stratal slicing benefits and challenges in the petroleum industry seismic interpretation meth odology varies according to a subject s scale in basinal to field scale hundreds of meters the goal is to map gross stratigraphic and structural features that are associated with petroleum systems including stratigraphy and depositional history hydrocarbon generation migration and entrapment seismic stratigraphy and sequence stratigraphy are common tools for this purpose at the reservoir scale meters to tens of meters the goal becomes characterizing distribution and physical properties related to volumetrics and production in a reservoir system in this task details are crucial seismic lithology and inversion seismic geomorphology and sedimentology and attribute analysis are some of the tools developed for this purpose

quantitative seismostratigraphic inversion of a prograding delta from seismic data quantitative stratigraphy predicts the geometry of geologic strata and their petrophysical properties based on mathematical models of geological processes and parameters which affect the formation and evolution of geologic strata such processes include erosion sediment transport and deposition quantitative stratigraphic inversion estimates the process parameters from a priori data by systematic modeling until the predictions are compatible with the observations in the case of quantitative seismostratigraphic inversion the a priori data are predominantly of the seismic kind to evaluate feasibility we designed a preliminary algorithm which we applied in a prograding delta environment we found that by fixing the sediment influx rate subaerial transport rate and the initial topography we were able to reproduce the basic features of the delta with only three to five parameters which included subaqueous transport rate and its depth dependent decay rate base level and sediment source location and spatial extent

horizon volumes with interpreted constraints abstracthorizons are geologically significant surfaces that can be extracted from seismic images color coding of horizons based on amplitude or other attributes can help reveal ancient sedimentary environments and structural features extracted horizons are also used for building structure models and stratigraphic interpretations we propose two methods for constructing seismic horizons aligned with reflectors in a 3d seismic image the first method generates horizons one at a time the second method generates an entire volume of horizons at once by first computing a relative geologic time volume from seismic normal vectors rather than gradually building a horizon by extending one or more seed points to a surface along seismic reflectors both of our methods generate whole horizons at once by solving partial differential equations derived from seismic normal vectors the most significant new aspect of both methods is the ability to specify perhaps interactively during interpretation a small number of

predictive painting of 3d seismic volumes predictive painting is a numerical algorithm that spreads information in 3d volumes according to the local structure of seismic events the algorithm consists of two steps first local spatially variable inline and crossline slopes of seismic events are estimated by the plane wave destruction method next a seed trace is inserted in the volume and the information contained in that trace is spread inside the volume thus automatically painting the data space immediate applications of this technique include automatic horizon picking and flattening in applications to both prestack and poststack seismic data analysis synthetic and field data tests demonstrate the effectiveness of predictive painting

seismostratigraphic inversion appraisal ambiguity and uncertainty geologic process models predict the geometry of geologic strata and their petrophysical properties based on mathematical models of geological processes that affect the formation and evolution of geologic strata such processes include erosion sediment transport and deposition the resulting forward model is typically nonlinear given observations and a misfit measure one may attempt inversion of these models to estimate process parameters that yield compatible predictions for seismostratigraphic inversion seismic data are used as observations we tested such an algorithm in a prograding delta environment to examine the effect of using different seismic attributes as observations and thus different choices of misfit measures the first measure based on the degree of parallelism between seismic reflectors and modeled geologic strata demonstrated a trade off between geologic time and the sediment influx rate used to parameterize the model a second misfit measure used unwrapped seismic instantaneous phase as a crude proxy to relative geologic time which regularized the model parameters then last we combined the two measures to take advantage of their individual characteristics for most of these inversion experiments we obtained results that capture the geometry of the geologic strata as observed on the seismic data with the exception of the depositional time rate trade off where the same strata can be obtained in a shorter geologic interval when rates are increased we found the inversion to be surprisingly stable with a unique cluster of acceptable parameters despite the nonlinearity of the geologic forward model

an introduction to this special section chronostratigraphy in 1977 we saw the publication of aapg memoir 26 seismic stratigraphy applications to hydrocarbon exploration in this book peter vail and his colleagues in a series of papers introduced the industry to the concepts of seismic sequences the construction of chronostratigraphic charts and how the seismic data could be used to estimate the global rise and fall of sea level in this work they also showed how the shape of the reflections and their lapping relationships could be used to predict depositional environment which could be used to predict sediment type and facies

building 3d subsurface models conforming to seismic structural and stratigraphic features abstractsubsurface modeling from seismic and borehole data is important for reservoir prediction geophysical exploration and production a reasonable model should honor borehole rock properties and conform to seismic structural and stratigraphic features such a subsurface model can be difficult to build in cases complicated by faults and unconformities automatic and semiautomatic methods have been proposed to build subsurface models from seismic and borehole data however seismic structural and stratigraphic features and borehole measurements are not fully used in most methods i have developed a workflow to fully use seismic and borehole data to build subsurface models that honor borehole measurements and conform to seismic horizons faults unconformities and stratigraphic features such as channels in this workflow i first automatically remove the faulting and folding in seismic and borehole data and map them into an unfaulted and flattened space in which seismic reflectors and borehole measure

reconstruction of depocenter evolution through time using relative stratigraphic thickness in this article we describe a new approach to seismic stratigraphic interpretation we build on the concept of the relative geologic time attribute introduced by stark 2004 to define a relative stratigraphic thickness attribute which can then be interpreted to reconstruct depocenter migration from seismic data the principles of seismic stratigraphy were established in the classic aapg memoir 26 at this time 1977 manual interpretation of 2d seismic was still typical in the e p industry simple truncation geometries such as onlap downlap and toplap were used to characterize sequence boundaries and flooding surfaces recent work continues to emphasize these 2d concepts for example using them in introductory sequence stratigraphic exercises the routine use of 3d seismic emerged in the 1980s and with it computer assisted interpretation the main focus of the industry was on large structural traps highly effective 3d structural interpretation workflows developed in the 1980s still form the core

the wheeler diagram flattening theory and time abstract wheeler diagrams are excellent tools to represent time stratigraphy these diagrams are produced by considering interpreted surfaces as snapshots of geologic times linked with transit cycles of the base level the base level defined in the nineteenth century can be regarded as an ultimate time reference for stratigraphic units the application of the base level concept to deep marine settings is a more recent development even though the same definition applies to all depositional environments flat timelines are also known as flattening theories can produce similar looking diagrams and have an edge that they operate in 3d however flattening of a dataset can be achieved with various techniques which are reviewed and the optimum algorithm which has a future application for hydrocarbon and research communities is improved to honor geological constraints such as faults and horizons a secondary aspect of the wheeler diagrams is the dual nature of geological timelines the diagrams are originally plotted on a relative geological time scale and no formal technique has yet been recommended for time calibration in this paper a nomogram approach is proposed to calibrate the timelines the representation of unconformities that are parallel to bedding planes is another important idea presented in this paper

geotime a 3d automatic tool for chronostratigraphic seismic interpretation and filtering chronostratigraphic seismic interpretation provides insight into basinal evolution because it maps the internal stratigraphic architecture this method has been widely used for well placement optimization and reservoir model building after many years of research at total a software tool called geotime has been developed for automatic chronostratigraphic analysis of seismic data particularly in complex geologic settings this tool first creates automatically from the seismic a 3d isogeologic time volume which highlights all stratigraphic surfaces then a 3d wheeler diagram volume is obtained by segmenting the seismic volume into different depositional or nondepositional packages this diagram provides better understanding of the spatial distribution of deposition through geologic time finally this tool can be used to automatically or semi automatically track chronostratigraphic surfaces

relative geologic time age volumes relating every seismic sample to a geologically reasonable horizon the age volume described in this paper can significantly increase the amount of useful geologic information extracted from a seismic data volume this paper has three goals the first is to introduce and describe the relative geologic time volume referred to herein as either an rgt volume or an age volume every seismic sample in an age volume contains an estimate of the relative geologic time for that sample which automatically relates every sample to a geologic horizon the second goal is to discuss some of the applications and advantages of using a rgt volume to store and access seismic interpretation for example it can be used to sculpt a seismic volume along a desired horizon or view depositional changes as a function of geologic time the third goal is to describe two methods for generating such a volume the first employing standard interpretation techniques and the second relying on unwrapping instantaneous phase unwrapping the instantaneous phase is a new holistic approach to interpreting seismic data that can produce a very detailed seismic interpretation the goal of building and using an rgt volume is to extract significantly more geologic information from the seismic data than is available from conventional methods the rgt volume is both a way of storing and retrieving seismic horizons to generate such a volume each seismic sample needs to be assigned an estimate of relative geologic time which in essence connects it to a geologically reasonable horizon in normal sections these relative geologic time values will increase with depth or traveltime high gradients in the rgt volume could be indicative of faults unconformities fluid contacts or interpretation errors while a constant value surface in a rgt volume is a seismic horizon figure 1 contains a portion of the seismic data used to illustrate the

using pca to characterize and differentiate loess deposits in wisconsin and upper michigan usa abstract data on loess thickness as well as a variety of particle size fractions were determined for 875 samples taken from several loess sheets across wisconsin and upper michigan because the particle size characteristics of these samples varied widely within and between the loess sheets we used principal components analysis pca as a way of isolating the major textural components or signals that exist across the various loess sheets the purpose of this research was to examine and interpret these principal components or particle size signatures common to the different loesses in order to better understand the loess sheets character formation mechanisms and likely sources our initial assumption that many of these loesses varied markedly from the classical silty loess was supported by the particle size data and the pca although component 1 was interpreted as thick silty loess dominated by medium silts component 2 was mainly composed of very fine sand and coarse silt and is better viewed as coarse loess components 3 and 4 were less texturally homogeneous and may reflect mixing between the loess and the underlying sediment especially where the loess is

stratal slice the next generation vail and his colleagues 1977a b laid a foundation for seismic chronostratigraphy by analyzing the relative rise of sea level indicated by coastal onlap these workers invented a novel way of converting a stratigraphic cross section in the depth or traveltime domain to a chronostratigraphic chart in the wheeler domain figure 1a and figure 1b with the widespread use of seismic data in the industry such conversion can now be achieved conveniently with the proper software at the basinal regional or prospect scale figure 1c and figure 1d

generating a relative geologic time volume by 3d graph cut phase unwrapping method with horizon and unconformity constraints abstractconstruction of a relative geologic time rgt volume is vital to seismic geomorphological and sedimentological interpretation seismic instantaneous phase unwrapping provides an excellent approach for generating an rgt volume although several 2d or 3d seismic phase unwrapping results have been published there is a clear need for discussions on concrete methods for seismic phase unwrapping we have developed the graph cut phase unwrapping method which performs well in the interferometric synthetic aperture radar image processing it has advantages of strong discontinuity preserving ability and high computing efficiency to make it suitable for 3d seismic phase unwrapping the method is improved by extending it from 2d to 3d and by introducing the seismic horizon and unconformity constraints the strong and continuous conformable seismic events which can be easily tracked by certain autopicking methods are introduced as horizon constraints for guiding the phase unwrapping to ensure a constant

least squares horizons with local slopes and multigrid correlations most seismic horizon extraction methods are based on seismic local reflection slopes that locally follow seismic structural features however these methods often fail to correctly track horizons across discontinuities such faults and noise because the local slopes can only correctly follow laterally continuous reflections in addition seismic amplitude or phase information is not used in these methods to compute horizons that follow consistent phase e g peaks or troughs to solve these problems we propose a novel method to compute horizons that globally fit both local slopes and multi grid correlations of seismic traces in this method we first estimate local reflection slopes by using structure tensors and compute laterally multi grid slopes by using dynamic time warping to correlate seismic traces within multiple laterally coarse grids these coarse grid slopes can correctly correlate reflections that may be significantly dislocated by faults or other discontinuous structures we then compute a

domain transform a tool for imaging and interpreting geomorphology and stratigraphy in seismic volumes the presence of complex structure on seismic data often makes it difficult to recognize and interpret depositional systems in the volume a number of techniques under the broad topic of chronostratigraphy have been developed in recent years to address this problem and enable more complete imaging and interpretation of seismic geomorphology and stratigraphy a domain transform dt is an interpretation guided process designed to remove some or all structural deformation from a seismic volume it improves the imaging of paleo depositional systems by creating a volume that consists of approximations of paleo depositional surfaces such volumes are ideal for imaging analysis and interpretation of seismic geomorphology and stratigraphy

an east west trending quaternary tunnel valley in the south eastern north sea and its seismic sedimentological interpretation a combination of a dense reflection seismic grid and up to 50 m long records from sediment cores and cone penetration tests was used to study the geometry and infill lithology of an e w trending buried tunnel valley in the south eastern north sea in relation to previously known primarily n s trending tunnel valleys in this area the geometry and infill of this 38 km long and up to 3 km wide valley is comparable but its e w orientation is exceptional the vertical cross section geometry may result from subglacial sediment erosion of advancing ice streams and secondary incision by large episodic meltwater discharges with high flow rates the infill is composed of meltwater sands and reworked till remnants on the valley flanks that are overlain by late elsterian rhythmic laminated lacustrine fine grained sediments towards the centre of the valley a depression in the valley centre is filled with sediments most likely from the holsteinian transgression and a subsequent post holsteinian lacustrine quiet water setting the exceptional axis orientation of this tunnel valley points to a regional n s oriented ice front during the late elsterian copyright 2012 john wiley sons ltd