a tectonostratigraphic framework for the mid norway region abstract the tectonostratigraphic analysis presented here aims to establish a broad stratigraphic framework within which the likely distribution of both reservoir and source rock intervals within the deep water voering and more basins can be evaluated in terms of hydrocarbon potential the devonian to triassic interval can be effectively discounted by its extreme depth of burial across most of the study area the middle jurassic is interpreted to provide a potential reservoir target in the gjallar ridge area the cretaceous is seismically mappable across the region and has been divided into five tectonostratigraphic sequences late cretaceous reservoirs are considered to offer targets in the nyk high area six tectonostratigraphic sequences are described within the cenozoic succession paleocene reservoirs are interpreted to offer targets over both the ytterskallen and ormen lange areas of the more basin source rock maturity is critical for exploration success mapping shows the late jurassic earliest cretaceous spekk formation to be overmature over most of the area though the presence of possible dhis indicates the probable presence of major gas accumulations in the region only on the western flank of the vigrid syncline does the spekk shallow sufficiently to lie within the potential oil window it is concluded that the region has the potential to become a significant new hydrocarbon province for the 21st century

determination of trapping pressure and temperature of petroleum inclusions using pvt simulation software a case study of lower ordovician carbonates from the lunnan low uplift tarim basin abstract we report a case study carried out on lower ordovician reservoir carbonates of the lunnan low uplift tarim basin to determine trapping pressures and temperatures of petroleum inclusions from the intersection of isochores of coeval petroleum and aqueous fluid inclusions using pvt sim software there are four types of petroleum inclusions from this sequence their trapping pressures and temperatures are type i 80 105 c 199 230 bar type ii 135 145 c 235 250 bar type iii 155 165 c 344 360 bar and type iv 220 252 c 345 390 bar respectively which are consistently higher than their homogenization temperature and saturation pressures by about 5 15 c and 25 70 bar to confirm the reliability of the pvt simulation approach fluid inclusions were synthesized in calcite under controlled temperature and pressure conditions and studied using the same methods the calculated trapping pressure and temperature of the synthetic petroleum inclusions closely match the actual pressure and temperature applied in the experiment by reference to the burial and geothermal history of the tarim host rocks it was inferred that types i ii and iii petroleum inclusions represent fluids associated with three distinct phases of petroleum emplacement in the lower ordovician strata of this area occurring during late silurian to early devonian cretaceous to early tertiary and late tertiary respectively type iv petroleum inclusions occur only in some fine calcite veins from few samples and are believed to be related to an anomalous thermal event in this area on the basis of the trapping pressures and trapping temperatures of the petroleum inclusions three main phases of the petroleum filling of the lower ordovician reservoirs can be delineated phase i and phase iii petroleum events were related to petroleum migration and accumulation from the lunnan low uplift or nearby area the petroleum of the phase ii petroleum event appears to have originated from middle and upper ordovician source rocks in the northern slope area of the manjiaer depression with a long distance migration

petroleum geology of the puguang sour gas field in the sichuan basin sw china abstract the puguang sour gas field in northeastern sichuan basin is the largest gas discovery in the paleozoic marine strata in china with at least 9 trillion cubic feet tcf of proven gas reserves it is one of the many anticlinal structures formed during the indo sinian orogeny with gas being trapped in a composite structure lithology pool the presence of the upper permian coal measures lower silurian and lower cambrian marine shales provided excellent hydrocarbon source rocks the lower triassic and upper permian oolitic dolomites serve as high quality reservoir rocks with 10 25 porosity and 1 1000 md permeability largely due to diagenetically produced secondary porosity the lower and middle triassic evaporate beds have acted as the direct top seal for the large lower triassic upper permian gas accumulation the thick upper triassic and jurassic mudstone beds regionally cap the underlying marine carbonate strata the deep seated basement faults acted as vertical hydrocarbon migration conduits during faulting and became effective flow barriers when the faulting ceased the deep burial of a paleo oil accumulation in reservoirs rich in sulfate resulted in extensive thermochemical sulfate reduction tsr this together with the new gas injection and structural reconfiguration transformed a paleo oil pool to a large sour gas pool

hydraulics morphology and energy dissipation in an alpine step pool channel 1 to investigate the relationship between hydraulics and channel morphology in step pool channels we combined three dimensional velocity measurements with an acoustic doppler velocimeter and topographic surveys in a steep step pool channel the rio cordon italy measurements were organized around step pool and tread units and occurred within a range of 36 57 of bankfull discharges as flow moved from steps to their downstream pools in our study reach an average of approximately two thirds of the total energy was dissipated as measured by relative head loss through step pool sequences much of this head loss was achieved by elevation potential energy loss rather than velocity reductions although an overall expected pattern of flow acceleration toward step crests and deceleration in pools was present pool velocities were high especially where upstream step crests were irregular and where residual pool depths were low many steps were porous or leaky with irregular cross channel bed and water surface topography producing high velocity jets and less flow resistance than channel spanning dammed steps longitudinal variations in hydraulics are thus often overshadowed by lateral variations arising from morphologic complexities velocity and turbulence characteristics in the rio cordon show marked differences from data we have collected in a more stable and wood rich channel in the colorado rockies in which ponded steps are more prevalent and pools are slower and more turbulent comparison of these channels illustrates that step pool structure and hydraulics are strongly influenced by flow regime sediment supply lithology time since the last step forming flood and availability of in stream wood

comment on step pool streams adjustment to maximum flow resistance by athol d abrahams gang li and joseph f atkinson the writer wishes to congratulate the authors for their very interesting development on step pool streams recent advances on stepped channel flows with fixed bed provide additional information on the topic the discusser will show that the maximum flow resistance condition implies a characteristic flow pattern basically the bed profile of maximum flow resistance on step pool streams is achieved for flow conditions near the transition between nappe and skimming flow

trapping pressure estimation of single gaseous inclusion using pvt simulation and its preliminary application in ne sichuan china abstract in this paper we proposed an alternative way to estimate volumetric vapour liquid ratio of gaseous or light petroleum inclusions without fluorescence using regularly shaped inclusions to estimate volumetric vapour liquid ratios through geometric methods the method was applied to the inclusions from the rock samples of the lower triassic feixianguan and jialingjiang formations ne sichuan china the trapping pressures of inclusion fluids were calculated by integrating pvt simulation software volumetric liquid vapour ratios determined by the proposed method and homogenization temperatures measured by microthermometry fluid densities and gas oil ratios gor were also estimated the estimated trapping pressures and temperatures are slightly lower for the jialingjiang formation 29 69 31 33 mpa 93 5 105 2 c than for the feixianguan formation 31 02 34 38 mpa 98 148 c and the trapping time of the inclusions in the jialingjiang formation and feixianguan formation were estimated at about 173 170 ma and 178 168 ma respectively the distribution of high pressures correlates with the presence of pyro bitumen in the reservoir rocks suggesting the migrated fluid is derived mainly from the secondary cracking of oil the modeled fluid density and gor correspond to a typical light oil or condensate suggesting an origin for the trapped hydrocarbons as an intermediate product in this process

biostratigraphy and paleoceanography of the cretaceous seaway between norway and greenland abstract the narrow seaway between greenland and norway in cretaceous time was over 1500 km long and 300 km wide and partly of bathyal water depth during aptian through campanian it received a large volume of fine grained siliciclastic sediments with intercalated gravity flow sandstone wedges as a conduit for heat transport between the low latitudes and polar region atlantic watermasses particularly affected the eastern norwegian margin of this seaway despite its high latitude setting calcareous and few siliceous planktonic microfossils thus play an important role in regional stratigraphy and facies analysis and a majority of fossil events correlate to nw european basins the eastern margin sedimentary succession may be subdivided in several broad lithologic units 1 thin multicolored marly sediments of hauterivian barremian age with a shallow marine falsogaudryina nodosariid ostracod assemblage 2 dark mudstones and minor sands aptian early cenomanian in age with an upper bathyal agglutinated assemblage and monotypic hedbergella floods 3 thick mudstone facies with thin slope apron turbidite sands and an impoverished benthic planktonic assemblage of late cenomanian coniacian age deposited in an upper bathyal oxic dysaerobic environment where turonian sedimentation rates are low a planktonic foraminiferal assemblage with whiteinella hedbergella dicarinella and marginotruncana occurs 4 grayish laminated mudstones santonian campanian in age with local sands in the north a low diversity middle to upper bathyal benthic planktonic foraminiferal assemblage and an inoceramus prisms and radiolarian diatom flood a campanian agglutinated foraminiferal bloom also is known from the atlantic oceanic realm 5 more marly sediments of maastrichtian age with a low diversity planktonic benthic foraminiferal assemblage using the distribution of 1755 foraminiferal and dinoflagellate microfossil events in over 30 exploration wells a rasc ranking and scaling probabilistic zonation served as a template to build a cretaceous zonal model with 19 assemblage and interval zones including over 100 events variance analysis ranks 72 events according to reliability in correlation three new index taxa include uvigerinammina una and ammoanita globorotaliaeformis albian and fenestrella bellii campanian widespread planktonic flood events occur in late albian through early cenomanian early mid turonian late santonian earliest campanian and mid maastrichtian the result of northwards shifts of warmer water masses and disruptions in water stratification in the dysaerobic basins an earliest cretaceous hiatus separates jurassic from cretaceous strata ongoing block faulting coupled to thermal subsidence and global sealevel rise increased water depth in aptian albian time from neritic to bathyal and created sand accommodation space in dysaerobic restricted settings in cenomanian coniacian time sedimentation rates in the central basin increased 10 fold whereas paleo waterdepth did not deepen this relatively brief less than 10 m y tectonic episode resulting in deposition of deep water sands is tentatively linked to stress re orientation in the rockall area a widespread upper maastrichtian danian hiatus the result of shoulder uplift reflects break up prior to the onset of paleogene seafloor spreading in the norwegian sea

characteristics of fluid inclusions and implications for the timing of hydrocarbon accumulation in the cretaceous reservoirs kelasu thrust belt tarim basin china abstract the kelasu thrust belt is a key area for oil and gas exploration within the tarim basin of china an area containing abundant oil and gas resources but where the processes that controlled hydrocarbon accumulation remain unclear this study reconstructs the accumulation history of hydrocarbons within the kelasu thrust belt by studying multiple sets of fluid inclusions from the cretaceous reservoirs using laser raman infrared spectroscopy fluorescence spectroscopy total scanning fluorescence and ptv simulation analyses the resulting data yield the following results 1 three types of cretaceous hydrocarbon bearing fluid inclusions are present and they record three periods of hydrocarbon accumulation period i involved low maturity medium oil as recorded by the presence of yellow green fluorescent oil inclusions with this accumulation occurring between the neogene jidike and kangcun stages 20 5 ma period ii involved high maturity light oils or condensates that are recorded by the presence of blue white fluorescent oil inclusions with this accumulation occurring during the early kuche stage 5 2 5 ma period iii involved the significant accumulation of gas as recorded by non fluorescent gas inclusions during and after the late kuche stage 2 5 0 ma 2 inclusion pvt simulations indicate that the pressures during the trapping of oil inclusions within the west kelasu reservoirs increase with increasing capture temperature suggesting that west kelasu cretaceous oil reservoirs formed over a short period of time in contrast the trapping pressures of oil inclusions within the east kelasu area are invariant with increasing trapping temperature indicating that the formation of east kelasu cretaceous oil reservoirs was a relatively slow and gradual process this most likely relates to the fact that the east kelasu reservoirs are close to the hydrocarbon generation centre in an area with sufficient hydrocarbon supply with hydrocarbon accumulation processes involving all of the stages of hydrocarbon generation recorded by the source rocks in this area in comparison the west kelasu reservoirs are far from the hydrocarbon generation centre and as such record only one phase of oil filling 3 significant tectonism associated with the uplift of the south tianshan mountain during the late kuche stage caused widespread changes to cretaceous paleo oil reservoirs in this area this led to some cretaceous paleo oils being transported to shallower traps to form secondary oil reservoirs whereas others were transported to the surface and were lost with residual paleo oils were also changed to condensate gas as a result of gas washing after the addition of large amounts of late stage gas

deformation structures in organic rich shales seismic images of upper jurassic organic rich siliciclastic rocks are studied along the 2000 km 1243 mi norwegian margin these rocks are considered the main source rock for most of the large oil and gas fields in the north sea and norwegian sea we report characteristic seismic expressions of thin skinned gravitational gliding structures that are strata bound to the organic rich formations the most characteristic structures are listric faults that offset and rotate the upper part and sole out near the base of the organic rich zone these may be present in large areas 10 000 km2 3861 mi2 but are usually restricted to tilted areas the strike of the faults was perpendicular to the downdip direction of the movement of mass and fault directions can therefore be used as paleodip indicators several types of contraction structures are observed and all are formed at a maximum of a few hundred meters of burial although they are not limited to organic rich shales such strata bound structures may help identify organic rich intervals in basins where their presence is unknown we suggest that adding organic material to clay leads to reduced permeability compaction related vertical fluid flow may cause fluid overpressure to build up at the base of a less permeable organic rich layer during early burial this high fluid pressure zone becomes a low friction decollement surface on which overlying sediments slide to form characteristic thin skinned deformation structures

reconstruction of the evolution of deep fluids in light oil reservoirs in the central tarim basin by using pvt simulation and basin modeling abstract to better understand the fluid phase state and its evolution in a deep environment an integrated pvt simulation and basin modeling method for two light oil reservoirs in the central tarim basin was proposed and applied the fluid phase models were built using pvt simulation technology after successfully recovering the fluid compositions the envelopes of fluid from either the awatage formation 2a for well zs1 or the wusongar formation 1w for well zs5 show the order from cricondenbar pm critical point cp to cricondentherm tm suggesting a single liquid phase for the present fluids in the cambrian subsalt dolomite reservoirs the result of this study indicates that the two reservoirs did not experience phase changes phase differentiation or oil cracking and maintained a universal state of the liquid phase over time by combining the evolutionary history of temperature and pressure derived from basin modeling the fluid density and viscosity experienced relatively complicated fluctuation processes and the fluctuations of fluid viscosity over geologic history are much more apparent than the variations in fluid density the density and viscosity of the awatage formation 2a for well zs1 are found to be lower than those of the wusongar formation 1w for well zs5 the results reveal that factors such as good trap conditions a stable tectonic background a low paleo geothermal gradient 1 6 2 8 c 100 m and the weak effect of thermal sulfate reduction tsr altogether act on the early accumulated light oil and gas that has been preserved as a single liquid phase over time these results are significant for future explorations of large scale liquid petroleum in cambrian subsalt dolomite reservoirs of the central tarim basin

dimensions of standing waves at steps in mountain rivers 1 oscillations of the water surface are common features of flows around critical conditions fr 1 and of both natural and structure induced undular hydraulic jumps the paper describes experimental tests and field data on the dimensions of standing waves created by artificial drops in steep gravel bed rivers the purpose of the research is to analyze what parameters affect the phenomenon to provide semiempirical formulations for wave dimensions and to assess whether previous models for undular hydraulic jumps and antidunes are reasonably predictive the dimensionless wavelength and wave amplitude were correlated to the froude number at the sill the first wavelength appears linearly related to the froude parameter whereas the amplitude of the first wave shows a less defined behavior possibly indicating that a maximum value occurs for sill froude numbers around 1 6 1 7 the corresponding wave steepness i e wave amplitude length results between 0 15 0 16 and this range also characterizes the point at which the dimensionless trough depth below the sill achieves a local maximum probably related to hydrodynamic conditions just before wave breaking the transition between roller and undular jumps at drops is then argued to likely represent a critical stage in step pool streams and the hydraulic and morphological implications of this finding are also discussed with particular emphasis on step stability and step wavelength

velocity characteristics along a small step pool channel this paper summarizes measurements of velocity along three reaches of a small mountain channel with step pool bedforms a one dimensional electromagnetic current meter was used to record velocity fluctuations at 37 fixed measurement points during five measurement intervals spanning the peak of the annual snowmelt hydrograph measurement cross sections were located upstream from a bed step at the step lip downstream from the step and in a uniform gradient run data analyses focused on characteristics of velocity profiles and on correlations between velocity characteristics and the potential control variables bedform type reach gradient and flow depth to test the hypothesis that velocity characteristics are related to channel bedform types anova and ancova tests were performed for the average velocity and coefficient of variation of point velocity data results indicate that high frequency velocity variations correlate to some degree with both channel characteristics and discharge velocity became more variable as stage increased particularly at low gradient reaches with less variable bed roughness velocity profiles suggest that locations immediately downstream from bed steps are dominated by wake turbulence from mid profile shear layers locations immediately upstream from steps at step lips and in runs are dominated by bed generated turbulence adverse pressure gradients upstream and downstream from steps may be enhancing turbulence generation whereas favourable pressure gradients at steps are suppressing turbulence the bed generated turbulence and skin friction of runs appear to be less effective energy dissipators than the wake generated turbulence and form drag of step pool bedforms copyright 2000 john wiley sons ltd

cretaceous depositional systems in the norwegian sea heavy mineral constraints deep water cretaceous sandstones in the norwegian sea were deposited by a number of distinct sediment transport systems tapping different sediment source terrains three distinct sandstone types k1 k2 and k3 have been identified distinguished and mapped on the basis of a combination of heavy mineral parameters sandstone type k1 occurs on the trondelag platform halten terrace and nordland ridge but does not appear to be present in the deeper water voring basin sandstone type k1 was ultimately derived from the scandinavian landmass with detritus sourced from metasediments of the caledonian fold belt intrusives of the trans scandinavian igneous belt and to a smaller extent svecofennian basement k1 sandstones were deposited on an unstable slope by debris flows and slumps with minor reworking by bottom currents sandstone type k3 was derived from the western gneiss region farther south on the scandinavian landmass sandstone type k2 occurs in more basinal locations in the norwegian sea and was not supplied by the systems operating along the scandinavian margin because its mineralogy contrasts with that of k1 and k3 k2 mineralogy is not consistent with a source in the lofoten area or east greenland therefore k2 is believed to represent the deposits of a separate axial transport system fed by a source that lay in northeast greenland k2 zircon ages indicate involvement of early proterozoic approximately 2000 ma and archean basement together with metasediments of the caledonian fold belt previous sedimentological models for the cretaceous of the norwegian sea suggest that sand deposition occurred as slumps and debris flows along the continental slope resulting in discontinuous and unpredictable sandstone units unless they become amalgamated into thick reservoir sequences the mineralogical evidence indicates that this model can be applied only to sandstone types k1 and k3 by contrast sandstone type k2 represents sediment introduced from the conjugate margin of the basin and occurs up to 200 km from its detrital source region therefore k2 is likely to occur as more predictable sheetlike bodies on the basin floor

geology of giant gas fields in china twenty five gas fields with recognized ultimate recoveries larger than 25 billion cubic meters have been found in six basins in china the earliest was found in 1959 and the latest in 2005 recognition of more recent discoveries as giants will probably further increase the population examination of reservoir age lithology trap and depositional environment leads to the conclusion that there are no diagnostic characteristics common to all of the giants however coaly source rocks traps in close proximity to major gas kitchens reservoirs and caprocks with reasonable quality late gas accumulation and continuous gas supply are the preferred parameters uncommonly thick reservoir rocks or unusual development of porosity and permeability are not required the fact that giant gas fields exist in reasonable numbers and have been discovered steadily through the years suggests that more efforts are needed to find the remaining gas resources in china

origins of natural gases from marine strata in northeastern sichuan basin china from carbon molecular moieties and isotopic data abstract to determine the origin maturity formation mechanism and secondary process of marine natural gases in northeastern sichuan area molecular moieties and carbon isotopic data of the carboniferous and triassic gases have been analyzed typical samples of marine gas precursors including low maturity kerogen dispersed liquid hydrocarbons dlhs in source rocks residual kerogen and oil have been examined in a closed system and several published geochemical diagrams of gas origins have been calibrated by using laboratory data results show that both carboniferous and triassic gases in the study area have a thermogenic origin migration leads to stronger compositional and weak isotopic fractionation and is path dependent carboniferous gases and low h 2 s gases are mainly formed by secondary cracking of oil whereas high h 2 s gases are clearly related to the tsr thermal sulfate reduction process gases in ne sichuan show a mixture of heavy 13 c enriched methane in comparison to the lower maturated ethane of triassic gas samples suggesting a similar source and maturity for ethane and propane of carboniferous gases and a mixture of heavy ethane to the propane for triassic gases based on the data plotted in the diagram of chung et al 1988 the residual kerogen from silurian marine shale and palaeo oil reservoirs are the main source for carboniferous gases and that the residual kerogen from silurian and permian marine rocks and permian paleao oil reservoirs constitute the principal source of triassic gases

seismic geomorphological analysis and hydrocarbon potential of the lower cretaceous cromer knoll group heidrun field norway the heidrun field located on the halten terrace of the mid norwegian continental shelf was one of the first giant oil fields found in the norwegian sea traditional reservoir intervals in the heidrun field lie within the jurassic synrift sequence most norwegian continental shelf fields have been producing from these jurassic reservoirs for the past 30 yr production has since declined in these mature fields but recently exploration for new reservoirs has resurged in this region the jurassic rifted fault blocks form a narrow continental shelf in norway thereby greatly reducing the areal extent for exploration and development within existing fields as the rift axis is approached farther offshore these jurassic reservoirs become very deep too risky to drill and uneconomical this risk has prompted exploration in more recent years of the shallower cretaceous postrift stratigraphic succession cretaceous turbidites have been found in the norwegian and north seas and the discovery of the agat field in the norwegian north sea confirms the existence of a working petroleum system capable of charging cretaceous reservoirs these cretaceous reservoirs were deposited as slope and basin floor fans within a series of underfilled rifted deeps along the norwegian continental shelf and are thought to be sourced from the localized erosion of jurassic rifted highs we use three dimensional seismic and well data to document the geomorphology of a deep water lower cretaceous wedge cromer knoll group within the hanging wall of a rift related half graben formed on the halten terrace offshore mid norway seismic attribute extractions taken within this lower cretaceous wedge reveal the presence of several lobate to elongated bodies that seem to cascade over fault bounded terraces associated with rifted structures these high amplitude elongated bodies are interpreted as deep water sedimentary conduits that are time equivalent to the cretaceous basin floor fans in more distal parts of the basin to the west these half graben fills have the potential to contain high quality cretaceous sandstones that might represent a potential new reservoir interval within the heidrun field

individual characterization of petroleum fluid inclusions composition and p t trapping conditions by microthermometry and confocal laser scanning microscopy inferences from applied thermodynamics of oils abstract this paper proposes a new method to characterize individual oil bearing fluid inclusions it uses both the homogenisation temperatures measured by microthermometry and the degree of gas bubble filling measured by confocal laser scanning microscopy in conjunction with thermodynamic modelling for describing liquid gas phase transitions and the volumetric behaviour of hydrocarbon mixtures it is associated with a two parameter compositional model that describes the wide range of compositions of petroleums we show that this method can give 1 useful estimations of the compositions and pressure temperature entrapment conditions of oils in fluid inclusions and 2 insights into the various processes that have affected these fluids either before entrapment liquid gas unmixing gas leaching mixing etc or after leakage etc

gas geochemistry from conventional to unconventional domains abstract gas geochemistry is developing into a powerful tool to understand geological processes and affirm source origins of geo fluids major and trace gases including abundances and isotopes have shown considerable application in natural gas systems for example progress in unconventional gases such as shale gas tight gas and extreme conditions in the deep oceans represent more emerging areas and application of these novel gas related techniques examples where gas geochemistry continues to place key constraints on the origin and migration characteristics of natural gas the p t characteristics of fluids in both subaerial and deep geothermal reservoirs and the dynamics of the accumulation cycles to name but a few this volume will reflect this diversity in scope and application of gas geochemistry focusing on deeper and broader applications in unconventional domains of novel gas geochemical techniques and applications

methane dominated thermochemical sulphate reduction in the triassic feixianguan formation east sichuan basin china towards prediction of fatal h2s concentrations abstract new sour pools have recently found in the lower triassic feixianguan fm carbonate reservoirs in the east sichuan basin in china with h 2 s up to 17 4 by volume a recent blowout from a well drilled into this formation killed hundreds of people as a result of the percentage concentrations of h 2 s in order to assess the origin of fatal h 2 s as well as the cause of petroleum alteration h 2 s concentrations and the isotopes 34 s and 13 c have been collected and measured in gas samples from reservoirs anhydrite pyrite and elemental sulphur 34 s values have been measured for comparison the high concentrations of h 2 s gas are found to occur at depths 3000 m temperature now at 100 c in evaporated platform facies oolitic dolomite or limestone that contains anhydrite nodule occurrence within the reservoirs where h 2 s concentrations are greater than 10 its 34 s values lie between 12 0 and 13 2 cdt this is within the range of anhydrite 34 s values found within the feixianguan fm 11 0 to 21 7 average 15 5 3 5 cdt thus h 2 s must have been generated by thermochemical sulphate reduction tsr locally within the reservoirs burial history analysis and fluid inclusion data reveal that the temperature at which tsr occurred was greater than about 130 140 c suggesting that the present depth temperature minimum is an artifact of post tsr uplift both methane and ethane were actively involved in tsr since the petroleum became almost totally dry no alkanes except methane and methane 13 c values become significantly heavier as tsr proceeded methane 13 c difference thus reflects the extent of tsr while it is tempting to use a present day depth control 3000 m to predict the distribution of h 2 s in the feixianguan fm this is an invalid approach since tsr occurred when the formation was buried some 1000 2000 m deeper than it is at present the likelihood of differential uplift across the basin means that it is important to develop a basinal understanding of the thermal history of the feixianguan fm so that it is possible to determine which parts of the basin have been hotter than 130 140 c

transition flow in step pool systems pressure distributions and drag forces abstractstep pool systems occur naturally in steep mountain streams and as man made structures in steep channel sections where they serve as energy dissipating structures three different flow regimes may occur the dominant flow regime is the cascading nappe flow regime at higher discharges the skimming flow regime develops with an almost plane water surface in between these flow regimes a transition flow regime occurs a physical model was used to measure the pressure distribution around a single step for a particular step pool geometry and for different flow regimes nappe transition skimming to achieve this 14 simultaneously recording piezoresistive pressure transducers were distributed around the step the results showed that the regime change from nappe to transition flow is associated with a discontinuity of the average froude number of a step pool unit as well as drops in pressures and water depth relative instantaneous drag forces reached a maximum for this regime change this implies

geochemical characteristics of the zhaolanzhuang sour gas accumulation and thermochemical sulfate reduction in the jixian sag of bohai bay basin abstract natural gas from the zhaolanzhuang field of the jizhong superdepression bohai bay basin contains the highest proportions of h 2 s 40 92 among the sour gases encountered in china the gas payzones include the eocene oligocene kongdian formation ek and the es4 member of the shahejie formation the sedimentary sequence consists of halite anhydrite carbonate sandstone and shale interbeds deposited in the evaporative brackish water lacustrine salt lake setting in the deepest part of the jinxian sag the total thickness of evaporites is more than 1000 m of which halite accounts for over 40 various organic rich mudstones intercalated with the evaporites are currently within the conventional hydrocarbon window with a depth of 2500 3500 m and likely the source for the oil and sour gas in the zhaolanzhuang field the temperatures of the gas reservoirs range from 75 to 100 c too low for significant thermochemical sulfate reduction the co occurrence of abundant elemental sulfur with the sour gas and the 34 s values of the various sulfur containing compounds indicate that the h 2 s gases were most likely derived from much deeper source kitchens where significant thermochemical sulfate reduction has occurred

flow regimes bed morphology and flow resistance in self formed step pool channels received 3 july 2008 revised 28 december 2008 accepted 13 january 2009 published 25 april 2009 1 we used a mobile bed flume with scaled grain size distribution channel geometry and flow to examine morphology and hydraulics of stepped channels we hypothesized that 1 step geometry and flow resistance differs significantly as a function of the range of grain sizes present 2 a transition from nappe to skimming flow occurs in stepped channels with mobile beds for conditions similar to stepped spillways and 3 the partitioning of flow resistance changes significantly when flow passes from nappe to skimming conditions results support each of these hypotheses and help to illuminate the complexity of v q relationships in stepped channels in which a dramatic decrease in flow resistance and increase in velocity accompany the transition from nappe to skimming flow near step forming events therefore a single flow resistance equation applicable to both ordinary and large floods may not be ideal in stepped channels nonetheless models based on dimensionless velocity and unit discharge appear more robust compared to those based on the darcy weisbach friction factor

controls on at a station hydraulic geometry in steep headwater streams colorado usa detailed hydraulic measurements were made in nine step pool five cascade and one plane bed reach in fraser experimental forest colorado to better understand at a station hydraulic geometry ahg relations in these channel types average values for ahg exponents m 0 49 f 0 39 and b 0 16 were well within the range found by other researchers working in steep gradient channels a principal component analysis pca was used to compare the combined variations in all three exponents against five potential control variables wood d84 grain size distribution coefficient of variation of pool volume average roughness area projected wetted area and bed gradient the gradient and average roughness area were found to be significantly related to the pca axis scores indicating that both driving and resisting forces influence the rates of change of velocity depth and width with discharge further analysis of the exponents showed that reaches with m b f are most likely dominated by grain resistance and reaches below this value m b f are dominated by form resistance copyright 2010 john wiley sons ltd

combined use of confocal laser scanning microscopyand pvt simulation for estimating the composition andphysical properties of petroleum in fluid inclusions we present a method to determine the composition and pvt properties of petroleum inindividual petroleum fluid inclusions confocal laser scanning microscopy is used to generatethree dimensional images of single petroleum inclusions because liquid petroleum fluorescesunder the laser the images readily distinguish the liquid and vapour within the inclusion and canbe used to determine the inclusions volumetric liquid vapour ratio using pvt modellingsoftware the liquid vapour ratio is used along with the homogenisation temperature to determinethe bulk composition phase envelope isochore and a range of physical properties of the includedpetroleum this is done using an iterative series of pvt calculations which match twoparameters 1 the molar volume of the petroleum at room and homogenisation temperatures 2 the liquid vapour ratio of the inclusion at room temperature key uncertainties in the methodare explored including the accuracy with which the liquid vapour ratio can be determined thecomposition of the titrant gas used in the iterative procedure and the composition of thepetroleum chosen to model the physical properties of the included petroleum data from coevalinclusions suggest that the saturation pressure gas oil ratio viscosity molar volume densityand surface tension of included petroleum are determined with a precision of a few percent confirmation of the accuracy of the method awaits tests using inclusions grown in the laboratoryunder carefully controlled pvtx conditions however it is likely that the physical properties ofincluded petroleums are more accurately modelled by fluids which are genetically related tothem if proven to be accurate the method will provide a routine method for determiningpalaeopressure in petroleum systems finally we present data from a central north sea examplewhich are geologically realistic and which for the first time record the evolution of fluid pressureand petroleum composition in a petroleum reservoir

tectonic development of the mid norway continental margin abstract the area reviewed covers the mid norway continental margin between latitudes 62 n and 68 n main structural elements as defined at the base cretaceous level are the trondelag platform underlying the inner shelf the more and voring basins located beneath the outer shelf and slope and the more platform and the outer voring plateau forming a base of slope trend of highs sediments contained in the mid norway basin range in age from late palaeozoic to cenozoic the basement was consolidated during the caledonian orogenic cycle devonian and early carboniferous wrench movements along the axis of the arctic north atlantic caledonides are thought to have preceded the namurian onset of crustal extension rifting processes were intermittently active for some 270 my until crustal separation between greenland and fennoscandia was achieved during the early eocene during the evolution of the norwegian greenland sea rift system a stepwise concentration of tectonic activities to its axial zone the area of subsequent continental separation is observed during the late palaeozoic to mid jurassic a broad zone was affected by tensional faulting during the late jurassic and cretaceous the trondelag platform was little affected by faulting whilst major rift systems in the more and voring basins subsided rapidly and their shoulders became concomitantly upwarped during the latest cretaceous and early palaeogene terminal rifting phase only the western more and voring basins were affected by intrusive and extrusive igneous activity following the early eocene crustal separation and the onset of sea floor spreading in the norwegian greenland sea the voring segment of the mid norway marginal basin subsided less rapidly than the more segment during the early and mid tertiary minor compressional deformations affected the voring basin and to a lesser degree the more basin tensional forces dominated the late palaeozoic to early cenozoic evolution of the mid norway basin and effected strain mainly in the area where the crust was weakened by the previous lateral displacements the lithosphere thinned progressively and the effects of the passively upwelling hot asthenospheric material became more pronounced massive dyke invasion of the thinned crust preceded its rupture