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

Hlousek, F.; Hellwig, Olaf; Buske, Stefan

doi:10.1002/2015jb012330

Cited by 15 publications

(19 citation statements)

References 24 publications

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“…We may be able to overcome this limitation by performing further focussing enhancement approaches, such as coherency‐based Fresnel Volume Migration (Hloušek et al . ). Further improvement of the current results is the subject of further research.…”

Section: Resultsmentioning

confidence: 97%

“…In KPSDM, the image value V at the subsurface point m is obtained by a weighted summation of the recorded wavefield over the corresponding diffraction surface ( A ) for this point (Schneider ; Hloušek et al . ):

V false(boldm false) = \frac{- 1}{2 π} \underset{A}{\int \int} w false(boldm, boldr false) \dot{boldu} false(boldu, t_{S} + t_{R} false) d r,

where

t_{S}

and

t_{R}

represent the traveltimes from the source S and the receiver R , respectively, to the image point m .

\overset{u}{true}

denotes the time derivative of the recorded wavefield, and r denotes the distance from the receiver to the image point m .…”

Section: Seismic Depth Imaging Approachmentioning

confidence: 99%

“…; Hloušek et al . ) and so equation becomes

\begin{matrix} true \\ right V false(boldm false) & = & left \frac{- 1}{2 π} \underset{A}{-3pt \int -3pt \int} f (m, r) w (m, r) \overset{u}{true} (u, t_{S} + t_{R}) d boldr, \end{matrix}

where the weighting factor

f (m, r)

is defined as (Hloušek et al . ):

f false(boldm, boldr false) = \{\begin{matrix} left 1, & left if d \leq r_{f} \\ left \frac{d - \sqrt{2} r_{f}}{r_{f} false(1 - \sqrt{2} false)}, & left if r_{f} < d < \sqrt{2} r_{f} \\ left 0, & left if d \geq \sqrt{2} r_{f} . \end{matrix}

…”

Section: Seismic Depth Imaging Approachmentioning

confidence: 99%

“…This paper explains the 3D seismic depth imaging carried out in the project DESCRAMBLE. We performed the seismic depth imaging using Kirchhoff Pre‐Stack Depth Migration (KPSDM) (Schneider ; Buske ) and Fresnel Volume Migration (FVM) (Buske, Gutjahr and Sick ; Hloušek, Hellwig and Buske ). Figure shows the general workflow used in our approach.…”

Section: Introductionmentioning

confidence: 99%

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Advanced three‐dimensional seismic imaging of deep supercritical geothermal rocks in Southern Tuscany

Jusri

Bertani

Buske

2019

Geophysical Prospecting

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A B S T R A C TThe seismic K-Horizon is the key to gaining understanding on the deep supercritical geothermal rocks in Southern Tuscany. The K-Horizon is hosted in metamorphic rocks, which cause strong seismic wavefield scattering resulting in a poor signal-to-noise ratio. Our study aims to reveal high-resolution seismic images of the K-Horizon below a geothermal field in Southern Tuscany, using an advanced threedimensional seismic depth imaging approach. The key seismic pre-processing steps in the time domain include muting a large amount of persistent noise based on the statistical analysis of the seismic amplitudes, and tomostatics technique to correct for static effects. We carried out seismic depth imaging using Kirchhoff Pre-Stack Depth Migration and Fresnel Volume Migration techniques. Each migration technique was tested with constant and heterogeneous three-dimensional velocity models. Due to the difficulties in determining emergent angles for this low signal-to-noise ratio data set, the migration results with the heterogeneous three-dimensional velocity model show less coherent reflections compared to the migration results using the constant velocity model. Both velocity models however lead to relatively the same structure and depth of the K-Horizon, indicating the similarity of the average velocities along the wave propagation paths in both velocity models. With both velocity models Fresnel Volume Migration yields the K-Horizon with better reflection coherency and higher signal-to-noise ratio than standard Kirchhoff Pre-Stack Depth Migration. Nevertheless, both migration techniques have been able to reveal the K-Horizon with relatively high resolution and provide a reliable basis for geothermal rock characterization as well as steering of the first geothermal well penetrating the K-Horizon.

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Section: Resultsmentioning

confidence: 97%

V false(boldm false) = \frac{- 1}{2 π} \underset{A}{\int \int} w false(boldm, boldr false) \dot{boldu} false(boldu, t_{S} + t_{R} false) d r,

where

t_{S}

and

t_{R}

represent the traveltimes from the source S and the receiver R , respectively, to the image point m .

\overset{u}{true}

denotes the time derivative of the recorded wavefield, and r denotes the distance from the receiver to the image point m .…”

Section: Seismic Depth Imaging Approachmentioning

confidence: 99%

“…; Hloušek et al . ) and so equation becomes

\begin{matrix} true \\ right V false(boldm false) & = & left \frac{- 1}{2 π} \underset{A}{-3pt \int -3pt \int} f (m, r) w (m, r) \overset{u}{true} (u, t_{S} + t_{R}) d boldr, \end{matrix}

where the weighting factor

f (m, r)

is defined as (Hloušek et al . ):

f false(boldm, boldr false) = \{\begin{matrix} left 1, & left if d \leq r_{f} \\ left \frac{d - \sqrt{2} r_{f}}{r_{f} false(1 - \sqrt{2} false)}, & left if r_{f} < d < \sqrt{2} r_{f} \\ left 0, & left if d \geq \sqrt{2} r_{f} . \end{matrix}

…”

Section: Seismic Depth Imaging Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Advanced three‐dimensional seismic imaging of deep supercritical geothermal rocks in Southern Tuscany

Jusri

Bertani

Buske

2019

Geophysical Prospecting

View full text Add to dashboard Cite

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“…Hlousek et al [8] applied FVM to 2D seismic reflection data acquired in a crystalline environment at the German continental deep drilling site (KTB) near Windischeschenbach (South-East Germany). In the KTB drilling site, the FVM significantly improved the seismic images and revealed previously undetected structures in the seismic sections.…”

Section: Introductionmentioning

confidence: 99%

Cost-Effective Seismic Exploration: 2D Reflection Imaging at the Kylylahti Massive Sulfide Deposit, Finland

et al. 2019

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We show that by using an advanced pre-stack depth imaging algorithm it is possible to retrieve meaningful and robust seismic images with sparse shot points, using only 3–4 source points per kilometer along a seismic profile. Our results encourage the use of 2D seismic reflection profiling as a reconnaissance tool for mineral exploration in areas with limited access for active seismic surveys. We used the seismic data acquired within the COGITO-MIN project comprising two approximately 6 km long seismic reflection profiles at the polymetallic Kylylahti massive sulfide mine site in eastern Finland. The 2D seismic data acquisition utilized both Vibroseis and dynamite sources with 20 m spacing and wireless receivers spaced every 10 m. For both source types, the recorded data show clear first breaks over all offsets and reflectors in the raw shot gathers. The Kylylahti area is characterized by folded and faulted, steeply dipping geological contacts and structures. We discuss post-stack and pre-stack data processing and compare time and depth imaging techniques in this geologically complex Precambrian hardrock area. The seismic reflection profiles show prominent reflectors at 4.5–8 km depth utilizing different migration routines. In the shallow subsurface, steep reflectors are imaged, and within and underneath the known Kylylahti ultramafic body reflectivity is prominent but discontinuous.

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Advanced seismic imaging techniques characterize the Alpine Fault at Whataroa (New Zealand)

et al. 2016

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The plate‐bounding Alpine Fault in New Zealand is an 850 km long transpressive continental fault zone that is late in its earthquake cycle. We have acquired and processed reflection seismic data to image the subsurface around the main drill site of the Deep Fault Drilling Project (DFDP‐2). The resulting velocity models and seismic images of the upper 5 km show complex subsurface structures around the Alpine Fault zone. The most prominent feature is a strong reflector at depths of 1.5–2.2 km with an apparent dip of 48° to the southeast below the DFDP‐2 borehole, which we assume to be the main trace of the Alpine Fault. Above the main reflector, parallel reflectors suggest the presence of a ∼600 m wide damage zone. Additionally, subparallel reflectors are imaged that we interpret as secondary branches of the main fault zone. Conjugate faults imaged by the data show the complexity of the subsurface. The derived P wave velocity model reveals a 300–600 m thick sedimentary layer with velocities of ∼2.3 km/s above a schist basement with velocities of 4.5–5.5 km/s. A low‐velocity layer can be observed within the basement at 0.8–2 km depth. A small‐scale low‐velocity anomaly appears at the top of the basement that can be correlated to the fault zone. The results provide a reliable basis for a seismic characterization of the DFDP‐2 drill site that can be used for further structural and geological investigations of the architecture of the Alpine Fault in this area.

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

Cited by 15 publications

References 24 publications

Advanced three‐dimensional seismic imaging of deep supercritical geothermal rocks in Southern Tuscany

Advanced three‐dimensional seismic imaging of deep supercritical geothermal rocks in Southern Tuscany

Cost-Effective Seismic Exploration: 2D Reflection Imaging at the Kylylahti Massive Sulfide Deposit, Finland

Advanced seismic imaging techniques characterize the Alpine Fault at Whataroa (New Zealand)

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