The fault shadow problem as an interpretation pitfall

Trinchero, Eduardo

doi:10.1190/1.1438549

Cited by 21 publications

(5 citation statements)

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“…In this model, the illumination by wavefield improved the definition of reflectors beneath the Upar Fault associated with the branches in the blind imbricate fan (highlighted in magenta). Also, illuminated section for model 1 showed the same shadow zone beneath the Chusma Fault (polygon in dashed blue line) (Trinchero, 2000), which is attributed to the high dip in the Chusma Fault and the contrast between igneous, sedimentary rocks and the Saldaña Formation in the basement (De Freitas, 2000). The illuminated section in model 1 shows a non illumination zone under Saldaña Formation rocks in the SE.…”

Section: Resultsmentioning

confidence: 75%

Aplicación del método de iluminación por campo de onda en un modelo subthrust en la Cuenca del Valle Superior del Magdalena (Colombia)

Chajín¹,

Camacho²,

Otero³

2021

bol. geol.

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Complex structures like subthrust show high risk during the definition of structural traps in low quality seismic images in depth, so we can use the structural interpretation to simulate the subthrust illumination by wavefield of a prospect area in order to reduce the uncertainty and support the oil exploration process. In general, we performed an exercise of 2D geophysical modeling using a wavefield illumination simulator. At first, we interpreted two geological models from a seismic line in depth. The geological interpretation was adjusted with information about structural styles in this part of Upper Magdalena Basin. Then, we use a velocity scenario and assign these velocities to both geological models. The wavefield illumination method allows us to see all of the wavepaths in the different pair of source-receivers in order to do a fast evaluation of the structure illumination. This could be used to improve the seismic acquisitions in structurally complex media.

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Section: Resultsmentioning

confidence: 75%

Aplicación del método de iluminación por campo de onda en un modelo subthrust en la Cuenca del Valle Superior del Magdalena (Colombia)

Chajín¹,

Camacho²,

Otero³

2021

bol. geol.

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“…Table 1 -P-velocities definition for the geologic units of an inline in the study area for scenarios 1, 2 and 3. (Trinchero, 2000), showed inside a black rectangle in the figures 3 and 4. The inline was interpreted in depth domain generating two scenarios: the first with low dip faults similar to the interpreted faults in time domain (Figure 3); and the second, where the faults were interpreted with high dips, almost vertical dips (Figure 4).…”

Section: Methodsmentioning

confidence: 99%

“…C) Velocities scenario 3 (maximum), Formation 1b 5,730 Km/sec. Stage 2: Depth to time conversion, to evaluate the pull-up effect: The position and geometry of the prospect area in time domain were evaluated, to analyze the seismic image low quality in the shadow zone beneath the faults 1, 2, 3 and 4(Trinchero, 2000), showed inside a black rectangle in the figures 3 and 4. The inline was interpreted in depth domain generating two scenarios: the first with low dip faults similar to the interpreted faults in time domain (Figure3); and the second, where the faults were interpreted with high dips, almost vertical dips (Figure4).…”

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confidence: 99%

Velocity model influence in the position and geometry of a prospect area located in VSM Basin, by image ray tracing

Duarte¹,

Chajín²,

Beltrán³

et al. 2019

Proceedings of the 16th International Congress of the Brazilian Geophysical Society&Expogef

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Complex structures like subthrust show high risk during the definition of structural traps in time (PSTM) and depth (PSDM) low quality seismic images, so we can use the structural interpretation in time or depth domain to evaluate the velocity model influence in the position and geometry of a prospect area. Ecopetrol acquired a 3D PSTM seismic program in 2011, which has been reprocessed twice in order to improve PSTM image in fault shadow zones and clarify the structural setting to define the closure in a possible trap in the study area to reduce the exploratory risk.In addition, we did an exercise of 2D geophysical modeling using time-depth and depth-time conversion in one inline from the 3D survey. We use time to depth conversion based in image ray tracing, and a structural model interpreted in time (PSTM) and where we test three different velocity field scenarios to do a sensitivity analysis in the velocity model. Then, for depth to time conversion by image ray, we used two different structural models and with velocities derived from RTM seismic processing. Image ray establish a link between time and depth and allows a quick evaluation of structural geometry and pull-up effect presence simultaneously in both domains.

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“…This issue is known as the fault shadow problem. Thereby, lateral velocity variations across the fault can disrupt, pull up, or pull down reflectors in the footwall of the fault and can be misinterpreted, for example, as fault bifurcation (Fagin, 1996;Trinchero, 2000;Couples et al, 2007). Usually, this problem is addressed by prestack depth migration, which 130.194.20.173.…”

Section: Study Site Ii: Speyerdorfmentioning

confidence: 99%

17. High-Resolution Seismic Imaging of Near-Surface Fault Structures within the Upper Rhine Graben, Germany

Musmann¹,

Hermann²

2010

Advances in Near-Surface Seismology and Ground-Penetrating Radar

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High-resolution reflection seismic profiles were acquired at two study sites in the Upper Rhine Graben, Germany, to image fault zones in the near-surface domain. The profiles fill the gap left by large-scale 3D seismic imaging focused on targets several kilometers deep. The survey design comprises a very dense sampling of reflection points with frequencies as high as 360 Hz emitted by a small hydraulic vibrator. Dip-moveout processing with poststack migration is required to image the fault systems properly. At the first study site, a broad normal fault zone with a width of about 300 m was imaged. It shows two major faults accompanied by numerous smaller parallel and subparallel faults. At the second study site, the survey reveals a horst structure with two bounding normal faults that branch into several smaller ones with depth. Thicker sedimentary units in the hanging walls of the faults suggest synsedimentary fault growth. Significantly, the high-resolution, 2D near-surface seismic measurements provide deeper insight into the architecture and kinematics of the fault systems than is possible from 3D measurements that are focused on deeper targets.

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The fault shadow problem as an interpretation pitfall

Cited by 21 publications

References 0 publications

Aplicación del método de iluminación por campo de onda en un modelo subthrust en la Cuenca del Valle Superior del Magdalena (Colombia)

Aplicación del método de iluminación por campo de onda en un modelo subthrust en la Cuenca del Valle Superior del Magdalena (Colombia)

Velocity model influence in the position and geometry of a prospect area located in VSM Basin, by image ray tracing

17. High-Resolution Seismic Imaging of Near-Surface Fault Structures within the Upper Rhine Graben, Germany

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