Thin beds, tuning, and AVO

2014 ◽  
Vol 33 (12) ◽  
pp. 1394-1396 ◽  
Author(s):  
Wes Hamlyn
Keyword(s):  
Seismic Interpretation ◽  
Avo Analysis ◽  
Seismic Amplitudes ◽  
The Impact

In this tutorial, we will explore two topics that are particularly relevant to quantitative seismic interpretation — thin-bed tuning and AVO analysis. Specifically, we will examine the impact of thin beds on prestack seismic amplitudes and subsequent effects on AVO attribute values.

The impact of migration on AVO

Geophysics ◽  
1996 ◽  
Vol 61 (6) ◽  
pp. 1603-1615 ◽  
Author(s):  
Charles C. Mosher ◽  
Timothy H. Keho ◽  
Arthur B. Weglein ◽  
Douglas J. Foster
Keyword(s):  
Signal To Noise Ratio ◽  
Spatial Location ◽  
Coherent Noise ◽  
Amplitude Variation With Offset ◽  
Prestack Migration ◽  
Avo Analysis ◽  
Time Migration ◽  
Seismic Amplitudes ◽  
Spatial Positioning ◽  
The Impact

Amplitude variation with offset (AVO) analysis is often limited to areas where multidimensional propagation effects such as reflector dip and diffractions from faults can be ignored. Migration‐inversion provides a framework for extending the use of seismic amplitudes to areas where structural or stratigraphic effects are important. In this procedure, sources and receivers are downward continued into the earth using uncollapsed prestack migration. Instead of stacking the data as in normal migration, the prestack migrated data are used in AVO analysis or other inversion techniques to infer local earth properties. The prestack migration can take many forms. In particular, prestack time migration of common‐angle sections provides a convenient tool for improving the lateral resolution and spatial positioning of AVO anomalies. In this approach, a plane‐wave decomposition is first applied in the offset direction, separating the wavefield into different propagating angles. The data are then gathered into common‐angle sections and migrated one angle at a time. The common‐angle migrations have a simple form and are shown to adequately preserve amplitude as a function of angle. Normal AVO analysis is then applied to the prestack migrated data. Examples using seismic lines from the Gulf of Mexico show how migration improves AVO analysis. In the first set of examples, migration is shown to improve imaging of subtle spatial variations in bright spots. Subsequent AVO analysis reveals dim spots associated with dry‐hole locations that were not resolvable using traditional processing techniques, including both conventional AVO and poststack migration. A second set of examples shows improvements in AVO response after migration is used to reduce interference from coherent noise and diffractions. A final example shows the impact of migration on the spatial location of dipping AVO anomalies. In all cases, migration improves both the signal‐to‐noise ratio and spatial resolution of AVO anomalies.

Using relative geologic time to constrain CNN-based seismic interpretation and property estimation

Geophysics ◽  
2021 ◽  
pp. 1-44
Author(s):  
Aria Abubakar ◽  
Haibin Di ◽  
Zhun Li
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Seismic Interpretation ◽  
Seismic Survey ◽  
Geologic Time ◽  
Seismic Amplitude ◽  
Property Estimation ◽  
Constrained Learning ◽  
Seismic Amplitudes ◽  
Multiplicative Regularization

Three-dimensional seismic interpretation and property estimation is essential to subsurface mapping and characterization, in which machine learning, particularly supervised convolutional neural network (CNN) has been extensively implemented for improved efficiency and accuracy in the past years. In most seismic applications, however, the amount of available expert annotations is often limited, which raises the risk of overfitting a CNN particularly when only seismic amplitudes are used for learning. In such a case, the trained CNN would have poor generalization capability, causing the interpretation and property results of obvious artifacts, limited lateral consistency and thus restricted application to following interpretation/modeling procedures. This study proposes addressing such an issue by using relative geologic time (RGT), which explicitly preserves the large-scale continuity of seismic patterns, to constrain a seismic interpretation and/or property estimation CNN. Such constrained learning is enforced in twofold: (1) from the perspective of input, the RGT is used as an additional feature channel besides seismic amplitude; and more innovatively (2) the CNN has two output branches, with one for matching the target interpretation or properties and the other for reconstructing the RGT. In addition is the use of multiplicative regularization to facilitate the simultaneous minimization of the target-matching loss and the RGT-reconstruction loss. The performance of such an RGT-constrained CNN is validated by two examples, including facies identification in the Parihaka dataset and property estimation in the F3 Netherlands dataset. Compared to those purely from seismic amplitudes, both the facies and property predictions with using the proposed RGT constraint demonstrate significantly reduced artifacts and improved lateral consistency throughout a seismic survey.

scholarly journals A case study on semiautomatic seismic interpretation of unconformities and faults in the southwestern Barents Sea

2018 ◽  
Vol 6 (2) ◽  
pp. SD29-SD40 ◽  
Author(s):  
Aina J. Bugge ◽  
Stuart R. Clark ◽  
Jan E. Lie ◽  
Jan I. Faleide
Keyword(s):  
Barents Sea ◽  
Seismic Interpretation ◽  
Connected Components ◽  
Normal Faults ◽  
Morphological Operations ◽  
Image Region ◽  
The North ◽  
Seismic Amplitudes ◽  
Cenozoic Sediments

Recently, there has been a growing interest in automatic and semiautomatic seismic interpretation, and we have developed methods for extraction of 3D unconformities and faults from seismic data as alternatives to conventional and time-consuming manual interpretation. Our methods can be used separately or together, and they are time efficient and based on easily available 2D and 3D image-processing algorithms, such as morphological operations and image region property operations. The method for extraction of unconformities defines seismic sequences, based on their stratigraphic stacking patterns and seismic amplitudes, and extracts the boundaries between these sequences. The fault-extraction method extracts connected components from a coherence-based fault-likelihood cube where interfering objects are addressed prior to the extraction. We have used industry-based data acquired in a complex geological area and implemented our methods with a case study on the Polhem Subplatform, located in the southwestern Barents Sea north of Norway. For this case study, our methods result in the extraction of two unconformities and twenty-five faults. The unconformities are assumed to be the Base Pleistocene, which separates preglacial and postglacial Cenozoic sediments, and the Base Cretaceous, which separates the severely faulted Mesozoic strata from prograding Paleocene deposits. The faults are assumed to be mainly Jurassic normal faults, and they follow the trends of the eastern and southwestern boundaries of the Polhem Subplatform; the north–south-trending Jason Fault complex; and the northwest–southeast-trending Ringvassøy-Loppa Fault complex.

scholarly journals Symmetry between Theoretical and Physical Investigation of Water Contamination Using Amplitude Variation with Offset Analysis of Ground-Penetrating Radar Data

Symmetry ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 991
Author(s):  
Ibrar Iqbal ◽  
Gang Tian ◽  
Zhejiang Wang ◽  
Zahid Masood ◽  
Yu Liu ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Ground Penetrating Radar ◽  
Water Contamination ◽  
Experimental Models ◽  
Theoretical Modeling ◽  
Avo Analysis ◽  
Geophysical Surveys ◽  
Phase Liquid ◽  
Ground Penetrating ◽  
The Impact

We evaluated the symmetry of theoretical and experimental analysis of water contamination such as non-aqueous phase liquid (NAPL) by using amplitude variations with offset analysis (AVO) of ground-penetrating radar (GPR) data. We used both theoretical and experimental approaches for AVO responses of GPR to small distributions of contamination. Theoretical modeling is a tool used to confirm the feasibility of geophysical surveys. Theoretical modeling of NAPL-contaminated sites containing wet sand—both with the water and light non-aqueous phase liquid—was applied by keeping in consideration the GPR AVO analysis in acquisition. Reflectivity was significantly altered with the changes in the contents of water and NAPL during modeling. The wet and dry sands introduced in our model changed two major phenomena: one, the wave pattern—implying a slight phase shift in the wave; and two, an amplitude jump with the dim reflection radar gram observed in the model. Experimental data were collected and analyzed; two observations were recorded during physical data analysis. First, relative permittivity confirmed the presence of NAPL in an experimental tank. Second, reflection patterns with jumps in amplitude and changes in polarity confirmed the theoretical investigation. Our results demonstrate that GPR AVO analysis can be as effective for detection of non-aqueous phase liquid (NAPLs) as it has been used to determine moisture contents in the past. The theoretical and experimental models were in symmetry, and both found a jump in reflection strength. The reflection pattern normally jumped with NAPL-intrusion. From the perspective of water contamination, this study emphasizes the need to take into account the impact of GPR AVO analyses along with the expert’s adaptive capacities.

scholarly journals The impact of seismic interpretation on the hydrocarbon trapping at Falak field, Meleiha, Western Desert, Egypt

2018 ◽  
Vol 27 (4) ◽  
pp. 785-793 ◽  
Author(s):  
Salah Shebl Saleh Azzam ◽  
Hasan Hasan Elkady ◽  
Taha Mohammed Mohammed Rabea
Keyword(s):  
Seismic Interpretation ◽  
Western Desert ◽  
The Impact
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