a methodology for 7d warping and deformation monitoring using time lapse seismic data a methodology is presented for vector analysis of the image displacements warping between successive 3d seismic image volumes that provides 7d analysis including lateral and vertical displacements of in situ subsurface deformation around hydrocarbon reservoirs the key challenges are 1 assessment of just vertical shifts is insufficient and vector displacements should be determined 2 robust vertical displacements can usually be derived but lateral shifts are less well defined because of the generally smooth data character in a horizontal horizon plane 3 subvoxel resolution is necessary for correct matching and deformation analysis 4 velocity and strain effects are intrinsically combined in time lapse seismic images 5 separation of accumulated and local effects is necessary 6 apparently coherent and smooth displacement fields do not necessarily provide good strain analysis 7 warping is easily degraded by noise and good cross matching is a prerequisite to address these challenges a full 3d local warp vector derivation methodology is proposed which involves 1 constraint using prior estimates 2 local refinement with subvoxel resolution and 3 3d and vectorial conditioning using a deformable mesh with sensitivity to image match quality the warping approach is extended to separate accumulated from local effects and to analyze in situ deformation based on the displacement vector volume this is achieved by a finite element approach to determine an elemental pseudostrain tensor field and an iterative procedure to separate the pseudostrain into velocity and strain components the approach up to the strain analysis is demonstrated using a real data example which indicates the potential of the methodology accumulated overburden effects are separated to reveal a local compaction signature in the reservoir but realistic quantitative values of strain have not yet been realized

a note on induced stress changes in hydrocarbon and geothermal reservoirs abstract earthquakes have been induced by oil and gas production where pore pressures have decreased in some cases by several tens of mpa it has previously been suggested that such earthquakes are caused by poroelastic stressing of crust surrounding the reservoir induced earthquakes are also common in geothermal fields such as the geysers where strong correlations between both steam production and condensate injection and earthquake activity have been observed over the last several decades stress measurements within hydrocarbon reservoirs show that the least horizontal stress decreases with declining reservoir pressure as predicted by poroelasticity for circular disk shaped reservoirs isothermal reduction in pore pressure induces a relative horizontal tension within the reservoir production induced stressing may promote frictional sliding on pre existing faults within the reservoir itself normal faulting is promoted if the regional stress is extensional and the biot coefficient is sufficiently large 0 85 for reasonable coefficients of friction on the other hand dilatant fracturing and normal faulting are always promoted in extensional environments near the edge of the reservoir or in regions of high pore pressure gradient it is suggested that such fracturing could enhance fracture permeability in tight rocks adjacent to portions of the reservoir that experience large reductions in pore pressure due to production in regional compressional environments production modestly favors reverse faulting above and below the reservoir the ratio of thermal to poroelastic stress can be quite large in geothermal reservoirs such as the geysers reservoir wide energy balance considerations suggest that the average temperature has declined at the geysers by 6 c during the past 20 years reservoir average stress changes are thus on the order of 2 mpa and are certainly much larger near injection wells and steam producing fractures

velocity structures imaged from long offset reflection data and four component obs data at jiulong methane reef in the northern south china sea abstract in this study p and s wave velocity models were built based on two pre stack depth migration psdm profiles of long offset reflection data and 25 four component ocean bottom seismometers obs data at jiulong methane reef off sw taiwan in the passive margin of the northern south china sea scs according to the velocity models the average p wave velocity and vp vs ratio of the free gas beneath the bottom simulating reflector bsr are 1 52 1 58 km s and 4 5 5 10 respectively the depth of the bsr is found at 80 300 m below the sea floor and the sedimentary thickness of the hydrate and the free gas are about 50 100 m and 70 100 m respectively p wave velocity of about 1 75 km s in the hydrate bearing sediment is southeastward increased to about 1 85 km s above the bsr similarly vp vs ratio of about 3 06 in the hydrate bearing sediment is increased southeastward to about 3 48 above the bsr based on the pseudo 3d map of gas hydrate saturation estimated from the psdm and obs models the average saturations of hydrate and free gas at jiulong methane reef are about 7 and 0 9 2 4 respectively the highest hydrate saturation 11 is located at 5 20 m above the bsr in the se portion of the jiulong methane reef on the other hand the highest gas saturation of about 2 is observed at 10 70 m below the bsr in the nw portion of the jiulong methane reef we suggested that several normal faults dipping southeastward beneath the continental slope provided conduits for gas migrating northwestward at jiulong methane reef therefore the highest gas saturation is observed below the anticline in the nw portion of the jiulong methane reef and the highest hydrate saturation high p wave velocity and high vp vs ratio is identified above the bsr in the se portion of the jiulong methane reef

acoustic response of gas hydrate formation in sediments from south china sea abstract gas hydrate has been recognized as a potential energy resource in south china sea scs understanding the acoustic response of gas hydrate formation in the scs sediments is essential for regional gas hydrate investigation and quantification the sediments were obtained from gravity core sampling at e 115 12 52363 n 19 48 40299 gas hydrate was formed within a gas water saturated scs sediments system combination of a new bender element technique and coated time domain reflectometry tdr was carried out to study the acoustic response of hydrate occurrence in scs sediments the results show the acoustic signal becomes weak when hydrate saturation sh is lower than 14 the acoustic velocities vp vs of the sediments increase with sh during hydrate formation and vs increases relatively faster when sh is higher than 14 these results indicate that tiny hydrate particles may firstly float in the pore fluid which causes a significant acoustic attenuation but has little influence on shear modulus as time lapses and sh approaches 14 numerous particles coalesce together and contact with sediment particles as a result vs has a sharp increase when hydrate saturation exceeds 14 several velocity models were validated with the experimental data which suggests a combination of the bgtl biot gassmann theory modified by lee model and the weighted equation is suitable to estimate sh in scs

4 d constrained depth conversion for reservoir compaction estimation application to ekofisk field ekofisk field in the norweigian sector of the north sea is a remarkable example of a strongly compacted chalk reservoir since the start of production in 1971 the water bottom has subsided by over 8 m as a result of reservoir compaction hermansen et al the field wide waterflood begun in 1989 was expected to halt pressure depletion and reservoir compaction after a few years of waterflooding ekofisk reservoir pressure began increasing but compaction and subsidence continued laboratory studies on chalk cores indicated that high porosity oil filled chalk compacts strongly when flushed with seawater these studies along with reservoir flow simulation and geomechanic modeling led to a model of a water weakening compaction sylte et al ongoing efforts deployed to monitor the reservoir compaction and seabed subsidence include twice a year compaction logging in a monitoring well daily gps measurements at the platforms and periodic bathymetry surveys nine surveys from 1970 to 1999

sub sample time shift and horizontal displacement measurements using phase correlation method in time lapse seismic hydrocarbon production and fluid injection affect the level of subsurface stress and physical properties of the subsurface and can cause reservoir related issues such as compaction and subsidence monitoring of oil and gas reservoirs is therefore crucial time lapse seismic is used to monitor reservoirs and provide evidence of saturation and pressure changes within the reservoir however relative to background velocities and reflector depths the time lapse changes in velocity and geomechanical properties are typically small between consecutive surveys these changes can be measured by using apparent displacement between migrated images obtained from recorded data of multiple time lapse surveys apparent displacement measurements by using the classical cross correlation method are poorly resolved here we propose the use of a phase correlation method which has been developed in satellite imaging for sub pixel registration of the images to overcome the limitations of cross correlation phase correlation provides both vertical and horizontal displacements with a much better resolution after testing the method on synthetic data we apply it to a real dataset from the norne oil field and show that the phase correlation method can indeed provide better resolution

reservoir monitoring and characterization using satellite geodetic data interferometric synthetic aperture radar observations from the krechba field algeria deformation in the material overlying an active reservoir is used to monitor pressure change at depth a sequence of 11 field estimates allows us to construct a measure of diffusive traveltime throughout a reservoir the dense distribution of traveltime values means that we can construct an exactly linear inverse problem for reservoir flow properties application to interferometric synthetic aperture radar insar data gathered over a carbon dioxide c o2 injection site in algeria reveals pressure propagation along two northwest trending corridors an inversion of the traveltimes indicates the existence of two northwest trending high permeability zones the high permeability features trend in the same direction as the regional fault and fracture zones model parameter resolution estimates indicate the features are well resolved

topography of the variscan orogen in europe failed not collapsed the variscan orogenic collage consists of three subduction collision systems rheno hercynian saxo thuringian and massif central moldanubian devonian to early carboniferous marine strata are widespread not only in the individual foreland fold and thrust belts but also in post tectonic basins within these foreland belts and on the cadomian crust of peri gondwanan microcontinental fragments which represent the upper plates of the subduction collision zones these marine basins preclude high elevations in the respective areas and also in their neighbourhood widespread late carboniferous intra montane basins with their coal bearing sequences are likewise incompatible with high and dry plateaus while narrow belts with high elevations remain possible along active margins within the orogen comparison of the variscides with the himalaya tibetan plateau is unfounded plausible reasons for the scarcity of high variscan relief include subduction of oceanic and even continental crust subduction erosion orogen parallel extension and most important lithospheric thinning accompanied by high heat flow and magmatism in many areas timing and areal array of magmatism and ht metamorphism are not compatible with a model of tectonic thickening and subsequent gravitational collapse it is suggested instead that lithospheric thinning and heating are due to mantle activities caused by the tethys rift the lower and middle crust were thermally softened and rendered unfit for stacking and isostatic uplift in terms of topography the variscides represent a failed orogen the ht regime also explains the abundance of granitoids and ht lp metamorphic rocks typical of the variscides melting in the ht regime extracted mafic components from variscan and cadomian crust as well as from cadomian metasomatized lithospheric mantle thus mimicking subduction related magmatism the onset of the ht regime at c 340 ma may also have triggered the final ascent of hp uhp felsic metamorphic rocks

branching of the tsushima current in 1981 83 abstract satellite derived sea surface temperatures illustrate the variability of the path of the tsushima current in the sea of japan in the spring of 1981 the tsushima current did not split as it left the korea strait and flowed into the sea of japan which is contrary to the historical concept of branching warm water remained along honshu the main island of japan making a strong front oriented in an east west direction hydrographic data confirm that this spring condition lasted through to the fall of 1981 on the other hand during the springs of 1982 and 1983 the branching is evident from satellite images one branch flowed northward along the east coast of korea and the other flowed eastward along honshu of japan

compressional wave velocity measurements through sandy sediments containing methane hydrate an experimental apparatus was built to measure p wave velocity vp of sandy sediment during hydrate formation from brine and free methane gas the influences of hydrate saturation initial brine saturation conversion ratio of water to hydrate and grain size of sand upon vp were investigated the experimental results demonstrate that vp strongly depends on both hydrate saturation and initial brine saturation whereas the influence of the grain size of sand is unremarkable during the formation of hydrate for different experimental runs at identical initial brine saturation vp increases with the increase of hydrate saturation while it decreases dramatically with the increase of initial brine saturation for a given hydrate saturation the correlation between vp and conversion ratio of water into hydrate was studied and it was found that the relation between vp and the conversion ratio of water to hydrate is approximately the same for different experimental runs regardless of how big the differences in initial saturation of brine and the size of sand grain are vp was calculated for four different hydrate distribution models the results suggest that low conversion ratio of water to hydrate hydrate mainly acts as a load component of a dry frame matrix whereas at higher conversion ratio of water to hydrate it partly acts as a cement that coats grains at grain contacts and thereby leads to a dramatic increase in vp compared with the hydrate saturation the conversion ratio of water to hydrate has a large role in distributing hydrate in the pores of sediments

deep convection and brine rejection in the japan sea received 15 october 2002 accepted 13 january 2003 published 19 february 2003 1 direct water mass renewal through convection deeper than 1000 m and the independent process of dense water production through brine rejection during sea ice formation occur at only a limited number of sites globally our late winter observations in 2000 and 2001 show that the japan east sea is a part of both exclusive groups japan sea deep convection apparently occurs every winter but massive renewal of bottom waters through brine rejection had not occurred for many decades prior to the extremely cold winter of 2001 the sites for both renewal mechanisms are south of vladivostok in the path of cold continental air outbreaks index terms 4283 oceanography general water masses 4243 marginal and semienclosed seas 4223 4215 climate and interannual variability 3309 citation talley l d v lobanov v ponomarev a salyuk p tishchenko i zhabin and s riser deep convection and brine rejection in the japan sea geophys res lett 30 4 1159 doi 10 1029 2002gl016451 2003

cross equalization data processing for time lapse seismic reservoir monitoring a case study from the gulf of mexico nonrepeatable noise caused by differences in vintages of seismic acquisition and processing can often make comparison and interpretation of time lapse 3 d seismic data sets for reservoir monitoring misleading or futile in this gulf of mexico case study the major causes of nonrepeatable noise in the data sets are the result of differences in survey acquisition geometry and binning temporal and spatial amplitude gain wavelet bandwidth and phase differential static time shifts and relative mispositioning of imaged reflection events we attenuate these acquisition and processing differences by developing and applying a cross equalization data processing flow for time lapse seismic data the cross equalization flow consists of regridding the two data sets to a common grid applying a space and time variant amplitude envelope balance applying a first pass of matched filter corrections for global amplitude bandwidth phase and static shift corrections followed by a dynamic warp to align mispositioned events and finally running a second pass of constrained space variant matched filter operators difference sections obtained by subtracting the two data sets after each step of the cross equalization processing flow show a progressive reduction of nonrepeatable noise and a simultaneous improvement in time lapse reservoir signal

spatial and temporal changes in sea surface temperature circulation and subpolar front of the east sea japan sea during the last 130 000 years abstract in order to reconstruct spatial and temporal changes in sea surface temperature sst of the east sea japan sea on glacial interglacial time scale alkenone temperature records from the both korean and japan margins have been investigated for the period over the last 130 kyr results show that the temperature gradient between the korean and japan margins was relatively small 2 c during the warm interval of the interglacial period mis 5e but it was large 10 c during the transitional period from the interglacial to the glacial mis 5a and b the temperature of the korean margin was colder than that of the japan margin during the transitional period based on the reconstructed alkenone temperature temporal changes in surface circulation and subpolar front spf have been investigated during the interglacial period when sea level was higher than today mis 5e the influx of the tsushima warm current twc was enhanced and the both korean and japan margins were influenced by the warm water at that time the spf appears to be located in the northern part compared to today during the transitional period when the sea level was lower than today mis 5a and b the twc volume transport was reduced contributing to the lower sst its effect on the surface temperature appears to be larger along the korean margin than the japan margin indicating that the strength of the east korea warm current appears to be strongly correlated with the twc volume transport the spf would displace southward orienting from southwest to northeast at that time during the glacial period when the sea level was very lower 100 m deep the influx of warm water was almost completely restricted and the cold water expanded into the southern area the spf would disappear at that time model simulation results also support the relationship between the twc volume transport and surface circulation and the sst

a method for estimating apparent displacement vectors from time lapse seismic images reliable estimates of vertical inline and crossline components of apparent displacements in time lapse seismic images are difficult to obtain for two reasons first features in 3d seismic images tend to be locally planar and components of displacement within the planes of such features are poorly resolved second searching directly for peaks in 3d crosscorrelations is less robust more complicated and computationally more costly than searching for peaks of 1d crosscorrelations i estimate all three components of displacement with a process designed to mitigate these two problems i address the first problem by computing for each image sample a local phase correlation instead of a local crosscorrelation i address the second problem with a cyclic sequence of searches for peaks of correlations computed for lags constrained to one of the three image axes

an east west contrast of upper ocean heat content variation south of the subpolar front in the east japan sea long term variability of nonseasonal ocean heat content ohc in the upper 500 m in the east japan sea ejs exhibits a distinct east west contrast during the recent 30 years the contrasting ohc variations are revisited and investigated more in detail by analyzing two observational data sets the gridded data from 1976 to 2007 and in situ data from 1976 to 2011 in the southwestern ejs that covers the zone of western boundary current the ohc variability shows in phase and predominant decadal variation in both east and west regions before 1995 but uncorrelated and predominant interannual variations after 1995 heaving effects due to major branches of warm currents in the ejs the east korea warm current ekwc in the western part and other two branches in the eastern part mainly contribute to the ohc variations the heaving effect in the western ejs is shown to be associated with changes in winter wind stress curl field in the northern ejs weakening of the subpolar gyre due to weakening of positive wind stress curl in the japan basin related with wintertime western pacific teleconnection pattern and siberian high appears to enhance the northward penetration of the ekwc resulting in an increase of ohc in the western ejs the heaving effect in the eastern ejs is significantly correlated with the siberian high but the causative mechanism is inconclusive this study also demonstrates the importance of using highly resolved data sets for areas affected by strong and narrow boundary currents in computing and understanding the ohc variability

stress induced temporal variations in seismic anisotropy observed in microseismic data summary in situ stress monitoring of crustal rocks is desirable as it yields insights into earthquake mechanisms volcanic eruptions and changes in hydrocarbon reservoirs shear wave splitting induced by stress controlled cracks in the shallow crust provides a way to infer this stress temporal variations in these observations can be difficult to quantify due to scatter in the data and discontinuous observations here we present evidence of temporal variations in shear wave splitting from a continuous time series with a high occurrence of microseismic events recorded in a borehole we interpret these observations in terms of stress controlled cracks and are able to infer changes in stress and via modelling suggest the cause of the anisotropy possible origins of the temporal variation in per cent anisotropy are tidal or oil field production processes our results suggest that shear wave splitting is a viable probe for inferring changes in crustal stress in cracked rock

time lapse seismic imaging using regularized full waveform inversion with a prior model which strategy full waveform inversion is an appealing technique for time lapse imaging especially when prior model information is included into the inversion workflow once the baseline reconstruction is achieved several strategies can be used to assess the physical parameter changes such as parallel difference two separate inversions of baseline and monitor data sets sequential difference inversion of the monitor data set starting from the recovered baseline model and double difference inversion of the difference data starting from the recovered baseline model strategies using syntheticmarmousi data sets we investigate which strategy should be adopted to obtain more robust and more accurate time lapse velocity changes in noise free and noisy environments this synthetic application demonstrates that the double difference strategy provides the more robust time lapse result in addition we propose a target oriented time lapse imaging using regularized full waveform inversion including a prior model and model weighting if the prior information exists on the location of expected variations this scheme applies strong prior model constraints outside of the expected areas of timelapse changes and relatively less prior constraints in the time lapse target zones in application of this process to the marmousi model data set the local resolution analysis performed with spike tests shows that the target oriented inversion prevents the occurrence of artefacts outside the target areas which could contaminate and compromise the reconstruction of the effective time lapse changes especially when using the sequential difference strategy in a strongly noisy case the target oriented prior model weighting ensures the same behaviour for both time lapse strategies the double difference and the sequential difference strategies and leads to a more robust reconstruction of the weak time lapse changes the double difference strategy can deliver more accurate time lapse variation since it can focus to invert the difference data however the double difference strategy requires a preprocessing step on data sets such as time lapse binning to have a similar source receiver location between two surveys while the sequential difference needs less this requirement if we have prior information about the area of changes the target oriented sequential difference strategy can be an alternative and can provide the same robust result as the doubledifference strategy

a new perspective on origin of the east sea intermediate water observations of argo floats abstract the east sea intermediate water esiw defined as the salinity minimum in the east sea hereafter es sea of japan is examined with respect to its overall characteristics and its low salinity origin using historical argo float data from 1999 to 2015 our findings suggest that the esiw is formed in the western japan basin 40 42 n 130 133 e especially west of the north korean front in north korean waters where strong negative surface wind stress curl resides in wintertime the core esiw near the formation site has temperatures of 3 4 c and less than 33 98 psu salinity warmer and fresher than that in the southern part of the es in order to trace the origin of the warmer and fresher water at the sea surface in winter we analyzed the data in three different ways 1 spatial distribution of surface water properties using monthly climatology from the argo float data 2 seasonal variation of heat and salt contents at the formation site and 3 backtracking of surface drifter trajectories based on these analyses it is likely that the warmer and fresher surface water properties found in the esiw formation site are attributed to the low salinity surface water advected from the southern part of the es in autumn

target oriented joint least squares migration inversion of time lapse seismic data sets two related formulations are proposed for target oriented joint least squares migration inversion of time lapse seismic data sets time lapse seismic images can be degraded when reservoir overburden is complex or when acquisition geometries significantly differ because the migration operator does not compensate for the resulting amplitude and phase distortions under these circumstances time lapse amplitudes are poor indicators of production related changes in reservoir properties to correct for such image degradation time lapse imaging is posed as joint inverse problems that utilize concatenations of target oriented approximations to the linear least squares imaging hessian in both formulations spatial and temporal constraints ensure inversion stability and geologically consistent time lapse images using two numerical time lapse data sets we confirmed that these formulations can attenuate illumination artifacts caused by complex overburden or geometry differences and that they yield better quality images than obtainable with migration

nature and timing of late mississippian to mid pennsylvanian glacio eustatic sea level changes of the pennine basin uk the pennine basin of northern england contains a comparatively complete serpukhovian moscovian succession characterized by high resolution ammonoid zonation and cyclic paralic sedimentation two new isotope dilution thermal ionization mass spectrometry zircon ages from a bentonite deposited during the arnsbergian mid serpukhovian regional substage and tonstein of earliest bolsovian early moscovian regional substage have been determined the weighted mean 206 pb 238 u ages of 328 34 0 55 and 314 37 0 53 ma total uncertainty respectively require modification of the time scale for the western europe regional chronostratigraphy the areal extent of acme ammonoid facies is used as a proxy for the magnitude of 47 discrete flooding events incised valleys major sequence boundaries are used as a proxy for the magnitude of sea level falls the frequency of these events in the light of the new radiometric dating indicates the following 1 there is temporal coincidence between major glaciations in gondwana and phases of increased frequency of sequence boundaries in the pennine basin 2 high amplitude flooding surfaces have an average frequency of c 400 ka 3 average cycle durations during the pendleian early arnsbergian and chokierian bolsovian of c 111 and c 150 ka respectively reflect short duration eccentricities 4 multiple flooding surfaces with the same ammonoid assemblages may equate with sub 100 ka precession or obliquity frequencies supplementary material u pb method description and data procedure for the calculation of the areal extent of marine bands and tables showing a full listing of biostratigraphical data used in the study are available at www geolsoc org uk sup18505

post variscan cooling history of the central western sudetes ne bohemian massif poland constrained by apatite fission track and zircon u th he thermochronology abstract apatite fission track aft and zircon u th he zhe dating techniques were combined to reveal post orogenic history of the rudawy janowickie mts in the west sudetes bohemian massif permian to jurassic zhe ages of 271 2 24 8 171 3 11 5 ma obtained for crystalline basement rocks indicate post orogenic cooling and progressive unroofing of the ne bohemian massif on the other hand cretaceous zhe ages of 130 5 8 8 99 7 6 7 ma prove that the rudawy janowickie mts region remained under 190 c during the mid cretaceous suggesting a deep burial zhe ages from the cretaceous sediments located to the east of the rudawy janowickie mts range between 298 8 16 8 and 181 8 11 9 ma documenting that the burial did not exceed 6 km in the axial part of the intra sudetic through aft ages range from 105 9 6 1 to 51 1 4 3 ma the eocene aft ages revealed by the granite basement and the cretaceous aft age revealed by the metamorphic cover suggest the existence of at least two different thermo tectonic blocks experiencing different post variscan cooling and exhumation aft results strongly support 3 3 3 5 km exhumation for the rudawy janowickie mts since the cenomanian which in combination with zhe results clearly contradicts some of the previously proposed evolutionary scenarios for the sudetes

cross matching with interpreted warping of 3d streamer and 3d ocean bottom cable data at valhall for time lapse assessment legacy streamer data and newer 3d ocean bottom cable data are cross matched and analysed for time lapse analysis of geomechanical changes due to production in the valhall field the issues relating to time lapse analysis using two such distinctly different data sets are addressed to provide an optimal cross matching workflow that includes 3d warping additionally an assessment of the differences between the imaging using single azimuth streamer and multi azimuth ocean bottom cable data is provided the 3d warping utilized in the cross matching procedure is sensitive to acquisition and processing differences but is also found to provide valuable insight into the geometrical changes that occur in the subsurface due to production as such this work also provides a demonstration of the use of high resolution 3d interpreted warping to resolve the 3d heterogeneity of the compaction and subsidence this is an important tool for valhall and possibly other fields where compaction and subsidence and monitoring thereof are key factors in the reservoir management since the predominant observed production induced changes are compaction of the soft high porosity chalk reservoir due to pore pressure reduction and the resultant overburden subsidence such reservoir compaction could have significant implications for production by changing permeabilities and production rates furthermore the subsidence effects could impact upon subsea installations and well bore stability geomechanical studies that have previously been used to model such subsidence and compaction are only constrained by observed surface displacements and measured reservoir pressure changes with the geological overburden being largely neglected the approaches suggested herein provide the potential for monitoring and assessment in three dimensions including the probable heterogeneity and shearing that is needed for full understanding of reservoir compaction and the resultant effects on the overburden to for example mitigate well bore failures

satellite observations of sea surface temperature and sea surface wind coupling in the japan sea 1 we investigate ocean atmosphere coupling in the japan sea by using microwave satellite measurements of sea surface temperature sst and sea surface wind from 1 june 2002 to 31 december 2004 first it is observed that instantaneous wind speeds are modified by sst front meanders in widespread areas in the japan sea increased reduced wind speeds are found over warmer colder water then we compute sst and wind speed anomalies by spatial high pass filtering in order to present their time evolution along 132 e sst and wind speed anomalies are negatively correlated off vladivostok 41 n in winter this is consistent with the interpretation that there is large turbulent heat flux loss due to the wind speed maximum off vladivostok or the gap exit region of the northwesterly wind jet however except for this region in winter we find strong positive correlation between sst and wind speed anomalies throughout the year at any latitudes wind speed anomalies are linearly related to sst anomalies meanwhile we identify two pairs of positive and negative sst anomaly bands in the time space structure of the japan sea and compare the band locations with meridional sst gradient magnitude as a result the two boundaries of the sst anomaly bands are associated with the polar front and the tsushima warm current front additionally it is found that discontinuous sst anomaly patches correspond to oceanic eddies these results lead to the conclusion that sea surface winds over the japan sea come under the influence of those sst frontal systems

warping prestack imaged data to improve stack quality and resolution accurate seismic imaging requires that a geologic feature be located at the same lateral and vertical position in images obtained by 3d prestack migration from different data bins such as common offset or common angle subvolumes misalignment of those images degrades the quality of the stack for dipping reflectors and lateral discontinuities imperfect imaging causes both lateral and vertical misalignment in current practice the vertical component of the misalignment is used to estimate updates in velocity and other imaging parameters the lateral component is largely ignored we show that recent developments in seismic attribute analysis allow us to examine the lateral misalignment of prestack volumes with similar resolution to that achieved in examining vertical moveout to measure lateral moveout we pick maxima from local 2d crosscorrelations computed between slices from 3d attribute volumes we then use these measurements to correct for the lateral misalignment by applying a warping procedure to the corresponding slices in the prestack migrated seismic data we apply our technique to a 3d land survey acquired over the fort worth basin in texas and obtain subtle but potentially important improvements in the quality and resolution of the stack as well as in the attribute images computed from the corrected data

high precision u pb zircon ca id tims dates from western european late visean bentonites three new u pb zircon chemical abrasion isotope dilution thermal ionization mass spectrometry dates obtained from late visean belgian bentonites are reported and are used to estimate the periodicity of early warnantian shallowing upwards carbonate parasequences that are interbedded with the dated bentonites early warnantian parasequences exhibit mean cycle periodicity values that are consistent with the c 100 ka milankovitch cycle which is the dominant milankovitch frequency recognized from recent pleistocene glacial records and thus strengthen the arguments for 1 these sedimentary cycles being of glacio eustatic origin and 2 the initiation of the main phase of late palaeozoic glaciation before the start of or during earliest warnantian times the new dates also provide additional high precision age constraints for the improved calibration of the mississippian time scale using the new dates the stratigraphical age of the clyde plateau volcanic formation midland valley of scotland is revised from holkerian to early asbian supplementary material u pb zircon ca id tims data tables and the method of the mean cycle periodicity calculations are available at www geolsoc org uk sup18747

spring season flow of the tsushima current and its separation from the kuroshio satellite evidence attempts to determine where and how separation between the kuroshio and tsushima current occurs have been inconclusive spring season satellite data acquired over a number of years reveals two conditions important to this question 1 an areally extensive zone of mixing between the kuroshio and shelf waters occurring along the edge of the east china sea shelf and 2 plumes of warm water from the kuroshio extending into the mixed water west of kyushu this mixed water is observed to form the tsushima current in the outer shelf of the northern east china sea and korea strait warm plumes branching from the north wall of the kuroshio are seen with particular clarity in imagery of april 23 1981 and february 21 1982 details of the split suggest that branching was a transient event

japan sea thermohaline structure and circulation part i climatology abstract in this study the u s navy s generalized digital environmental model gdem climatological temperature and salinity data on a 0 5 0 5 grid is used to investigate the seasonal variabilities of the japan east sea jes thermohaline structure and circulations the gdem for the jes was built up on historical 1930 97 136 509 temperature and 52 572 salinity profiles a three dimensional estimate of the absolute geostrophic velocity field was obtained from the gdem temperature and salinity fields using the p vector method the seasonal variabilities of the thermohaline structure and the inverted currents such as the subpolar front the salinity minimum and maximum in the japan sea intermediate water and the tsushima warm current and its bifurcation are identified

loading rate impact on fracturing pattern lessons from hydrocarbon recovery lacq gas field france using scaling parameters of induced seismicity in size and space domains seismic b value and spatial correlation dimension d respectively we analyze the fracturing pattern of the gas reservoir of lacq in correlation with the production rate on the basis of previous observations and a previous model segall et al 1994 we assume that the cause of induced seismicity is a poroelastic stressing such that the production rate can be viewed as a stress rate for the rocks adjacent to the reservoir during the 20 year study period the production rate has decreased dramatically leading to a change of poroelastic stress rate from 4 5 10 3 to 1 5 10 3 mpa yr accordingly we observe a significant decrease in the size of activated fractures and a reduction of the spatial clustering of fracturing both arguing for a stress rate impact on the fracturing pattern in the gas field we interpret these changes in terms of a change in the deformation mode of stressed rocks from a more brittle to a more ductile behavior as the stress rate was decreased this hypothesis is supported by independent evidence from a number of experimental numerical and field studies the loading rate thus appears as a possible candidate to drive changes of b and d in time and space the apparent sensitivity of the earth s crust fracturing pattern to loading rate variations of much lower frequency than the tidal variations suggests that the earth s crust deformation mode itself be frequency dependent also our observations may have strong implications in contexts where the loading rate is induced by human intervention e g hydrocarbon recovery mines suggesting the possibility of adjusting the loading rate so as to shape the fracturing pattern locally according to human needs

a sims zircon age for a biostratigraphically dated upper visean asbian bentonite in the central european variscides bardo unit polish sudetes a lower carboniferous platform sedimentary sequence the paprotnia beds in the bardo unit of the central sudetes ne part of the bohemian massif sw poland is biostratigraphically well dated based on rich macro and micro fossil evidence as late visean late asbian crenistria go iii zone the beds contain several bentonite layers one of which was dated using the u pb shrimp method on volcanic zircons and yielded an age of 334 3 ma this date fits well to the recently established chronostratigraphic limits of the visean and is consistent with the newest isotopic age constraints of 336 5 332 ma for the asbian boundaries

quantitative estimation of compaction and velocity changes using 4d impedance and traveltime changes in some hydrocarbon reservoirs severe compaction of the reservoir rocks is observed this compaction is caused by production and it is often associated with changes in the overburden time lapse or 4d seismic data are used to monitor this compaction process since the compaction causes changes in both layer thickness and seismic velocities it is crucial to distinguish between the two effects two new seismic methods for monitoring compacting reservoirs are introduced one based on measured seismic prestack traveltime changes and the other based on poststack traveltime and amplitude changes in contrast to earlier methods these methods do not require additional empirical relationships such as for instance a velocity porosity relationship the uncertainties in estimates for compaction and velocity change are expressed in terms of errors in the traveltime and amplitude measurements these errors are directly related to the quality and repeatability of time lapse seismic data for a reservoir at 3000 m depth wit h9mo fcompaction and assuming a 4d timeshift error of 0 5 ms at near offset and 2 ms at far offset we find relative uncertainty in the compaction estimate of approximately 50 60 using traveltime information only

application of an edge detection method to satellite images for distinguishing sea surface temperature fronts near the japanese coast abstract this study applies an edge detection method to satellite sea surface temperature sst images in order to distinguish sst fronts frequently occurring near the japanese coast first we develop a new set of edge detection algorithms the method is based on an entropic approach using jensen shannon divergence which is certified as a robust technique for detecting edge pixel candidates additionally we incorporate ridge line extraction morphological filter to obtain edge pixels which is suited to delineate intricate frontal features the methodology allows us to detect reasonable amount of possible fronts to the fullest extent according to the original image resolution therefore it enables us to analyze finer scale fronts near the coast as well as larger scale fronts associated with major currents then we present four case study examples of sst fronts near the japanese coast by applying the method to advanced very high resolution radiometer avhrr sst images with a grid size of 0 01 we describe the configuration and seasonal variability of the sst frontal systems from the viewpoint of occurrence probability sst gradient magnitude and orientation to the local bathymetry as compared with the previous observational studies consequently it is demonstrated that application of the method can derive new views of finer scale and highly variable sst fronts moreover this study first verifies the capability of comprehensive and statistical description of sst front configurations and variations near the japanese coast by applying edge detection method to sequences of satellite sst images

wind and bathymetric forcing of the annual sea surface temperature signal in the east japan sea 1 the relationship between the annual cycle of sea surface temperature sst in the east japan sea and wind forcing and bathymetry is examined using avhrr derived sst fields and satellite derived scatterometer wind fields on the basin scale sst north of the subpolar front spf is characterized by relatively larger amplitude 10 c and variance 94 and earlier phase than water to the south furthermore north of the spf earlier sst cooling coincides with regions of high winds on a much smaller spatial scale the data show earlier sst cooling over the siberian seamount is a result of the relatively shallow water over the seamount coupled with the complete erosion of the seasonal thermocline in mid february

quantitative 3d strain analysis in analogue experiments simulating tectonic deformation integration of x ray computed tomography and digital volume correlation techniques abstract the combination of scaled analogue experiments material mechanics x ray computed tomography xrct and digital volume correlation techniques dvc is a powerful new tool not only to examine the 3 dimensional structure and kinematic evolution of complex deformation structures in scaled analogue experiments but also to fully quantify their spatial strain distribution and complete strain history digital image correlation dic is an important advance in quantitative physical modelling and helps to understand non linear deformation processes optical non intrusive dic techniques enable the quantification of localised and distributed deformation in analogue experiments based either on images taken through transparent sidewalls 2d dic or on surface views 3d dic x ray computed tomography xrct analysis permits the non destructive visualisation of the internal structure and kinematic evolution of scaled analogue experiments simulating tectonic evolution of complex geological structures the combination of xrct sectional image data of analogue experiments with 2d dic only allows quantification of 2d displacement and strain components in section direction this completely omits the potential of ct experiments for full 3d strain analysis of complex non cylindrical deformation structures in this study we apply digital volume correlation dvc techniques on xrct scan data of solid analogue experiments to fully quantify the internal displacement and strain in 3 dimensions over time our first results indicate that the application of dvc techniques on xrct volume data can successfully be used to quantify the 3d spatial and temporal strain patterns inside analogue experiments we demonstrate the potential of combining dvc techniques and xrct volume imaging for 3d strain analysis of a contractional experiment simulating the development of a non cylindrical pop up structure furthermore we discuss various options for optimisation of granular materials pattern generation and data acquisition for increased resolution and accuracy of the strain results three dimensional strain analysis of analogue models is of particular interest for geological and seismic interpretations of complex non cylindrical geological structures the volume strain data enable the analysis of the large scale and small scale strain history of geological structures

time lapse pre stack seismic data registration and inversion for co2 sequestration study at cranfield pre stack seismic data are indicative of subsurface elastic properties within the amplitude versus offset characteristic and can be used to detect elastic rock property changes caused by co2 injection we perform time lapse pre stack 3 d seismic data analysis for monitoring co2 sequestration at cranfield the time lapse amplitude differences of cranfield datasets are found entangled with time shifts to disentangle these two characters we apply a local correlation based warping method to register the time lapse pre stack datasets which can effectively separate the time shift from the time lapse seismic amplitude difference without changing the original amplitudes we demonstrate the effectiveness of our registration method by evaluating the inverted elastic properties these inverted time lapse elastic properties can be reliably used for monitoring co2 plumes

global time scale and regional stratigraphic reference scales of central and west europe east europe tethys south china and north america as used in the devonian carboniferous permian correlation chart 2003 dcp 2003 the boundaries of the devonian carboniferous and permian stages of the global stratigraphic reference scale abbreviated to global stratigraphic scale gss are described in relation to the biostratigraphic and or lithostratigraphic units of the regional stratigraphic reference scales abbreviated to regional stratigraphic scales rss of central and west europe east europe tethys south china eastern tethys and north america in their type regions the boundaries of gss units rarely coincide with those of homonymous rss units moreover the definitions of some rss units have changed several times over the last decades and subsequent misunderstanding of the stratigraphical significance of these changes has often introduced errors into proposed global correlation charts the stratigraphic framework proposed in our global devonian carboniferous permian correlation chart 2003 dcp 2003 devonian carboniferous permian correlation chart 2003 menning m schneider j w alekseev a s amon e o becker g von bitter p h boardman d r bogoslovskaya m braun a brocke r chernykh v chuvashov b i clayton g dusar m davydov v i dybova jachowicz s forke h c gibling m gilmour e h goretzki j grunt t a hance l heckel p h izokh n g jansen u jin y g jones p kading k ch kerp h kiersnowski h klets a klug ch korn d kossovaya o kotlyar g v kozur h w laveine j p martens th nemyrovska t l nigmadganov a l paech h j peryt t m rohn r roscher m rubidge b schiappa t a schindler e skompski s ueno k utting j vdovenko m v villa e voigt s wahlman g p wardlaw b r warrington g weddige k werneburg r weyer d wilde v winkler prins c f work d m 2004 abschlusskolloquium dfg schwerpunktprogramm 1054 evolution des systems erde wahrend des jungeren palaozoikums im spiegel der sedimentgeochemie abstracts univ erlangen germany 2004 p 43 herein abbreviated to dcp 2003 and cited as dcp 2003 in references is an attempt to reduce these errors the dcp 2003 is the stratigraphic base for project 1054 of the deutsche forschungsgemeinschaft dfg the evolution of the late palaeozoic in the light of sedimentary geochemistry this composite time scale has been carefully balanced as far as data allows to remove unnecessary artificial compression and expansion of time intervals biozonations and depositional events the ages selected in dcp 2003 are markedly different to those in the geologic time scale 1989 gts 1989 harland w b armstrong r l cox a v craig l e smith a g smith d g 1990 a geologic time scale 1989 cambridge univ press cambridge harland w b armstrong r l cox a v craig l e smith a g smith d g 1990 a geologic time scale 1989 cambridge univ press cambridge pp 1 263 and in gradstein and ogg gradstein f m ogg j 1996 a phanerozoic time scale episodes 19 1 2 3 4 insert whereas they are closer to those of the geologic time scale 2004 gts 2004 gradstein f m ogg j g smith a g 2004 a geologic time scale 2004 cambridge univ press cambridge pp 1 589 mostly the ages are rounded to the nearest 0 5 ma in order to avoid estimates of questionable accuracy whereas ages of 0 1 ma in the gts 2004 and their error bars of 0 4 ma to 2 8 ma for the devonian to permian stage boundaries suggest an improved accuracy in contrast in the dcp 2003 questionable ages and positions of stratigraphic boundaries are marked by arrows c 2006 elsevier b v all rights reserved

comment on dorr and zulauf elevator tectonics and orogenic collapse of a tibetan style plateau in the european variscides the role of the bohemian shear zone int j earth sci geol rundsch 2010 99 299 325 the present comment disproves the tectonic model of a late devonian early carboniferous tibetan style collisional plateau in the tepla barrandean tb part of the bohemian massif which later collapsed by thermal weakening of the underlying crust contrary to this model the tb neither reveals major crustal thickening nor uplift and erosion and eastern continuations of the tb were during the relevant time span areas of open marine sedimentation late devonian early carboniferous marine sediments widespread also in the armorican and central massifs of france testify to low topography in central parts of the variscan orogen notional traces of a permo carboniferous ice cap on the french massif central do not support the plateau model because they are questionable and much younger than the inferred plateau stage of the tb the relative uplift of high grade metamorphic rocks to the nw and the se of the tb is not due to sinking of an elevated tb but instead to the hydraulic and buoyant expulsion of hp material from the saxo thuringian and moldanubian subduction channels the rise of lower grade ht rocks along the southwestern margin of the bohemian massif was effected by late carboniferous transpression the high temperature and the resulting low viscosity of the rising materials were probably not caused by variscan mantle delamination but relate to lithospheric thinning and heating at the tip of the westward propagating tethys rift

sea surface temperature fronts in the east japan sea and temporal variations 1 the spatial pattern of sea surface temperature sst fronts and its seasonality are presented for the entire east japan sea they are based on semi monthly sea surface temperature sst gradient maps constructed from declouded sst images over the period 1990 1995 fronts in the east sea can be assigned to the subpolar front spf in its central sea areas and to other fronts along the continental shelves it is observed for the first time that the spf located mostly along about 40 n between 132 3 e and 138 e bifurcates at both its eastern and western ends the spatial structure of the spf shows strong seasonality associated with temporal variations of a warm eddy off the east coast of korea surface cooling due to siberian cold air south of vladivostok and bifurcation of the tsushima warm current west of the tsugaru strait we have also observed an isolated frontal zone trapped by a seamount in the northeastern part of the japan basin

time lapse seismic data registration and inversion for co2 sequestration study at cranfield abstractthe time lapse seismic survey for co2 sequestration study at cranfield can be problematic because of misalignments between time lapse data sets such misalignments can be caused by the seismic data processing workflow and may result in the wrong interpretation of time lapse seismic amplitude differences we propose an efficient local correlation based warping method of registering the time lapse poststack data sets which can align these data sets without changing original amplitudes application of our registration method to cranfield time lapse data demonstrates its effectiveness in separating time shift character from seismic amplitude signature after registration time lapse differences show an improved consistency in vertical cross sections and a more localized distribution of difference amplitudes along the horizon allowing us to apply a high resolution basis pursuit inversion bpi for acoustic impedances inversion results show that decreases in acoustic impedances occur mostly at the to

alkenone temperature estimates for the east sea during the last 190 000 years abstract the late quaternary records of alkenone based sea surface temperature sst from a core located in the western margin of the east sea japan sea showed that the estimated temperature fluctuated greatly the variability being consistent with orbital scale global climate records during the period of marine isotope stage mis 6 the alkenone temperatures were low 7 10 c whereas during mis 5 5 the temperature increased rapidly up to 21 c during the entire period of mis 5 the temperature decreased from 21 c to 13 c then the temperature fluctuated between 10 c and 15 c during miss 4 and 3 after that it continued to fluctuate between 15 c and 17 c variation in the east sea sst is considered to be closely related to changes in the east asian monsoon system and seawater transport by the tsushima warm current the glacial surface cooling could be associated with the strong winter monsoon and or weakened summer monsoon in east asia during the glacial period when the sea level was low the influx of warm water was restricted and this might have enhanced the lowering of the surface temperature these conditions most likely caused significant changes in surface water circulation a basin scale cyclonic gyre might have occurred in the east sea without the development of the subpolar front during the interglacial period the surface warming seems to be related to the intensified summer monsoon system the high stand of the sea level and climate change most likely caused the development of cyclonic and anti cyclonic gyres in the north and south respectively and the subpolar front in the central part of the sea

rapid subsidence over oil fields measured by sar interferometry the lost hills and belridge oilfields are in the san joaquin valley california the major oil reservoir is high porosity and low permeability diatomite extraction of large volumes from shallow depths causes reduction in pore pressure and subsequent compaction forming a surface subsidence bowl we measure this subsidence from space using interferometric analysis of sar synthetic aperture radar data collected by the european space agency remote sensing satellites ers 1 and ers 2 maximum subsidence rates are as high as 40 mm in 35 days or 400 mm yr measured from interferograms with time separations ranging from one day to 26 months the 8 and 26 month interferograms contain areas where the subsidence gradient exceeds the measurement possible with ers sar but shows increased detail in areas of less rapid subsidence synoptic mapping of subsidence distribution from satellite data powerfully complements ground based techniques permits measurements where access is difficult and aids identification of underlying causes

the effect of severe storms on the ice cover of the northern tatarskiy strait the tatarskiy strait is the northernmost region of the japan sea with an ice covered area in winter of about 4 104 km2 this study uses the daily passive microwave images of the region from the special sensor microwave imager ssm i which was launched in 1987 to estimate the production of ice and japan sea bottom water in winter the prevailing winds in the strait are northerly and cold these conditions create a region of reduced ice concentration in the northern strait which leads to an enhanced ice production throughout the season in addition to these prevailing winds each winter one or two severe storms generate very strong northerly winds and cold temperatures in the strait these storms create a large transient polynya in the strait at a time simultaneous with the greatest heat flux out of the open water calculation of the ice growth from open water in the northern strait yields about 25 km3 of ice per season of which severe storms provide about 25 the total ice production is sufficient to form about 5 12 102 km3 of the japan sea bottom water which is about 50 100 of the renewal rate required from 14c data because the oxygen bottom layer thickness decreased between 1969 and 1984 the study also investigates the frequency of the severe storms in the northern strait during 1966 1990 and finds that these storms are about 3 times as frequent at the beginning of this period than at the end this suggests the storms may play a role in the generation of the japan sea bottom water

time lapse seismic analysis of pressure depletion in the southern gas basin in the southern gas basin sgb of the north sea there are many mature gas fields where time lapse monitoring could be very beneficial in extending production life however the conditions are not immediately attractive for time lapse seismic assessment this is primarily because the main production effect to be assessed is a pore pressure reduction and frame stiffening because of gas production in tight sandstone reservoirs that also have no real seismic direct hydrocarbon indicators modelling based on laboratory measurements has shown that such an effect would be small and difficult to detect in seismic data this paper makes two main contributions firstly this is to our knowledge the first time lapse study in the sgb and involves a real data assessment of the viability for detecting production in such an environment secondly the feasibility of using markedly different legacies of data in such a study is addressed including an assessment of the factors influencing the crossmatching from the latter it is found that significant spatially varying time shifts need to be and are successfully resolved through 3 d warping after the warping the primary factors limiting the crossmatching appear to be residual local phase variations possibly induced by the differing migration strategies structure reverberations and different coherencies of the volumes caused by differences in acquisition structure azimuth and acquisition fold despite these differences a time lapse amplitude signature is observed that is attributable to production the character of the 4 d amplitude anomalies may also indicate variations in stress sensitivity e g because of zones of fracturing additionally warping derived time attributes have been highlighted as a potential additional avenue for detection of pressure depletion in such reservoirs although the effects are subtle they may indicate changes in stress pressure in and around the reservoir because of production however to fully resolve the subtle time lapse effects in such a reservoir the data differences need to be better addressed which may be possible by full re processing and pre stack analysis but more likely dedicated 4 d acquisition would be required