Migration of the 3-D deep-seismic reflection survey at the KTB location, Oberpfalz, Germany

Körbe, M.; Stiller, Manfred; Horstmeyer, Heinrich; Rühl, Thomas

doi:10.1016/s0040-1951(96)00178-3

Cited by 12 publications

(7 citation statements)

References 9 publications

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“…Different strategies can be used to determine this angle, e.g., using the best fit line for all receivers. We use the local line direction for each receiver and employ a covariance analysis [e.g., Kanasewich, 1981]. This method was originally used to calculate the main polarization direction for a wavefield within a time window and recorded with multicomponent receivers.…”

Section: Fvmmentioning

confidence: 99%

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Improved structural characterization of the Earth's crust at the German Continental Deep Drilling Site using advanced seismic imaging techniques

2015

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This paper describes the principles of three novel seismic imaging techniques and their application to two deep seismic reflection data sets from the vicinity of the German Continental Deep Drilling Site (KTB). These imaging techniques are based on Kirchhoff prestack depth migration and use an inherent restriction of the migration operator to focus the wavefield to its actual reflection point. For Fresnel volume migration, the emergent angle at the receivers is estimated and then used to propagate the wavefield back into the subsurface along which the Fresnel volume is determined. The migration operator is restricted to this volume, thereby focusing the image to the part of the isochrone which physically contributes to the reflection. For coherency migration, the coherency of the wavefield at neighboring traces is calculated and used as a weighting factor within the migration integral, leading to a comparable focusing to the reflection point. For coherency‐based Fresnel volume migration, both approaches are combined, resulting in an even more focused seismic image with significantly increased image quality. We applied these methods to two seismic data sets from the area around the KTB: a survey with standard split‐spread geometry (KTB8502) and a sparse data set with a small number of source points in combination with short receiver lines (INSTRUCT93). The focusing approaches yield major improvements in the final images for both data sets. Incoherent noise and migration artifacts are reduced and the visibility of crustal structures is strongly enhanced, allowing for an improved geologic and tectonic characterization.

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Section: Fvmmentioning

confidence: 99%

“…represent the lengths of these axes. Thus, we are able to calculate not only the line direction but also the function f l which represents a measure of the linearity[Kanasewich, 1981]:…”

mentioning

confidence: 99%

Improved structural characterization of the Earth's crust at the German Continental Deep Drilling Site using advanced seismic imaging techniques

2015

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“…The receiver lines 1–4 of shot 18615 are shown in Figure 4. The SE1 reflections can clearly be seen in the time interval between 2.5 and 3.1 s. Previous migration results have shown that the SE1 dips steeply to the northeast at an angle of ∼55° [ Körbe et al , 1997; Buske , 1999]. The geophone lines are orthogonal to its strike, and, therefore, the arrival time of the SE1 reflection increases on each geophone line from the left to the right.…”

Section: Reflections From the Se1 Reflector And From The Erbendorf Bodymentioning

confidence: 80%

“…The SE1 is a fault‐like continuation of the Franconian Lineament, which at the surface trends roughly NW‐SE and separates sediments in the SW from crystalline rocks in the NE. The geometry of these and other structures has become clearer as the migration method used became more advanced, going from poststack migration of an areal set of zero‐offset seismograms to prestack migration of all single shots [ Körbe et al , 1997; Harjes et al , 1997; Buske , 1999; see also Simon et al , 1996]. …”

Section: Introductionmentioning

confidence: 99%

Seismic reflections from the crystalline crust below the Continental Deep Drilling Site KTB: Modeling and inference on reflector properties

2002

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[1] The three-dimensional (3-D) reflection-seismic data set ISO-89 3D was recorded near the deep borehole KTB in southeastern Germany. Reflections from the SE1 reflector and from the top of the Erbendorf body (EB) in the upper crystalline crust can be identified in 5-10% of the single-shot sections. The reflectors have been first identified in previous studies of stacked and migrated seismic data. In this paper the velocity and density variations of these two structures are estimated in a new way using true amplitude single-shot (vibroseis) data. The method uses the direct wave P g as a reference phase and models the amplitude ratios of the SE1 and EB reflections to P g . Modeling in this paper uses a combination of ray theory and the reflectivity method, and the SE1 and the top of the EB are assumed to be obliquely oriented 1-D structures. P g modeling shows that a depth-dependent velocity function within the uppermost crystalline basement explains the amplitudes and travel times of this phase with sufficient accuracy. The largest observed amplitude ratios SE1/P g and EB/P g are explained by laminated models with strong velocity contrasts and with reflection coefficients of magnitude 0.1-0.2 (SE1) and 0.05-0.15 (EB). The total thickness of the reflecting zones is less than $300 m. P g amplitude modeling requires low Q p factors (<100) to a depth of $1 km, whereas at larger depths, values of several hundred are necessary to keep the SE1 and EB velocity contrasts in realistic ranges. Both reflectors can be interpreted as cataclastic zones. For the SE1 this interpretation agrees with the view that it is a steeply dipping thrust fault which continues the tectonic Franconian Lineament into the upper crust. We assume that the EB is the fractured top of a high-velocity zone at depths below $10 km, known from earlier wide-angle measurements. Both reflectors have large weakly reflecting or nonreflecting parts. The SE1 is nonreflecting at the intersection with the KTB borehole.

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“…The thorough processing and migration of this dataset was performed by the DEKORP group in the DEKORP Processing Centre Clausthal‐Zellerfeld (Stiller , ; Körbe et al . ).…”

Section: Geological Setting and 3d Seismic Datamentioning

confidence: 97%

3D fracture networks in the crystalline upper crust ‐ A new seismic model of the Continental Deep Drilling Site (South Germany)

Szalaiova

Iwanowski-Strahser

Rabbel

2015

Geophysical Prospecting

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A B S T R A C TBased on three-dimensional seismic reflection data, we present the first comprehensive three-dimensional model of the fault and fracture inventory of the crystalline upper crust penetrated by the Continental Superdeep Drillhole (Kontinentale Tiefborung, Oberpfalz, Southeast Germany). The investigated volume spans ß19×19 km 2 down to 16-km depth. It can be regarded as a typical example of metamorphic crust that has undergone numerous phases of ductile and brittle deformation since the start of the Variscan orogeny. We developed an automated workflow for identifying and quantifying the crustal fracture network in order to prepare a basis for an assessment of fluid pathways and geothermal potential of crystalline crust. The workflow comprises the following steps: determination of (i) a three-dimensional model of major faults by structural tensor analysis and (ii) a three-dimensional model of middle-scale fractures by log-Gabor filtering and image processing; (iii) validation of results by comparison with geophysical borehole data, with independent seismic and seismicity data; and (iv) definition of a three-dimensional fracture density function serving for a statistical assessment of fracture connectivity and "relative permeability." This assessment is based on probabilistic fractionation and percolation theories. The derived three-dimensional distribution of "relative permeability" may be used as a kernel function for inverting hydraulic permeability from hydrothermal field experiments. By comparing borehole and three-dimensional seismic data, we could confirm that the faults and fractures of the Kontinentale Tiefbohrung area follow a fractal law that is consistent with Turcotte's fractionation model. An important conclusion from this is that upscaling and downscaling between one-dimensional borehole and three-dimensional seismic data appear possible. The corresponding one-, two-, and three-dimensional fractal dimension are about 0.8, 1.9, and 2.8, respectively.

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Migration of the 3-D deep-seismic reflection survey at the KTB location, Oberpfalz, Germany

Cited by 12 publications

References 9 publications

Improved structural characterization of the Earth's crust at the German Continental Deep Drilling Site using advanced seismic imaging techniques

Improved structural characterization of the Earth's crust at the German Continental Deep Drilling Site using advanced seismic imaging techniques

Seismic reflections from the crystalline crust below the Continental Deep Drilling Site KTB: Modeling and inference on reflector properties

3D fracture networks in the crystalline upper crust ‐ A new seismic model of the Continental Deep Drilling Site (South Germany)

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