane the bujon 1 fi oil has similarities with fi oils from the iagifu 7x and p nyang 2x wells in the papuan fold belt secondly an algal dominated lacustrine source rock is indicated by the biodegraded koko 1 rft crude oil the unbiodegraded fi oil from koko 1 and the bujon 1 oil stains from the toro and imburu formations these lacustrine oils have high abundances of tricyclic terpanes pregnane homopregnane and gammacerane contain carotane and have high c26 c25 tricyclic terpane ratios the source of the lacustrine oils is inferred to contain moderate amounts of terrestrial organic matter indicated by a dominance of c29 steranes and abundant aromatic higher plant biomarkers and could be gypsiferous shales embedded in oligocene miocene carbonates or triassic age sediments deposited on igneous basement during early rifting associated with the break up of gondwana the kimu 1 fi oil was generated from a mature marine suboxic source rock but has a different geochemical composition to free oil from a similar interval which was derived from a carbonate rich source rock none of the fi oils correlate well with oil families previously described in papua new guinea accordingly the oils recovered from fis in this part of the papuan basin support the presence of laterally varying source rock compositions and qualities and indicate that there are opportunities to develop new charge models for features across the papuan foreland furthermore koko 1 bujon 1 and kimu 1 fi oils have different geochemical compositions compared to the associated free oils or oil stains indicating that each of these localities has a multi phase charge history further work to lower exploration risk in the papuan foreland should be directed to understanding the distribution maturity and expulsion history of these newly recognised potential source rocks

a temporarily changing holocene sediment budget for a loess covered catchment central belgium abstract this study presents a holocene sediment budget for the nethen catchment a typical river catchment 55 km 2 in the belgian loess belt soil erosion and hillslope sediment storage are quantified by extrapolating detailed data obtained from soil profile truncation studies in three representative zero order sub catchments floodplain sediment storage is estimated by augerings along several transects across the main river and some of its tributaries the sediment budget shows that ca 38 of the soil eroded during the holocene is redeposited as colluvium on hillslopes and in dry valley bottoms another 23 of the eroded sediment is now stored as alluvium in the floodplain the remaining 39 or 21 10 6 mg is exported from the catchment dating of both colluvial and alluvial sediment deposits reveals that sediment dynamics between the hillslopes the dry valley bottoms and the floodplain behave highly non linearly before 500 bc sediment delivery from the hillslopes to the river channels was near maximum however since the onset of significant agriculture in the late bronze age early iron age increased rates of soil erosion are only reflected in the colluvium but not in the floodplain resulting in very low hillslope sediment delivery ratios from the medieval period onwards soil erosion increased even further mainly as a result of a further increase in agricultural land use but now also accelerated floodplain sedimentation took place due to an improved slope channel coupling and the management of floodplains

quantitative spore colour spores exhibit changes in colour with increasing depth of burial these changes have found wide application for thermal maturity determination in hydrocarbon source rocks at present colours are determined visually here the application of the commission internationale de l eclairage colour system to the measurement of spores is described such that colour can be defined by the chromaticity co ordinates x y and the luminance l which define a colour solid the colour changes seen in spores with increasing burial define a maturation pathway in this colour solid which shows two distinct trends the first is a well defined progressive colour change to a cusp at which a broad spread of colours from yellow to brown occur in a single sample this is the interval over which hydrocarbons are generated and which is clearly defined by these colour differences the second trend is through a series of brown colours with an increasing lack of sensitivity of the spores to colour changes these changes are calibrated to vitrinite reflectivity the data and conclusions are amplified and supported through changes in colour chemistry and exine reflectivity in artificially matured lycopodium spores comparisons are made with existing qualitative spore colour scales the implications for maturation determination are that spore colour is a good thermal maturity index for the interval prior to oil generation and that it is suitable for quantitative modelling studies it demonstrates the interval of oil generation at the cusp but after this point it becomes inaccurate and inferior to other methods such as vitrinite reflectivity

potassium leached zones at the contacts of the garn formation mid norwegian continental shelf evidence for the role of shale in sandstone diagenesis abstract

reservoir geochemistry of stockstadt oilfield compositional heterogeneities reflecting accumulation history and multiple source input abstract within the stockstadt oilfield which produces from an upper and a lower reservoir unit heterogeneities in the composition of the accumulated oil depend on the porosity and permeability of the reservoir sandstones and on their stratigraphic and structural position the spatial distribution of the compositional heterogeneities are interpreted to reflect the accumulation history of the field with increasing burial in the kitchen area the oligocene septarienton the main source bed for the field generated and expelled progressively more mature oil geochemical data indicate that the higher maturity oil displaced an early expelled low mature oil that subsequently filled the low porosity intervals of the reservoir later accumulated more mature oils are thus found in the high porosity intervals in addition an admixture of a high wax oil expelled from a local deposit of an eocene ooil shale messel equivalent led to the waxy character of some oils of the lower reservoir unit

brightness of pollen as an indicator of thermal alteration by means of a computer driven image processor statistical thermal alteration index sttai abstract the brightness or gray level of pollen of pinus podocarpus abies picea and tsuga from the neogene sediments in northern japan was measured using a transmitted light microscope with a computer driven digital image processor the mean value of the modes for the complete array of the indigenous pollen in a rock sample was called here the statistical thermal alteration index sttai in the present investigation an inverse relationship between sttai and vitrinite reflectance r o in sediments was found the application of sttai to samples from three boreholes indicated a decreasing trend with depth by using this trend threshold values of intense oil generation can be evaluated 145 110 therefore sttai can be a useful parameter for determining organic maturation and for identifying the threshold zone of intense oil generation

hydrocarbon generation in the permian irati organic rich shales under the influence of the early cretaceous parana large igneous province abstract the increasing global demand for natural gas and petroleum byproducts is turning organic rich shales into an important target for hydrocarbon exploration and production current understanding about hydrocarbon generation in unconventional plays such as oil shales and gas shales is still evolving especially in sedimentary basins where hydrocarbon generation is influenced by magmatism this is the case for the permian oil shales of the irati formation in the parana basin southern south america the irati shales are considered an atypical petroleum system due to thermal effects of the parana large igneous province lip emplaced during the early cretaceous in this context the focus of this study was to characterize the thermal conditions of hydrocarbon generation in the irati formation as well as the composition of related aqueous diagenetic fluids the kerogen from the irati organic rich shales has an aromaticity around 30 ar 30 as determined by carbon nuclear magnetic resonance 13c nmr and vitrinite reflectance ro of around 0 6 fluid inclusions in calcite and quartz veins present aqueous fluids with salinity of 0 5 wt of nacl equivalent and homogenization temperatures greater than 250 c hydrocarbon fluid inclusions were classified as black oil through their vapor fraction volumes fv 1 6 9 1 and homogenization temperatures th in the 60 80 c range methane ch4 or carbon dioxide co2 fluid inclusions were absent within the analyzed calcite and quartz veins the pvt model for trapped fluid inclusions suggests a shallow hydrocarbon petroleum system 2 5 km depth active during the early cretaceous synchronous with the parana lip

temperature profile around a basaltic sill intruded into wet sediments abstract the transfer of heat into wet sediments from magmatic intrusions or lava flows is not well constrained from field data such field constraints on numerical models of heat transfer could significantly improve our understanding of water lava interactions we use experimentally calibrated pollen darkening to measure the temperature profile around a basaltic sill emplaced into wet lakebed sediments it is well known that upon heating initially transparent palynomorphs darken progressively through golden brown and black shades before being destroyed however this approach to measuring temperature has not been applied to volcanological questions we collected sediment samples from established miocene fossil localities at clarkia idaho fossils in the sediments include pollen from numerous tree and shrub species we experimentally calibrated changes in the color of clarkia sediment pollen and used this calibration to determine sediment temperatures around a miocene basaltic sill emplaced in the sediments results indicated a flat temperature profile above and below the sill with t 325 c within 1 cm of the basalt sediment contact near 300 c at 1 2 cm from the contact and 250 c at 1 m from the sill contact this profile suggests that heat transport in the sediments was hydrothermally rather than conductively controlled this information will be used to test numerical models of heat transfer in wet sediments on earth and mars

photometric methods for measuring the thermal maturity on strew mounted kerogen slides abstract the optical examination of strew mounted kerogen slides is essential for evaluating the source quality and thermal maturity of potential source rocks the methods currently used to assess thermal maturity on kerogen slide should be improved because the data currently obtained are qualitative and operator dependent the use of two photometric methods to measure the thermal maturity of kerogen on strew mounted slides are introduced the kerogen analyst can measure the transmittance of spore pollen and the reflectance of vitrinite on a kerogen slide and convert the data to a calibrated thermal maturity scale tai thermal alteration index the advantages of using the photometrically measured transmittance and reflectance to assess the thermal maturity of a sample are 1 the method is semi quantitative 2 the parameters measured are physically defined and are easy for interlaboratory comparison of the data 3 the parameters measured supplement each other and 4 this method is applicable at all levels of maturity major limitations of this photometric methods are 1 the vitrinite reflectance is less reliable when measured from the kerogen slides of immature samples and 2 the palynomorph transmittance is thickness dependent

digital quantification of the miospore coloration to assess the thermal maturity novel rgb based measuring technique abstract the post depositional thermal maturity and its related chemical changes induce the sporomorphs color alteration which is a common useful tool in the optical microscopy of the organic matters om and their pre geochemical studies the present contribution uses the modern available opportunity of digital technology to achieve a quantifying system technique which includes color measurements and their possible graphic presentation the normal digital images of sporomorphs from several ages and geological settings are used to obtain color measurements in the form of digital red green and blue triple color system rgb these measurements were accomplished using some software programs such as photoshop or imagej with employing average microscope setup the triple rgb color readings are plotted on a ternary diagram which is divided into three fields these fields express the maturity levels the presented new rgb based quantifying technique is economic and provides a simple examination for maturity which is linked to the hydrocarbon generation this can partially replace or walk side by side with the vitrinite reflectance microscopy

sources of ca2 in the major carbonate cements in eocene sandstones and conglomerates evidence from sr isotopes sr ca ratios and rare earth elements abstract different sources of calcium have important effects on the formation and distribution of carbonate cements on the basis of identifying all possible sources of calcium comprehensive quantitative analyses of sr c and o isotopic values and trace elements including rare earth elements were conducted to determine the ca2 sources and their changes in the same type of carbonate cements at different vertical positions in the same reservoirs ferroan calcite and ankerite were the major types of carbonate cements ca2 in ferroan carbonate cements in the sandstones near the mudstone sandstone m s interfaces was derived primarily from diagenetic fluids mixed with ca2 originating from the transformation of smectite to illite and from original sedimentary water in the adjacent mudstones however ca2 in the ferroan carbonate cements in the sandstones away from the m s interfaces originated from the transformation of smectite to illite the dissolution of carbonate minerals and original sedimentary water in source rocks the gradual change of ca source of the same type of ferroan carbonate cements indicates the diversity of migration direction of diagenetic paleo fluid in the same period during the transformation of smectite to illite concentration gradients were created from mudstones to sandstones ca2 mg2 fe2 and other cations in the mudstones diffused to the adjacent sandstones and provided sources of ferroan carbonate cements at the edge of the sandstones pore water with ca2 mg2 fe2 co32 and other cations in the source rocks was collectively charged into sandstones during oil emplacement and promoted the precipitation of ferroan carbonate cements in residual pore water due to oil emplacement and material supplied by the adjacent mudstones the content of ferroan carbonate cements in the sandstones was lower and the reservoir porosity was higher at a greater distance from the m s interfaces however in thick bedded sandstones due to lack of material supply from the adjacent mudstones ca2 mg2 fe2 and co32 in the ferroan carbonate cements were mainly derived from source rocks as a result no significant changes were observed in the content of ferroan carbonate cements and reservoir porosity in the vertical direction

geoarchaeology the four dimensional 4d fluvial matrix and climatic causality abstract geoarchaeology is the application of geological and geomorphological techniques to archaeology and the study of the interactions of hominins with the natural environment at a variety of temporal and spatial scales geoarchaeology in the uk over the last twenty years has flourished largely because it has gone beyond technological and scientific applications over the same period our ability to reconstruct the 3 dimensional stratigraphy of fluvial deposits and the matrix of fluvial sites has increased dramatically because of a number of technological advances these have included the use of lidar laser imaging and radar to produce high resolution digital surface models the use of geophysics particularly ground penetrating radar and electrical resistivity to produce sediment depth models and the use of gis and data visualisation techniques to manipulate and display the data these techniques along with more systematic and detailed sedimentological recording of exposed sections have allowed the construction of more precise 3 dimensional volumetric models of the matrix of artefacts within fluvial deposits additionally a revolution in dating techniques particularly direct sediment dating by luminescence methods has enabled the creation of 4 dimensional models of the creation and preservation of these sites these 4 dimensional models have the ability to provide far more information about the processes of site creation preservation and even destruction and also allow the integration of these processes with independent data sources concerning cultural evolution and climatic change all improvements in the precision of dating fluvial deposits have archaeological importance in our need to translate events from a sequential or geological timeframe to human timescales this allows geoarchaeology to make a more direct contribution to cultural history through the recognition of agency at the individual or group level this data can then form a component of biocomplexity or agent based modelling which is becoming increasingly used in the natural sciences particularly ecology and geomorphology and which can be used to test scenarios including the impact on and response of hominins to abrupt or catastrophic environmental change whilst catastrophic events clearly represent the atypical they can be illuminating in revealing cognitive processes resulting in abandonment coping mitigation and innovation these points are exemplified using two in depth case studies one from the holocene geoarchaeological record of the river trent in central england and the other from the palaeolithic record from rivers in south west britain in the former the interaction between climate change and human activity is illustrated at the year to century timescale whilst in the other the timescale is millennial these case studies have deliberately been chosen to be as different as possible in temporal and spatial scale with the aim of examining the applicability of methodological and theoretical aspects of geoarchaeology lastly the paper considers the problem of scale in geoarchaeology and concludes it is process dependency which ultimately affects the questions we can ask and that questions of human response to climate change are fundamentally a product of materiality and cognitive processes this demands an in depth contextual approach to such questions rather than database driven assertions of causality

thermal history modeling of the georges bank u s a thermal inversion of transmittance color index tci and vitrinite reflectance vr data abstract using a one dimensional basin analysis model for the cost g 2 well in the georges bank area offshore east coast u s a thermal inversion of measured vitrinite reflectance vr data and of the transmittance color index tci converted to an equivalent vr value yielded essentially identical paleoheat flux variations with time the paleoheat flux showed two peaks at 175 ma bp and at 125 75 ma bp the earlier event corresponds to continental breakup and the beginning of the rift phase the latter event corresponds to continued drifting of the continents and formation of new oceanic basement beside answering some important tectonic questions the observations corroborated the theoretical and empirical connections between tci and vr found for the g 2 well and for other wells in different geological settings this fact together with the fact that tci measurements on physically amorphous organic material can be made on rocks devoid of vitrinite or spores and pollen carbonates pre late silurian rocks and siliceous black shales should promote the utility of tci as an effective geothermal history indicator

fluid inclusions record thermal and fluid evolution in reservoir sandstones khatatba formation western desert egypt a case for fluid injection a fluid inclusion and petrographic study focused on quartz overgrowths was performed in reservoir sandstones from the jurassic khatatba formation salam oil field egypt s western desert the combination of detailed fluid inclusion petrography and scanning electron microscope sem cathodoluminescence imaging has allowed us to relate individual fluid inclusion assemblages that is the most finely discriminated groups of petrographically associated fluid inclusions to specific growth zones of authigenic quartz establishing the relative timing of entrapment of the inclusions after entrapment fluid inclusions in authigenic quartz have been preserved without reequilibration as indicated by the narrow ranges of homogenization temperatures 4 5 degreesc in most fluid inclusion assemblages three main growth zones are distinguished under sem cathodoluminescence in the quartz overgrowths and are termed q1 q2 and q3 from the oldest to the youngest zone q1 is further subdivided into three subzones and contains abundant primary aqueous inclusions their homogenization temperatures range from 162 to 130 degreesc with the earliest assemblages having the highest temperatures and with some large temperature fluctuations indicated between successive assemblages most q1 inclusions have salinities in the freshwater to seawater range with a trend toward increasing salinity through time zone q2 contains primary aqueous inclusions with homogenization temperatures overall range 148 125 degreesc also recording large temperature fluctuations and cooling events the q2 fluid inclusions have high salinities 5 20 wt nacl equivalent with salinity increasing through time zone q3 contains both aqueous and oil inclusions of primary origin the q3 aqueous inclusions have homogenization temperatures overall range 134 112 degreesc recording overall cooling and high salinities 21 24 wt nacl equivalent in early q3 subzones oil inclusions appear to be of medium gravity undersaturated with respect to gas in later q3 subzones oil inclusions are of gas saturated lighter oil our results indicate that fluid flow involving drastic changes in temperature and salinity was responsible for the precipitation of some of the quartz cement the earliest quartz q1 precipitated from freshwater and seawater at temperatures significantly higher than those expected from the burial history and thermal maturity of these rocks this quartz is interpreted to have precipitated during cooling of injected fluids that originated as hot connate fluids from deeper parts of the basin the q2 precipitation is interpreted to have resulted from episodes of injection of hot saline brines from below late quartz cement q3 precipitated during oil charge from progressively cooler and more saline brines interpreted to have refluxed from the surface it preserves a record of increasing oil maturity and gas saturation through time

laminated sediments human impact and a multivariate approach a case study in linking palynology and archaeology steisslingen southwest germany abstract situated in the alpine foreland lake steisslingen provides sediments covering the last 16 000 sidereal years the exceptional value as an environmental archive is due to large laminated sections found in several long cores counting of organic varves allowed the establishment of a detailed varve based age model a high resolution pollen analysis for the period 5457 bc to 813 ad was carried out and compared with an archaeological mapping of a 5 km radius around lake steisslingen the combined interpretation of the palynological and archaeological evidence facilitates a reconstruction of the settlement history and the evolution of the landscape over the last eight millenia several important aspects of vegetational and settlement history are illuminated the mathematical ordination method of correspondence analysis is used to extract the main dimension of explanation from the pollen data a single curve is generated and thought to reflect human impact the validity of this assumed proxy is tested against the vegetational and archaeological evidence of the micro scale area since neolithic times from the steisslingen example we conclude that human impact is the most important and in a mathematical sense continuous factor in vegetational development of those landscapes which are settled since prehistoric times

scale linkage and contingency effects of field scale and hillslope scale controls of long term soil erosion anthropogeomorphic sediment flux in agricultural loess watersheds of southern germany abstract agricultural landscapes with a millennial scale history of cultivation are common in many loess areas of central europe over time patterns of erosion and sedimentation have been continually modified via the variable imposition of anthropogenic discontinuities and linkages on fragmented hillslope sediment cascades which eventually caused the complicated soilscape pattern these field records challenge topographically oriented models of hillslope erosion and simple predictions of longer term change of spatial soilscape by cultivation activities a thorough understanding how soilscape patterns form in the long term however is essential to develop spatial concepts of the sediment budget particularly for the spatial modeling of anthropogenic hillslope sediment flux using gis in this study i used extensive datasets of anthropogenic soil truncation and burial in a typical undulating loess watershed in southern germany 10 km2 wetterau basin n of frankfurt a m spatial soilscape properties and historic sediment flux as caused by cultivation over seven millennia were evaluated by these data the soilscape pattern on the low gradient hillslopes of the study area was found to be marked by a statistical near random pattern of varying depth thickness of truncation and overthickened burial moreover it was shown that truncation and burial had developed independently from each other and did not correlate with either hillslope gradient or downslope curvature hence in the field any combination of few nearly preserved severely truncated or completely removed soil profiles with either no some or a thick sediment cover is present thereby lacking an obvious spatial pattern here i suggest putting long term change of the soilscape into a contextual anthropogeomorphic systems perspective that accommodates components of human induced soil erosion operating at different spatial scales to interpret the longer term spatial consequences at the hillslope system level in the study area system scale linkages are marked by the spatial intersection of a finer scaled managed field system with a broader hillslope scale framework of natural erosion controls in the low gradient study area field borders exert control over the spatial reference of soil erosion and sedimentation sites over time this brought about a growing historical and spatial contingency change to the soilscape because of arbitrary spatial changes of the field system which are inherent in its socio agricultural maintenance thus the very low gradient and low erosivity setting of the study area have singled out the agency of human induced spatial and connectivity controls and contingency for long term spatial hillslope sediment flux although these findings may be less true for different settings they allow for deriving a generic conceptual model of the linkages between natural and anthropogenic subsystems to interpret the effects of long term human induced sediment flux accordingly the resulting balance between on hillslope net storage and net delivery to streams is scaling with basic physiographic properties of erosivity and sedimentation as well as the degree of anthropogenic hillslope fragmentation for loess areas in europe variable fields are fundamental anthropogeomorphic units that determine appropriate system scaling for historic sediment flux analysis and constrain retrodiction and prediction of changing fluxes at a point and a time at watershed scales methodical implications address adequate sampling strategies to record soilscape change as a result of which a critical review of the applicability of the catena concept to long cultivated hillslopes in central europe was included finally the suggested refined generic model of long term human controlled sediment flux involves a number of research opportunities particularly for linking modeling approaches to long term field records of cultivation related change in the soilscape

modelling the impact of land use change and farm dam construction on hillslope sediment delivery to rivers at the regional scale abstract landscapes in southeastern australia have changed dramatically since the spread of european colonisation in the 19th century due to widespread forest clearance for cultivation and grazing erosion and sediment yields have increased by a factor of more than 150 in the 20th century erosion and sediment yield were reduced again due to an increasing vegetative cover furthermore during the last decades thousands of small farm dams were constructed to provide drinking water for cattle these dams trap a lot of sediment thereby further reducing sediment delivery from hillslopes to river channels changes in sediment delivery since european colonisation are documented in sediment archives within this study these changing rates in hillslope erosion and sediment delivery were modelled using a spatially distributed erosion and sediment delivery model watem sedem that was calibrated for australian ecosystems using sediment yield data derived from sedimentation rates in 26 small farm dams the model was applied to the murrumbidgee river basin 30 000 km 2 under different land use scenarios first the erosion and sediment yield under pre european land use was modelled secondly recent land use patterns were used in the model finally recent land use including the impact of farm dams and large reservoirs was simulated the results show that the watem sedem model is capable of predicting the intensity of the geomorphic response to changes in land use through time changes in hillslope erosion and hillslope sediment delivery rates are not equal illustrating the non linear response of the catchment current hillslope sediment supply to the river channel network is predicted to be 370 higher compared to the pre european settlement period yet farm dams have reduced this back to 2 5 times the pre 19th century values the role of larger reservoirs is even more important as they have reduced the current sediment supply downstream to their pre european values thus completely masking the increased hillslope erosion rates from land use change however the model does so far not include valley widening and sediment storage in river systems therefore modelled rates of sediment delivery are lower than observed values

review and update of the applications of organic petrology part 1 geological applications abstract organic petrology developed as coal petrology at the beginning of the 20th century dedicated mainly to the study of coals because of their utilization in industry coal petrology was then considered a branch of coal science later with the development of specialized nomenclature classification of coal components and the standardization and improvement of analytical microscopical methods this discipline expanded in interests and name becoming organic petrology organic petrology carries a broader context being as well a tool applied in the study of dispersed organic matter in sedimentary rocks due to its importance in exploration for fossil fuel resources at present organic petrology is a discipline widely recognized for its role in fundamental and applied research with respect to both coal utilization and in geosciences throughout the 20th century several important monographs have been published on the discipline of organic petrology including stach s textbook of coal petrology 1st edition 1935 2nd 1975 3rd 1982 updated as the more general organic petrology by taylor et al 1998 more recently the text applied coal petrology the role of petrology in coal utilization was published by suarez ruiz and crelling 2008 this review is the first in a two part review series that describes and updates the role of organic petrology in geosciences a second part complementing this one and focused on the applications of organic petrology to other scientific fields will follow

neoproterozoic cambrian petroleum system evolution of the micang shan uplift northern sichuan basin china insights from pyrobitumen rhenium osmium geochronology and apatite fission track analysis the neoproterozoic strata of the sichuan basin are a key target for oil and gas to evaluate the hydrocarbon evolution and its relationship with tectonic events in the micang shan uplift northernmost sichuan basin we apply solid bitumen geochemistry bitumen reflectance and fluorescence and re os geochronology the geochemistry of the solid bitumen indicates that it is highly mature pyrobitumen that formed contemporaneously with dry gas generation during oil thermal cracking the pyrobitumen is enriched in both re 106 191 ppb and os 3030 5670 parts per trillion the re os isotope data imply an early jurassic date for pyrobitumen formation which coincides well with age estimates from fluid inclusion data and basin modeling the re os date for pyrobitumen formation coupled with previously presented apatite fission track aft analysis show that exhumation of the neoproterozoic strata occurred during the cretaceous in the micang shan uplift this extensive uplift led to the erosion of any potential gas reservoirs and surface exposure of bitumen bearing neoproterozoic strata in contrast the more southern and central portions of the sichuan basin have experienced less severe exhumation and as a result neoproterozoic sourced gas systems are present this study shows that through the combined application of re os and aft methodologies the timing of gas generation and subsequent erosion of any potential gas reservoirs in the micang shan uplift northern sichuan basin can be quantified moreover the re os and aft data illustrate the potential to constrain the timing of gas generation in petroleum systems worldwide

petroleum inclusions in sedimentary basins systematics analytical methods and applications abstract fluid dynamics in sedimentary basins is of tremendous interest both from a scientific and an economic point of view integration between fluid inclusion and present day fluid data provides the time aspect necessary for reconstruction of fluid flow paths and can be used for mapping fluid dynamics both on a regional basin scale or on the more local scale of petroleum reservoirs this paper presents a review of analytical and modelling methods for petroleum in fluid inclusions essentially four types of data for petroleum inclusions can be established through analysis and modelling 1 textures which give indirect information of the time aspect 2 fluid composition 3 fluid properties and 4 pressure temperature of trapping during the last decade development of analytical methods for determination of inclusion fluid compositions has taken place traditional correlation studies for characterisation of maturity and source facies may now therefore include fluid inclusion data the development has also been directed towards an improved understanding of the physical properties of petroleum inclusions although these methods are in their early stages concerning precision and accuracy data necessary for fluid flow modelling such as fluid densities viscosities pressure and temperature can be estimated

soil erosion and sediment deposition in the belgian oess belt during the holocene establishing a sediment budget for a small agricultural catchment a method to establish a holocene sediment budget for a 103 ha agricultural catchment representative for the belgian loess belt is presented soil erosion and sediment deposition were determined based on 185 coring locations and a large excavation in the valley bottom results were integrated in a gis and interpolation techniques applied to derive spatial patterns of erosion and sedimentation total soil erosion sediment deposition and sediment export were calculated and the results show that volumes are highly dependent on the interpolation technique used sediment delivery ratios between 20 and 42 are derived and are consistent with data reported in previous studies this clearly shows that the majority of the sediments produced during the holocene have been stored near their source area and have not been delivered to the downstream rivers the spatial distribution of soil erosion and sediment deposition within the catchment is strongly dependent on slope gradient and position within the catchment which suggests that since human impact began topography has been the main factor determining long term soil erosion and sedimentation

petroleum evolution within the tarim basin northwestern china insights from organic geochemistry fluid inclusions and rhenium osmium geochronology of the halahatang oil field the newly discovered halahatang oil field in the northern tarim basin has a potential resource of more than 70 billion bbl of oil oil organic geochemical data from the halahatang oil field indicate that the oils are of moderate maturity biodegraded and represent one oil family derived from the same paleozoic marine source modeling of coeval aqueous and hydrocarbon bearing inclusion data provide fluid trapping temperatures and pressures of 100 c to 110 c and approximately 39 to 59 mpa 5656 8557 psi respectively the fluid inclusion data coupled with the previous basin model studies suggest a single prolonged oil migration event during the permian the re os isotope data of the oil yields an early permian re os age of 285 48 ma the age agrees with the timing of maturation of the paleozoic source via burial history modeling but is slightly older 5 55 m y than the oil migration and accumulation timing implied by the basin modeling coupled with fluid inclusion analysis and the published reservoir illite k ar dates thus the oil re os date suggests that oil generation in the halahatang depression of the tarim basin occurred during the early permian rather than the silurian as previously proposed with subsequent oil migration and accumulation occurring during the middle late permian as recorded by basin modeling coupled with fluid inclusion analysis and illite k ar dating in addition to promoting petroleum exploration in the tarim basin this study which combines crude oil re os isotope dating and traditional analytical methods organic geochemistry and fluid inclusion analysis to constrain petroleum evolution is applicable to hydrocarbon systems worldwide

the relationship between petroleum emplacement and carbonate reservoir quality examples from abu dhabi and the amu darya basin abstract the relative importance of petroleum emplacement in inhibiting diagenetic processes and preserving porosity and permeability in lower cretaceous thamama group kharaib formation carbonate reservoirs of abu dhabi uae and in callovian kimmeridgian carbonate reservoirs of the amu darya basin in uzbekistan and turkmenistan has been evaluated by combining geologic petrophysical and geochemical data when petroleum emplacement is synchronous with and prior to significant burial cementation in carbonates primary petroleum inclusions are trapped in the cements the process appears to be characterised by steep intra field porosity depth trends within a more gradual regional decline in porosity with depth this has profound implications for the prediction of porosity in carbonate reservoirs reservoir quality is better in grainstones and packstones compared to adjacent wackestones and lime mudstones in the kharaib formation because of preserved macroporosity intergranular vuggy mouldic the pore system in the finer units is dominated by micropores these features indicate a primary textural control on porosity and permeability within the grainstones and packstones macroporosity is variably filled by late equant sparry calcite cements porosity and permeability variations in grainstones and packstones at a reservoir scale are therefore controlled by the variation in amount of equant sparry calcite cement this in turn depends on the timing of the precipitation of this cement relative to petroleum emplacement as shown by fluid inclusion data where petroleum emplacement has occurred relatively early at migration foci prior to significant burial cementation by equant sparry calcite reservoir quality is preserved where it has occurred after significant burial cementation reservoir quality has been destroyed in the amu darya sequences primary macroporosity is commonly preserved down to depths of 11 000 ft 3 5 km with differences in the porosity and permeability characteristics of grainstones being controlled by variations in the amount of early probably freshwater cement and the extent of associated dissolution small volumes of burial cements do occur but they do not contain petroleum inclusions consequently there is no firm evidence that petroleum emplacement has inhibited diagenesis in this area this part of the study has shown that it is not always possible to obtain conclusive evidence from the diagenesis to pin down the processes responsible for the preservation of reservoir quality and that petroleum filling may not always be the primary cause the relationships documented here show that the race for space between diagenetic waters and petroleum is a major control on reservoir quality in the thamama group carbonate reservoirs but is not so important for the jurassic carbonates in the amu darya basin

relationship between reservoir diagenetic evolution and petroleum emplacement in the ula field north sea abstract the diagenetic and petroleum filling histories of the ula field have been studied by analysing aqueous and petroleum inclusions occurring in authigenic cements this study shows that diagenesis continues actively after the arrival of petroleum in the sandstones although the reaction rates and petroleum saturation remain obscure microthermometric measurements of fluid inclusions in authigenic quartz suggest an onset of extensive quartz cementation at temperatures around 110 c i e 2 5 km and that this cementation has continued to the present day synchronously with quartz cementation authigenic albite was formed as inter and intragranular cements large amounts of petroleum inclusions locally occur in the albite and quartz cements these inclusions were trapped in the cements as the main charge of petroleum arrived at the structure diffusion through thin water layers between the petroleum and the mineral surface would probably have dominated mass transfer of solutes for the precipitation of authigenic quartz and albite it is evident from analysis of the petroleum inclusions in early formed k feldspar overgrowths that some secondary migrated petroleum probably arrived in the reservoir at a shallow burial depth before the rapid subsidence in the last 25 my compared with petroleum in the free porosity of the ula formation the petroleum in the k feldspar inclusions is evidently sourced from a different source facies and most maturity parameters testify to the latter being less mature later trapped petroleum inclusions in quartz and albite have characteristics found both in k feldspar and in the ula formation dst oil and thus is likely to reflect the progressive change in the ula field petroleum charge which occurred during the time period of quartz diagenesis

fluid inclusion petrography and tectonic burial history of the al ali no 2 well evidence for the timing of diagenesis and oil migration northern oman foredeep cores cut in shallow marine lower and middle cretaceous carbonates in the al ali no 2 well umm al qaiwain united arab emirates display a five stage sequence of calcite cementation fracturing and stylolitization these stages are correlated with the tectonic history of the northern oman orogeny occurrence of fluorescent hydrocarbon fluid inclusions is restricted to stage 2 and stage 3 fracture filling calcites that are crosscut by stylolites stylolite formation during rapid burial beneath abyssal campanian foredeep sediments restricts hydrocarbon migration to post mid cenomanian and pre mid campanian time

petroleum migration faults and overpressure part ii case history the haltenbanken petroleum province offshore norway abstract petroleum inclusion and geochemical data from core extracts were applied to deduce a model for oil migration overpressure development and palaeo leakage of oil from currently dry structures in the haltenbanken vest area the existence of fluorescent oil type inclusions in quartz in the smorbukk asgard 2 field suggest that oil migrated into this structure 70 50 million years before present ma bp this is also the case for the dry structures 6506 12 4 6506 11 3 and 6506 11 1 west of the main smorbukk fault zone black oil inclusions with medium gas oil ratio gor occur in these fields together with condensate type petroleum inclusions this suggests that the dry structures transformed from containing oil to condensate before leakage petroleum extracted from inclusions in these structures and in nearby fields have identical marine type ii kerogen signatures source rocks at the spekk formation level in the current drainage area of smorbukk and these dry structures were immature 70 50 ma bp and the smorbukk sor asgard 3 field did not fill at this early time thus oil must initially have entered into smorbukk from areas to the w sw through the currently pressure sealing smorbukk fault zone which today marks the westward limit of the smorbukk field diagenesis in this fault zone caused the much later overpressure development and petroleum was lost from the 6506 12 4 6506 11 3 and 6506 11 1 structures as overpressure built up regionally petroleum loss from these structures with their often thick seals must have occurred via self propagating open fracture induced mechanisms lack of petroleum in the cretaceous strata above these structures suggests that leakage occurred to even shallower strata this could imply that the cretaceous strata in halten vest were overpressured at the time of leakage in contrast the oil in the cretaceous lysing and lange formation above the jurassic reservoirs in smorbukk and smorbukk sor most likely originated based on geochemistry and gors from the jurassic reservoirs below and not from cretaceous strata this migration event would have been facilitated if it occurred before these sands became overpressured as they are today modelling suggests that the spekk formation became mature in the smorbukk sor region

the factors controlling the abundance and migration of heavy vs light oils as constrained by data from the gulf of suez part ii the significance of reservoir mass transport processes abstract reservoir flow processes have a major impact on the oil quality and distribution of heavy vs light oils both within reservoirs and on the petroleum system scale in the gulf of suez gos gravitational segregation of black oil columns is a common phenomenon an understanding of the mass transport processes in these reservoirs is important for evaluating their impact on the composition of migrating petroleum 2d simulation results show that pressure diffusion is a too slow process to be the main cause for the vertical compositional gradients a reservoir filling model which is a refined version of the geological model of gussow linked to the composition of the gos expelled petroleum fluids and their pvt behaviour and constrained by the gos oil field data is presented this model gives viable explanations for a formation of gravitationally segregated oil columns b tar mat occurrences and their affinity to low maturity heavy oils and c wide spread occurrences of heavy oils and their relationship with light oils in this model continuous density overturning by compositionally controlled bulk flow is the prime cause for the formation of gravitationally segregated columns occurring when a the charge to the reservoir displays a maturity related decrease in density with time and b the reservoir volume relative to the charge volume is large enough for the reservoir to retain a wide maturity range lateral compositional variability in many reservoirs is today interpreted to image the initial filling of the reservoirs it is demonstrated that such lateral gradients can form effectively from re orientation of vertical gradients via ordinary diffusion these gradients have symmetry elements relative to the petroleum mass distribution in the reservoir fill and spill from gravitationally segregated columns enhance the efficiency of the migration of heavy oils

the relationship between petroleum exotic cements and reservoir quality in carbonates a review exotic minerals i e those that do not have an obvious source of components within the host rocks can be major porosity occluding cement and replacement phases in subsurface carbonate reservoirs here we present and discuss petrographic and fluid inclusion data from a number of petroleum systems these have had different geological histories but a common factor is the presence of exotic mineral cements and late stage dissolution the effect of these cements and late stage dissolution on reservoir quality is also considered petroleum filling does not appear to inhibit the precipitation of exotic cements in the way that it appears to inhibit the precipitation of calcite burial dolomite and anhydrite are the most important of these volumetrically but they are often accompanied by other late stage cements such as fluorite kaolin quartz barite celestite sphalerite and galena generally in much smaller quantities in accounting for the concentration of the material contained in these cements compared with the host rocks stylolitisation is a possible mechanism in some cases but in many others import from sources external to the reservoir is required

past hydrological events reflected in the holocene fluvial record of europe abstract a comprehensive database of radiocarbon dated fluvial units in great britain poland and spain has been compiled to investigate the relationship between environmental change flooding and holocene river dynamics following the methodology recently developed by macklin and lewin macklin m g lewin j 2003 river sediments great floods and centennial scale holocene climate change journal of quaternary science 18 101 105 radiocarbon dates in fluvial sequences that coincide with a modification in sedimentation rate or style have been highlighted allowing geomorphologically significant changes in holocene river activity to be identified data analysis has been undertaken at both national and sub national scales and on catchments of different size type and land use history multiple phases of higher flood frequency characterized by accelerated erosion and sediment deposition on floodplains are recognized and compared with a range of climate proxies the relative and varying roles of climate and land use on river dynamics are considered and the value of the database for reconstructing past hydrological events as well as for predicting river response to future environmental change is assessed

sediment yield and storage variations in the negron river catchment south western parisian basin france during the holocene period in the negron river catchment area 162 km2 surface sediment stores are composed of periglacial calcareous greze 5 106 t and loess 21 106 t and holocene alluvium 12 6 106 t peat 0 6 106 t and colluvium 18 5 106 t seventy five per cent of the holocene sediments is stored along the thalwegs present net sediment yield calculated from solid discharge at the negron outlet is low 0 6 t km 2 a 1 due to the dominance of carbonate rocks in the catchment mean sediment yield during the holocene period is 7 0 t km 2 a 1 from alluvium stores and 7 6 t km 2 a 1 from colluvium stores thus the gross sediment yield during the holocene period is about 18 7 t km 2 a 1 and the sediment delivery ratio 3 per cent the yield considerably varies from one sub basin to another 3 9 to 24 5 t km 2 a 1 according to lithology about 25 per cent and 50 per cent of initial stores of periglacial greze and loess respectively were reworked during the holocene period sediment yield has increased by a factor of 6 in the last 1000 years due to the development of agriculture the very high rate of sediment storage on the slope during that period 88 per cent of the yield can be accounted for by the formation of cultivation steps rideaux it is predicted that the current destruction of these steps will result in a sediment wave reaching the valley floors in the coming decades subboreal and subatlantic sediments and pollen assemblages in the taligny marsh where one third of the alluvium is stored show the predominant influence of human activity during these periods in the negron catchment copyright 2002 john wiley sons ltd

quantitative fluorescence techniques for detecting residual oils and reconstructing hydrocarbon charge history abstract two new fluorescence techniques quantitative grain fluorescence qgf and quantitative grain fluorescence on extract qgf e can detect palaeo oil zones and current residual oil zones in petroleum wells respectively qgf and qgf e measure the fluorescence emission spectra of trace fluorescence from reservoir grains and their extracts qgf is measured on dry disaggregated reservoir grains after a cleaning procedure involving solvent hydrogen peroxide and acid whereas qgf e is measured on the solvent extract from the qgf cleaned grains palaeo oil zones have distinct qgf spectra with spectral peaks between 375 and 475 nm and elevated fluorescence intensities compared with spectra for rocks that have always been water saturated current and residual oil zones have distinct qgf e spectra with spectral peaks at around 370 nm and elevated qgf e intensities compared with that for current water zones both qgf and qgf e responses increase upwards from the palaeo oil water and residual oil water contacts respectively an oil producing well from timor sea nw australia was investigated in detail using the qgf and qgf e techniques to illustrate how they can be used to reconstruct hydrocarbon migration history

the application of fluid inclusions to migration of oil and diagenesis in petroleum reservoirs abstract fluid inclusions can be used to interpret thermal history and petroleum maturation and migration relative to burial history temperature pressure and composition data collected from fluid inclusions are used to determine the environment of diagenesis and the timing of cementation and migration cements in petroleum reservoirs contain both oil and aqueous fluid inclusions fluorescence spectroscopy is used to identify oil inclusions and to determine the maturity of entrapped oil the lifetime of fluorescence induced by a pulsed laser is related to the api gravity of entrapped oil interpretation of fluid inclusion data depends on knowing the origin of fluid inclusions and the probability that they survive in the burial environment those aspects of fluid inclusion study are investigated by synthesizing oil and aqueous inclusions in calcite crystals in laboratory experiments examples of how fluid inclusions are used to determine the physico chemical environments of diagenesis in petroleum reservoirs and the timing of cementation and migration are given for the wealden basin england the mishrif formation dubai the smackover formation gulf coast u s a and jurassic sandstones offshore norway in the wealden basin temperature data from fluid inclusions are used to determine that oil migration occurred in the cretaceous and that the reservoir rocks have been uplifted to varying degrees at a time after migration distribution of oil inclusions indicates that generation and migration of oil was principally in the western part of the basin the geochemistry of oil inclusions in calcite cements from the mishrif formation dubai are used to determine the type and maturity of entrapped oil temperature data from oil and water inclusions are used to relate reservoir diagenesis to burial history and the migration of oil in deep smackover reservoirs oil contains h 2 s the origin of the h 2 s is examined by study of fluid inclusions containing h 2 s in jurassic sandstones offshore norway fluid inclusion studies show that silica cementation is related to burial depth whereas a later calcite cementation originated from invasion of a hot fluid

geochemical assessment of petroleum migration phenomena on a regional scale case studies from brazilian marginal basins geochemical effects of secondary migration on marine oils derived from a single source of enhanced salinity have been investigated in the sergipe alagoas basin but no molecular migration characteristics that are independent of source constraints were identified mixed oils from the potiguar basin derived from both lacustrine freshwater and marine source beds of enhanced salinity reveal compositional trends which are related to source rock features and maturity conditions heterogeneities in their oil compositions can be related to the history of migration and reservoir filling also short term stratigraphic variations seen for biomarker compositions observed in core samples of source rocks from the potiguar basin help explain anomalies in the trends defined by the migrated mixed oils in the basin

alluvial chronologies and archaeology of the gila river drainage basin arizona abstract late quaternary alluvial chronologies are established for five streams gila river salt river tonto creek santa cruz river and san pedro river in the gila basin of southern arizona each streams has a complex history of deposition erosion and landscape stability that structured and fragmented the archaeological record over the last 15 000 years the limitations that geologic processes imposed on the archaeological record of these alluvial environments must be recognized before meaningful interpretations of prehistory can be made these stratigraphic sequences also provide the basis for reconstructing changes to the alluvial landscape of each valley over time all five streams were intensively utilized during the late prehistoric period a d 300 1450 by the hohokam the hohokam were irrigation agriculturalists who were dependent upon these streams for survival thus the regional stability and instability of the floodplain environments of southern arizona influenced the expansion contraction reorganization and collapse of the hohokam

holocene river activity analysing 14c dated fluvial and colluvial sediments from germany records of fluvial dynamics in response to long term changes of climate and land use impacts are rare therefore cumulative probability functions cpfs of 401 14c ages originating from german rivers and hillslopes were compiled to reconstruct phases of increased geomorphic activity and stability during the holocene an improved analytical method is suggested to normalise cpfs and eliminated the effects of wiggles of the calibration curve and the young age bias nine periods of activity are identified peaking at 7050 6250 5525 3690 2250 1350 820 325 bc and since 875 ad and are compared with climatic palaeohydrological and human impact proxy data until 2250 bc events of geomorphic activity are mainly coupled to wetter and or cooler climatic phases due to growing population and intensive agricultural activities during the bronze age the increased geomorphologic activity between 1300 and 820 bc cannot unequivocally be related to climate since 875 ad the growing population density is considered as the major external forcing differential geomorphic activity of hillslopes and floodplains suggest that the hillslope channel coupling during the holocene is mainly controlled by human impact with a strong increased coupling after 1500 bc

a high resolution late holocene landscape ecological history inferred from an intramontane basin in the western taurus mountains turkey abstract late holocene vegetation and geomorphological history is reconstructed from a 800 cm long high resolution palynological and sedimentological record sampled from bereket a 6 3 km 2 semi arid to sub humid intramontane basin in the western taurus mountains southwest turkey the well dated bereket record provides from cal 360 bc to cal ad 400 a unique record of biennial to decadal landscape changes caused primarily by intensive human impacts against a background of global climate variations during this period land clearance with multiple fire episodes intensive agricultural practices and grazing pressure profoundly altered the pre existing warm mixed forest increasing moisture availability since cal 280 bc has acted as a trigger to crop cultivation and mountain adapted arboriculture starting with juglans regia during the beysehir occupation phase pollen from olive groves have been recorded above 1400 m a s l only at cal 23 bc and have disappeared definitively at cal ad 294 during this phase the sediment accumulation rate was extremely high reflecting landscape instability from cal ad 450 to recent times the area has mainly recorded pasture and minor cultivation activities reflected in stable soils and thin colluvial depths